Side Population Cells in Human Adenomyotic Lesions Display Characteristics of Endometrial Stem Cells

Abstract

Introduction: The precise etiology and physiopathology of ademyosis is still unknown. The aim of this research is to in- vestigate if stem cells are found in adenomyosis and to characterize the role of adenomyotic lesion-derived side population (SP) cells in pathogenesis of adenomyosis. Methods: We recruited 31 women (range 37-48 years) treated by hysterectomy for adenomyosis. Adenomyotic samples were collected and The SP cells in the tissues were identified by flow cytometry. ATP-binding cassette transporter 2 + (ABCG2 + ) cells were isolated from human adenomyotic samples by magnetic activated cell sorting (MACS), further sub- jected to colony formation, induced differentiation in four conditions and mobility/invasion assay. The cell lines generated from ABCG2 + cells were analyzed by immunofluorescence, quantitative real-time PCR and western blot analysis. Results: The side population represents 1.59±0.48% of the total cell population in adenomyotic lesions. Cloning efficiency of the ABCG2 + cells was 11.27±1.74%. When co-cultured with endometrial cells, ABCG2 + cells differentiated into endo- metrium-like cells. Moreover, if 17β-estradiol was administrated to the co-culture system, a significantly higher efficiency of differentiation was detected (P<0.05). ABCG2 + cells in co-culture system displayed a higher efficiency of differentia - tion, compared to that in culture without feeder cells (p<0.05). The wound closure and transwell assays demonstrated that 17β-estradiol stimulates the migration/invasion of ABCG2 + cells in a dose-dependent manner, with a peak effect at a concentration of 10 -8 M. Conclusions: The adenomyosis-derived ABCG2 + cells display stem cell-like properties and may be involved in the patho- genesis of adenomyosis.