The debate about whether egg stem cells exist could be at an end after a study conducted by researchers at the Karolinska Institutet in Sweden strongly suggests there is no such thing as an egg stem cell.
The study was conducted on more than 24,000 cells collected from the ovaries of 21 patients. The researchers used single-cell analysis to study the cells, in addition to cells collected from the ovarian medulla. The study set out to explore whether egg stem cells exist and also to develop a complete cell map of the human ovary.
The study revealed the main cells in the human ovary are egg cells, immune cells, endothelial cells, granulosa cells, stromal cells, and perivascular cells. The study found no evidence of ovary stem cells.
Several studies have been conducted to find egg stem cells in ovaries, some of which suggest that egg stem cells exist while other suggest they do not. There is a commonly held belief that oogonial stem cells exist in the ovarian cortex and that the cells can captured by DDX4 antibody isolation. In 2012, scientists at Massachusetts General Hospital claimed to have generated new eggs cells from human ovarian stem cells; however, several animal studies suggested that egg stem cells do not exist, and instead the cells that were isolated were perivascular cells. The latest study substantiates the findings of the animal studies. The cells that have been isolated by other researchers are actually perivascular cells. The research supports the view that there is a finite number of oocytes in the ovary.
A considerable amount of research is being conducted into female fertility and involuntary childlessness, including the potential for stem cells to be used in novel fertility treatments. What has held research back is a lack of knowledge about the cellular composition of a healthy human ovary. The complete cell map presented by the researchers lays the groundwork on which new treatments for infertility can be based – Treatments that focus on the existing egg cells in the ovary rather than trying to create egg cells from stem cells.
You can read more about the study in the paper – Single-cell analysis of human ovarian cortex identifies distinct cell populations but no oogonial stem cells – which was recently published in the journal Nature Communications. DOI: 10.1038/s41467-020-14936-3