The relationship between reduced functioning kidney mass and chronic rejection in rats

Impact of donor gender on male rat recipients of small-for-size liver grafts

The aim of this study was to assess the impact of donor gender on small-for-size (SFS) liver transplantation in male recipients using a rat model. Adult female or male Lewis rats were used as donors and male Lewis rats as recipients. Size-matched (SM) and SFS liver grafts from either male or female donors were transplanted into male recipients. Animals receiving SFS grafts were sacrificed at postoperative week 1, week 4, and week 12, respectively (n = 6-8 per group), those receiving SM grafts after 3 months. The cumulative survival rate (SVR) in the female-to-male (F-M) SFS group was significantly lower (62%; 13 of 21) compared with the male-to-male (M-M) group (90%; 18 of 20) (P < 0.05). Spontaneous death occurred in the F-M SFS combination either in the early postoperative period (<3 weeks) in animals with confluent hepatic necrosis or in the late postoperative period (>8 weeks) in animals with biliary obstruction. In contrast, no death was observed in the early posttransplantation period after M-M liver transplantation. The relative graft size in the SM F-M group was significantly higher (graft-to-recipient weight ratio [GRWR] 2.40% +/- 0.8%) than in the SFS M-M group (GRWR 1.35% +/- 0.2%; P < 0.001). Regardless of graft size, the outcome was worse in terms of SVR as well as regarding the incidence and severity of biliary complications in F-M compared with M-M liver transplantation. In conclusion, male recipients of female livers had a less favorable outcome irrespective of graft size. Confluent hepatic necrosis as well as biliary obstruction were perceived as consequence of a severe perfusion problem in F-M liver transplantation, which was possibly related to an enhancement of ischemia-reperfusion (I/R) injury by the lack of estrogen in male recipients of female grafts.

Increasing transplant mass results in long-term allograft survival and recovery from transplant vasculopathy

Late allograft rejection due to transplant vasculopathy continues to be a major clinical problem. Increasing the ratio of donor transplant size to recipient weight has been shown to reduce the incidence of late allograft failure. Using a murine pancreas transplant model we have tested the hypothesis that increasing the donor transplant size in a recipient can promote long-term allograft survival by promoting recovery from transplant vasculopathy. Recipients of an allograft that showed extensive vasculopathy were transplanted with a second donor transplant. The effect of the second allograft on the vasculopathy present in the first graft was measured. Transplanting a second allograft reversed all signs of ongoing rejection, including transplant vasculopathy, resulting in long-term survival of the first graft. Vasculopathy was only reversed if the first and second grafts were from the same mouse strain, suggesting an antigen-specific mechanism. However, the recovery of the first graft was not associated with antigen-specific peripheral tolerance.