Comparative study of human eutopic and ectopic endometrial mesenchymal stem cells and the development of an in vivo endometriotic invasion model

Objective To elucidate the role of endometrial stem-progenitor cells in the etiology of endometriosis and to develop an animal model to study the invasion ability of endometrial cells. Design Gene expression and cell function studies were designed. Setting Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan. Patient(s) Human endometrial mesenchymal stem cells (MSCs) were isolated from 22 different endometrium biopsies after surgery for treatment of endometriosis. Intervention(s) Endometrial MSCs developed from eutopic and ectopic endometrial tissues. Main Outcome Measure(s) Characterization of MSC phenotypes (i.e., differentiation induction and gene expression by flow cytometric analysis); comparative study of cell functions (i.e., cell growth, migration, and invasion assays). The invasion of implants in an animal model was examined by histologic staining. Result(s) We compared the characteristics of eutopic and ectopic endometrial MSCs from the same endometrial donor. Although both showed similar mesenchymal cell phenotypes, ectopic endometrial MSCs showed distinctly greater ability of cell migration and invasion. Furthermore, in an in vivo cell invasion model using cells grown in scaffold and transplantation in immune-deficient mice, the ectopic endometrial MSCs were found to form many new blood vessels and to invade surrounding tissue. Conclusion(s) These results indicate unique invasion and angiogenesis characteristics of ectopic endometrial MSCs that may underlie the pathogenesis of ectopic endometriosis. The animal invasion model will be useful for future characterization of endometrial MSCs.