It’s well known that female fertility decreases with age. Starting at age 30, female reproductive potential gradually decreases. In addition, there is an increased risk of miscarriage or giving birth to a child with birth defects at a higher age. These problems are thought to be primarily due to a decline in the quality of the eggs themselves.
Recent studies have shown that blocking cathepsin B protease, an enzyme that plays a significant role in the aging of eggs, can prolong fertility.
Drug Extends the Life of Eggs
Researchers at Princeton University led by Coleen Murphy, professor of molecular biology, have identified a drug that prolongs the viability of eggs in worms. For their study, the researchers used the nematode Caenorhabditis elegans, a harmless worm that has a lifespan of about two to three weeks and has a simple genome that is remarkably similar to that of humans. Just like fertility in women, the fertility of the worm begins to steadily decline once it reaches middle age.
The researchers discovered a key protein in the eggs that prolonged the life of the oocytes (unfertilized eggs) by 10 percent when it was blocked.
Nematode: Similar Genes as Humans
Earlier research has already shown that these worms experience the same reproductive decline in mid-life and that their fertilized eggs exhibit a comparable decline in quality as human eggs with age. The researchers investigated a down-regulated group of proteins, cathepsin proteases, which are rare in high-quality eggs and more commonly found in oocytes that have become degraded. The existence of a drug that blocks precisely these proteins gave the researchers the opportunity to test its effects on fertility.
Cathepsin B Inhibitor Can Prolong Fertility
The researchers studied the worms on the first day of their adult life and allowed them to develop normally up to the third day of adulthood. On this day, some of the worms were treated with a cathepsin B inhibitor, while the other worms were left to mature without the drug. On the seventh day of adult life, the researchers made a startling discovery: Worms that had not been treated with the C-B blocker had eggs that were small and deformed, which is expected in worms of that age. However, the worms that were given the protein blocker had healthy and normal eggs even at a later age. In addition, researchers found an increased prevalence of cathepsin B protease in older worms with insufficient oocyte quality. This protein is considered the cause of poor egg quality. When the protein was blocked, a dramatic increase in the period during which the eggs were of good quality could be observed. The life of the healthy eggs was prolonged by four days.
What Does That Mean for Female Fertility?
Fortunately, Murphy and her team found a study with cows that showed similar results. Although the study is considered controversial by some, the findings suggest that the Cathepsin B inhibitor may also play a role in the fertility of women by potentially prolonging it in the future. While the researchers say that testing the drug on humans isn’t foreseeable anytime soon, the results of the study are promising and justify further research.