The Technical Roadblocks and Scientific Hurdles Remaining for Clinical IVG Application

Scientists in the United States have achieved a groundbreaking "proof of concept" by creating early stage human embryos after manipulating DNA from ordinary skin cells to produce functional, fertilizable eggs. The research, conducted by a team at Oregon Health & Science University (OHSU), utilized a new technique that blends cloning methods with a chemically induced cell division process to overcome a significant hurdle in fertility science. While none of the embryos progressed beyond a six day blastocyst stage, the feat is a major step forward in the field of in vitro gametogenesis (IVG), which aims to make sperm and eggs outside the body.

The revolutionary technique begins with Somatic Cell Nuclear Transfer (SCNT), the same cloning method used to create Dolly the sheep. Researchers took the nucleus, which contains the full complement of 46 chromosomes, from a human skin cell and transferred it into a donor egg that had its own nucleus removed. The challenge then was to reduce the chromosome count, as a healthy egg should only have one set of 23 chromosomes. The scientists induced an artificial division process, which they termed "mitomeiosis," to coax the cell into discarding half its chromosomes. These resulting egg like cells were then successfully fertilized with donor sperm, forming early embryos.

The potential impact of this research on infertility is immense. The technology could eventually offer a pathway to have genetically related children for women who no longer have viable eggs due to age, premature menopause, or medical treatments like chemotherapy. Furthermore, since the skin cells can be taken from either a male or female partner, the method could allow same sex couples to have a child genetically related to both partners. For example, in a male same sex couple, the skin cell from one partner could be used to create the egg, which is then fertilized by the other partner's sperm.

Despite the impressive scientific advance, the process is far from ready for clinical application. The resulting embryos were riddled with chromosomal abnormalities, as the "mitomeiosis" process often resulted in a random, unequal division of chromosomes. This led to embryos with the wrong number or assortment of chromosomes, which would not be viable. The success rate of the experiment was also low, with only about 9% of the fertilized cells developing to the blastocyst stage before the experiment was stopped. Experts estimate at least a decade of further research is needed to perfect the technique and address significant safety and ethical concerns, including the legal and moral status of embryos created in this way.