Whole Endometrial Fragments Form Characteristics of In Vivo Endometriosis in a Mesothelial Cell Co-Culture System: An In Vitro Model for the Study of the Histogenesis of Endometriosis

Abstract

OBJECTIVE: We have previously reported on the effects of tumor necrosis factor-α (TNF-α) and interleukin-1 (IL-1) on the adhesion of human endometrial stromal cells to peritoneal meso thelial cells in vitro. The relevance of this co-culture system to in vivo endometriosis remains to be established. We contrasted endometrial fragments with endometrial stromal cells to determine their relevance.

METHODS: Human mesothelial cells were isolated from peritoneal fluid from four normal women via Ficoll-Paque gradient centrifugation at 400 × g for 30 minutes and grown in M199 medium containing epidermal growth factor (10 ng/mL) and 10% fetal calf serum. The homo geneous cells were cultured on collagen-coated plates until a monolayer formed. Endometrial stromal cells or whole endometrial fragments, isolated from endometrial tissue of four normal women, were put on the mesothelial monolayer and cultured at 37°C for 24 days. After fixation, the samples were incubated with monoclonal antibody to epithelial membrane antigen, cytokeratin, and vimentin, and processed with standard immunohistochemical techniques.

RESULTS: Observation under phase contrast microscopy revealed that, in this co-culture system, whole endometrial fragments demonstrated characteristic morphology of in vivo endometriosis, whereas isolated endometrial stromal cells did not.

CONCLUSION: Whole endometrial fragments, but not isolated endometrial stromal cells, form morphologically characteristic structures similar to in vivo endometriosis in this co-culture system. It is hoped that this system might be useful for studying certain aspects of the histogenesis of endometriosis. (J Soc Gynecol Invest 1994;1:65-8)