Experimental transplantation of size-reduced, adult kidneys into pediatric recipients

Renal transplantation in infants is frequently complicated by graft thrombosis and accelerated rejection reactions. We herein tested the hypothesis that the amount of blood required to sustain normal perfusion of an adult renal allograft transplanted into a pediatric recipient would surpass the cardiac output and aortic blood flow of the recipient and that the ensuing low flow in full-size grafts (FSG) would induce a release of thrombogenic substances.

In a porcine renal transplant model, adult FSG were transplanted into pediatric recipients. Macro- and microhemodynamic as well as metabolic data were recorded. Surgically size-reduced grafts (RSG) served as controls.

Donor weight was 55.1+/-4.8 kg and 9.6+/-0.9 kg for recipients. FSG weight was 122+/-16 g and 65+/-14 g for RSG. Blood flow in donor kidneys was 20% higher than the infrarenal aortic blood flow of recipients. After reperfusion, mean arterial pressure in recipients of FSG but not RSG dropped to 64 mmHg, despite an increase in cardiac output by 60%. FSG but not RSG were polyuric and proteinuric. The release of endothelin and thromboxane B2 into the circulation was higher from FSG when compared with RSG (P<0.05 for endothelin after 60 min; NS for thromboxane B2).

After transplantation of FSG into pediatric recipients, the macrohemodynamic limitations of the recipient cause microcirculatory disturbances in the graft, which contribute to the release of vasoconstrictive and prothrombotic substances and an impaired early graft function. Some of those effects can be ameliorated by surgically size reducing the renal graft.