Therapeutic applications of embryonic stem cells.

Embryonic stem (ES) cells have the potential to proliferate indefinitely in culture and can differentiate into any cell type. The emergence of ES cell lines from human embryos in the past 5 years has attracted profound public and scientific interest, given the far-reaching potential applications of these cells in regenerative medicine. In the future, it is possible that human ES (hES) cells might serve as an unlimited source of cells for transplantation therapy under conditions that result from cell degeneration or malfunction, and that genetically manipulated hES cells might serve as vectors to carry and express genes in target organs following transplantation in the course of gene therapy. This chapter reviews the properties of hES cells and their potential advantages and limitations for cell-based therapies. We also describe various approaches that might be utilized with hES cells to avoid potential immune rejection after allogeneic transplantation and hence circumvent the need for systemic immune suppression. Up-to-date research in establishing committed tissue-specific progenitors from ES cells and evidence of their function after transplantation in various animal disease models is also reviewed. The chapter concludes that hES cells show great promise for regenerative medicine although significant developments are still required to exploit their potential for cell and gene therapy.