Epidermal growth factor promotes the differentiation of stem cells derived from human umbilical cord blood into neuron-like cells via taurine induction in vitro

Results of recent investigations have demonstrated the plasticity of mesenchymal stem cells (MSC) can differentiate into neural lineages. In this study, we explored the experimental condition of differentiation into neuron-like cells or rhodopsin (RHOS)-positive cells induced by epidermal growth factor (EGF) and taurine in vitro and to investigate their biological characteristics. MSC were obtained from umbilical cord blood (UCB) of term deliveries. Cultured cells were treated with Dulbecco's modified Eagle's medium/F12 (pH 7.0-7.2) supplemented with 30 ng/ml EGF. After the third cell passage, the cells were trysinized and analyzed with a flow cytometer using the following monocloned antibodies: CD90, CD29, CD34, CD44, and CD45. Taking another MSC of the third passage, its basal medium was replaced with alpha minimum essential medium supplemented with taurine (50 micromol/L). Cells were cultured for an additional 8-10 d, fixed, and then immunocytochemically analyzed. Primary antibodies included the following: neuron-specific enolase (NSE), RHOS, and nestin. In our study, we isolated a cell population derived from UCB, which possesses morphological characteristics similar to those of MSC isolated from bone marrow. In the cytometric analysis, MSC did not present labeling for the hematopoietic line (CD34 and CD45) and were positive for CD29, CD44, and CD90. After induction by taurine, 80.5 +/- 16.2% of the cell population expressed NSE, 36.8 +/- 9.6% expressed RHOS, and 29.6 +/- 9.3% expressed Nestin, while only 7.9 +/- 3.5% expressed NSE in the control group. This study demonstrates that partial MSC induced by taurine and EGF can differentiate into neuron-like cells or RHOS-positive cells in vitro, which may provide a promising therapeutic strategy for the treatment of some forms of retinal degeneration.