Parthenogenetic embryonic stem cells in nonhuman primates

Parthenogenesis is a naturally occurring process where an oocyte is activated without sperm contribution. In mammals, parthenogenetic (PG) embryos cannot develop to term. The most commonly used method of artificially making diploid PG embryos is using via chemical activation of the egg and by preventing extrusion of the second polar body. Parthenogenetic embryonic stem (PGES) cells are derived from the inner cell mass of PG embryo at the blastocyst stage. They are pluripotent, i.e., they can differentiate into all three germ layers: ecto-, meso-, and endoderm, and can be propagated as stem cells in culture for prolonged periods of time. PGES cells offer an easily obtainable pool of stem cells that can be used as a source for derivation of autologous tissues, albeit limited to females in reproductive age. PGES cells derivation does not require destruction of a viable embryo and therefore bypasses the ethical debates surrounding the use of naturally fertilized embryos. Nonhuman primates are the closest species to human in the tree of evolution and therefore are excellent models for studying human development and diseases. PGES cells from nonhuman primate and human parthenogenetically activated oocyte have recently been derived (1-3). These cells offer a valuable tool for studying the developmental, differentiation, and functional potential of the PGES cells in the context of their clinical application in organ and tissue transplantations in humans.