A therapy that has been shown to prevent feline pregnancies may open a new line of research to achieve a definitive contraceptive method for humans.
The technique, explain the researchers of the Hospital General de Massachusetts In a study published in “Nature Communications», is based on the injection of a single dose of a viral vector containing hormona antimülleriana (AMH), a natural hormone, which prevented ovulation and conception in cats for at least two years.
During previous research evaluating AMH as a method of protecting ovarian reserve in women receiving chemotherapy, lead author David Pepinfound that raising the AMH level beyond a certain threshold suppressed the growth of ovarian follicles, effectively preventing ovulation and conception.
“AMH (also known as Müllerian inhibitory substance, or MIS) is a naturally occurring non-steroidal hormone produced by the ovaries in human females and other mammals, and in the testes in males,” he notes. Patricia K. Donahoeco-author of this study.
In 2017, Pépin and his collaborators were the first to publish the contraceptive potential of AMH in rodents.
Working with felines, the researchers created an adeno-associated viral (AAV) gene therapy vector with a slightly altered version of the feline AMH gene to raise AMH levels.
Human therapies using similar AAV vectors to deliver various therapeutic genes have been shown to be safe and effective and have been approved by the US.
“A single injection of the gene therapy vector causes the cat’s muscles to produce AMH, which is normally only produced in the ovaries, and raises the overall level of AMH about 100 times higher than normal,” says Pépin.
Our goal is to demonstrate that safe and effective permanent contraception in companion animals can be achieved through gene therapy.
Hospital General de Massachusetts
The researchers treated six cats with the gene therapy at two different doses, and three cats served as controls. A male cat was brought to the female colony for two mating trials lasting four months. The researchers followed the cats for more than two years, evaluating the effect of the treatment on reproductive hormones, ovarian cycles and fertility.
All control queens produced kittens, but none of the gene therapy-treated queens became pregnant.. The suppression of ovarian follicle development and ovulation did not affect important hormones such as estrogen. No adverse effects were observed in any of the treated cats, demonstrating that at the doses tested, gene therapy was safe and well tolerated.
“The treatment kept AMH levels high for more than two years, and we are confident that those contraceptive levels will be maintained in the animals for much longer,” says the vet. Philippe Godin, co-author and MGH researcher. Additional studies in larger numbers of cats are needed to confirm these promising findings, he adds.
“Our goal is to demonstrate that safe and effective permanent contraception in companion animals can be achieved through gene therapy,” concludes Godin.
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