New Fertility Research Can Extend Egg Health with Age

Women have been told for years that it is very difficult to reproduce after their mid-30s. Researchers at Princeton University have identified a drug that can successfully extend egg viability with age. This drug can successfully extend fertility in women in their mid-30s by around three to six years.

Coleen Murphy, professor of molecular biology at Princeton University, has identified some proteins responsible for reducing egg viability with time.^[1] She says that women in their mid-30s experience decline in fertility, age-related birth defects and increased occurrences of miscarriage. She says all these problems arise due to decline in the quality of eggs with age rather than reduced number of eggs.

Murphy specializes in studying longevity in the worm Caenorhabditis elegans. These worms share similar genes as those in humans, especially the genes that control aging process in their three-week long lives. Prior to this study, the researchers observed that these worms also experience reduced mid-life fertility. Their oocytes or unfertilized eggs showed almost similar decline in egg quality with age to humans.

The researchers identified the proteins that are less common or are down-regulated in the lower quality oocytes. They focused on a particular group of downregulated proteins known as cathepsin B proteases. These proteins are rarely found in good-quality eggs but are very commonly observed in the low-quality eggs. A drug that can inhibit these proteins can help in finding a novel way to delay decline in egg health with time. Inhibiting these proteins would lead to three possibilities-First, there would be no effect of blocking these inhibitors, second, these are complementary proteins that arise to combat aging of oocytes and blocking them would even worsen the problem and lastly, blocking these would help in delaying the aging process.

When the drug was administered in the worms, the eggs were found healthy even after a long time than the eggs of the control group. They first administered the drug at the onset of reproductive window equivalent to the puberty in humans. Though the drug worked, it would not work in adult women. The drug was then later administered in between the reproductive period. There was a significant difference in the quality of the eggs of worms who were given the drug and the control group of worms. Another experiment could extend fertility by around 10 percent by knocking out the responsible gene for cathepsin B proteins. In humans, this could imply that fertility can be extended by around three to six years. The same cathepsin B proteins had similar effects in cows.

However, there is a great difference between worms and mammals, but new researchers keep finding similar genes and drugs that could retain women’s fertility with age. The drug that could inhibit cathepsin B proteins is far from being tested in humans. Dr. Murphy emphasizes that this one thing done in between of reproductive window of women might improve rest of their reproductive windows.

This study was recently published in journal Current Biology ^[2].