According to the National Institutes of Health (NIH), when couples have trouble conceiving a baby, one-third of the time it is due to a problem with the man’s ability to produce mature sperm. However, in a new, revolutionary study, research using stem cell-based sperm that were created from infertile men’s skin suggests that infertility in these men may be reversible.
In a new study conducted at Stanford University and published in the journal Cell Reports, researchers took skin samples from two fertile men and three infertile men. Study results showed that the three infertile men were not able to produce mature sperm because they had a mutation in the AZF1 genome, which is a condition called azoospermia.
Using the men’s skin samples, researchers transformed them into induced pluripotent stem cells (iPS cells), which have the ability to become almost any type of tissue found within the human body. Researchers then implanted the iPS cells into the testes of mice. Remarkably, the implanted iPS cells formed into sperm precursor cells called germ cells.
Normally, germ cells undergo a period of mitotic proliferation, meiosis, and then develop into mature sperm. However, these germ cells did not continue the process of developing into mature sperm. Researcher Renee Reijo Pera, who is regarded as one of the world authorities on embryonic stem cells, believes that evolutionary differences between mice and humans prevented the production of mature sperm cells.
Infertility is common and affects approximately 10 to 15 percent of all couples, but now stem cell-based sperm created from infertile men’s skin offers hope of reversing infertility. Pera said, “Genetic causes of infertility are prevalent in men, and that progress made in this area could go a long way toward helping thousands, if not millions, of people around the world” be able to possibly have children. The findings of the study suggest that infertile men may in fact have the potential to produce viable germ cells, but Pera explains they are lost over time.
However, if it is indeed true that infertile men have the potential to produce viable germ cells, Pera said, young boys who have the AZF1 mutation may be able to preserve germ cells by collecting and freezing samples of testes tissue that could then be used later in life to possibly father a child. Pera explains it might be possible to transplant the stem cell-based germ cells directly into the testes once the young boys reach adulthood.
Previously, Pera and her colleagues created germ cells using human embryonic stem cells. These cells were used to conduct experiments in mice, which proved that animal skin cells could be turned into stem cells and then turned into germ cells. Researchers implanted the germ cells into sterile mice, and the mice became fertile.
From this new study, researchers were able to determine that stem cell-based sperm created from infertile men’s skin may be able to help reverse infertility. This discovery could help countless men who suffer from infertility by helping researchers understand the genetic causes of male infertility, and one day possibly help those men be able to father a child of their own.
By Donna W. Martin