Neural differentiation of midbrain cells on various protein-immobilized polyethylene films

The effect of surface modification of polyethylene (PE) film on differentiation of midbrain (MB) cells obtained from rat embryos was determined by their micromass culture system. When cultured on untreated PE film, cell differentiation was suppressed to approximately two-thirds of that observed in a control culture dish. On the contrary, type I collagen-immobilized PE film increased differentiated foci of the MB cells more than did the untreated PE film. RGDS (Arg-Gly-Asp-Ser) peptide immobilization onto PE film resulted in almost the same differentiation activity as the collagen immobilized PE film. Bovine serum albumin (BSA) immobilization onto PE film enhance the differentiation activity more than did the untreated PE film, but not up to the levels of collagen- and RGDS-immobilized PE. The number of differentiated foci of the MB cells on untreated PE film were increased by the addition of the condition medium prepared from the collagen-immobilized PE film. However, the number of foci was not increased by the addition of other condition media obtained from control dish, untreated, BSA-, and RGDS-immobilized PE. On the other hand, none of these condition media enhanced a differentiation of the neuronal cell line of PC12 cells, suggesting that some factors effectively differentiate midbrain cells, composed of neuronal epithelial and mesenchymal cells, but not the PC12 cells secreted in the condition media prepared from collagen-immobilized PE. In addition, it is probable that neural growth factor was not secreted in these condition media, which could not induce the differentiation of PC12 cells.