Direct visualization of cortical peritubular capillary of transplanted human kidney with reperfusion injury using a magnifying endoscopy

Background. We developed a direct imaging system of renal microcirculation by a magnifying-endoscopy that enables visualization of the movement of erythrocyte in glomerular and cortical peritubular capillary (CPC). We investigated the microcirculation of CPG in the early phase of both living- and cadaveric-donor transplant kidneys. Methods. Erythrocyte velocity in CPC were monitored and measured in 20 renal transplants at 20, 60, 90, and 120 minutes after reperfusion. The kidney grafts came from 11 living donors and 9 non-heart-beating cadaveric donors. Results. In living-donor transplants, erythrocyte velocity in CPC at 20 minutes after revasculatization declined to one third of baseline value just before nephrectomy and recovered to the prenephrectomy value 120 minutes after reperfusion. In contrast, it continued to be disturbed for 90 minutes in cadaveric-donor transplants. Erythrocyte velocity in CPC more significantly deteriorated in cadaveric transplants than in those of living transplants at 20 through 60 minutes after the revascularization. In living-donor transplants, erythrocyte velocity did not correlate with donor age, both warm (WIT) and cold ischemic time (CIT), time to the initial urination, and best creatine clearance. In the cadaveric transplants, ischemic time, both WIT and CIT, did not correlate with the erythrocyte velocity. However, donor age, duration of acute tubular necrosis, and best creatine clearance after transplantation significantly correlated with the erythrocyte velocity. Conclusion. The measurement of erythrocyte velocity in CPC is a reliable method for predicting the recovery of renal function and reserved renal function of kidney allografts undergoing prolonged ischemia.