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Banking sperm stem cells could restore fertility for men after chemo

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In their study, published in the current issue of Cell Stem Cell, previously frozen stem cells restored production of sperm that successfully fertilized eggs to produce early embryos.

Infertility can be a side effect of some cancer treatments because the drugs work by destroying rapidly dividing cells, which includes sperm precursor cells. Men who know they will be undergoing chemotherapy can bank sperm prior to treatment.

“But that is not an option for young boys who haven't gone through puberty, can't provide a sperm sample and are many years away from thinking about having babies," said senior investigator Kyle Orwig, Ph.D., associate professor at Pitt School of Medicine and an investigator at Magee-Womens Research Institute.

However, even very young boys have spermatogonial stem cells in their testicular tissue that are poised to begin producing sperm during puberty. To see whether it was possible to restore fertility using these cells, Dr. Orwig and his team biopsied the testes of pre-pubertal and adult male macaque monkeys and then froze the cells from the small samples.

The monkeys were then treated with chemotherapy agents known to impair fertility.

A few months later, the team re-introduced each monkey's own spermatogonial stem cells back into his testes. Sperm production was established from transplanted cells in nine out of 12 adult animals and three out of five pre-pubertal animals after they reached maturity.

In another test, spermatogonial stem cells from unrelated monkeys were transplanted into infertile monkeys. Sperm taken from the transplant recipients was later used to successfully fertilize 81 eggs.

"This study demonstrates that spermatogonial stem cells from higher primates can be frozen and thawed without losing their activity and that they can be transplanted to produce functional sperm that are able to fertilize eggs and give rise to early embryos," Dr. Orwig said.

The findings are encouraging because several centers in the United States and abroad already bank testicular tissue for boys in anticipation that new stem cell-based therapies will be available in the future to help them father their own biological children.

This latest study builds on one published earlier this year in which the Pitt team was able to grow spermatogonial stem cells in the lab using stem cells collected from skin. That study was published in the Aug. 27 online issue of Cell Reports.

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