Frozen testicular tissue is still viable TWO YEARS later, find scientists –

According to one study, reintroducing cryogenically frozen testicular cells to infertile men can give them the ability to become pregnant again.

Scientists have succeeded in inducing healthy sperm production in sterile mice inoculated with testicular tissue collected 20 years ago.

Previous research in monkeys had shown that it is possible to use frozen cells for months, but the latest study shows that long-term freezing is also possible.

The discovery could pave the way for a new type of treatment for prepubertal boys who are often castrated by powerful drugs used to treat cancer.

Adult men in the UK and US can pay to freeze their sperm, but men who are unable to produce functional sperm still have little choice in preserving their fertility.

In 2019, the first macaque was born using cryogenically preserved testicular cells, an important step towards validating human testing.

Boys do not have mature sperm in their testicles, but there are many “sperm stem cells”. These cells produce sperm, but only after puberty.

The most recent study involved sperm stem cells from rodents.

They were frozen for three different periods: 23 years, up to four months, and one day.

The cells were kept in liquid nitrogen to prevent the natural degradation that occurs when biological tissue is removed from the body.

They were then injected into genetically modified mice to prevent their bodies from rejecting the foreign tissue.

All three groups produced viable sperm within months of transplantation.

However, cells frozen for years were less robust than cells stored for shorter periods of time.

Mice fed cells frozen for more than 20 years produced less elongated spermatids, which then went on to form swimming sperm.

More importantly, “viability is never lost during prolonged cryopreservation,” the University of Pennsylvania team said.

Dr. Eoin Whelan, a stem cell expert and principal investigator, said: “Our work has shown that rat spermatogonial stem cells can be successfully frozen for more than 20 years, transplanted into a sterile recipient animal, and reproduce the ability to produce sperm, albeit at a low rate. .

“This may provide a method to correct fertility loss in prepubertal boys undergoing cancer treatment.”

The researchers say the finding is more important than ever, as childhood cancer survival rates have increased over the past few decades.

In the UK, five-year survival rates for all cancers have increased from 36% to 84% since the 1970s as a result of advances in treatment.

While clearly a step in the right direction, one of the most serious side effects of modern treatments is the loss of fertility.

Chemotherapy, especially alkylating drugs, can damage sperm in men and damage sperm-forming cells, known as germ cells, in boys.

Radiation therapy can also lower sperm count and testosterone levels.

The study was published in the journal Biology PLOS †

The testicular tissue collection has been available on the NHS since 2015 as part of a limited site trial.

It is being offered as an “experimental” technology to boys about to be treated for cancer that could affect their fertility.

It’s unclear how many patients have had the tissue replanted after reaching 18 years of age.

And to date, there are no known cases of a baby being born from someone transplanted with cryogenically frozen testicular cells.