Platelets are a possible regulator of human endometrial re-epithelialization during menstruation

Problem: The human endometrium periodically breaks down and regenerates. As platelets have been reported to contribute to the tissue remodeling process, we examined the possible involvement of platelets in endometrial regeneration. Method of study: The distribution of extravasating platelets throughout the menstrual cycle was immunohistochemically examined using human endometrial tissues. EM-E6/E7/hTERT cells, a human endometrial epithelial cell-derived immortalized cell line, were co-cultured with platelets, and the effects of platelets on the epithelialization response of EM-E6/E7/hTERT cells were investigated by attachment and permeability assays, immunohistochemical staining, and Western blot analysis. Results: Immunohistochemical study showed numerous extravasated platelets in the subluminar stroma during the menstrual phase. The platelets promoted the cell-to-matrigel attachment of EM-E6/E7/hTERT cells concomitantly with the phosphorylation of focal adhesion kinase. They also promoted cell-to-cell contact among EM-E6/E7/hTERT cells in parallel with E-cadherin expression. Conclusion: These results indicate the possible involvement of platelets in the endometrial epithelial re-epithelialization process.