Derivation of histocompatible stem cells from ovarian tissue.

Somatic cell nuclear transfer, the first established technique for producing patient-specific autologous stem cells, inevitably requires the sacrifice of viable embryos. To circumvent the serious ethical issues associated with this use of embryos, researchers have developed several alternative methods for the production of histocompatible stem cells. In our research, we have used two methods to derive histocompatible stem cells from murine ovarian tissue. First, we have established autologous stem cells by culturing degeneration-fated preantral follicles to produce developmentally competent, mature oocytes and then parthenogenetically activating these mature oocytes to acquire genetic homogeneity. Second, we have used cell-to-cell interactions to derive stem cells from ovarian stromal cells without undertaking genetic modification. We have successfully derived autologous murine stem cells by manipulating primary and early secondary follicles in vitro, and this method has proved successful even for follicles retrieved from aged ovaries. Furthermore, we believe that it will be possible to isolate stem cells directly from non-germline ovarian tissue or to derive stem cells by culturing the ovarian cells with other somatic cells. If achieved, these aims will greatly advance the development of induced pluripotent stem cell technology, as well as tissue-specific stem cell research. In this review, we introduce the relevant technologies for establishing histocompatible stem cells from ovarian tissue cells without undertaking genetic manipulation and review the current limitations of, and future research directions in, stem cell biology.