Basic fibroblast growth factor in the primary olfactory pathway: Mitogeniceffect on ensheathing cells

The mitogenic effect of basic fibroblast growth Factor and nerve growth fac tor (2.5S) on olfactory ensheathing cell culture was examined by bromodeoxy puridine uptake. It was found that, at 10 ng/ml, basic fibroblast growth fa ctor elicited about a three-fold increase in proliferation, while the stimu latory effect of nerve growth factor was considerably less. The increased p roliferation resulting From basic fibroblast growth factor could be attribu ted to perlecan, which was shown to be expressed by ensheathing cell in cul ture. Perlecan is known to induce high-affinity binding of basic fibroblast growth factor to receptors on cell membranes. Immunohistochemical staining demonstrated that basic fibroblast growth factor was abundantly expressed in select regions of the lamina propria underlying the olfactory epithelium . In these regions, contiguous patches of olfactory epithelium also showed the presence of basic fibroblast growth factor. Although basic fibroblast g rowth factor was present on the periphery of nerve bundles in the olfactory nerve layer of the bulb, all other laminae did not demonstrate the presenc e of this factor. The immunohistochemistry and cell culture results show that regions of the lamina propria and small patches of the olfactory epithelium, by their pres ence of basic fibroblast growth factor, are potential sites of ensheathing cell proliferation in vivo. (C) 1998 IBRO. Published by Elsevier Science Lt d.