The blood shed during women's menstrual cycles may provide a new type of stem cell that could develop into many types of human cells, say researchers.

Every month, a fertile woman sheds her uterine lining and then re-grows a new one during the endometrial phase of the menstrual cycle. Scientists have long speculated that something like stem cells must be helping the cells of the uterine lining, or endometrium, re-grow so quickly.

Recent research has indicated that the uterine lining is indeed a rich source of adult stem cells. But there have been questions about how to harvest those cells.

Now, a small, recently published study has found that endometrial stem cells are still present in menstrual blood.

Xiaolong Meng of the Bio-Communications Research Institute, a private research institute in Wichita, Kansas, has led a team who studied cells taken from the menstrual blood of two women.

The team says they found cells that behaved very much like stem cells:

  • They replicated themselves easily
  • They were able to differentiate themselves into many different cell types under the right conditions
  • They showed characteristic cell surfaces of stem cells.

The team found that the cells doubled about every 19.4 hours, proliferating more rapidly than the stem cells harvested from umbilical cords, called mesenchymal cells.

The researchers were also able to develop menstrual blood cells into at least nine different cells, including heart, liver and lung cells."

The researchers conclude that the cells -- which they are calling endometrial regenerative cells -- could be cultured at a large scale and hold many potential uses.

"We have many problems with our current methods of stem cell therapy, like those taken from bone marrow. They may be rejected by the recipient and/or have limited potential to generate new tissue," said Meng.

"Now we've found a possible new way to overcome these difficulties by using cells from menstrual blood."

The findings are published in the Journal of Translational Medicine.

Although the potential therapeutic uses for menstrual stem cells are unclear, a U.S.-based company has already launched a service to allow women to collect and cryopreserve their menstrual blood.

The website for the service, called C'elle, says menstrual stem cells have the potential of providing women "with a broad range of personalized regenerative medicine."