腎臓移植の研究 5.腎臓の凍結保存にかんする実験的研究

Abstract

The canine kidneys were freeze-preserved at -90~ -160℃ using liquid nitrogen. The optimum concentration and the condition of infusion and extraction of cryoprotective agent were investigated. The condition of freezing and thawing were also examined. Function of the preserved kidneys were tested by means of extracorporeal circulation method by which direct renal blood flow (DRBF), extraction ratio of para-aminohippurate and sodium thiosulfate (EPAH and EsTS) and clearance of PAH or STS (CPAH and CSTS) were evaluated. Histological changes of the kidneys were examined through the process of procedure. Autotransplantation have been tried with 4 freeze-preserved kidneys. (1) The renal tubular damage occurred even by infusion and extraction of cryoprotectant without freezing, because of the hyper-osmolar gradient. Sufficient blood recirculation of the kidney was not obtained after perfusion of glycerol due to severe outflow block, however this circulating disturbance was steadily diminished by infusion with gradual increase of concentration and extraction with gradual decrease of concentration using 20% DMSO. (2) Evident deep fissures appeared on the kidney at rapid freezing rate exceeding 10℃ per minute, but no injury was produced at slow freezing rate. The best DRBF was obtained in slow freezing and rapid thawing of the kidney which was infused with gradual increase of concentration and extracted with gradual decrease of concentration using 20% DMSO. EPAH and CPAH were good in slow freezing and slow thawing of the kidney, however ESTS and CSTS were good in slow freezing and rapid thawing of the kidney. (3) After cryopreservation, renal function was almost markedly disturbed. Especially tubular function damage was severe, however, glomerular function damage remained slight. (4) Histological changes of the freeze-thawed kidneys showed evident exfoliation and destruction of tubular epithelium, but few changes in glomerular or vascular system. It seems to be difficult to prevent this tubular epithelium injury effectively with the 20% DMSO or 30% glycerol used in this study. (5) The canine kidneys were infused with gradual increase of concentration and extracted with gradual decrease of concentration using 20% DMSO and freezed at slow rate and thawed at rapid rate. After autotransplantation of these 4 kidneys, all autografts resulted in necrosis, and the dogs died of uremia on the 3 to 4th day after contralateral nephrectomy.