FibronectinPromotes Rat Schwann CellGrowth and Motility

�Techniques are now availableforculturingwell characterized and purified Schwann cells. Therefore, we investigated the roleof fibronectin in the adhesion, growth, and migration of cultured rat Schwann cells. Double-immunolabeling shows that, in primary cultures of rat sciaticnerve, Schwann cells(90%) rarelyexpress fibronectin,whereas fibroblasts(10%) exhibit a granular cytoplasmic and fibrillar surface-associated fibronectin.Secondary cultures of purified Schwann cellsdo not express fibronectin.Exogenous fibronectin has a small effecton promoting the adhesion of Schwann cellsto the substrate and does not significantlyaffect cell morphology, but itproduced a surface fibrillar network of fibronectin on the secondary Schwann cells.Tritiatedthymidine autoradiography revealed that addition of fibronectin to the medium, even at low concentrations, markedly stimulates Schwann cellproliferation,in both primary and secondary cultures.In addition, when cellmigration was measured in a Boyden chamber assay,fibronectinwas found to moderately, but clearly,stimulate directed migration or chemotaxis .