Endometriosis is a chronic health condition in women where cells from the lining of the uterus grow outside the uterus (such as the ovaries or fallopian tubes). Endometriosis is common, occurring in up to 11% of women of childbearing age. The disorder can cause pain, irregular bleeding, and infertility. No permanent cure is available for the condition, although pain relievers, hormone treatments, and surgery can provide at least temporary relief.
Because scientists think that inflammation may be important in developing endometriosis, they studied whether all-trans-RA could affect endometriosis in mice. RA is a nutrient the body makes from vitamin A, and it is known to have an anti-inflammatory effect.
Researchers supported by the Fertility and Infertility Branch developed endometriosis in mice by injecting endometrial tissue into the body cavity. The injected endometrial tissue produced green fluorescent protein so, under the correct light, researchers could accurately identify and count endometrial lesions. One half of the injected mice were treated with RA; the other half received a placebo. At day 14 after tissue injection, the scientists evaluated the endometrial lesions.
The RA-treated mice had significantly fewer endometrial lesions, significantly fewer lesions that had developed their own blood supply, and significantly less lesion volume than the placebo-treated mice. The amounts of two proteins associated with inflammation were also significantly lower in the treated mice. These results suggest that RA may hold treatment value for women with endometriosis (PMID: 22464761).