The characterization of growth factor activity in human brain.

The purification of fibroblast growth factor from bovine brain has been reported (Gospodarowicz, D., Bialecki, H., and Greenberg, G. (1978) J. Biol. Chem. 253, 3736-3743). Westall et al. (Westall, F. C., Lennon, V. A., and Gospodarowicz, D. (1978) Proc. Natl. Acad. Sci. U. S. A. 75, 4675-4678) showed that bovine brain fibroblast growth factor was composed of three fragments derived by limited proteolysis from myelin basic protein. In the present study using similar purification methods, we isolated a fraction enriched in growth factor activity from human brain. The mitogenic activity could not be resolved from myelin basic protein by chromatographic procedures but, upon isoelectric focusing, the mitogen and myelin basic protein were readily dissociated. At least two potent growth factors (pI values 7.2 to 7.4 and 8.1 to 8.6) were identified. Studies of a relatively crude basic extract of human brain suggested that the brain may contain a number of growth factors.