April Flowers for redOrbit.com Your Universe Online

A new study, from the Stanford University School of Medicine and Montana State University, demonstrates that, when implanted into the reproductive system of a mouse model, stem cells created from adult, infertile men will yield primordial germ cells. Primordial germ cells normally become sperm cells.

The findings, published in Cell Reports, help to further our understanding of a genetic cause of male infertility and basic sperm biology. The research team says that their approach holds considerable potential for clinical applications.

All of the infertile male participants suffer from a genetic mutation that prevents their bodies from producing mature sperm. The study suggests that the men with this condition called azoospermia might have produced germ cells at some point in their early lives, but these cells were lost as the men matured to adulthood.

Our results are the first to offer an experimental model to study sperm development, said Renee Reijo Pera of the Institute for Stem Cell Biology & Regenerative Medicine and Montana State University. Therefore, there is potential for applications to cell-based therapies in the clinic, for example, for the generation of higher quality and numbers of sperm in a dish.

It might even be possible to transplant stem-cell-derived germ cells directly into the testes of men with problems producing sperm, she added. Considerable study to ensure safety and practicality is needed, however, before reaching that point.

Infertility is a fairly common problem, affecting between 10 and 15 percent of couples in the US. The researchers say that many men are affected by genetic causes of infertility, most commonly due to the spontaneous loss of key genes on the Y sex chromosome. Until now, the causes of infertility at the molecular level have not been clear.

The fact that the research team was able to create primordial germ cells from the infertile men is very promising, but they note that these stem cells created far fewer of these sperm progenitors than the stem cells of men without the genetic mutations. They are sure, however, that this research provides a much needed model to study the earliest steps of human reproduction.

We saw better germ-cell differentiation in this transplantation model than weve ever seen, said Reijo Pera, former director of Stanfords Center for Human Embryonic Stem Cell Research and Education. We were amazed by the efficiency. Our dream is to use this model to make a genetic map of human germ-cell differentiation, including some of the very earliest stages.

Humans share many cellular and physiological processes with common laboratory animals such as mice or fruit flies. In reproduction, however, there are significant variances, making it challenging to recreate the human reproductive processes in a laboratory setting. In addition, many crucial steps, such as the development and migration of primordial germ cells to the gonads,occur in the relatively short first days or weeks after conception.

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Stem Cells Of Infertile Men Used To Create Preliminary Sperm Cells