The "monthly curse" may be anything but: menstrual blood appears to be a rich and easily accessible source of adult stem cells, claim two competing research groups.
Each month, after a woman's uterine lining is shed, it has to be rebuilt in preparation for a fertilised egg. This feat involves growing the billions of cells making up the 5 millimetre-thick lining in just seven days.
Recent research has indicated that the uterine lining, or endometrium, is a rich source of adult stem cells. But retrieving those cells is as invasive as harvesting adult stem cells from other sources, such as bone marrow.
Now two separate groups say they have found these endometrial stem cells in menstrual blood.
Both groups say the cells in question show all the hallmarks of stem cells: they replicate themselves without differentiating, they can be made to differentiate into many different cell types under the right conditions, and they show characteristic cell surfaces of stem cells.
Xiaolong Meng of the Bio-Communications Research Institute, a private research institute in Witchita, Kansas, US, and his colleagues studied cells taken from menstrual blood from two women.
The researchers say they found cells that proliferated more rapidly than mesenchymal stem cells derived from umbilical cords, doubling about every 19.4 hours. They also showed classic adult stem cell markers, as well as a few embryonic stem cell markers, such as one "master" marker called Oct-4.
The researchers also found that their cells could be coaxed into differentiating into nine different types of cells, including fat, muscle, bone and nerve.
Julie Allickson, chief scientist at Cryo-Cell International, the world's biggest cord blood bank, based in Oldsmar, Florida, US, has also found stem cells in menstrual blood, although the work remains unpublished. Like Meng, she says the cells are highly proliferative, differentiate into at least five separate lineages and express stem cell markers.
What is more, Cryo-Cell has patented a collection, processing and freeze-storage technique, called "C'Elle", which enables women to preserve their own menstrual stem cells. Although at this point the stored cells are intended for use by only the woman herself, there is speculation that the cells may help others as well. "There are indicators that they could be used for first or second degree relatives, or beyond," says Allickson.
Caroline Gargett, of Monash University in Victoria, Australia, who first identified endometrial stem cells in the uterine lining, admits she is a little surprised. "I'd always thought the body wouldn't want to be shedding too many stem cells," she says. Both sets of findings are "very interesting and very significant", she says.
Cryo-cell has partnered with four outside stem-cell researchers to examine potential use of the cells in treating heart disease, diabetes, and spinal cord injury. Meng's group is also investigating the cells' use in diabetes.
Journal reference: Journal of Translational Medicine (DOI: 10.1186/1479-5876-5-57)