Background: The aim was to measure the capillary blood pressure in transplanted human islets.
Methods: Human islets were isolated at the Central Unit of the beta-cell Transplant in Brussels, Belgium. After transport to our laboratory, the islets were implanted under the renal capsule of normoglycemic nude mice. Two weeks later the capillary and venous blood pressures in the islet graft and adjacent renal parenchyma were measured with a micropuncture technique.
Results: Capillary blood pressure was approximately 5-8 mmHg in both graft and renal capillaries: twice as high as in native islets. Venous blood pressures were similar (4-5 mmHg) in the veins draining the graft and in the renal interlobular veins. All veins leading from the graft emptied into the renal parenchyma, that is, into interlobular veins.
Conclusions: The capillary hypertension seen in transplanted human islets is probably necessary to secure adequate drainage through the renal veins. Whether this contributes to the poor results of long-term islet graft survival is unknown.