Human Endometrial Epithelial Cells (EEC) Constitutively Express More Intercellular Adhesion Molecule (ICAM)-1 than Endometrial Stromal Cells (ESC) in Culture

Problem: Intercellular adhesion molecule‐1 (ICAM‐1) is thought to play an important role in pathophysiological processes in endometrial tissue. The aim of this study was to quantify and compare the expression of ICAM‐1 mRNA and protein in cultured endometrial epithelial cells (EEC) versus endometrial stromal cells (ESC). Method of study: EEC and ESC were isolated from human endometrium and cultured. At confluency, ICAM‐1 mRNA was measured by real‐time reverse transcriptase‐polymerase chain reaction, the membrane‐bound form (mICAM‐1) by immunocytodensitometry, and the soluble form (sICAM‐1) by enzyme‐linked immunosorbent assay. Results: At the transcriptional level, we observed a 1.7‐fold increase in ICAM‐1 expression in EEC versus ESC. mICAM‐1 immunostaining in EEC [cell‐relative membrane‐bound signal‐specific optical density (CR‐M‐SOD): 0.056 ± 0.05] was stronger ( P < 0.05) than in ESC (CR‐M‐SOD: 0.009 ± 0.07). EEC were found to secrete more ( P < 0.01) sICAM‐1 ([sICAM‐1] = 15.59 ± 2.96 ng/mL) than ESC ([sICAM‐1] = 5.14 ± 2.61 ng/mL). Conclusions: Cultured EEC constitutively express significantly more ICAM‐1 mRNA and protein than ESC.