Platelet-rich plasma (PRP) and growth hormone did not restore regular cycles in naturally aged rats
Platelet-rich plasma (PRP) and growth hormone did not restore regular cycles in naturally aged rats
On August 26, 2026, the authors posted a preprint describing an experiment in 40-week-old female rats. The rats received PRP from young or old females, or growth hormone for 56 days. None of the treatments restored regular cycles, ovarian measures, and blood hormone levels together.
The preprint examined whether treatment could restore the function of the aging ovary, rather than improve a single tissue marker. PRP is plasma containing a high concentration of platelets and their associated signaling molecules. It was injected directly into the ovaries. Growth hormone is sometimes added to in vitro fertilization protocols. Before treatment, the authors compared 40-week-old rats with 12-week-old rats and confirmed that the older animals had fewer early follicles, the structures in which oocytes develop.
Previous ovarian PRP studies often modeled chemotherapy-induced, ischemic, or other acute injuries. In those experiments, the intervention is tested for its ability to repair tissue after a specific injury. In this study, the authors asked whether PRP or growth hormone could restore reproductive function impaired by aging. Two groups received a single injection of PRP into both ovaries, using plasma from either young or old donors. A third group received growth hormone for 56 days. The control animals underwent the same operation and received a buffered saline solution.
One outcome was the estrous cycle, the recurring sequence of reproductive states in a female rat. During the final eight days of the experiment, a complete cycle occurred in one of 14 control rats, one of 12 rats given PRP from young donors, and zero of 12 rats given PRP from old donors. None of the eight rats in the growth hormone group completed a full cycle. The authors then assessed the cycle alongside ovarian weight, follicle counts, and blood levels of three hormones.
PRP from young donors increased AMH staining in growing follicles. AMH is a hormone produced by cells in these follicles. At the same time, regular cycles did not return, follicle counts did not increase, and blood hormone levels did not change.
“Partial or local changes in the ovary do not amount to genuine restoration of reproductive function.”
In another experiment in aged rodents, inhibiting IL-11, a signaling protein associated with inflammation, reduced ovarian fibrosis (tissue scarring) and improved fertility measures. The current preprint tests whether the effects of PRP and growth hormone combine into the restoration of a regular cycle.
Natural ovarian aging affects follicles, the cells surrounding them, and hormonal rhythms. The authors therefore examined the cycle, ovarian tissue, and hormones together, because restoring function lost with age requires these levels to work in coordination.