Study sheds light on why male fertility diminishes with age

Researchers at Kyoto University have discovered a key genetic component in the replenishment of sperm in adult males.

The study found that by understanding the workings of stem cells responsible for the replenishment of sperm they could have a better understanding of why male fertility diminishes with age. The team focused on spermatogonial stem cells or SSCs, which are responsible for producing sperm.

"So-called Myc genes play an important role in stem cells's ability to self-renew," Takashi Shinohara of Kyoto University, said in a press release.

Scientists in the Shinohara lab showed how the Myc gene regulates the self-renewal of mouse SSCs through glycolysis control, a key part of cells' energy-making abilities, by injecting two types of SSCs into mice.

They injected the mice with normal cells and Myc gene-suppressed cells. After a two-month time period, the total number of abnormal SSCs was significantly less than normal cells in the mice.

Analysis showed that the capacity for self-renewal had been compromised, showing important implications for sperm production in the mice.

Suppressed SSCs could self-renew but at a slower rate than normal and this diminished rate coincided with impaired glycolysis meaning that the cells were not generating enough energy.

"These findings could have important implications for infertility research in the future," Shinohara said. "Stimulating the metabolism of SSCs could improve their proliferation. However, more careful study of the molecular pathways is necessary."

The study was published in Genes & Development.

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