Role of miRNAs in neurovascular injury and repair

Abstract

MicroRNAs (miRNA) are endogenously produced small, non-coded, single-stranded RNAs. Due to their involvement in various cellular processes and cross-communication with extracellular components, miRNAs are often coined the “grand managers” of the cell. miRNAs are frequently involved in upregulation as well as downregulation of specific gene expression and thus, are often found to play a vital role in the pathogenesis of multiple diseases. Central nervous system (CNS) diseases prove fatal due to the intricate nature of both their development and the methods used for treatment. A considerable amount of ongoing research aims to delineate the complex relationships between miRNAs and different diseases, including each of the neurological disorders discussed in the present review. Ongoing research suggests that specific miRNAs can play either a pathologic or restorative and/or protective role in various CNS diseases. Understanding how these miRNAs are involved in various regulatory processes of CNS such as neuroinflammation, neurovasculature, immune response, blood-brain barrier (BBB) integrity and angiogenesis is of empirical importance for developing effective therapies. Here in this review, we summarized the current state of knowledge of miRNAs and their roles in CNS diseases along with a focus on their association with neuroinflammation, innate immunity, neurovascular function and BBB.

Keywords

microRNAs central nervous system diseases neuroinflammation neurovascular injury neurovascular repair innate immunity angiogenesis neurotropic factors BBB integrity

Introduction

MicroRNAs (miRNAs, miRs) are endogenously produced small, non-coded, single-stranded RNAs which are about 19–24 nucleotides long. They can be referred to as ‘grand managers’ because of their involvement in various cellular processes, and cross-communication with extracellular components along with different cell types.^1,2 The role of miRNAs in regulating protein-coding genes has been annotated in human genome studies.³ Though the multifaceted role of miRNAs in different diseases is not yet fully explored, the recent discoveries of new miRNAs and their roles attract much attention.

Neurological or central nervous system (CNS) disorders possess significant global health concerns. CNS diseases can emerge from a multifaceted range of factors, including neurodegenerative processes, ischemic events, hemorrhages, and inflammatory responses. When the CNS is prone to any infectious or abnormal conditions, resident glial immune cells induce an inflammatory response via chemokines, pro-inflammatory cytokines, and reactive oxygen species. This induced neuroinflammation promotes tissue repair processes and protects against pathogens and neurotoxins or may lead to apoptosis and cytotoxicity of the target brain cells.

There has been a considerable amount of research on the role of miRNA in CNS-related diseases. Increasing evidence underscores the crucial role of miRNAs in governing both the injury/damage and repair/recovery process of CNS diseases. They are approached as biomarkers for diseases⁴ and potential therapeutic interventions in various CNS diseases.⁵ The regulatory role of miRNA in innate immunity leading to the involvement in neuroinflammation is vastly studied.^6,7 In the present review, we summarized the current findings regarding miRNA influence on the systemic functioning of the CNS including innate immune response and neuroinflammation, neurovascular integrity and angiogenesis, and blood-brain-barrier (BBB), as well as the role of miRNA in specific CNS diseases such as stroke, vascular dementia, Alzheimer’s disease, Parkinson’s disease, traumatic brain injury, and brain tumors.

MicroRNA

miRNA history

The discovery of the first miRNA, lin-4, in 1993 can be marked as an evolutionary era of molecular biology. Lee and colleagues discovered the mechanism and importance of transcript gene lin-4 in the downregulation of lin-14 protein for initiation of progression of the first larval stage (L1) to L2 of the nematode Caenorhabditis elegans.^8,9 Later a collaborative study between Lee and Wightman group uncovered the pairing of complementary regions of the 3’untranslated region (3’UTR) of lin-4 gene and lin-14 messenger RNA (mRNA), leading to translational repression of lin-14.¹⁰ More extensive studies using the basis of this research discovered homologs of this gene later in humans.¹¹ Various studies following these findings have contributed to the concept of miRNA, which continues to grow.

miRNA biogenesis

The biogenesis of miRNAs is a multi-step process that initiates from the transcription of genes via RNA polymerase-II into typical hair-pin loop-shaped primary miRNAs. This structure is recognized and converted into percussor miRNA by microprocessor complex subunit – DiGeorge syndrome critical region 8 (DGCR8) protein and Drosha ribonuclease-III enzyme by forming a microprocessor complex. The precursor miRNA is then transported from the nucleus to the cytoplasm via Exportin-5 and then converted into double-stranded miRNAs by the DICER enzyme. Argonaute protein AGO-2 unwinds the miRNA to form an RNA-indued silencing complex (RISC) which can cause post-translational suppression or transcript degradation of mRNA by attaching to 3′UTR of target genes.¹²

miRNA function/mechanism

The mechanism of action of miRNA begins by binding of miRNA sequence with 3′UTR of mRNA, which leads to repression of mRNA translation. On the contrary, an increase in translation can occur due to the binding of miRNA sequence to 5′UTR of mRNA,¹³ proving the binding-specific action of miRNA. Moreover, an interaction between miRNA and protein can occur via the proteic receptor, also called a miRceptor.¹⁴

miRNA in innate immune response and neuroinflammation

Innate immunity can be termed ‘immunity by birth’. Monocytes, dendritic cells, macrophages, natural killer cells, and granulocytes are the various cells of the innate immune system working as a first line of defense. The influence of diverse miRNAs and their function in governing these cells underscores the foundational importance of miRNAs in innate immunity regulation. The imbalance in levels and function of miRNA leads to neuro-inflammation.⁷ There has been proof of the involvement of miRNA in various steps of the innate immune network such as feedback regulation of immune homeostasis, expression of costimulatory and adhesion molecules, and mainly the release of cytokines/chemokines.¹⁵ miR-223 is proven to have a regulatory role in myeloid differentiation, neutrophil and macrophage functions.¹⁶ One of the studies found that deletion of the Dicer-1 protein used in miRNA biogenesis affected the miRNA levels in macrophages, causing downregulation in inflammatory cytokines upon innate immunity activation.¹⁷ This identifies a link between miRNAs, immune responses and inflammation.

Research shows that there exist pro-inflammatory and anti-inflammatory miRNAs, suggesting these transcription regulators can be either pathological or protective in the setting of CNS dysfunction. As an anti-inflammatory regulator, miR-193b-3p inhibits histone deacetylase 3 expression and thus reduces inflammation.¹⁸ miR-23a, miR-23b, and miR-19 act on inhibitors of nuclear factor-κB (IκB) kinase-alpha (IKK-α), TAB2, TAB3, and nuclear factor-kappa beta (NF-κB) immune genes to suppress the inflammatory activity.^19,20 miRNAs have been demonstrated to be strict modulators of toll-like receptor (TLR) expression and thus can increase or decrease immune response. For example, Let-7b and miR-146b act on TLR4 to induce anti-inflammatory activity stimulated by innate immunity.^21,22 miR-93 has been shown to be one such miRNA that upregulates the expression of TLR2 and TLR4, leading to an increase in neuroinflammation. miR-181c is another miRNA that functions on TLR4.²³ By inhibiting this TLR, miR-181c has been shown to hinder the production of inflammation. miR-181c-3p also serves as a post-infarct anti-inflammatory regulator.¹⁴ In addition to reducing damaging inflammation, miR-181c also upregulates the expression of tripartite motif 2 (TRIM2) in the setting of cerebral hypoxia. TRIM2, in turn, prevents the ubiquitination and subsequent destruction of neurofilament light (NF-L). NF-L is a significant contributor to neural remodeling and dendritic branching. Through this complex pathway, miR-181c protects from continually escalating cognitive impairment by promoting neuroplasticity.

Macrophages are types of white blood cells involved in causing immune responses in the CNS. Microglia polarization from phenotype M1 (pro-inflammatory) to phenotype M2 (anti-inflammatory) is advantageous as it leads to an anti-inflammatory effect ²⁴ and a neuroprotective effect after ischemic insult.²⁵ Several miRNAs play a positive or negative role in the polarization of macrophages in turn contributing to and regulating the production of pro-inflammatory cytokines.¹⁵ For example, miR-155, and miR-9 regulate M1 macrophage which has a pro-inflammatory effect^15,26 whereas, miR-21 and miR-146 regulate M2 macrophage which has an anti-inflammatory effect.¹⁵ MiR-155 has been implicated as a significant contributor to neuroinflammation due to its additional functions in the regulation of cytokines production via macrophage coordination.²⁷ Recent research has also shown that miR-3473b acts as an anti-inflammatory at the beginning of stroke and as another pro-inflammatory with stroke progression by exaggerating neuroinflammation.²⁸ At the beginning of the stroke, miR-3473b suppresses macrophage-mediated inflammation. As the stroke insult progression continues, miR-3473b negatively regulates the suppressor of cytokine signaling 3 to induce the progression of stroke via pro-inflammatory factors such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). This duality in the functioning of miRNAs as pro- or anti-inflammatory in the context of CNS disorders is portrayed as a double-edged sword when it comes to their correlation with neuroinflammation.

Role of miRNAs in modulating neurovascular unit integrity and angiogenesis

Neurovasculature refers to the network of blood vessels that supply nutrients and oxygen to the brain and spinal cord. The neurovascular unit (NVU) is an important target of neurovasculature and it is comprised of neurons, astrocytes, microglia, pericytes, myocytes, endothelial cells, and blood-spinal cord barrier.²⁹ The miRNAs released by several components of the NVU have been observed to maintain NVU integrity by participating in angiogenesis, modulation of neurotropic factors (NTFs), and neuronal coupling.³⁰

In the context of angiogenesis and vascular integrity, miR-126 is found to regulate the response of endothelial cells to vascular endothelial growth factor (VEGF) by repressing negative regulators of the VEGF pathway, including the Sprouty-related protein, SPRED1, and phosphoinositol-3 kinase regulatory subunit 2 (PIK3R2).³¹ Current research suggests that endothelial-derived miRNA, miR-126-3p may upregulate the growth of neurites, directly contributing to neuroplasticity.³⁵ miRNAs released by NVUs also play a role in the regulation of cellular function in neurovasculature. For example, miR-181c-3p could directly downregulate platelet-activating factor receptors and thus, hinders microglial apoptosis.³² An astrocyte-derived miRNA, miR-190b, downregulates neuronal death via autophagy-related gene-7, and further neuroprotection is offered by microglial-derived miRNA.³³ miR-124, expressed in the penumbra post-infarction, actively inhibits the accumulation of astrocytes through the downregulation of signal transducer and activator of transcription 3 (STAT3), thus reducing glial scar development and improving post-stroke outcomes.³⁴ Furthermore, miR-26a was also implicated in influencing the expression of hypoxia-inducible factor-1α and VEGF via the PI3K/AKT pathway, further bolstering its role in angiogenesis. miRNAs like – miR-126, miR-137, miR-145, and miR-493 are found to modulate neurovascular integrity and function such as apoptosis, neuroinflammation, neurogenesis, and angiogenesis through regulation of mitogen-activated protein kinase (MAPK) signaling pathway.³⁷

The NTFs are endogenous peptides or small protein biomolecules mainly belonging to three families: glial cell line-derived neurotrophic factor (GDNF) family ligands, neuropoietic cytokines, and neurotrophins. NTFs such as brain-derived neurotrophic factor (BDNF), neurotrophin 3 (NT-3), neurotrophin 4 (NT-4), and nerve growth factor (NGF) are responsible for deciding the fate of the neuron by regulating neurite survival and differentiation, synaptic plasticity and neurotransmitter synthesis.³⁸ miRNAs are found to cause modulation of different NTFs and hence affect the NVU integrity to control neurovasculature function. For instance, miR-15a, -26a/b, -134, -206, and -210 are found to directly regulate BDNF activity and expression.³⁹ miR-132 and -182 are found to downregulate BDNF protein levels via activating cAMP-response element binding protein transcriptional factors in human neuronal cell models and depression patients.⁴⁰ Whereas miR-155 has been found to increase NGF protein expression and its downregulation inhibits cytokine signaling-1 expression and NF-κB activation in myocardial infraction mice model.⁴¹ miR-21 downregulates NT3 mRNA levels⁴² and miR-17/20⁴³ downregulates NT4, while -21-5p upregulates NT4.⁴⁴ Apart from this, miR-144 downregulates mesencephalic astrocyte-derived neurotrophic factor, and miR-134 and miR-141 downregulate cerebral dopamine neurotrophic factor to cause neurodegeneration in Parkinson’s disease.⁴⁵ Hence, miRNAs affect NTFs which in turn have a role in neurovasculature and CNS disease progression.

Role of miRNA in blood-brain barrier

The BBB is a highly specialized and selective barrier that separates the bloodstream from the brain's extracellular fluid, regulating the passage of molecules and cells into and out of the central nervous system. BBB disruption-induced increased permeability is the major factor for brain edema after brain injury in CNS diseases. Loss of BBB integrity can also expose neuronal tissue to circulation-derived inflammatory cytokines and other injurious molecules. Therefore, modulating BBB function and integrity is a very important pathway to change the disease progress and outcome.⁴⁶ One of the pivotal roles of miRNA in regulating neurovascular function is via the maintenance of the integrity of the BBB.^47,48 miRNA can target endothelial junctions and tight junctions to affect the integrity of BBB positively or negatively. For example, miR-132 decreases the degradation of tight junction proteins vascular endothelial-cadherin and β-Catenin to offer BBB protection in ischemic stroke mice via inhibiting the matrix metallopeptidase (MMP) 9 gene.⁴⁹ miR-132 in neurons blocks eukaryotic elongation factor-2 (eEF2K) expression which upregulates the cadherin-5 (Cdh5) expression in endothelial cells of BBB promoting the brain vascular integrity.⁵⁰ Whereas miR-210 disrupts junction proteins such as occludin and β-catenin, thereby damaging the integrity of BBB. Hence, inhibition of mR-210 significantly decreases the BBB damage.⁵¹ Similarly, inhibition of miR-15a/16-1,⁵² and miR-182⁵³ can restore the integrity of BBB by rescuing Zonula Occludens-1 expression. Inflammatory cytokines play an important role in mediating the disruption of BBB and increasing BBB permeability. Targeting inflammation is one of the roles of miRNA in modulating BBB function, such as miR-21-5p maintains the integrity of BBB by decreasing the inflammation via downregulating proinflammatory cytokines such as TNF-α and IL-6.⁵⁴ Endothelial cells, as one of the key cellular components of the BBB, are also regulated by miRNAs. miR-182 inhibition attenuates apoptosis of endothelial cells in BBB via mammalian target of the rapamycin (mTOR)/forkhead box O (FOXO1) pathway,⁵³ while miR-23 stimulates endothelial cell survival by inhibiting inflammatory factors like TNF-α, IL-6, and NF-κB.⁵⁵ Inhibition of miR-181c has been reported to increase BBB integrity via upregulation of phosphoinositide-dependent kinases-1 maintaining actin cytoskeleton.⁵⁶ Besides endothelial cells, pericytes play a vital role in maintaining BBB homeostasis in CNS.⁵⁷ miRNAs like miR-27b, and miR-150 can modulate the functioning of pericytes by targeting semaphorin 6 A/D and endothelial receptor tyrosine kinase Tie-2 respectively, leading to the promotion of interaction of endothelial cells with pericytes and leading to inhibition of claudin-5 expression and endothelial cell survival respectively.^58,59 Thus, miRNAs play a role in CNS homeostasis by maintaining BBB integrity and modulating BBB function.

miRNAs in the diseases of CNS

CNS diseases comprise of a broad spectrum of disorders that affect the brain and spinal cord. CNS diseases often result from complex interactions between genetic predispositions, environmental factors, and molecular dysregulations within the nervous system. miRNAs have emerged as key regulators of various physiological processes within the CNS, including neuronal development, neurovasculature and neuroinflammation. Figure 1 illustrates detailed information regarding miRNA biogenesis along with their cellular targets and pathways involved in the regulation of various CNS diseases. Dysregulation of miRNA expression has been implicated in the pathogenesis, diagnostic markers and treatment of CNS diseases. The most common CNS diseases are discussed as follows –

Figure 1.

The biogenesis, downstream cellular targets and targeted pathways of miRNAs in stroke, Alzheimer’s Disease (AD), Parkinson’s Disease (PD), Vascular Dementia (VD), Traumatic Brain Injury (TBI) and brain tumor. The biogenesis of miRNA begins with gene transcription by RNA polymerase-II, forming hairpin-shaped primary miRNA. It is processed into precursor miRNA by Drosha enzyme. Precursor miRNA is transported to the cytoplasm via Exportin-5 and converted into double-stranded pre-miRNA by DICER enzyme. Pre-miRNA (circulating or packed in EXs) gets converted to mature miRNA and acts on various cells. In CNS, miRNAs act on cellular targets such as neurons, astrocytes, endothelial cells, and microglial cells to affect neuroinflammation, immune response, BBB, neurovasculature and angiogenesis via various pathways such as NF-kB, TNF-a, TLR4, IKK-a, occluding, ZO1, VCAM, b-catenin, VEGFR2 and PI3K. With these actions, miRNAs have a regulatory role in CNS diseases such as stroke, AD, PD, VD, TBI, and brain tumors.

Stroke

Stoke is one of the current leading causes of death worldwide with high morbidities. Amongst the two types of strokes, ischemic stroke is more prevalent than hemorrhagic stroke. Ischemic stroke occurs when the brain is deprived of blood due to artery blockage. On the other hand, hemorrhagic stroke is when the blood vessels are ruptured inside the brain. Both of these types lead to significant disability as it is known to cause the death of all types of brain cells such as neurons, astrocytes, pericytes, microglia, endothelial cells, etc. Stroke pathophysiology is a complex and interconnected process, culminating in brain cell death through a cascade of events. The planning of stroke recovery involves a complex interplay of processes, such as angiogenesis, neurogenesis, synaptogenesis, and neuronal and synaptic plasticity. These dynamic mechanisms collaborate to promote the brain's healing and functional rehabilitation after a stroke.⁶⁰ Numerous miRNAs have been studied and consequently implicated in the pathogenesis or repair of cerebral ischemia through a variety of functions. miR-191 has been hypothesized to contribute to the pathogenesis of stroke via its inhibition of vascular endothelial zinc finger 1-induced angiogenesis to promote ischemic brain injury.⁶¹ Conversely, miR-21 has been shown to have a pro-angiogenic effect via activation of AKT and extracellular signal-regulated kinase (ERK) pathway.⁶² miR-182 has been shown to inhibit the mTOR/FOXO1 pathway, downregulating apoptosis and maintaining BBB integrity following stroke.⁵³ miR-3552 has been shown to regulate well-established stroke biomarker Caspase-3 which functions to promote cell apoptosis in the setting of stroke.⁶³ miR-497 is another miRNA contributing to stroke pathology via selectively targeting and downregulating antiapoptotic genes B cell lymphoma-2 (Bcl-2) and Bcl-w.⁶⁴ miR-223 provides a protective role following reperfusion of ischemic tissue by downregulating the expression of glutamate receptors – Glutamate receptor 2 and NR2B.⁶⁵ Some miRNAs protect the integrity of BBB by reducing endothelial cell apoptosis through different pathways. For example, miR-126-3p downregulates vascular cell adhesion molecule-1 to attenuate intracranial stroke-induced BBB disruption.⁶⁶ miRNAs also play a crucial regulatory role in the process of post-stroke recovery, such as angiogenesis.⁶⁷ For example, miR-21⁶² and miR-31⁶⁸ have pro-angiogenic effects. Expression of miR-26a has also been shown to be upregulated in the context of cerebral infarct.³⁶ miR-26a expression was correlated to endothelial lumen proliferation, suggesting a role in post-stroke angiogenesis. In astrocytes, miRNAs like miR-29a, miR-29b, miR-130a, and miR-210 regulate apoptosis, and angiogenesis and exert anti-inflammatory effects.⁶⁹ miRNAs such as miR-126a, miR-297, miR-140, and miR-17-5p in pericytes act as proangiogenic and also maintain BBB stability.⁶⁹ There is an involvement of miRNAs such as miR-124 in the production of IL-10, miR-106, miR-132, and miR-181c in mediating the anti-inflammatory effect via microglial cells.⁶⁹ In summary, the role of multiple miRNAs in the regulation of stroke pathogenesis calls for their implementation in treatment strategies.

Alzheimer’s disease

Alzheimer's disease (AD) is a neurodegenerative disorder recognized as the most common cause of dementia which typically transpires with ageing, leading to memory impairment and cognitive decline. The pathogenesis of AD is characterized by the buildup of amyloid β and tau proteins, along with neuroinflammation, which ultimately leads to the degeneration and demise of brain cells. The current therapies for AD include the use of Acetylcholinesterase enzyme (AChE) inhibitors and N-methyl-D-aspartate (NMDA) inhibitors. Some future therapies are currently under study, such as immunotherapy, anti-amyloid, and anti-tau therapy for reduction, prevention, and clearance of amyloid β and tau protein, respectively.⁷⁰ miRNAs are wildly used as very efficient biomarkers of AD, such as – miR-26b, miR-30e, miR-34a, miR-34c, miR-107, miR-125b, miR-146a, miR-151, miR-200c, miR-210, and hsa-miR-485 have been hypothesized to predict the early onset of AD nearly 20 years before the onset of disease.⁷¹ Several miRNAs have been investigated as significant regulators of Aβ and tau expression and metabolism. For example, miR-210 is found to dysregulate the synaptic functioning in AD to cause cognitive impairment through the synaptosomal-associated protein of 25 KDa (Snap25).⁷² miR-124-3p is found to cause attenuation of apoptosis of neuroblastoma cells in vitro through inhibition of abnormal hyperphosphorylation of Tau protein by directly targeting caveolin-1.⁷³ miR-339-5p⁷⁴ has been hypothesized to be a modulator of Aβ metabolism. Current research suggests miR-339-5p downregulates the expression of β-site APP-cleaving enzyme 1 (BACE1), an enzyme that plays a crucial role in cleaving the initial Aβ precursor protein into insoluble Aβ filaments. As expected, researchers discovered miR-339-5p was decreased in AD brain specimens along with corresponding high BACE1 protein levels. Researchers fortified this proposed relationship by demonstrating that miR-339-5p transfection in primary human brain cultures resulted in declining BACE1 levels. While more research is required to further elucidate this mechanism, it is worth noticing that the pathogenesis of AD likely hinders and/or downregulates this miRNA early in the disease process to accomplish the characteristic accumulation of Aβ filaments. Additionally, restoring miR-339-5p levels in AD patients may also present promise in slowing the accumulation of Aβ filaments and thus progression of cognitive impairment. Further investigations are needed to thoroughly explore and grasp the functions of diverse miRNAs, given their potential as biomarkers to address their potential as therapeutic agents for AD.

Parkinson’s disease

Parkinson's disease (PD) stands as the second most widespread neurodegenerative disorder globally, following closely behind AD. It is characterized by the progressive degeneration of dopaminergic neurons in the substantia nigra pars compacta, accompanied by the formation of Lewy bodies, which consist mainly of misfolded α-synuclein. The current treatment for PD involves various pharmacological therapies such as anticholinergics, anti-glutamatergic, monoamine oxidase inhibitors, dopamine agonists, catechol-o-methyl transferase inhibitors, and adenosine A2 receptor antagonists.⁷⁵ The role of miRNAs in PD is studied in diagnosis as biomarkers as well as regulators. Amongst various studied miRNAs, miR-30, miR-29, let-7, miR-485, and miR-26 have been implicated in PD pathogenesis.⁷⁶ miRNAs - let-7, miR-128, miR-433, miR-485-5p, miR-132, and miR-212 were found to be dysregulated in cerebrospinal fluid (CSF) of PD patients hence proving their function as a biomarker and their potential in the therapy.⁷⁷ miR-124 have been proven to modulate several pathways in PD such as – NF-κB, STAT3, calpain 1/p25/cyclin-dependent kinases 5 (CDK5), ERK-mediated, 5′ adenosine monophosphate-activated protein kinase (AMPK), and Bcl-2-interacting mediator of cell death (Bim) pathways to regulate neuroinflammation, apoptosis, autophagy, oxidative damage, mitochondrial dysfunction and cell survival.^78,79 miR-26a is found to act on death-associated protein kinase 1 (DAPK1) which is a widely distributed serine/threonine kinase to formulate cellular and molecular pathologies of PD.⁸⁰ In one of the studies of the rotenone-induced PD rat model, miR-211-5p was found to augment autophagy and relieve endoplasmic reticulum stress by affecting Beclin-1, catalase, IL-1β, α-synuclein, E74-like factor 2/new Ets-related factor (ELF2/NERF) and protein kinase RNA-like ER kinase (PERK)/eukaryotic initiation factor 2-alpha (eIF2α)/C/EBP homologous protein (CHOP) pathways.⁸¹ Immune cells such as macrophage and microglia play a regulatory role in PD as they can be either pro- or anti-inflammatory depending on the polarization state. miRNAs are found to modulate the immune cells in PD. miR-132-3p is found to regulate the population of microglial cells via glutaredoxin (GLRX) to regulate dopaminergic neurodegradation and neuroinflammation in PD.⁸² miR-150-5p is found to be a target of rhabdomyosarcoma 2-associated transcript (RMST), a key regulator of neural stem cells to regulate the release of inflammatory cytokines and neuronal apoptosis which is developed in PD.⁸³

Vascular dementia

Vascular dementia (VD) stands out as one of the most prevalent causes of dementia. Hence, early diagnosis of VD assumes paramount significance in averting disease progression and vascular cognitive impairment. In VD, myelinated brain tissue is frequently impacted, and the primary pathologic manifestation involves the calcification of arterioles. The molecular mechanism behind the adverse effects of VD is oxidative stress, neuroinflammation, and compromised BBB integrity, mainly followed by endoplasmic reticulum stress, changes in homeostasis of cholesterol, and various lipoproteins.⁸⁴ The current treatment for managing VD includes managing risk factors, non-pharmacological treatment for preventing the progression of the disease, and therapeutics such as anti-dementia and cerebrovascular problems.⁸⁵ The biomarker and regulatory roles of miRNAs in VD is recently studied. In VD patients as compared to healthy human controls, circulating miRNAs such as miR- 376a-3p and -409-3p were decreased, and miR-363-3p, -32-5p, -451a, -486-5p, and -502-3p were increased.⁸⁶ Apart from the diagnostic function of miRNAs in VD, they are studied to have a regulatory role via different mechanisms. For example, miR-26b protects the brain from dementia by alleviating microglia inflammatory response and targeting IL-6.⁸⁷ Zhang et. al and team have combined the data for various functions of miRNAs in VD and the use of various miRNA mimics and antagomirs in treating VD.⁸⁴ miR-93 demonstrates a strong presence in the serum of VD patients, and treatments aiming to attenuate serum miR-93 have shown promise in alleviating pathologic neuroinflammation. Because loss of endothelial and neurovascular integrity is closely associated with ongoing VD pathogenesis, miR-126 has also been implicated as an important factor in the development of VD.⁸⁸ miR-126 has been demonstrated to modulate endothelial cells, platelets, and inflammatory molecules to promote vascular integrity following VD by contributing to angiogenesis, and maintenance of vascular patency via modulation of the ERK and AKT pathways.⁸⁹ A recent inquiry into the association between miR-126 and VD found that infarction and ischemia associated with VD significantly decrease miR-126 expression and thus contribute to the loss of vascular integrity. Furthermore, injections of miR-126 were demonstrated to improve vascular functioning and angiogenesis. miR-126’s crucial role in maintaining vessel patency presents promise as a therapeutic target for patients with suspected vascular dysfunction and/or cerebral hypoperfusion. Recent research has proposed that miR-26b binds to the mRNA of IL-6 to reduce the production of this inflammatory cytokine.⁸⁷ Reduction of IL-6 in turn reduces both neuroinflammation and neural apoptosis. Reduced levels of miR-26b were found in the hippocampus of experimental ischemia models, leading credence to the potential link between miR-26b and VD pathology. Loss of important cytokine modulators such as miR-26b may comprise one of the first steps in the pathogenesis of VD. The role of miR-26a in generating greater levels of angiogenesis proves beneficial in VD as well as in stroke by bolstering collateral circulation and providing greater perfusion in areas of hypoperfusion.⁹⁰ Further inquiry into the relationship between miRNAs and cerebrovascular health presents a novel opportunity to develop more efficient treatments, particularly those that harness endogenous repair mechanisms.

Traumatic brain injury

Traumatic brain injury (TBI) refers to a form of acquired brain injury resulting from an external force applied to the head. It can result in a spectrum of physical, cognitive, and emotional impairments, the duration of which hinges on the severity of the injury. These effects may manifest over a short or extended period, making it crucial to assess and manage TBI cases comprehensively for better outcomes and recovery. Recent research has shown that miRNAs are involved in the pathophysiology of TBI and may serve as biomarkers for diagnosis, prognosis, and treatment response. These miRNAs are involved in secondary brain damage induction or prohibition via the regulating inflammatory response, neuronal cell regeneration, regulation of intracellular transport and apoptosis, and controlling the BBB leakage to regulate neuroplasticity.⁹¹ Studies have identified specific miRNAs that are altered following TBI, including miR-21, miR-146a, miR-155, and miR-124.⁹² miR-21-5p is found to regulate the neuroinflammation post-TBI via acting on the microglial M1/M2 polarization.⁹³ In the TBI mice model, miR-23a is found to reactivate the AKT/mTOR pathway and hence modulate neurological apoptosis and inflammation response.⁹⁴ miR-212-5p is found to play a protective role against ferroptosis which causes neuronal death in controlled cortical impacted TBI mice model by partially targeting prostaglandin-endoperoxide synthase-2 (Ptgs2).⁹⁵ In repetitive mild TBI upregulating miR-124-3p is found to improve cognitive outcomes by Rela/ApoE signaling pathway.⁹⁶ miR-351-5p is found to alleviate lipid peroxidation which in turn relieves the stress on the endoplasmic reticulum and exerts anti-ferroptotic effects by acting on 5-lipoxygenase.⁹⁷ miR-873a-5p improves neurological deficits and attenuates microglia-mediated neuroinflammation induced by TBI by inhibiting the NF-κB signaling pathway.⁹⁸ Additionally, miRNAs have been implicated in the regulation of genes involved in neurodegeneration and neuroinflammation, which are critical features of TBI. This emphasizes the necessity for further comprehensive research into the role of miRNAs in regulating TBI and its potentially fatal consequences.

Brain tumor

Brain tumors represent a diverse group of abnormal growths within the brain or its surrounding tissues, including benign (non-cancerous) or malignant (cancerous). They can originate from various cell types, leading to a wide range of tumor types with distinct characteristics and behaviors. Brain tumors can arise from both primary brain tissue and from cells that have migrated from other parts of the body (metastatic tumors). Gliomas are the most common type of primary brain tumors that originate from glial cells, which provide support and protection for neurons. The profiling of miRNA expression has been shown to impact the activity of oncogenes (tumor suppressor genes) implicated in gliomagenesis, tumor growth, proliferation, apoptosis, and the posttranscriptional regulation of anti-oncogenes.^99,100 For example, miR-93¹⁰¹ and miR-296¹⁰² are found to cause angiogenesis of glial tumors in human glioma cells in vitro via inducing suppression of integrin-β8 expression and overexpression of VEGF2 respectively to increase tumor cell survival, growth and neurosphere formation. As a major angiogenesis regulator, miR-126 enhances the formation of glioma cancer stem cells via down-regulation of insulin receptor substrate-1 in a neurotrophin signaling pathway.¹⁰³ miR-132 is found to promote the formation of glioblastoma-initiating cell phenotypes by downregulating tumor suppressor candidate-3¹⁰⁴ and polypyrimidine tract-binding protein 2 (PTBP2)¹⁰⁵ to cause cell proliferation and self-renewal of U87 glioblastoma cells in vitro. Whereas Chen et al. and group found that hepatic leukemia factor-mediated miR-132 can directly suppress threonine tyrosine kinase protein expression, thus exerting inhibitory effects on cancer cell proliferation, metastasis and radioresistance in U87 glioblastoma cells in-vitro.¹⁰⁶ These studies demonstrated that miRs could exert different functions by targeting different downstream pathways. Other study by Wang et al. and group found that miR-132 targets and downregulates the expression of Glioma-associated oncogene protein 1 to inhibit the invasion and proliferation of the U251 glioma cell line.¹⁰⁷ A discrepancy in the outcome of miR-132 could be due different cell lines were used. Moreover, various miRNAs are used to enhance the sensitivity of tumor cells to anti-cancer treatments and outcomes of radiation and chemotherapies. For instance, miR-21 amplifies the cytotoxic impact of temozolomide, doxorubicin, paclitaxel, and sunitinib in U87 glioblastoma cells in vitro.¹⁰⁸ miR-203 has been shown to enhance radio and chemosensitivity by suppressing epithelial-mesenchymal transition in U87 glioblastoma cells by targeting Snail Family Transcriptional Repressor 2.¹⁰⁹

Taken all together, the biomarker role of miRNAs has been widely studied and we summarized the biomarker role (either up or downregulation) of miRNAs in CNS diseases in Table 1. Moreover, we have summarized the role of specific miRNA and its downstream pathway in CNS diseases in Table 2.

Table 1.

Biomarker role of the miRNAs in stroke, Alzheimer’s Disease, Parkinson’s Disease, Vascular Dementia, Traumatic Brain Injury and brain tumor.

Diseases	miRNA – Upregulation	miRNA – Downregulation
Stroke^129,130	hsa-let-7e, hsa-miR-1261, hsa-miR-129-5p, hsa-miR-1321, hsa-miR-145, hsa-miR-184, hsa-miR-198, hsa-miR-210, hsa-miR-214, hsa-miR-220c, hsa-miR-5481	hsa-let-7a/c/f/I, hsa-miR-126, hsa-miR-1299, hsa-miR-130a, hsa-miR-151-5p, hsa-miR-182, hsa-miR-183, hsa-miR-186, hsa-miR-192
Alzheimer’s disease^131,132	miR-125b, miR-146a, miR-200c, miR-26b, miR-30e, miR-34a, miR-34c, hsa-miR-361-5p, hsa-miR-30e-5p, hsa-miR-93-5p, hsa-miR-15a-5p, hsa-miR-143-3p, hsa-miR-335-5p, hsa-miR-106b-5p, hsa-miR-101-3p, hsa-miR-424-5p, hsa-miR-106a-5p, hsa-miR-18b-5p, hsa-miR-3065-5p, hsa-miR-20a-5p, hsa-miR-582-5p	miR-107, miR-210, miR-485, hsa-miR-1306-5p, hsa-miR-342-3p, 15 b-3p
Parkinson’s disease^133 –135	miR-195, miR-137, hsa-miR-7-5p, hsa-miR-22-3p, hsa-miR-136-3p, hsa-miR-139-5p, hsa-miR-330-5p, hsa-miR-433-3p, hsa-miR-495-3p, hsa-miR-29a-3p, hsa-miR-30b-5p, hsa-miR-103a-3p, hsa-miR-137	miR-29c, miR-146a, miR-214, miR-221, miR-185, miR-15b, miR-124, hsa-let-7a/f, hsa-miR-142-3p, hsa-miR-222, hsa-miR-141, hsa-miR-214, hsa-miR-146b-5p, hsa-miR-193a-3p
Vascular dementia^136,137	miR-455-3p, miR-4668-5p, miR-3613-3p, miR-4674, miR-135a	miR-6722, miR-193a, miR-23a, miR-29a, miR-130b
Traumatic brain injury^92,138	miR-434-3p, miR-9a-3p, miR-136-3p, miR-323-3p, miR-124-3p, miR-212-3p, miR-132-3p	miR-455-5p, miR-140-3p, miR-149-5p
Brain tumor^139,140	miR-17, miR-21, miR-210, miR-155, miR-221, miR-10b, miR-132, miR-224	miR-34a, miR-124, miR-149, miR-153, miR-154, miR-218, miR-330, miR-323, miR-328

Table 2.

Different promising miRNAs with downstream target pathways involved in a major regulatory role in stroke, Alzheimer’s Disease, Parkinson’s Disease, Vascular Dementia, Traumatic Brain Injury and brain tumor.

Disease	miRNA	Downstream target pathways	Function of miRNA
Stroke	miR-21⁶²	AKT, ERK	Involved in angiogenesis and neuroprotection
	miR-124¹⁴¹	DAPK1	Alleviates stroke-induced neuronal death
	miR-182⁵³	mTOR/FOXO1	Involved in maintenance BBB integrity and inhibition of apoptosis
	miR-191⁶¹	Vezf1	Involved in inhibition of angiogenesis
	miR-210⁶⁹	NOX2/NOX4	Involved in inhibiting oxidative stress and apoptosis
Alzheimer’s disease	miR-124^73,142	Caveolin-1, CREB, BACE1	Involved in inhibiting hyperphosphorylation of tau, Suppressing synaptic plasticity and Aβ deposition
	miR-210⁷²	Snap25	Involved in decreasing synaptic functioning
	miR-339-5p⁷⁴	BACE1	Involved in inhibition of Aβ filament accumulation
Parkinson’s disease	miR-26a⁸⁰	DAPK1	Involved in causing neuronal cell death
	miR-124³⁴	AMPK, AnnexinA5, Caspase-3	Involved in apoptosis and autophagy
	miR-132-3p⁸²	GLRX	Involved in dopaminergic neurodegradation and neuroinflammation
	miR-150-5p⁸³	RMST	Involved in release of inflammatory cytokines and neural apoptosis
	miR-211-5p⁸¹	Beclin-1, catalase, ELF2/NERF	Involved in augmentation of autophagy, ER stress
Vascular dementia	miR-26b⁸⁷	IL6	Involved in neuroinflammation, apoptosis, and angiogenesis
	miR-124⁸⁴	BACE1	Involved in formation of Aβ and improves dementia
	miR-126⁸⁹	ERK, AKT	Involved in angiogenesis and reduction of neuroinflammation
	miR-132⁸⁴	Nav1.1, Nav1.2	Involved in protection against learning and memory impairments
Traumatic brain injury	miR-21-5p⁹³	M1/M2 polarization	Involved in inflammation, oxidative stress, apoptosis, and neuroplasticity
	miR-124¹⁴³	PI3K/AKT, JAK/STAT3	Involved in neuronal differentiation, neuroprotection, and tumor development
	miR-351-5p⁹⁷	5-lipoxygenase	Involved in attenuating ferroptosis and ER stress
	miR-873a-5p⁹⁸	NF-κB	Involved attenuation of neuroinflammation
Brain tumor	miR-93¹⁰¹	Integrin-β8	Involved in tumor cell survival
	miR-124¹⁴⁴	Cyclin-dependent kinase 6	Involved in neuronal differentiation
	miR-132¹⁰⁷	Tumor suppressor candidate-3, PTBP2	Involved in formation of glioblastoma phenotypes
	miR-137¹⁴⁴	Cyclin-dependent kinase 6	Involved in neuronal differentiation
	miR-296¹⁰²	VEGF2	Involved in tumor cell survival

A novel delivery approach of miRNAs through exosomes

EXs as natural carriers of miRNAs

As we have discussed the different roles of miRNAs in various CNS diseases, the next questions are how do we use miRNAs or deliver miRNAs systemically or locally? Traditionally, we administer exogenous miRNAs by intravenous or local injections, such as brain or heart injections.¹¹⁰ The advancement in the field of miRNA delivery occurred with the use of viral vectors such as retroviral, lentiviral and adenoviral vectors. However, there are some issues reported with these delivery systems such as the degradation of the miRNAs in the circulation and low efficiency of the penetration to the brain.¹¹⁰ To overcome these issues, researchers from other groups and our group found a great vehicle for miRNAs, exosomes (EXs), originating from the multivesicular endosomal cell compartment. EXs are nanosized extracellular vesicles, typically ranging from 30–150 nm in size.¹¹¹ Once discharged, EXs can either remain in the extracellular vicinity near the point of discharge or traverse into biological fluids like plasma, urine, and CSF.¹¹² EX-carried miRNAs are increasingly being used in various CNS diseases as excellent diagnostic markers and therapeutic agents.¹¹³ Deep-sequencing technology has presented a reliable approach to detect deregulated exosomal miRNAs in CSF of PD and AD patients enabling fair robustness regarding specificity and sensitivity in the diagnosis.¹¹⁴

EX-miRNAs mediate cell-specific communications in CNS

Research has found that EXs can deliver miRNAs to various cells to mediate a cross-communication.¹¹⁵ Because of the nanosize, EXs were reported to be able to cross the BBB which provides an excellent option for treating/managing CNS diseases. Our research has shown that intravenously injected stem cell-released EXs could cross the BBB and merge with the brain ECs, neurons, astrocytes and glial cells. More importantly, the injected EXs could deliver their carried miR-126 to the brain by increasing the level of miR-126 in the brain.¹¹⁶ Previous studies from other groups further showed that intravenously injected EXs could deliver their carried miR-124-3p to the brain.⁹⁶ Additionally, EXs are excellent delivery systems for endogenous miRNAs as they naturally encapsulate and protect miRNAs from degradation by RNases in the extracellular environment.¹¹⁷ For instance, the delivery of miRNAs in cartilage repair through EXs is reported to be more efficient than direct injections in the management of osteoarthritis.¹¹⁸ Apart from improvement in efficacy, EXs can also reduce the harmful effects of miRNAs via site-specific action. Shimbo et al. introduced miR-143 into MSCs, and upon delivery to osteosarcoma cells, the miR-143 present within the EXs was able to significantly inhibit the migration of the cancerous cells.¹¹⁹ After delivered, EXs could be rapidly taken up by recipient cells to mediate cell-specific function. Our in vitro time-dependent experiments showed that the endothelial progenitor cells (EPC)-released EXs could deliver their carried miR-126¹¹⁶ or miR-210¹²² to the neurons, ECs and astrocytes as early as 6 hours after co-incubation. The incorporated miR-126 into the ECs could modulate the level of angiogenic pathways (VEGFR2/PI3k) in ECs to enhance EC function and cell viability. More importantly, EXs can deliver miRNAs to specific cell types via receptor-mediated binding, thus being rapidly taken up by recipient cells, minimizing off-target effects exhibited through systemic circulation.¹²⁰ A study by Mathiyalagan et. al demonstrated cell-specific delivery of miRNAs through EXs via in vitro monitoring of human CD34+ stem cell-derived EX-mediated delivery of miRNA precursors in human umbilical vein endothelial cells.¹²¹ Pusic et. al found that nasal administration of IFNγ-stimulated rat dendritic cells secreted EXs accumulate in the brain specifically oligodendrocytes and to a lesser extent in microglial cells to promote the myelination.¹²² Deng et al found that bone marrow-derived mesenchymal stem cells-derived EXs deliver miR-138-5p to the astrocytes to offer neuroprotection by downregulating neutrophil gelatinase-associated lipocalin and inflammatory factors in IS mice.¹²³

EX-miRNAs as promising therapeutic approach for CNS diseases

Since the EX-miRNAs are functional, the therapeutic role of EX-miRNAs has been recently studied. In mice with repetitive mild TBI, the intravenously injected microglial-EX was taken up by neurons in the injured brain. Besides, miR-124-3p in the EXs was found to get transferred into hippocampal neurons and alleviate neurodegeneration by targeting an inhibitory transcription factor of ApoE, Rela and hence affecting Rela/ApoE signaling pathway to promote the β-amyloid proteolytic breakdown, thereby inhibiting β-amyloid abnormalities.⁹⁶ Our lab also has found that in IS, EPC-EXs mediated miR-210 have a protective role in the brain against oxidative stress and cell apoptosis as well as promote cell viability both in vitro and in vivo partially though VEGFR2/PI3k and TrkB/PI3k pathway to recover neurological function by increasing angiogenesis and neurogenesis.^124,125 To overcome the limitations of EX applications such as rapid clearance, low loading capacity and low target specificity, engineering EXs provide excellent delivery systems and therapeutic agents. According to the recent advancements of methods of engineering EXs, either surface modification or loading modification of EXs can be achieved by various techniques such as plasmid transfection, sonication, electroporation, membrane fusion, co-incubation etc.¹²⁶ In CNS diseases, effectively targeting the brain is challenging as EXs tend to localize in the liver and spleen. Whereas engineered EXs have shown target specificity to the brain. For example, blood-derived EXs when loaded with dopamine to treat PD, showed less toxicity and better therapeutic impact on PD mouse model.¹²⁷ Tang et al confirmed the therapeutic potential of engineered EX-based miRNA in CNS disease. In this study, they used rabies virus glycoprotein peptide–modified EXs and loaded with miR-25 and miR-181a. After peripheral injection in the transgenic SCA3 mice model of spinocerebellar ataxia type 3, a substantial reduction of ATXN3 aggregation and cytotoxicity was observed.¹²⁸ This evidence strongly demonstrates that EXs could be a powerful vehicle or avenue to facilitate the role of miRNAs in managing CNS diseases.

Conclusion and perspectives

In conclusion, miRNAs play an important role in modulating the function of neurovascular via multiple pathways, which leads to regulating the progression of CNS diseases. Given that miRNAs exist widely in the circulation as well as other body fluids, miRNAs have advanced biomarker and therapeutic roles in treating CNS diseases. Nonetheless, the mechanisms that underlie the regulation of neurovascular inflammation and repair through miRNAs deserve further investigation. This pursuit is crucial for the development of miRNA-based therapeutic strategies for CNS disease that lead to specific cell targets more effectively.

Here are some important miRNAs in neurovascular injury and repair –

Modulation of immune cell activation: miR-9, miR-124, and miR-155 have been shown to regulate the activation of immune cells, such as microglia and T cells.

Regulation of neuroinflammation: miR-9 and miR-155 have been shown to regulate pro-inflammatory cytokines. miR-21 and miR-146 have been shown to regulate anti-inflammatory cytokines. The duality of the role of miRNAs in neuroinflammation opens up a passage to investigate and modulate the use of miRNAs as therapeutic agents to treat neurovascular repair after injury.

Regulation of neurovascular unit integrity and angiogenesis: miR-132, miR-124, and miR-29 have been shown to regulate the expression of NTFs, such as BDNF, which play critical roles in neurovascular repair and plasticity. miRNAs, such as miR-124 and miR-132 have been shown to promote angiogenesis and endothelial cell proliferation, which can contribute to neurovascular repair after injury.

Regulation of BBB integrity: miR-124, miR-155, and miR-146a have been shown to regulate BBB integrity by targeting the tight junction complex and basement membrane genes.

Footnotes

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the National Institute of Neurological Disorders and Stroke (1R01NS102720), Chronic Disease Research Program (WV-INBRE grant, P20GM103434), and West Virginia Clinical and Translational Science Institute (WV-CTSI) grant (2U54GM104942).

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Authors’ contributions

H.S., B.S., and E.M. searched the literature and drafted the manuscript. J.C.B. critically revised the manuscript. All authors have made contributions to the work and approved it for publication.

ORCID iD

Ji Chen Bihl

References

Roitbak

MicroRNAs and regeneration in animal models of CNS disorders. Neurochem Res 2020; 45: 188–203.

Bartel

Chen

CZ.

Micromanagers of gene expression: the potentially widespread influence of metazoan microRNAs. Nat Rev Genet 2004; 5: 396–400.

Sun

Julie Li

Huang

, et al. microRNA: a master regulator of cellular processes for bioengineering systems. Annu Rev Biomed Eng 2010; 12: 1–27.

Rao

Benito

Fischer

MicroRNAs as biomarkers for CNS disease. Front Mol Neurosci 2013; 6: 39.

Hussein

Magdy

MicroRNAs in Central nervous system disorders: current advances in pathogenesis and treatment. Egypt J Neurol Psychiatry Neurosurg 2021; 57: 1–11.

Nejad

Stunden

Gantier

MP.

A guide to miRNAs in inflammation and innate immune responses. Febs J 2018; 285: 3695–3716.

O'Connell

Chaudhuri

Rao

, et al. MicroRNAs enriched in hematopoietic stem cells differentially regulate long-term hematopoietic output. Proc Natl Acad Sci U S A 2010; 107: 14235–14240.

Lee

Feinbaum

Ambros

The C. elegans heterochronic gene lin-4 encodes small RNAs with antisense complementarity to lin-14. Cell 1993; 75: 843–854.

O'Brien

Hayder

Zayed

, et al. Overview of MicroRNA biogenesis, mechanisms of actions, and circulation. Front Endocrinol (Lausanne) 2018; 9: 402.

10.

Bhaskaran

Mohan

MicroRNAs: history, biogenesis, and their evolving role in animal development and disease. Vet Pathol 2014; 51: 759–774.

11.

Pasquinelli

Reinhart

Slack

, et al. Conservation of the sequence and temporal expression of let-7 heterochronic regulatory RNA. Nature 2000; 408: 86–89.

12.

Sun

Liu

Jickling

, et al. MicroRNA-based therapeutics in central nervous system injuries. J Cereb Blood Flow Metab 2018; 38: 1125–1148.

13.

Vasudevan

Tong

Steitz

JA.

Switching from repression to activation: microRNAs can up-regulate translation. Science 2007; 318: 1931–1934.

14.

Fabbri

MicroRNAs and miRceptors: a new mechanism of action for intercellular communication. Philos Trans R Soc Lond B Biol Sci 2018; 373: 20160486.

15.

Momen-Heravi

Bala

miRNA regulation of innate immunity. J Leukoc Biol 2018; 6: 20180414.

16.

Yuan

Berg

Lee

, et al. MicroRNA miR-223 as regulator of innate immunity. J Leukoc Biol 2018; 104: 515–524.

17.

Gantier

Stunden

McCoy

, et al. A miR-19 regulon that controls NF-kappaB signaling. Nucleic Acids Res 2012; 40: 8048–8058.

18.

Lai

Liang

, et al. Systemic exosomal miR-193b-3p delivery attenuates neuroinflammation in early brain injury after subarachnoid hemorrhage in mice. J Neuroinflammation 2020; 17: 74.

19.

Zhai

, et al. MiR-23a inhibited IL-17-mediated proinflammatory mediators expression via targeting IKKalpha in articular chondrocytes. Int Immunopharmacol 2017; 43: 1–6.

20.

Zhu

Pan

Song

, et al. The microRNA miR-23b suppresses IL-17-associated autoimmune inflammation by targeting TAB2, TAB3 and IKK-alpha. Nat Med 2012; 18: 1077–1086.

21.

Teng

Wang

Dai

, et al. Let-7b is involved in the inflammation and immune responses associated with Helicobacter pylori infection by targeting toll-like receptor 4. PLoS One 2013; 8: e56709.

22.

Curtale

Mirolo

Renzi

, et al. Negative regulation of toll-like receptor 4 signaling by IL-10-dependent microRNA-146b. Proc Natl Acad Sci U S A 2013; 110: 11499–11504.

23.

Fang

Min

, et al. MicroRNA-181c ameliorates cognitive impairment induced by chronic cerebral hypoperfusion in rats. Mol Neurobiol 2017; 54: 8370–8385.

24.

Min

Jang

Cho

, et al. Alternatively activated brain-infiltrating macrophages facilitate recovery from collagenase-induced intracerebral hemorrhage. Mol Brain 2016; 9: 42.

25.

Walsh

Campos

Hart

, et al. M2 monocyte microparticles are increased in intracerebral hemorrhage. J Stroke Cerebrovasc Dis 2017; 26: 2369–2375.

26.

Jablonski

Gaudet

Amici

, et al. Control of the inflammatory macrophage transcriptional signature by miR-155. PLoS One 2016; 11: e0159724.

27.

Zingale

Gugliandolo

Mazzon

MiR-155: an important regulator of neuroinflammation. Int J Mol Sci 2021; 23: 20211222.

28.

Wang

Chen

, et al. miRNA-3473b contributes to neuroinflammation following cerebral ischemia. Cell Death Dis 2018; 9: 11.

29.

Muoio

Persson

Sendeski

MM.

The neurovascular unit – concept review. Acta Physiol (Oxf) 2014; 210: 790–798.

30.

Forro

Bajko

Balasa

, et al. Dysfunction of the neurovascular unit in ischemic stroke: highlights on microRNAs and exosomes as potential biomarkers and therapy. Int J Mol Sci 2021; 22: 5621.

31.

Fish

Santoro

Morton

, et al. miR-126 regulates angiogenic signaling and vascular integrity. Dev Cell 2008; 15: 272–284.

32.

Song

Zhang

Chen

, et al. Cortical Neuron-Derived exosomal MicroRNA-181c-3p inhibits neuroinflammation by downregulating CXCL1 in astrocytes of a rat model with ischemic brain injury. Neuroimmunomodulation 2019; 26: 217–233.

33.

Pei

Zhu

, et al. Astrocyte-derived exosomes transfer miR-190b to inhibit oxygen and glucose deprivation-induced autophagy and neuronal apoptosis. Cell Cycle 2020; 19: 906–917.

34.

Liu

Feng

, et al. The potential role of MicroRNA-124 in cerebral ischemia injury. Int J Mol Sci 2019; 21: 20191223.

35.

Pan

Wang

, et al. MicroRNA-126 regulates angiogenesis and neurogenesis in a mouse model of focal cerebral ischemia. Mol Ther Nucleic Acids 2019; 16: 15–25.

36.

Liang

Chi

Lin

, et al. MiRNA-26a promotes angiogenesis in a rat model of cerebral infarction via PI3K/AKT and MAPK/ERK pathway. Eur Rev Med Pharmacol Sci 2018; 22: 3485–3492.

37.

Gugliandolo

Silvestro

Sindona

, et al. MiRNA: involvement of the MAPK pathway in ischemic stroke. A promising therapeutic target. Medicina (Kaunas) 2021; 57: 20211001.

38.

Ruozi

Belletti

Bondioli

, et al. Neurotrophic factors and neurodegenerative diseases: a delivery issue. Int Rev Neurobiol 2012; 102: 207–247.

39.

Numakawa

Richards

Adachi

, et al. MicroRNA function and neurotrophin BDNF. Neurochem Int 2011; 59: 551–558.

40.

Gao

, et al. Alterations of serum levels of BDNF-related miRNAs in patients with depression. PLoS One 2013; 8: e63648.

41.

Huang

Rao

, et al. Inhibition of microRNA-155 attenuates sympathetic neural remodeling following myocardial infarction via reducing M1 macrophage polarization and inflammatory responses in mice. Eur J Pharmacol 2019; 851: 122–132.

42.

Risbud

Lee

Porter

BE.

Neurotrophin-3 mRNA a putative target of miR21 following status epilepticus. Brain Res 2011; 1424: 53–59.

43.

Willmarth

Zhou

, et al. microRNA 17/20 inhibits cellular invasion and tumor metastasis in breast cancer by heterotypic signaling. Proc Natl Acad Sci U S A 2010; 107: 8231–8236.

44.

Piotrzkowska

Miller

Kucharska

, et al. Association of miRNA and mRNA levels of the clinical onset of multiple sclerosis patients. Biology (Basel) 2021; 10: 10.

45.

Konovalova

Gerasymchuk

Arroyo

, et al. Human-specific regulation of neurotrophic factors MANF and CDNF by microRNAs. Int J Mol Sci 2021; 22: 20210907.

46.

Takata

Nakagawa

Matsumoto

, et al. Blood-brain barrier dysfunction amplifies the development of neuroinflammation: Understanding of cellular events in brain microvascular endothelial cells for prevention and treatment of BBB dysfunction. Front Cell Neurosci 2021; 15: 661838.

47.

Wang

Zhu

, et al. Targeting microRNAs to regulate the integrity of the blood-brain barrier. Front Bioeng Biotechnol 2021; 9: 673415.

48.

Chakraborty

Sharma

, et al. MicroRNAs: possible regulatory molecular switch controlling the BBB microenvironment. Mol Ther Nucleic Acids 2020; 19: 933–936.

49.

Zuo

Manaenko

, et al. MicroRNA-132 attenuates cerebral injury by protecting blood-brain-barrier in MCAO mice. Exp Neurol 2019; 316: 12–19.

50.

Zhang

, et al. Neurons secrete miR-132-containing exosomes to regulate brain vascular integrity. Cell Res 2017; 27: 882–897.

51.

Dasgupta

, et al. MicroRNA-210 suppresses junction proteins and disrupts Blood-Brain barrier integrity in neonatal rat Hypoxic-Ischemic brain injury. Int J Mol Sci 2017; 18: 20170624.

52.

Sun

Zhang

, et al. Endothelium-targeted deletion of the miR-15a/16-1 cluster ameliorates blood-brain barrier dysfunction in ischemic stroke. Sci Signal 2020; 13: 20200407.

53.

Zhang

Tian

, et al. MicroRNA-182 exacerbates blood-brain barrier (BBB) disruption by downregulating the mTOR/FOXO1 pathway in cerebral ischemia. Faseb J 2020; 34: 13762–13775.

54.

Huang

Gao

, et al. miR-21-5p alleviates leakage of injured brain microvascular endothelial barrier in vitro through suppressing inflammation and apoptosis. Brain Res 2016; 1650: 31–40.

55.

Zhao

, et al. The poly-cistronic miR-23-27-24 complexes target endothelial cell junctions: Differential functional and molecular effects of miR-23a and miR-23b. Mol Ther Nucleic Acids 2016; 5: e354.

56.

Tominaga

Kosaka

Ono

, et al. Brain metastatic cancer cells release microRNA-181c-containing extracellular vesicles capable of destructing blood-brain barrier. Nat Commun 2015; 6: 6716.

57.

Zheng

Chopp

Chen

Multifaceted roles of pericytes in central nervous system homeostasis and disease. J Cereb Blood Flow Metab 2020; 40: 1381–1401.

58.

Demolli

Doddaballapur

Devraj

, et al. Shear stress-regulated miR-27b controls pericyte recruitment by repressing SEMA6A and SEMA6D. Cardiovasc Res 2017; 113: 681–691.

59.

Fang

, et al. MicroRNA-150 regulates blood-brain barrier permeability via tie-2 after permanent Middle cerebral artery occlusion in rats. Faseb J 2016; 30: 2097–2107.

60.

Kuriakose

Xiao

Pathophysiology and treatment of stroke: present status and future perspectives. Int J Mol Sci 2020; 21: 20201015.

61.

Zhao

Wang

, et al. MiR-191 inhibit angiogenesis after acute ischemic stroke targeting VEZF1. Aging (Albany NY) 2019; 11: 2762–2786.

62.

Liu

Chen

, et al. MiR-21 induced angiogenesis through AKT and ERK activation and HIF-1alpha expression. PLoS One 2011; 6: e19139.

63.

Dong

Zhao

, et al. Circulating miRNA-3552 as a potential biomarker for ischemic stroke in rats. Biomed Res Int 2020; 2020: 4501393.

64.

Koutsis

Siasos

Spengos

The emerging role of microRNA in stroke. Curr Top Med Chem 2013; 13: 1573–1588.

65.

Harraz

Eacker

Wang

, et al. MicroRNA-223 is neuroprotective by targeting glutamate receptors. Proc Natl Acad Sci U S A 2012; 109: 18962–18967.

66.

Niu

MicroRNA-126-3p attenuates intracerebral Hemorrhage-Induced blood-brain barrier disruption by regulating VCAM-1 expression. Front Neurosci 2019; 13: 866.

67.

Wang

Olson

EN.

AngiomiRs–key regulators of angiogenesis. Curr Opin Genet Dev 2009; 19: 205–211.

68.

Tsai

, et al. The M type K15 protein of Kaposi's sarcoma-associated herpesvirus regulates microRNA expression via its SH2-binding motif to induce cell migration and invasion. J Virol 2009; 83: 622–632.

69.

Stamatovic

Phillips

Martinez-Revollar

, et al. Involvement of epigenetic mechanisms and non-coding RNAs in Blood-Brain barrier and neurovascular unit injury and recovery after stroke. Front Neurosci 2019; 13: 864.

70.

Vaz

Silvestre

Alzheimer's disease: recent treatment strategies. Eur J Pharmacol 2020; 887: 173554.

71.

Zhao

Jaber

Alexandrov

, et al. microRNA-Based biomarkers in Alzheimer's disease (AD). Front Neurosci 2020; 14: 585432.

72.

Ren

, et al. MicroRNA-210-5p contributes to cognitive impairment in early vascular dementia rat model through targeting Snap25. Front Mol Neurosci 2018; 11: 388.

73.

Kang

Xiang

, et al. MiR-124-3p attenuates hyperphosphorylation of tau protein-induced apoptosis via caveolin-1-PI3K/akt/GSK3beta pathway in N2a/APP695swe cells. Oncotarget 2017; 8: 24314–24326.

74.

Long

Ray

Lahiri

DK.

MicroRNA-339-5p down-regulates protein expression of beta-site amyloid precursor protein-cleaving enzyme 1 (BACE1) in human primary brain cultures and is reduced in brain tissue specimens of Alzheimer disease subjects. J Biol Chem 2014; 289: 5184–5198.

75.

Jankovic

Tan

EK.

Parkinson's disease: etiopathogenesis and treatment. J Neurol Neurosurg Psychiatry 2020; 91: 795–808.

76.

Goh

Chao

Dheen

, et al. Role of microRNAs in Parkinson's disease. Int J Mol Sci 2019; 20: 20191112.

77.

Burgos

Malenica

Metpally

, et al. Profiles of extracellular miRNA in cerebrospinal fluid and serum from patients with Alzheimer's and Parkinson's diseases correlate with disease status and features of pathology. PLoS One 2014; 9: e94839.

78.

Angelopoulou

Paudel

Piperi

miR-124 and Parkinson's disease: a biomarker with therapeutic potential. Pharmacol Res 2019; 150: 104515.

79.

Esteves

Abreu

Fernandes

, et al. MicroRNA-124-3p-enriched small extracellular vesicles as a therapeutic approach for Parkinson's disease. Mol Ther 2022; 30: 3176–3192.

80.

Deng

Xiong

, et al. MicroRNA-26a/Death-Associated protein kinase 1 signaling induces synucleinopathy and dopaminergic neuron degeneration in Parkinson's disease. Biol Psychiatry 2019; 85: 769–781.

81.

Motawi

Al-Kady

Abdelraouf

, et al. Empagliflozin alleviates endoplasmic reticulum stress and augments autophagy in rotenone-induced Parkinson's disease in rats: targeting the GRP78/PERK/eIF2alpha/CHOP pathway and miR-211-5p. Chem Biol Interact 2022; 362: 110002.

82.

Gong

Huang

Chen

Mechanism of miR-132-3p promoting neuroinflammation and dopaminergic neurodegeneration in Parkinson's disease. eNeuro 2022; 9: 20220125.

83.

Chen

Zhang

Wei

, et al. LncRNA RMST regulates neuronal apoptosis and inflammatory response via sponging miR-150-5p in Parkinson's disease. Neuroimmunomodulation 2022; 29: 55–62.

84.

Zhang

Sun

Zhou

, et al. Regulatory microRNAs and vascular cognitive impairment and dementia. CNS Neurosci Ther 2020; 26: 1207–1218.

85.

Sun

MK.

Potential therapeutics for vascular cognitive impairment and dementia. Curr Neuropharmacol 2018; 16: 1036–1044.

86.

Prabhakar

Chandra

Christopher

Circulating microRNAs as potential biomarkers for the identification of vascular dementia due to cerebral small vessel disease. Age Ageing 2017; 46: 861–864.

87.

Kang

Zhang

, et al. MicroRNA-26b regulates the microglial inflammatory response in hypoxia/ischemia and affects the development of vascular cognitive impairment. Front Cell Neurosci 2018; 12: 154.

88.

Han

Zhou

, et al. Circulating exo-miR-154-5p regulates vascular dementia through endothelial progenitor cell-mediated angiogenesis. Front Cell Neurosci 2022; 16: 881175.

89.

Jiang

Wang

, et al. An integrated hypothesis for miR-126 in vascular disease. Med Res Arch 2020; 8: 20200525.

90.

Tian

Zhu

Liu

, et al. IL-4-polarized BV2 microglia cells promote angiogenesis by secreting exosomes. Adv Clin Exp Med 2019; 28: 421–430.

91.

Pan

Sun

Feng

DF.

The role of MicroRNA in traumatic brain injury. Neuroscience 2017; 367: 189–199.

92.

Atif

Hicks

SD.

A review of MicroRNA biomarkers in traumatic brain injury. J Exp Neurosci 2019; 13: 1179069519832286.

93.

Yin

Han

, et al. Neuron-derived exosomes with high miR-21-5p expression promoted polarization of M1 microglia in culture. Brain Behav Immun 2020; 83: 270–282.

94.

Zhu

, et al. MicroRNA-23a-3p improves traumatic brain injury through modulating the neurological apoptosis and inflammation response in mice. Cell Cycle 2020; 19: 24–38.

95.

Xiao

Jiang

Liang

, et al. miR-212-5p attenuates ferroptotic neuronal death after traumatic brain injury by targeting Ptgs2. Mol Brain 2019; 12: 78.

96.

Guo

, et al. Increased microglial exosomal miR-124-3p alleviates neurodegeneration and improves cognitive outcome after rmTBI. Mol Ther 2020; 28: 503–522.

97.

, et al. A novel mechanism linking ferroptosis and endoplasmic reticulum stress via the circPtpn14/miR-351-5p/5-LOX signaling in melatonin-mediated treatment of traumatic brain injury. Free Radic Biol Med 2022; 178: 271–294.

98.

Long

Yao

Jiang

, et al. Astrocyte-derived exosomes enriched with miR-873a-5p inhibit neuroinflammation via microglia phenotype modulation after traumatic brain injury. J Neuroinflammation 2020; 17: 89.

99.

Sumazin

Yang

Chiu

, et al. An extensive microRNA-mediated network of RNA-RNA interactions regulates established oncogenic pathways in glioblastoma. Cell 2011; 147: 370–381.

100.

Wang

Role of MicroRNAs in malignant glioma. Chin Med J (Engl) 2015; 128: 1238–1244.

101.

Fang

Deng

Shatseva

, et al. MicroRNA miR-93 promotes tumor growth and angiogenesis by targeting integrin-beta8. Oncogene 2011; 30: 806–821.

102.

Wurdinger

Tannous

Saydam

, et al. miR-296 regulates growth factor receptor overexpression in angiogenic endothelial cells. Cancer Cell 2008; 14: 382–393.

103.

Rouigari

Dehbashi

Ghaedi

, et al. Targetome analysis revealed involvement of MiR-126 in neurotrophin signaling pathway: a possible role in prevention of glioma development. Cell J 2018; 20: 150–156.

104.

Cheng

Yin

Wang

ZY.

MicroRNA-132 induces temozolomide resistance and promotes the formation of cancer stem cell phenotypes by targeting tumor suppressor candidate 3 in glioblastoma. Int J Mol Med 2017; 40: 1307–1314.

105.

Lou

Cheng

, et al. Oncogenic miR‑132 sustains proliferation and self‑renewal potential by inhibition of polypyrimidine tract‑binding protein 2 in glioblastoma cells. Mol Med Rep 2017; 16: 7221–7228.

106.

Chen

Wang

, et al. HLF/miR-132/TTK axis regulates cell proliferation, metastasis and radiosensitivity of glioma cells. Biomed Pharmacother 2016; 83: 898–904.

107.

Wang

Han

Fan

, et al. miR-132 weakens proliferation and invasion of glioma cells via the inhibition of Gli1. Eur Rev Med Pharmacol Sci 2018; 22: 1971–1978.

108.

Zhang

Han

Wei

, et al. Combination treatment with doxorubicin and microRNA-21 inhibitor synergistically augments anticancer activity through upregulation of tumor suppressing genes. Int J Oncol 2015; 46: 1589–1600.

109.

Liao

Bai

Qiu

, et al. MiR-203 downregulation is responsible for chemoresistance in human glioblastoma by promoting epithelial-mesenchymal transition via SNAI2. Oncotarget 2015; 6: 8914–8928.

110.

Dasgupta

Chatterjee

Recent advances in miRNA delivery systems. Methods Protoc 2021; 4: 20210120.

111.

Doyle

Wang

MZ.

Overview of extracellular vesicles, their origin, composition, purpose, and methods for exosome isolation and analysis. Cells 2019; 8: 20190715.

112.

Wang

Guo

Yang

, et al. The novel methods for analysis of exosomes released from endothelial cells and endothelial progenitor cells. Stem Cells Int 2016; 2016: 2639728.

113.

Xia

Wang

Huang

, et al. Exosomal miRNAs in central nervous system diseases: biomarkers, pathological mediators, protective factors and therapeutic agents. Prog Neurobiol 2019; 183: 101694.

114.

Gui

Liu

Zhang

, et al. Altered microRNA profiles in cerebrospinal fluid exosome in Parkinson disease and Alzheimer disease. Oncotarget 2015; 6: 37043–37053.

115.

Ohno

Kuroda

Exosome-Mediated targeted delivery of miRNAs. Methods Mol Biol 2016; 1448: 261–270.

116.

Wang

Chen

Zhang

, et al. Exosomes from miRNA-126-modified endothelial progenitor cells alleviate brain injury and promote functional recovery after stroke. CNS Neurosci Ther 2020; 26: 1255–1265.

117.

Wang

Zhang

Weber

, et al. Export of microRNAs and microRNA-protective protein by mammalian cells. Nucleic Acids Res 2010; 38: 7248–7259.

118.

Foo

Looi

How

, et al. Mesenchymal stem cell-derived exosomes and MicroRNAs in cartilage regeneration: biogenesis, efficacy, miRNA enrichment and delivery. Pharmaceuticals (Basel) 2021; 14: 20211028.

119.

Shimbo

Miyaki

Ishitobi

, et al. Exosome-formed synthetic microRNA-143 is transferred to osteosarcoma cells and inhibits their migration. Biochem Biophys Res Commun 2014; 445: 381–387.

120.

Aranega

Lozano-Velasco

Rodriguez-Outeirino

, et al. MiRNAs and muscle regeneration: therapeutic targets in Duchenne muscular dystrophy. Int J Mol Sci 2021; 22: 20210419.

121.

Mathiyalagan

Sahoo

Exosomes-Based gene therapy for MicroRNA delivery. Methods Mol Biol 2017; 1521: 139–152.

122.

Pusic

Kraig

Pusic

AD.

IFNgamma-stimulated dendritic cell extracellular vesicles can be nasally administered to the brain and enter oligodendrocytes. PLoS One 2021; 16: e0255778.

123.

Deng

Chen

Gao

, et al. Exosomes derived from microRNA-138-5p-overexpressing bone marrow-derived mesenchymal stem cells confer neuroprotection to astrocytes following ischemic stroke via inhibition of LCN2. J Biol Eng 2019; 13: 71.

124.

Yerrapragada

Sawant

Chen

, et al. The protective effects of miR-210 modified endothelial progenitor cells released exosomes in hypoxia/reoxygenation injured neurons. Exp Neurol 2022; 358: 114211.

125.

Wang

Chen

Sawant

, et al. The miR-210 primed endothelial progenitor cell exosomes alleviate acute ischemic brain injury. Curr Stem Cell Res Ther 2023; 19: 1164–1174.

126.

Huang

Liao

, et al. Research advances of engineered exosomes as drug delivery carrier. ACS Omega 2023; 8: 43374–43387.

127.

Lin

Huang

, et al. Dopamine-loaded blood exosomes targeted to brain for better treatment of Parkinson's disease. J Control Release 2018; 287: 156–166.

128.

Tang

, et al. Therapeutic effects of engineered exosome-based miR-25 and miR-181a treatment in spinocerebellar ataxia type 3 mice by silencing ATXN3. Mol Med 2023; 29: 96.

129.

Sepramaniam

Tan

, et al. Circulating microRNAs as biomarkers of acute stroke. Int J Mol Sci 2014; 15: 1418–1432.

130.

Shen

Zheng

, et al. Identification of MicroRNAs as potential biomarkers for detecting ischemic stroke. Genes Genomics 2022; 44: 9–17.

131.

Nunomura

Perry

RNA and oxidative stress in Alzheimer's disease: Focus on microRNAs. Oxid Med Cell Longev 2020; 2020: 2638130.

132.

Cheng

Doecke

Sharples

RA, RA

, et al. Prognostic serum miRNA biomarkers associated with Alzheimer's disease shows concordance with neuropsychological and neuroimaging assessment. Mol Psychiatry 2015; 20: 1188–1196.

133.

Wang

, et al. Serum miR-221 serves as a biomarker for Parkinson's disease. Cell Biochem Funct 2016; 34: 511–515.

134.

Ding

Huang

Chen

, et al. Identification of a panel of five serum miRNAs as a biomarker for Parkinson's disease. Parkinsonism Relat Disord 2016; 22: 68–73.

135.

Yang

, et al. Circulating microRNAs and long non-coding RNAs as potential diagnostic biomarkers for Parkinson's disease. Front Mol Neurosci 2021; 14: 631553.

136.

Zhai

Zhao

Zhang

, et al. MicroRNA-Based diagnosis and therapeutics for vascular cognitive impairment and dementia. Front Neurol 2022; 13: 895316.

137.

Dong

Zheng

Nao

Circulating exosome microRNAs as diagnostic biomarkers of dementia. Front Aging Neurosci 2020; 12: 580199.

138.

Heiskanen

Das Gupta

Mills

, et al. Discovery and validation of circulating microRNAs as biomarkers for epileptogenesis after experimental traumatic brain Injury-The EPITARGET cohort. Int J Mol Sci 2023; 24: 20230201.

139.

Hermansen

Kristensen

BW.

MicroRNA biomarkers in glioblastoma. J Neurooncol 2013; 114: 13–23.

140.

Areeb

Stylli

Koldej

, et al. MicroRNA as potential biomarkers in glioblastoma. J Neurooncol 2015; 125: 237–248.

141.

Shi

Tian

Cai

, et al. Corrigendum: miR-124 alleviates ischemic Stroke-Induced neuronal death by targeting DAPK1 in mice. Front Neurosci 2021; 15: 745087.

142.

Fang

Wang

Zhang

, et al. The miR-124 regulates the expression of BACE1/beta-secretase correlated with cell death in Alzheimer's disease. Toxicol Lett 2012; 209: 94–105.

143.

, et al. Roles of microRNA-124 in traumatic brain injury: a comprehensive review. Front Cell Neurosci 2023; 17: 1298508.

144.

Silber

Lim

Petritsch

, et al. miR-124 and miR-137 inhibit proliferation of glioblastoma multiforme cells and induce differentiation of brain tumor stem cells. BMC Med 2008; 6: 14.