World's First Lab-Grown Human Sperm Stem Cells Created

Did you know that infertility affects one in seven men worldwide? One idea for treating this problem is spermatogonial stem cell (SSC) therapy — an approach that sees sperm stem cells transferred to a test tube where they are cultured and turned into fully-fledged sperm cells.

A key issue holding back this method is the fact that it has been very tricky finding the right conditions to get human SSCs to grow in the lab.

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In a new breakthrough, researchers at the University of California San Diego (UCSD) School of Medicine have developed a reliable method for culturing cells with the characteristics of human SSCs.

SSCs can generate more stem cells and up to 1,000 sperm every couple of seconds. The problem is that these specialized cells are very hard to differentiate from other cells in the testes.

A major step was made, however, when several laboratories, including the UCSD team, recently used a technique called single-cell RNA sequencing to analyze and define the likely molecular characteristics specific to human SSCs.

"We think our approach—which is backed up by several techniques, including single-cell RNA-sequencing analysis—is a significant step toward bringing SSC therapy into the clinic," senior author Miles Wilkinson, Ph.D., Distinguished Professor in the Department of Obstetrics, Gynecology and Reproductive Sciences at UC San Diego School of Medicine, said in a press release.

In the UCSD team's new study, published in the journal PNAS, Wilkinson's team details how it was able to differentiate and isolate SSCs from other, similar cells in the testes. By knowing this, they were able to interpret just the right conditions needed to culture SSCs into sperm cells that could be used for infertility treatment.

"Next, our main goal is to learn how to maintain and expand human SSCs longer so they might be clinically useful," Wilkinson said.