Impact of Cell Density on Differentiation Efficiency of Rat Adipose-derived Stem Cells into Schwann-like Cells

Background and Objectives: Schwann-like (SC-like) cells induced from adipose-derived stem cells (ASCs) may be one of the ideal alternative cell sources for obtaining Schwann cells (SCs). They can be used for treating peripheral nerve injuries. Co-culture with SCs or exposure to glial growth factors are commonly used for differentiation of ASCs to SC-like cells. However, the effect of initial cell density as an inductive factor on the differentiation potential of ASCs into the SC-like cells has not been yet investigated. Methods and Results: ASCs were harvested from rat and characterized. The cells were seeded into the culture flasks at three different initial cell densities i.e. 2×10³, 4×10³ and 8×10³ cells/cm² an overnight and differentiated toward SC-like cells using glial growth factors. After two weeks, the differentiation rate of ASCs to SC-like cells at different densities was assessed by immunofluorescence, fluorescence-activated cell sorting analysis and real time RT-PCR. Expression of the typical SCs markers, S-100 proteins and glial fibrillary acidic protein (GFAP) protein, was observed in all cell densities groups although the number of S100-positive and GFAP-positive cells, and the expression of p75NTR mRNA, another SC marker, were significantly higher at the density of 8×10³ cells/cm² when compared with the other cell densities groups (p<0.001). Conclusions: The results suggest that the higher differentiation rate of ASCs to SC-like cells can be obtained at initial cell density of 8×10³ cells/cm², possibly via increased cell-cell interaction and cell density-dependent influence of glial growth factors.