is available on the CIRM website.
Although this months full report showcases a couple interesting papers refining our understanding of stem cells in the brain, I want to focus this blog on something even more essential for life—eggs.
Two leading journals, Science and Nature, both published major papers in October on eggs. The article in Science detailed the work of a Japanese team that created viable mouse eggs by reprograming adult stem cells. This was an incredibly difficult feat. Eggs need to possess all the starting materials to begin to create an embryo, but they can only have one set of chromosomes including an X chromosome, unlike the two sets that would be in the initial embryo or stem cell, just like every other tissue in our bodies, except sperm of course that have a single set with either an X or Y chromosome. Eggs also need a special environment to nurture them to mature and be ready for fertilization. The stem cells this team used not only resulted in viable mouse pups, the cells also became grandparents, suggesting the offspring were pretty close to, if not completely normal.
The Nature paper describes a procedure that could allow mothers to avoid passing down certain genetic diseases to their children. About one in 5.000 people is born with a genetic disease not caused by errors in their chromosomes in their cells’ nucleus, but rather errors in the genes carried in structures within the cells called mitochrondria that generate energy for the rest of the cell. Gene variants in these mini-organelles and errors in their DNA have been linked to many rare diseases. But we only have one copy of each of these genes, because we only inherit the ones that were in the mitochondria of our mother’s eggs.
The research team from Oregon worked with human eggs and was able to produce genetically normal stem cell lines from eggs carrying mitochondrial mutations. They accomplished this feat by transferring the chromosomes from the nucleus of the original egg into donor eggs that had normal mitochondria.
The Oregon team predicted that the first human birth from using this procedure could come within three years. However, the Japanese team said that moving their work from the mouse model to human could take many years. Nonetheless, both projects have given us valuable new insight into an aspect of human development this is still shrouded in mystery, how normal eggs mature and begin to develop into an embryo.
My full report is available online, along with links to my reports from previous months.