Stem cells in endometrium and endometriosis.

Endometriosis is a common chronic gynecological disease that is classically defined by the presence of endometrial stromal and glandular tissues outside the uterine cavity. Pelvic pain and infertility are the nonspecific but the most common symptoms of the disease; however, no currently definitive treatment has been developed since its pathogenesis has not been completely understood. Currently, none of the proposed conventional theories can explain all aspects of endometriosis. Recent evidence supports the presence of endometrial stem/progenitor cells and their possible involvement in endometrial regeneration and differentiation. The stem cell theory is a new hypothesis which may clarify the underlying pathophysiologic mechanisms of endometriosis. However, this theory could not only account for an alternative pathogenic mechanism of endometriosis but could also be involved in all conventional theories. This article will review the evidence for the presence of endometrial stem/progenitor cells, their possible sources and their possible involvement in the pathogenesis of endometriosis.