Vascularization of endometrial tissue in abdominal cavity – the most important link in the pathogenesis of endometriosis or its vulnerable spot in terms of treatment? (review of literature)

Abstract

In this review, the stepwise mechanism of vascularization of retrogradely torn away endometrial tissue into the abdominal cavity during the formation of endometrioid heterotopy is described. The necessity of the formation of a specific microenvironment and functional rearrangement of endometrial tissue, based on the interaction of endometrial mesenchymal stem cells with peritoneal macrophages, is shown, which is the basis of adaptation to hypoxia and survival in new conditions. Attention is also paid to the similarity of tissue adaptation for endometriosis and tumor growth. The activation mechanisms for the synthesis of a number of angiogenic factors and their significance in the process of vascularization of endometrial tissue, as one of the key links in the pathogenesis of endometriosis, are highlighted. In addition, the example of the peritoneal localization of the endometriosis focus reflects the sequence of the formation of the vascular component of the communication system: an increase in vascular density in the tissue of the implantation area; vascularization of endometrioid heterotopy tissue due to angiogenesis; and the final stage of formation of the vascular network of the endometrial focus - vasculogenesis (as a mechanism for the formation of the microvasculature with the participation of circulating endothelial progenitor cells). Subsequently, the synthesis of angiogenic factors continues and actively contributes to the remodeling and increase in vascular density in the heterotopic tissue. The most important is that the increase in vascular density occurs mainly due to the immature pericyte-unprotected vessels of the microvasculature. These features constitute a fundamental basis for the diagnosis of endometriosis through the qualitative and quantitative determination of some factors in the peritoneal fluid, reflecting activation of vascularization, and for future methods of treating endometriosis by activating an angiostatic effect in the area of the pathologycal focus.