ASRM2015: Endometriosis may infiltrate the entire body

Researchers at Yale University presents data at the 71st Annual Meeting of the ASRM that it is possible for endometrial cells to migrate to the brain – and possibly the entire body – suggesting that stem cells play a role.

The existence of endometriosis in every organ in the human body, except for the spleen, has been observed in humans for a long time [1,2]. Extra-pelvic endometriosis, however, is an area that remains under-researched.

Dr Elham Neisani Samani, Yale School of Medicine

Having encountered numerous women who had endometriosis in unusual places (which clearly would not be explained by retrograde menstruation) Dr Elham Neisani Samani and her team set out to discover what mechanisms might be the cause of this [3].

They induced ectopic endometrial cells in ten healthy mice models (by implanting them with uterine horn fragments from donor mice of a different genetic lineage). Ten control mice underwent sham surgery to mimic the surgical intervention in the active group of mice.

When tissue samples from the subject mice were examined after eight weeks, sections taken from the mice’s brains tested positive for ectopic endometrial cells – in 100% of the mice.

Said Dr Neisani Samani:

Since the migration of cells to the brain occurred in all of the induced mice, this suggests that endometriosis gives off stem cells that then travel to organs outside of the pelvis.

The endometriotic implants may be clinically undetectable, but they are still biologically active and the molecular changes that consequently occur may contribute to inflammation.

It is therefore possible that endometriosis outside of the pelvis may be common, but is currently clinically unrecognised.

What type of endometriosis may this represent?

Professor Hugh Taylor of Yale University explained that peritoneal endometriosis is the most common, though not the only, type of endometriosis. This was the type that was implanted into the mice (which is currently the best animal model we have that mimic the same type of endometriosis as that found in women).

Professor Hugh Taylor, Yale School of Medicine

I’d be surprised if not all women with endometriosis have some of these microscopic implants in their bodies, which may explain some of the symptoms – beyond pelvic pain – that women with endometriosis experience.

These findings may confirm “the syndrome of endometriosis” and lead us towards understanding why we see systemic effects when a woman’s entire body is invaded by endometriosis.

said, Professor Taylor.

Implications for futures studies and treatment of endometriosis

Dr Neisani Samani’s next step is to look at whether these implanted endometrial cells migrate to other organs than the brain.

She and her team then need to characterise the cells and their mechanisms to see if she can discover what it is that “attract” these cells to move to other areas of the body; as well as the possible triggers that may cause the cells to “activate” and cause symptoms.

We need to find out out how these cells cause the damage.

said Dr Neisani Samani.

When asked whether this research implies that medical treatment, rather than surgery, is the way to go for endometriosis, the answer is a resounding “yes!” from both Drs Neisani Samani and Taylor – with the following caveat, however:

Today’s medical treatments are not good enough. We are hopeful that our research can contribute to the development of better – targeted – medical treatments for the different types of endometriosis and its associated symptoms.

They didn’t rule out surgical treatment, but emphasised that when dealing with different types of disease, with different behavioural patterns and consequent symptoms, treatments will invariably vary according to disease type and the woman’s symptoms.

We have a lot to learn still about endometriosis, but today we learned just a little bit more!

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  1. Markham SM et al. Extrapelvic endometriosis. Obstet Gynecol Clin North Am 1989;16:193–219.
  2. Honoré G. Extrapelvic endometriosis. Clin Obstet Gynecol 1999;42:699–711.
  3. Elham Neisani Samani et al. Frequent migration of ectopic endometrial cells to the brain in a murine model of endometriosis. 71st Annual Meeting of the American Society of Reproductive Medicine O-178.
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