[Identification of ectomesenchymal stem cells of human fetal facial processes and spontaneous differentiation to smooth muscle cells].

Objective: To investigate the characteristic and phenotype of ectomesenchymal stem cells of human fetal facial processes and the procedure of spontaneous differentiation to smooth muscle cells.

Methods: The primary ectomesenchymal cells of E 50 human fetal facial processes were isolated by 2.5 g/L trypsin and cultured with DMEM/F 12 with 10(-6) U/L leukemia inhibitor factor(LIF). The morphology and growth rate were observed by inverted microscop. After being withdrawn LIF, the characteristic of cells were identified by immunohistochemistry and RT-PCR. Ultrastructure was observed by transmission electron microscope.

Results: The cultured cells displayed monolayer growth and were fibroblast-like with 2-4 processes. The cells were stainely positived for anti-human natural killer cell marker-1, Vimentin, S-100, neuron specific enolase, myoglobin and VIII factor, but negatively for glial fibrillary acidic protein, neural fiblament, alpha-SMA and cytokeratin in immunohistochemistry. Two days after being withdrawn the LIF, cells expressed alpha-SMA in protein and mRNA levels. The cells were rich in muscular filament-like structure and dense bodies under transmission electron microscope.

Conclusion: Cultured cells are undifferentiated ectomesenchymal stem cells. The cells have the potential for differentiating spontaneously to smooth muscle cell.