Characterization of PC12 cell proliferation and differentiation-stimulated by ECM adhesion proteins and neurotrophic factors.

Among the various elements which influence axonal outgrowth in vivo is the physicochemical interaction of actively outgrowing nerve fibers with the various substrata they encounter during differentiation. Several experiments have explored the role of the extracellular matrix (ECM) in the control of neuronal differentiation. The nature, however, of the interactions between neurons and components of the ECM during regeneration and development are largely a matter of speculation. Although previous studies have already explored the influence of a number of ECM adhesion proteins and neurotrophic factors on neurite outgrowth, none have been carried in a systematic approach that allows for the simultaneous comparison of different surface conditions in relation to different neurotrophic factors. Motivated by the necessity of establishing controlled environments that allow for the rational design of stable neuronal/biomaterial interfaces, the long-term effects of NGF and FGF-2 on the behavior of PC12 cells plated on collagen and laminin modified surfaces were evaluated. A pheochromocytoma cell line derived from transplantable rat adrenal medulla, PC12 cells have been commonly employed as an instructive model for studying the underlying mechanisms of neuronal differentiation. Long-term characterization of PC12 proliferation and neuronal differentiation for an experimental duration of 7-22 days was achieved by both qualitatively and quantitatively assaying for cell count, neurite number, neurite mean length, and neurite stability. Neurite stability was determined in terms of resistance to loss after neurotrophic factor (NGF/FGF-2) withdrawal. The present findings demonstrate that ECM adhesion proteins collagen and laminin are equally effective in promoting PC12 proliferation. It was noted as well that NGF supplemented collagen cultures are significantly more efficient in providing long-term support to PC12 differentiation in terms of neurite number, mean length, and stability.