Scientists have identified a surprising potential source of stem cells: menstrual blood.

Stem cells are transmutable, meaning they have the ability to morph into other types of cells.

Researchers discovered that the endometrial lining of the uterus contains stromal stem cells, which are found in connective tissues, meaning that during a woman's monthly period, cells that have the ability to regenerate are shed.

Scientists believe they could easily collect these menstrual blood stromal cells and use them to create new fat, cartilage, bone, skin, heart and brain cells. They believe the cells have the potential to be used in transplants in which organ tissue needs to be regrown.

"Stromal stem cells derived from menstrual blood exhibit stem cell properties, such as the capacity for self-renewal and multipotency," said Amit N. Patel, director of Cardiac Cell Therapy at the University of Pittsburgh's McGowan Institute of Regenerative Medicine, in a release.

"Uterine stromal cells have similar multipotent markers found in bone marrow stem cells and originate in part from bone marrow."

When researchers grew the cells in the lab, they found that the stromal cells divided rapidly — slower than embryonic stem cells but more than bone-marrow derived cells.

"The preliminary results are extremely encouraging and support the importance of further study of these cells in several different areas including heart disease, diabetes and neurodegenerative disease," said Julie Allickson, vice-president of laboratory operations and research and development at Cryo-Cell International, the company that extracted and analyzed the cells.

The study is published in the current issue of the journal Cell Transplantation.