Modeling the early endometriotic lesion: mesothelium-endometrial cell co-culture increases endometrial invasion and alters mesothelial and endometrial gene transcription.

Objective: To determine the role of peritoneal mesothelial cells (PMCs) in the process of endometrial invasion into the peritoneum and to evaluate gene expression after endometrial-PMC co-culture.

Design: In vitro study.

Setting: University laboratory.

Patient(s): Reproductive-age women without endometriosis.

Intervention(s): None.

Main Outcome Measure(s): The rate of endometrial invasion through modeled peritoneum in the presence and absence of PMCs was evaluated. The influence of endometrial-PMC attachment on the expression of target genes, implicated in the pathogenesis of endometriosis, was examined by using reverse transcription polymerase chain reaction.

Result(s): Endometrial stromal cell (ESC) invasion through invasion chambers coated with Matrigel (MTGL) and with growth factor-reduced Matrigel (GFR-MTGL) was increased 10-fold when a PMC monolayer was present. Endometrial epithelioid cell (EM42) invasion increased greater than threefold through the MTGL and GFR-MTGL-coated membranes when a PMC monolayer was present. Endometrial stromal cell, EM42, and PMC transcription of extracellular signal-related kinase, colony stimulating factor-1, c-fms, and c-Met was increased after endometrial-PMC attachment. Similar changes were not seen when endometrial cells were exposed to PMC-conditioned media and when PMCs were exposed to endometrial cell conditioned media.

Conclusion(s): Peritoneal mesothelial cells increased invasion of ESCs and EM42s through modeled peritoneum. Endometrial-PMC co-culture led to alterations in gene transcription by endometrial cells and PMCs. This study suggests that PMCs contribute to the process of endometrial invasion into the peritoneum.