In vivo analysis of angiogenesis in endometriosis-like lesions by intravital fluorescence microscopy

Objective: To establish a novel endometriosis model that allows for repetitive in vivo analyses of angiogenesis in ectopic endometrtial tissue. Design: Intravital fluorescence microscopic study. Setting: Institute for Clinical and Experimetnal Surgery, University of Saarland. Animal(s): Female Syrian golden hamsters equipped with skinfold chambers. Intervention(s): Large (0.5 mm(2)) and small (0.1 mm(2)) endometrial fragments were mechanically isolated and transplanted autologously into skinfold chambers of untreated hormonally synchronized or bilateral ovariectomized hamsters. Main Outcome Measure(s): Angiogenesis, vascularization. and microhemodynamics were analysed over a 14-day period. Result(s): Inuntreated controls, endometrial fragments developed complete microvascular networks during the experimental observation period. Interestingly, microvascular blood flow was higher in large than in small fragments. Histologic examinations revealed proliferating endometriosis-like lesions with dilated endometrial glands surrounded by a richly vascularized stroma. Vascularization of endometrial fragments in synchronized animals did not differe from that of untreated controls. In contrasts, endometrial fragments in ovariectomized animals showed a delay in angiogenesis adn a significantly decreased blood perfusion, indicating the essential role of ovarian estrogens for ectopic vascularization and perfusion of endometrial tissue. Conclusion(s): This novel model od endometrial tissue transplantation is a useful experimental approach, not only to focus on the in vivo pathogenesis of endometriosis but also to develop antiangiogenic strategies for teh treatment of this disease.