The study was conducted by a team of researchers led by Jonathan Tilly at Massachusetts General Hospital (MGH).
As part of the study researchers gave adult female mice treated with infertility-inducing chemotherapy bone marrow transplants from non-treated, healthy adult females either one week or two months after chemotherapy.
Both the males and the donor females were black in coat colour while the recipient females were white-coated. As a result, the coat colour of any pups would indicate the source of egg cells used to make the offspring, with tan coats signifying eggs from the recipients and black coats indicating that the eggs had come from marrow donors.
The study found that out of the 10 females that received bone marrow transplants one week after chemotherapy, 9 achieved several successful pregnancies during the study period and all pups were offspring of the recipients.
Additional experiments indicated that resuming mating sooner after transplantation improved fertility rates. When chemotherapy doses were increased to levels expected to cause death in half the mice, those that also received bone marrow transplants had improved rates of both survival and long-term fertility.
The coat-colour results of the mating trial indicated that the transplanted marrow's contribution to restoring fertility did not involve cells destined to becoming fertilizable eggs.
To further investigate this observation researchers gave chemotherapy-treated females, marrow from transgenic females that expressed a green fluorescent protein (GFP) marker only on germline cells, which were precursor cells involved in producing oocytes.
Researchers confirmed that no immune cells from the germline-only GFP strain contained the marker protein, making it highly unlikely that GFP-labelled cells in the ovaries of females receiving germline-only-labeled marrow were anything other than oocytes.
"Right now, we really don't know exactly what it is in marrow that restores recipient oocyte production and rescues long-term fertility. However, we do know without question that immature oocytes can be generated from cells in adult bone marrow, but they are probably not critical to the fertility rescue observed after the transplants," the authors said.
The findings of the study were published in the August issue of Journal of Clinical Oncology.