Impact of organ preservation using HTK for graft flush and subsequent storage in UW in rat kidney transplantation

BACKGROUND: In kidney transplantation, preservation has a significant influence on organ function. Since previous reports have indicated a benefit of combining histidine-tryptophan-ketoglutarate (HTK) and University of Wisconsin (UW) solution, we evaluated the effects of initial flush with low viscosity HTK, followed by storage in UW. MATERIAL AND METHODS: Kidneys from inbred Lewis rats were procured using HTK or UW for initially perfusion and re-flushed after 30 min with either solution. In a third group, after perfusion with HTK, organs were re-flushed with UW. Organs were stored for 16-24 h (4 degrees C). Study parameters were high-energy phosphates, histology, apoptosis, recipient survival and urine excretion of 15-F2t -isoprostanes (oxidative stress marker). RESULTS: Prior to transplantation, tissue ATP/ADP concentrations were: HTK/UW > UW-only > HTK-only. In transplanted kidneys, histological damage was highest after preservation in HTK-only. Twenty-four hours after transplantation (24 h cold ischemia time - CIT), cleaved-PARP was most abundant using UW-only. 16 h of CIT resulted in higher urine concentrations of isoprostanes in the order HTK-only (368 +/- 308) > UW-only (157 +/- 105) > HTK/UW (67 +/- 26), and was lower in HTK/UW after 24 h of CIT (146 +/- 38) vs. UW-only (507 +/- 33 pg/mg creatinine). Survival (24 h CIT) was significantly reduced, and percentage of initial non-functioning (INF) kidneys highest in HTK-only (2.6 +/- 0.3 days, 100%), compared to UW-only (13 +/- 4.4 days, 75%) and HTK/UW (18.5 +/- 4.6 days, 33%). CONCLUSIONS: In long-term preservation, UW is superior over HTK. However, our results indicate that perfusion with HTK prior to storage in UW may improve the results of UW alone which is reflected by better survival, lower rate of INF, higher cellular energy conservation and a decrease of free radicals.