MICROVASCULAR PERMEABILITY FOLLOWING COMPOSITE TISSUE-TRANSPLANTATION

The microvascular endothelium and endothelial cells are primary target s during graft injection. this study measured endothelial cell damage by assessing microvascular permeability, and evaluated the role of sur gical trauma during the acute phase of transplant rejection. the autho rs developed an experimental model that allows for simultaneous measur ement of leukocyte activation and albumin leakage to assess endothelia l barrier function exposed to transplantation-induced trauma. Eighteen composite tissue isograft transplantations were performed between gen etically identical rats, and 18 cremaster muscle flaps were subjected to the same ischemic insult as the transplantation group to allow for a control group with which to compare the effects of ischemia without concomitant transplantation trauma. At 24 hours, 72 hours, and 7 days follow-up, microvascular permeability, leukocyte activation, functiona l capillary perfusion, and endothelial edema index were measured in bo th groups. There was a significant increase in the permeability index of the transplantation group at 24 hours follow-up (p = 0.005), with a n increasing trend at 72 hours and 7 days fallow-up (p < 0.001). The p ermeability index; number of rolling, sticking, and transmigrating leu kocytes; and rolling and sticking lymphocytes were significantly great er in the transplantation group at all follow-up points compared with the ischemic control group (p < 0.001). These findings demonstrate the added effect of transplantation trauma to ischemia and reperfusion in jury. We observed increased leukocyte-endothelial interactions and acu te destruction of endothelial cell barrier function during the acute r ejection period after composite limb tissue transplantation.