In Vivo Analysis of the Origin of Capillary Sprout Formation in Angiogenesis of Freely Transplanted Islets of Langerhans

Abstract

The transplantation of isolated pancreatic islets (islets of Langerhans) represents a promising tool to approach a therapeutic strategy for cure of diabetes mellitus (Hering et al., 1993; Federlin, 1993). After free transplantation, however, the islets require the process of angiogenesis and revascularization in order to establish an appropriate nutritional blood supply. Although there is some information on the microvasculature of transplanted islets, including the kinetics of angiogenesis (Menger et al., 1989), orientation of blood flow (Menger et al., 1994), sensitivity to hyperglycemia (Menger et al., 1992), and microvascular rejection (Menger et al., 1993; Vajkoczy et al., 1997; Beger and Menger, 1997), little is known on the origin of these newly formed microvessels, which may involve arteriolar, capillary, and/or venular vessel segments of the host tissue. The lack of this type of information may be due to the lack of appropriate models to study angiogenesis by directly visualizing this dynamic process in vivo.