Islet transplants in diabetic Lewis rats prevent and reverse diabetes-induced increases in vascular permeability and prevent but do not reverse collagen solubility changes.

The effects of islet transplantation on diabetes-induced increases in vascular permeability and collagen solubility were examined in new granulation tissue vessels and collagen formed after induction of streptozotocin diabetes in male Lewis rats. Albumin permeation was increased by 50% (p less than 0.001) and collagen solubility was decreased by 50% (p less than 0.001) in granulation tissue from untreated diabetic animals as compared with controls. The islet transplants reversed diabetes-induced vascular permeability increases in tissues formed prior to islet transplantation (tissue to blood isotope ratio = 2.1 +/- 0.1 - SD for controls, 3.2 +/- 0.2 for diabetic rats and 2.0 +/- 0.2 for diabetic rats given islets) and prevented permeability increases in new tissues formed following transplantation (tissue to blood isotope ratio = 2.1 +/- 0.1 for controls, 3.3 +/- 0.8 for diabetic rats and 1.9 +/- 0.2 for diabetic rats given islets). In contrast, while islet transplants prevented diabetes-induced decreased collagen solubility in tissues formed after transplantation (controls = 24%, diabetic rats = 12%, and diabetic rats given islets = 24%), collagen solubility in tissues formed prior to islet transplantation was virtually unaffected. These findings indicate that collagen changes induced by the diabetic milieu are not nearly as readily reversed by normalization of the diabetic milieu as (diabetes-induced) alterations in vascular functional integrity.