Endometrial stromal cell attachment and matrix homeostasis in abdominal wall endometriomas.

study questionHow does progesterone alter matrix remodeling in abdominal wall endometriomas compared with normal endometrium? SUMMARY ANSWER: Progesterone may prevent attachment of endometrial cells to the abdominal wall, but does not ameliorate abnormal stromal cell responses of abdominal wall endometriomas. WHAT IS KNOWN ALREADY: Menstruation is a tightly orchestrated physiologic event in which steroid hormones and inflammatory cells cooperatively initiate shedding of the endometrium. Abdominal wall endometriomas represent a unique form of endometriosis in which endometrial cells inoculate fascia or dermis at the time of obstetrical or gynecologic surgery. Invasion of endometrium into ectopic sites requires matrix metalloproteinases (MMPs) for tissue remodeling but endometrium is not shed externally. STUDY DESIGN SIZE, DURATION: Observational study in 14 cases and 19 controls. PARTICIPANTS /MATERIALS, SETTING,

methodsTissues and stromal cells isolated from 14 abdominal wall endometriomas were compared with 19 normal cycling endometrium using immunohistochemistry, quantitative PCR, gelatin zymography and cell attachment assays. P values < 0.05 were considered significant and experiments were repeated in at least three different cell preps to provide scientific rigor to the conclusions. MAIN RESULTS AND THE ROLE OF CHANCE: The results indicate that MMP2 and MMP9 are not increased by TGFβ1 in endometrioma stromal cells. Although progesterone prevents attachment of endometrioma cells to matrix components of the abdominal wall, it does not ameliorate these abnormal stromal cell responses to TGFβ1. LARGE SCALE DATA: N/A. LIMITATIONS REASONS FOR CAUTION: Endometriomas were collected from women identified pre-operatively. Not all endometriomas were collected. Stromal cells from normal endometrium were from different patients, not women undergoing endometrioma resection. WIDER IMPLICATIONS OF THE

findingsThis work provides insight into the mechanisms by which progesterone may prevent abdominal wall endometriomas but, once established, are refractory to progesterone treatment. STUDY FUNDING/COMPETING INTEREST(S): Tissue acquisition was supported by NIH P01HD087150. Authors have no competing interests.