Prefabrication of a neo-endocrine organ: a rat model

Previous work in the field of flap prefabrication has demonstrated that many tissues, including skin, bone, cartilage, muscle, and composite tissue, can be neovascularized with a carrier flap and transplanted to a distant site using microvascular technique. We have recently shown in a rat model that islets of Langerhans survive in large numbers when transplanted into a groin-based fasciovascular pedicled (FVP) flap. In the current study, we examined whether sufficient islet tissue can be transferred using microvascular free transfer of islet-containing flaps to reverse experimental diabetes. In the first phase of the experiment, islets from two Lewis rat donors were transplanted into the FVP flap of an isogeneic diabetic animal. Within 5 days, reversal of diabetes was noted in 4/4 experimental animals and in 0/4 control animals. In the second phase of the experiment, islet-FVP flaps were created in nondiabetic "carrier" animals. After 2 weeks the islet-containing flaps were harvested and transplanted to recipient diabetic Lewis rats using microvascular free transfer technique. Reversal of diabetes was noted within 10 days of free-flap transplant, and the diabetic state returned following removal of the flaps. Although preliminary, these results demonstrate that fasciovascular flaps can act as vehicles for the creation and transplantation of a functional neo-endocrine pancreas.