A team at Harvard Medical School has reported that ovaries taken from older female mice that had lost their ability to reproduce started working again after being placed inside young mice, and that those young mice gave birth to healthy pups1. The ovaries also looked younger on a lab measure of aging. The work was posted on bioRxiv, a website where scientists share papers before outside experts have checked them, so the results are not yet peer reviewed1.
The researchers say the findings suggest that the body around an organ helps set how old that organ acts. Their study was in mice only.
What happened
The team, led by Harvard Medical School professor Vadim Gladyshev, announced on Oct. 13 that young mice given ovaries from mice that had lost fertility gave birth to healthy pups1. South Korean outlet CHOSUNBIZ reported the work on Oct. 281.
The ovaries are the organs that make eggs and release female hormones such as estrogen1. As they age, they make fewer usable eggs, which affects fertility and, according to the coverage, women’s wider health1.
The researchers moved ovaries from 13-month-old mice, which they compare to women in their 40s, into 4-month-old mice, which they compare to people in their early to mid-20s1. Four to five months later, those mice gave birth to healthy pups. By then the transplanted ovaries were 17 to 18 months old, an elderly stage for a mouse1.
The evidence so far
To estimate how old the ovaries looked, the team built what it calls an “ovarian clock.” This is a lab measure based on which genes are switched on and on chemical changes to DNA, calibrated on mice of different ages1. When the team checked this clock 4 to 5 months after the transplants, older ovaries placed in young mice had become younger on the measure. Young ovaries placed in older mice had become older1.
The team also compared these results with a control group. When older ovaries were placed in mice of the same age, they did not become younger1. Inflammation, the body’s damage-and-repair response, moved the same way as the clock. It went down in older ovaries placed in young mice and went up in young ovaries placed in older mice1.
The researchers said the gene and signaling changes in the older ovaries placed in young mice looked similar to the changes seen with treatments that make mice live longer, such as eating much less (calorie restriction) or the drug rapamycin1. Rapamycin is an immune-suppressing drug used in organ transplants. It has extended lifespan in worms and mice1.
The study also tested the reverse direction. Older mice aged 17 to 18 months that received young ovaries showed better overall health, the team said, and they gave birth1. The young ovaries aged on the clock measure, but not as far as old ovaries. Meanwhile, the measured ages of the mice’s brain, liver and uterus went down1.
First author Sharif Iqbal, a postdoctoral researcher, described the results this way1:
“An organ’s biological age is not fixed at the time of transplantation but responds to the host body.”
He also said1:
“Young ovaries lowered the biological age of the brain, liver and uterus of aged recipient mice.”
Iqbal called this “evidence that the ovaries play a bigger role in aging and physiology than we thought”1.
What it does not show yet
Several limits apply to this study:
- Mice, not people. All the results come from mice. Comparing mouse ages to human ages, such as 13 months to a woman in her 40s, is a rough guide, not a direct match1.
- Not yet reviewed. The paper was posted before formal publication in a journal. Outside experts have not yet checked its methods or conclusions1.
- Numbers not reported. The coverage did not say how many mice were in each group, how many pups were born, or how often the transplants worked.
- Lab measures of age. “Younger” here mostly means a younger reading on the team’s own ovarian clock and lower inflammation. A clock reading is not the same as a longer or healthier life, and the coverage did not report lifespan results.
- Translated coverage. The main report was translated by AI from Korean, according to the publisher1. Details may shift once the full paper is read in the original.
The study also does not identify what in a young body causes the change. The researchers said that if those signals can be found, it might one day be possible to make ovaries younger without a transplant1. That idea has not been tested.
Who is behind it
The work comes from Gladyshev’s group at Harvard Medical School, with Iqbal as first author1. It builds on another study from the same lab. In September, Gladyshev reported that hearts transplanted in mice and in humans changed in line with the age of the person or animal receiving them1. The coverage lists two bioRxiv papers as references, one from September and one from October1.
The sources did not say who funded the ovary study or whether any author has company ties.
How it fits the field
Age-related decline in fertility is a large and active research area. Other work has focused on the egg itself. Researchers at Germany’s Max Planck Institute reported that adding a protein called Shugoshin 1, which falls with age, to eggs donated by fertility patients lowered the rate of chromosome errors from 53% in untreated eggs to 29%2. Melina Schuh, who leads that work and co-founded the company Ovo Labs to develop it, said the method could “nearly halve the number of eggs with [abnormal] chromosomes”2. Mexico Business News noted that this approach would not extend fertility beyond menopause2.
The size of the problem shows in the numbers. In the United Kingdom, the birth rate per embryo transferred falls from 35% for IVF patients under 35 to 5% for women aged 43 to 442.
Separately, some fertility clinics already sell what they call “ovarian rejuvenation.” This usually means platelet-rich plasma (PRP), a concentrate made from a patient’s own blood and injected into the ovaries, or stem cell treatments34. A Hindustan Times article described these as techniques that, “if proven beyond its experimental stage,” may benefit women with low ovarian reserve4. In the same article, Dr Sonia Malik of Nova IVF Fertility said ovarian PRP “does not produce any side effects” and is “becoming more popular”4. A Mumbai clinic’s blog claims that around 30 to 40% of women over 40 may see improved ovarian markers after such treatment3. The sources here did not include independent trials to check these claims.
The Harvard mouse work is different from these clinic treatments. It does not test an injection. It asks a more basic question: how much of an ovary’s aging comes from the ovary itself, and how much comes from the body around it.
What to watch next
- Peer review. Whether the paper is accepted by a journal, and whether reviewers ask for changes.
- Full numbers. How many mice took part, how many births there were, and how consistent the results were.
- The signals. Whether the team identifies which signals in a young body are tied to the younger readings. The researchers say this could point toward ways to keep egg quality and ovarian function for longer1.
- Replication. Whether other labs see the same effects with their own measures of age.
For now, the finding is an early lab result in mice. It fits a pattern the same lab reported for hearts. It has not been tested in women.
