Parthenogenesis a Promising Source of Embryonic Stem Cells

Researchers are experimenting with parthogenesis as a way to produce embryonic stem cells that could never become human beings and thereby avert the ethical concerns that have led to restrictions on embryonic stem cell research. Their work was reported in the April 26, 2003, issue of New Scientist.

In parthenogenesis, an unfertilized egg keeps two sets of chromosomes and begins developing as if it had been fertilized. Some insects and reptiles can reproduce this way but in mammals, the resulting embryos die after a few days. So destroying those cells to obtain stem cells would not cause concern. Although the technique works well in mice and monkeys, prior attempts with human eggs have not done well.

Now, researchers have grown parthenogenetic human embryos to the blastocyst stage, at which stem cells can be obtained. Cells taken from one of the embryos survived for a few days, and were perhaps the first parthenogenetic human cells. The next step is to get the cell line to grow in culture indefinitely to obtain a stem cell line. In monkeys, such as cell line has been growing for over two years. Analysis suggests that they are indistinguishable from normal embryonic stem cells.

"Patients are so interested in this procedure, and we are confident enough in its feasibility, that we have been willing to store eggs for use as soon as safety and effectiveness are shown,” said Jerry Hall of the Institute for Reproductive Medicine and Genetics (Los Angeles, CA, USA; www.preimplantationgenetictesting.com). However, much work still has to be done to ensure that any tissues made from parthenogenetic stem cells are absolutely normal.