Differentiation of endometrial stromal stem cells into osteoblasts and adipocytes in vitro

Objective: To investigate the multilineage differentiation capacity of stromal stem cells isolated and cultured from human endometrial tissues. Methods: Single-cell suspensions of endometrial stromal stem cells were obtained from hysterectomy tissues of women experiencing normal menstrual cycles. Purified stromal stem cell suspensions were then obtained by selecting cells with a further round of magnetic bead sorting using anti-EpCAM-coated Dynabeads. Rare human endometrial EpCAM-stromal stem cells were screened by inverted microscope each day and identified by flow cytometer. Then the cells were cultured in osteoblast-inducing culture medium, and osteoblast phenotype was assayed with alizarin red staining. The passage cells were cultured in adipogenesis-medium and stained with oil red O for identification. Results: Endometrial stromal stem cells grew as adherent cells and presented fibroblast-like in vitro, and could stably proliferate and be passed. The cells changed from fibroblast-like into ellipse after osteoblast-inducing cultivation. After induction for 21 d, alizarin red staining demonstrated the formation of mineralized nods in extracellular matrix. Under the inverted microscope, there existed significant lipid drops around the cell nucleus after adipogenesis-inducing cultivation for 21 d and detected by oil red O. Conclusion: Endometrial stromal stem cells can be induced to be osteo-inducing and adipogenisic, suggesting that the cells have the multilineage differentiation.