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Although not as commonly spoken about as female infertility, there are many men who are affected by their lack of sperm production-- a process known as spermatogenesis. In normal males, this process can generate more than 1,000 sperm per second-- and is the result of a special kind of cell-- the spermatogonial stem cell. But these cells are not well understood, and attempts to create them in the lab have not been very successful.

There is a new process developed by the researchers at the University of California San Diego that may be able to shed some light on these cells. If we can get a clearer picture of how they operate-- perhaps doctors can find ways to intervene when they no longer function properly. This article will look at:

• Extracting the stem cells for analysis
• What are spermatogonial stem cells?
• How can they help treat male infertility?

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Extracting the stem cells for analysis

Miles Wilkison, PhD is the lead author of this study and a professor in the Department of Obstetrics and Gynaecology at the University of California at San Diego. The technique that they used is called single-cell RNA sequencing-- which allowed the researchers to observe the spermatogonial stem cells and isolate them to create a clearer overall picture.

Single-cell sequencing has already been used to determine the activity of hundreds of different types of genes in the human genome. This particular technique had just not been applied to human testes before. By applying this method, the researchers were able to see many different stages of sperm precursor cells. By not limiting their scope to just fully developed spermatogonial cells, the scientists learned that these cells are present-- but dormant-- from a young age.

By using the single-cell RNA sequencing approach, scientists were also able to locate several new subtype cells that were likely to be spermatogonial cell precursors as well. It’s interesting to note that these cells were also found in newborns-- which lead researchers to wonder if these cells perhaps serve another purpose in addition to sperm production. Since spermatogenesis is not necessary until puberty, scientists are left to speculate what other functions could they serve that we are just not fully aware of.

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What are spermatogonial stem cells?

Spermatogonial stem cells are those cells that are responsible for sperm production in males-- and are are essential for male fertility. According to the results of this study, their precursors develop in males early on-- scientists were able to locate many different stages of sperm precursor cells. The scientists in this study were able to isolate and identify these cells using specific biomarkers that define spermatogonial stem cells. This was the first technique that was really able to give researchers a clear picture of the cells.

Being able to isolate and study spermatogonial stem cells is great news, since they are the only stems cells that are capable of transmitting a human genome from one generation to the next. Now that scientists have an effective way to study them, they can further research how diseases and other human malformities are passed on from generation to generation.

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How can this help treat male infertility?

There are over 100 million men around the world that suffer from infertility. Although there are many factors that affect fertility, if the sperm is not manufactured properly-- it will definitely lead to fertility problems. By studying the spermatogonial stem cells, scientists can learn what some of the causes are that affect a decrease in sperm production-- or why do the stem cells decrease or cease sperm production at all? This could be a valuable service to those couples going through infertility treatment and have no understanding as to why the male partner’s sperm is not properly functioning.

If the cause of infertility is known-- perhaps from chemotherapy due to cancer treatments-- scientists now have the tools available to isolate and possibly grow spermatogonial stem cells. Further research and techniques would be necessary, but this means there is the possibility of developing spermatogonial stem cell transplants-- and would be welcome news to the many men dealing with infertility.

The single-cell RNA sequencing has shed some light on the spermatogonial stem cells-- whose full purpose has just begun to be observed and documented. Now equipped with better access to view and monitor these cells, perhaps scientists are prepared to develop new treatments to assist with male infertility.