Angiogenesis Following Three-Dimensional Culture of Isolated Human Endometrial Stromal Cells

Background: Endometriosis is the presence of endometrial tissue outside of the uterine cavity and is the most common gynecologic disorder in women of reproductive age. We have preliminary evidence that in the presence of a 3-dimensional (3-D) fibrin matrix, human endometrial glands, stroma, and neovascularization can develop in vitro, mimicking the earliest stages of endometriosis. The aim of the present study was to determine if angiogenesis can be developed in a 3-D culture of human stromal cells in vitro. Materials and Methods: This was an in vitro study of human endometrial biopsies in 3-D culture of fibrin matrix and conducted at a university affiliated infertility center. Biopsies were taken from ten normal ovulating women undergoing infertility treatment. The samples obtained from fundus of the uterine cavity were minced, stromal cells isolated and placed in a 3-D fibrin matrix culture system. Degree of proliferation of stromal cells, invasion of the fibrin matrix, gland formation, vessel sprouting and immunohistochemical characterization of cellular components were recorded. Results: Three-dimensional culture of human stromal cells formed sheets of cells in the fibrin matrix. By 3-4 weeks, endothelial cell branching was observed and rudimentary capillary-like structures formed and endothelial cells confirmed by CD31 immunostaining. Conclusion: These data show that stromal cells from endometrial explants can proliferate and invade a fibrin matrix in vitro generating new vessels. This procedure represents a controlled, quantifiable model for the study of angiogenesis during the menstrual cycle, and in conditions such as endometriosis and cancer.