High osmolality-low pH flush solutions improve renal transplant function in rats

Area of Science:

• Nephrology
• Transplantation Biology
• Surgical Research

Background:

• Kidney transplantation faces challenges with reduced inulin clearance post-surgery.
• Warm ischemia and rejection contribute to impaired renal function after transplantation.
• Inbred rat models minimize genetic variability in transplantation studies.

Purpose of the Study:

• To investigate the impact of preservation solution composition and pH on transplanted kidney function.
• To identify optimal conditions for flushing donor kidneys to mitigate ischemia-reperfusion injury.
• To assess renal function using inulin clearance in a rat kidney transplant model.

Main Methods:

• Utilized inbred Brown Norway rats for donor and recipient pairs to prevent rejection.
• Flushed donor kidneys with various ice-cold solutions: saline, saline with mannitol (200-400 mM), and buffered solutions at different pHs (5.7, 6.4, 7.4).
• Transplanted kidneys into unilaterally nephrectomized recipients and evaluated function via inulin clearance one week post-transplant.

Main Results:

• Transplanted kidneys flushed with saline alone showed significantly reduced function (inulin clearance ratio 0.46).
• Adding 200 mM mannitol to saline improved function (ratio 0.89).
• Flushing with 200 mM mannitol and phosphate buffer at pH 5.7 restored function to control levels (ratio 0.97), indistinguishable from native kidneys.

Conclusions:

• Acidic pH (5.7) combined with mannitol in flush solutions is crucial for preserving transplanted kidney function.
• Optimized preservation solutions can effectively mitigate warm ischemia-induced damage in rat kidney transplantation.
• This study provides a basis for improving organ preservation protocols in transplantation.