Human sperm cells grown in vitro as a potential step to treat male infertility

Scientists have made progress towards a reliable technique for treating male infertility. 

The team, based at the University of California San Diego, developed a new methodology to isolate spermatological stem cells (SSCs), the stem cells that facilitate the growth of sperm cells, in the male testes and grow them outside the body.

'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,' said Professor Miles Wilkinson, the study's senior author and professor at the department of obstetrics, gynaecology and reproductive sciences.

SSCs were previously difficult to identify. The team achieved this by using RNA sequencing to define the molecular characteristics most likely to be specific to SSCs. The sequencing information also helped to determine the most suitable conditions for growing the cells in laboratory conditions. 

Using over 30 biopsies of human testes, they identified these conditions and went on to keep the SSCs alive for a month. The technique involved blocking the AKT pathway, a cell signalling pathway which controls cell division and survival.

This methodology could enable scientists to grow sperm in vitro and inject them back into the body to restore sperm production in men who have infertility that is related to a low sperm count.   

'I think this is a really big step forward in our field,' Professor Ans van Pelt, professor of reproductive biology at the University of Amsterdam in the Netherlands, who wasn't involved in the study, told the New Scientist. Although Professor van Pelt added that labs would have to be able to grow sperm cells outside the body for at least two months to get enough to recolonise the testes. 'But it's a very good start,' she said.

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

This research was recently published in Proceedings of the National Academy of Sciences.