Directed differentiation of pluripotent human cells to epithelial lineages.

摘要

Human embryonic stem (hES) cells and induced pluripotent stem (iPS) cells can proliferate extensively in culture and differentiate to the three embryonic germ layers; these pluripotent cells therefore hold much promise for use in scientific, diagnostic, and therapeutic applications. In order to harness this potential, researchers must identify efficient methods of differentiating these cell lines to specific lineages and characterize the functionality of their derivatives. We have employed quantitative analyses of differentiated hES cell populations to identify key signaling factors involved in ectodermal lineage specification. Retinoic acid (RA), in conjunction with endogenous or exogenous BMP signaling, is a stage-specific inducer of epithelial rather than neural differentiation from both hES cells and iPS cells. RA signaling drives expression of epithelial genes such as p63 and cytokeratin 18 (K18) in undifferentiated cells, and these ectodermal progenitors can be efficiently directed to definitive epithelia that uniformly express p63 and the basal keratinocyte marker K14. This differentiation process provides a robust means of generating essentially pure populations of hES cell-derived epithelial progenitors under defined conditions.;In addition, we have applied tissue engineering techniques to investigate the functionality of hES cell- and iPS cell-derived epithelia, culturing cells in three-dimensional (3D) microenvironments and at the air-liquid-interface (ALI) in organotypic skin cultures. Differentiated cells in 3D Matrigel cultures exhibit key properties associated with epithelial morphogenesis and form spheres of epithelial cells lined with a distinct basal cell layer, marked by expression of K14, p63, beta1-integrin, and laminin 5. When incorporated into organotypic skin cultures, hES cell-derived epithelia undergo terminal differentiation similar to that observed from primary keratinocytes or human epidermis. Furthermore, these derivatives continue to proliferate after 3 weeks at the ALI. Finally, we have demonstrated the ability of hES cell-derived endothelial cells (epithelia that line the vasculature) to detect and respond to fluid shear stress, a key property of the endothelium in vivo. Taken together, these findings provide evidence for the functionality of hES cell derivatives and mark a significant advancement in the differentiation and use of pluripotent cells in future research and clinical applications.