Hudson Institute researchers are closer to finding the cause of endometriosis, a debilitating condition that affects about one in 10 women of reproductive age and more than 730,000 in Australia, after making a world-first discovery of the role endometrial stem/progenitor cells in the disease.
In the study, published in the journal of Reproductive Biomedicine Online, Professor Caroline Gargett, Research Group Head Endometrial Stem Cell Biology and her team sought to show that endometrial stem/ progenitor cells play a role in causing endometriosis, as only these cells have capacity to remain alive for prolonged periods of time and to grow endometrial tissue.
While we know that endometriosis occurs when tissue (endometrium) similar to the lining of the womb grows outside the uterus and causes inflammation, the reason why it happens has remained unclear — until now.
There is currently no cure for endometriosis and the cause is not known.
By identifying the cause, new treatments can be developed that target the cells causing endometriosis.
Endometriosis occurs when cells from the lining of the endometrium (the inner lining of the uterus) establish growths in other areas of the body, usually in the pelvic cavity or on the ovary.
Despite being outside of the uterus, these lesions are still responsive to female reproductive hormones that trigger menstruation, and as result, may bleed during menstruation, causing inflammation, internal bleeding, scar tissue and severe pain.
Symptoms can include severe pelvic pain, infertility, heavy periods and nausea.
Century-old gynaecology theory proven
Professor Caroline Gargett‘s team were able to expand on a century-old gynaecological theory which posited that endometriosis was caused by the retrograde menstruation of endometrial tissue fragments entering the peritoneal (pelvic) cavity by flowing up through the fallopian tubes.
“When a woman menstruates some of that menstrual fluid, which is not just blood but also includes endometrial tissue fragments, goes backwards into the pelvic cavity. We call this retrograde menstruation,” Professor Gargett said.
“We have known this for nearly 100 years, but almost all women — not just those who suffer from endometriosis — experience some retrograde menstruation.” What was needed was to understand what was different between women with and without endometriosis, she said.
The study analysed menstrual blood samples from 41 women, with about half who had endometriosis and the rest were controls, as well as the fluid in the pelvic cavity of these menstruating women. A further 20 were not menstruating women. It took many years to complete due to the difficulty in undertaking laparoscopic surgery by one surgeon on day two of the women’s period.
Professor Gargett and her team not only proved that stem/progenitor cells were getting into the pelvic cavity through retrograde menstruation, but also set out to quantify the shedding of these cells.
“To establish the growth of a tissue somewhere else you need cells that can do that, and the only ones which can do it are stem/ progenitor cells. They are long-lived and can produce tissue of their own – mature cells can’t do that,” Professor Gargett said.
The findings are significant because they show that endometrial cells get shed into menstrual fluid and get transported by retrograde menstruation into the pelvic cavity, and can start an endometriosis growth or lesion.
“Identifying the cause of endometriosis is a key question asked by women with endometriosis and health professionals, because once this is known, new specific drugs can be designed to target the cells causing endometriosis or the process by which they travel to the pelvic cavity to set up endometriosis growths,” she said.
What are endometrial epithelial progenitor cells?
Endometrial epithelial progenitor cells are types of adult stem cells found in the lining of the uterus or womb that are responsible for maintaining the tissue. Their properties include being able to divide and renew themselves but also differentiate to form more mature cells of the tissue.
Why are endometrial stem cells important to endometriosis?
Adult endometrial stem cells are particularly important in rapidly growing tissues and those that undergo regeneration, such as the endometrium. They are rare cells but have now been found in almost all organs of the body.
Endometrial stem/progenitor cells are types of adult stem cells found in the lining of the uterus or womb. They are unspecialised cells that divide and renew themselves but at the same time generate the specialised cells of the organ or tissue in which they reside for the entire lifespan.
Only endometrial stem/progenitor cells have the capacity to initiate an endometriosis lesion outside the uterus. One of the team’s projects is examining the role of endometrial stem/progenitor cells in causing endometriosis.
Funders | NHMRC, RANZCOG
Collaborators | Monash Health, Monash University – Dept of Obstetrics and Gynaecology