title: Higher expression of vascular endothelial growth factor (VEGF) and its receptor VEGFR-2 (Flk-1) and metalloproteinase-9 (MMP-9) in a rat model of peritoneal endometriosis is similar to cancer diseases.
abstract: BACKGROUND
  Endometriosis is a common disease characterized by the presence of a functional endometrium outside the uterine cavity, causing pelvic pain, dysmenorrheal, and infertility. This disease has been associated to development of different types of malignancies; therefore new blood vessels are essential for the survival of the endometrial implant. Our previous observations on humans showed that angiogenesis is predominantly found in rectosigmoid endometriosis, a deeply infiltrating disease. In this study, we have established the experimental model of rat peritoneal endometriosis to evaluate the process of angiogenesis and to compare with eutopic endometrium.
  
  
  METHODS
  We have investigated the morphological characteristics of these lesions and the vascular density, VEGF and its receptor Flk-1 and MMP-9 expression, and activated macrophage distribution, using immunohistochemistry and RT-PCR.
  
  
  RESULTS
  As expected, the auto-transplantation of endometrium pieces into the peritoneal cavity is a well-established method for endometriosis induction in rats. The lesions were cystic and vascularized, and demonstrated histological hallmarks of human pathology, such as endometrial glands and stroma. The vascular density and the presence of VEGF and Flk-1 and MMP-9 were significantly higher in endometriotic lesions than in eutopic endometrium, and confirmed the angiogenic potential of these lesions. We also observed an increase in the number of activated macrophages (ED-1 positive cells) in the endometriotic lesions, showing a positive correlation with VEGF.
  
  
  CONCLUSIONS
  The present endometriosis model would be useful for investigation of the mechanisms of angiogenesis process involved in the peritoneal attachment of endometrial cells, as well as of the effects of therapeutic drugs, particularly with antiangiogenic activity.
authors.affiliation: Programa de Pesquisa em Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Cidade Universitária-Ilha do Fundão, 21941-590 Rio de Janeiro, RJ Brazil.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Machado
authors.forename: Plínio T
authors.initials: PT
authors.lastname: Berardo
authors.forename: Celia Y
authors.initials: CY
authors.lastname: Palmero
authors.forename: Luiz E
authors.initials: LE
authors.lastname: Nasciutti
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004715:Endometriosis / Q000378:metabolism* / Q000473:pathology; D005260:Female; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D009389:Neovascularization, Pathologic / Q000473:pathology; D010532:Peritoneal Diseases / Q000378:metabolism*; D051381:Rats; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism*
chemical_list: D042461:Vascular Endothelial Growth Factor A; D040301:Vascular Endothelial Growth Factor Receptor-2; D020780:Matrix Metalloproteinase 9