ASSESSMENT OF THE LONGEVITY OF THE LIVER USING A RAT TRANSPLANT MODEL

To assess the longevity of the liver, arterialized, orthotopic liver g rafts were performed using syngeneic male BN/BiRij rats, Young (5-mont h-old) livers were transplanted into B-month-old recipients (group I, n = 27), and old (28-month-old) livers were transplanted into 5-month- old rats (group II, n = 28). Recipient survival after transplantation was similar in both groups. The average age of the livers at the time of death was 16.7 months in group I and 39.1 months in group II, Four of the livers in group II survived for more than 4 years (48.1 to 52.4 months), Early deaths (less than 1 year) after transplantation were m ost commonly caused by biliary obstruction and cholangitis in both gro ups, Late deaths (more than 1 year) after grafting were mainly from he art failure or tumors, None of the animals died of liver failure or li ver disease. Weight gain in the rats, total serum protein levels, and alanine transaminase levels after transplantation did not differ signi ficantly between the two groups, There was a trend for the histologica l features of aging of the liver-fibrosis, bile duct proliferation, an d pigment deposition-to become more prevalent as the livers became ver y old (mean age, 46 months). Nevertheless, typical aging changes, as i ndividual findings, were absent in nearly half of the oldest organs, T he alterations in morphology had no apparent effect on the ability of the livers to sustain the lives of the recipients, The liver of the BN /BiRij rat was capable of surviving far beyond the maximum life span o f BN/BiRij rats, and rats in general, It did not become diseased in th e process.