31 Jan 2002

Parthenogenesis, the development of an unfertilized egg into an embryo, has been demonstrated in mice and cows. Although such embryos have never been cultured to full-term, they could provide a valuable source of embryonic stem (ES) cells. Michael West, at Advanced Cell Technologies, and coworkers report they have successfully adopted this strategy to develop primate ES cells. Their work appears in this Friday's Science.

The researchers coaxed 77 eggs of macaque monkeys (Macaca fasicularis) to divide, 28 successfully. Four eggs reached the blastocyst stage. Inner cell masses were then extracted, plated, and a single cell line was obtained, which could be propagated for ten months without differentiation.

West et al. demonstrated the pluripotency of this cell line by its ability to differentiate into a variety of cell types including spontaneously beating cardiomyocyte-like cells, smooth muscle cells, adipocytes, ciliated epithelium, and cells of the neural lineage. HPLC analysis confirmed that some of the latter released dopamine and serotonin.

To test the developmental capability of the cells in vivo, the scientists placed them in the peritoneal cavity of SCID mice, which could not reject them. Histological analysis revealed differentiation of the ES cells into cells of all three germ layers including muscle, bone, neurons, skin, and intestinal and respiratory epithelia.

"This is very intriguing, that you can start an egg dividing parthenogenetically and get a cell line," said Curt Freed, University of Colorado Health Science Center. "It's not a common event, but on the other hand one doesn't have to do it very often if you have 10 months of continuously dividing cells."—Tom Fagan