Use of Biotin for Stimulating Growth of Nerve Tissue and Other Cells in vitro

A rapidly increasing number of data show that biotin is of wide-spread metabolic significance for a wide range of living things, and the fact that this vitamin markedly increases the growth rate of yeast cells and bacteria indicates that it might have similar effects on other plant or animal cells. Our present limited knowledge about many of the viruses, particularly those of the neurotropic group, is due in large part to the difficulties encountered in trying to grow them in vitro. In view of the important relationship between the metabolic state of cells and the ability of viruses to infect them, 1 experiments were devised to test the effects of biotin on various cell types, especially nerve tissue, in an effort to apply the data thus obtained for initiating or improving the growth of viruses and rickettsiae in vitro.

The method used for studying the effects of biotin on living cells was a slight modification of a technic previously described, using hanging drop cultures. 2 A piece of tissue was removed, preferably from the midline of an embryo, and divided into two equally-sized (and usually, bilateral) halves. One piece was explanted into a clot made up of plasma, embryonic extract, and biotin in Tyrode solution. A control culture was made of the other half in a clot consisting of the same proportions of plasma, extract, and plain Tyrode solution. Since the biotin (obtained from the S. M. A. Corporation) was furnished in alcoholic solution, it was necessary to add an equivalent amount of alcohol to the Tyrode solution used in control cultures. In most of the concentrations (1/6 γ to 5/6 γ of biotin per cc), the amount of alcohol was too small to affect the results appreciably.