Using Stem Cells to Preserve Male Fertility

Cells

Key Takeaways:

  • A new study shows that preserving testicular tissue for prepubescent men can be a way of fertility preservation

  • New ways are being tested to prove the effectiveness of grafting previously frozen testicular tissue

Medical treatments for benign sickle cell disease, cancer, or the blood disorder known as thalassemia often come with side effects that can cause subfertility or, in some cases, permanent infertility in men.

The effects on fertility can come about as a result of pediatric treatments that prove deleterious to a person’s gonads. And while cryogenic preservation of assets is an option for adults undergoing medical treatments known to have negative impacts on fertility, this is not a viable avenue for prepubescent patients.

Now, though, a new study published in the March 2019 journal Science indicates that removing and freezing testicular tissue containing sperm cells could preserve a man’s fertility – though, the study cautions, “there are currently no protocols available to derive sperm from the banked tissue”.

Complications of freezing testicular tissue

The new study comes seven years after an article, published in the December 2012 issue of The Journal of Clinical Endocrinology & Metabolism, went into detail about several options for cultivating viable sperm cells from immature testicular tissue in primates.

At that time, the approach with the greatest potential appeared to be using grafts of immature testicular tissue; however, the study authors added, “germ cell maturation in vitro provides the best strategies to overcome problems of cancer contamination in cryopreserved testicular tissue”.

The study went on to discuss potential problems with freezing testicular tissue in prepubescent males, such as the right timing for a testicular biopsy, cryopreservation protocols, strategies for monitoring cancer cell contamination, and the ethical -- and legal -- dilemmas of providing testicular cryopreservation as a clinical procedure.

A better way?

Given the uncertainties and concerns raised in the previous study, the Science-published research by geneticist and postdoctoral associate Adetunji Fayomi from the University of Pittsburgh, and colleagues, indicates a possible way around some of the problems.

Fayomi and his team extracted testicular tissue from a prepubescent monkey, froze it, then revived it and grafted it into scrotal or back tissue of an adult monkey that had been castrated. According to a summary of the research published by Cosmos Magazine, the grafts wound up growing successfully and produced viable sperm, some of which was used to fertilize an egg. This procedure resulted in the birth of a female monkey.

It is important to note that the researchers encountered issues that, like the previous cited study, uncovered uncertainties: They made ten other similar attempts at the same procedure. These involved five other females, and all of the attempts failed.

However, in an accompanying editorial published in the same issue of Science, Nina Neuhaus and Stefan Schlatt of the Centre of Reproductive Medicine and Andrology in Germany minimized the significant failure rate in the experiment, noting the included procedures are comprehended better in humans than in other kinds of primates.

The authors prognosticated that, in the future, research “will be more efficient with human material” and, as a result, they suggested that “clinical trials testing this strategy on patient material should now be performed”.

What’s more, Kyle Orwig, senior author of the Science study and a professor of obstetrics, gynecology and reproductive sciences at the University of Pittsburgh School of Medicine, was quoted by Scientific American as saying that the team initially grafted tissue that had no sperm, but that when they collected the grafts, they were “producing millions and millions of sperm”. Orwig concluded that he and the team were “confident” that, were similar circumstances to occur when using human tissue, there would be “more than enough sperm to fertilize an egg and establish a pregnancy”.

Viability of future treatments

Orwig noted that even if using a similar treatment as was implemented in the study were to someday allow male childhood cancer survivors to father children, they still would likely need to use some form of assisted reproductive technology – either in vitro fertilization or artificial insemination.

The reason for this, he explains, is that challenges still remain when it comes to making the correct connections between the grafted tissue and the remainder of the male reproductive system.

“When we graft tissue,” Orwig says, “there’s no way for sperm to come out into the ejaculate.”

This means that the tissue needs to be extracted from the body and be treated in a lab in order to set free any sperm. It’s also possible, he added, that human males might wish to re-implant tissue grafts when they are teenagers instead of waiting for the time to have a family.

“That way, he’ll know even when he’s a teenager that he has sperm waiting for him, and he’ll be able to have a biological child in the future”.