Figure 6. Effect of FBS and NGF on PC12 cell proliferation on a poly-L-lysine coated Si₃N₄ surface.

PC12 cells were seeded onto poly-L-lysine coated Si₃N₄ surfaces in serum-supplemented growth medium and after 24 hours, cells were stimulated with NGF (50 ng/ml) in the presence/absence of FBS+horse serum. Cells were counted every 2 days. Three treatment groups were established: FBS (+) NGF (−) (○); FBS (+) NGF (+) (□); and FBS (−) NGF (+) (⋄). The values shown are the mean ± S.E. for twenty samples (Two trials of ten samples each). The presence of FBS significantly increased the cell proliferation rate (*, p<0.001 vs. FBS (−) NGF (+)); NGF significantly decreased the cell proliferation rate (*, p<0.001 vs. FBS (+) NGF (+)).