The impact of sirolimus on hepatocyte proliferation after living donor liver transplantation

BACKGROUND

There is a lack of data on the use of sirolimus after partial liver transplantation, especially regarding its impact on post-transplant regeneration.

METHODS

We reviewed adult living donor transplantations, with de novo sirolimus (n = 7) and without sirolimus (n = 21). Liver biopsies were stained for KI-67, a proliferation marker. Controls included specimens with normal liver parenchyma (n = 13).

RESULTS

Both groups had similar demographics, graft and patient survival and complication rates. During the first six wk and over the whole first year post-transplant, the use of sirolimus was associated with lower levels of hepatocyte proliferation compared to sirolimus-free patients, (overall, 0.3 [0-7.2] vs. 3 [0-49] KI-67 positive hepatocytes per high power field, p ≤ 0.05). The levels observed in the sirolimus group were similar to those seen in non-transplanted control patients with normal parenchyma (0.2 [0-1.3], p = NS). Post-transplant hepatocyte proliferation correlated with the serum levels of sirolimus (p ≤ 0.05), but not with those of tacrolimus or with the dose of mycophenolate mofetil (p = 0.9 and 0.3, respectively).

CONCLUSIONS

These data suggest that sirolimus is associated with decreased post-transplant hepatocyte proliferation. The clinical significance of this observation remains to be fully determined.

Portal venous pressure changes after sequential clinical islet transplantation

BACKGROUND

Sequential pancreatic islet transplantation via the portal vein has led to insulin independence in patients with type 1 diabetes. Complications associated with the injection of islets into the portal vein have been reported; therefore, in this study we sought to further characterize changes in portal venous pressure associated with islet infusion.

METHODS

Pre- and posttransplant portal venous pressures were recorded in 50 consecutive transplant procedures in 26 patients receiving highly purified, heparinized allogeneic islet preparations via a radiologically placed portal venous cannula. Doppler ultrasound scans of the portal vein were completed within 24 hr of transplantation.

RESULTS

Posttransplant portal vein pressures rose significantly with sequential transplantation (12.4 mm Hg vs. 17.3 mm Hg, P <0.05). Portal pressure change correlated significantly with islet packed cell volume (r =0.66, P <0.001) and also with the number of islets transplanted ( r=0.49, P <0.001). Segmental portal vein thrombosis was radiologically detected after two procedures (4%).

CONCLUSION

Multiple sequential islet transplants can be safely performed via the portal vein, provided that care is taken with islet purification and attention is paid to portal venous monitoring.

Small intestinal function following syngeneic transplantation in the rat

Improvements in immunosuppression have led to the use of small intestinal transplantation clinically. Previous studies have suggested that the transplantation process and immunosuppression with cyclosporin independently affect small intestinal function. This study describes the effects of syngeneic small intestinal transplantation and cyclosporine in rats on intestinal permeability and nutrient transport. Orthotopic transplantation of the small intestine was performed between syngeneic (Lewis) rats. Transplanted animals received chronic treatment with cyclosporine (10 mg/kg) or vehicle on alternate days. Sham operated controls received treatment with vehicle. Animals were followed for 60 days monitoring weight gain, feed intake, intestinal permeability, in vivo absorption of dietary fat and carbohydrate, and at sacrifice in vitro transmural flux of 3-O-methyl-D-glucose. Weight gain, feed intake, and absorption of fat and carbohydrate from the diet were not altered by intestinal transplantation alone; transplantation plus cyclosporine treatment caused a slight reduction in dietary fat absorption. Both the transplant and transplant plus cyclosporine groups demonstrated increased permeability to 51Cr-EDTA and mannitol but not lactulose. Jejunal and ileal 3-O-methyl-D-glucose net transmural flux was decreased in both transplant and transplant plus cyclosporin groups. Intestinal transplantation and cyclosporin treatment reduce mucosal glucose transport and increase intestinal permeability. These altered transport characteristics could affect dietary choices and the selection of immunosuppressive drugs during clinical transplantation efforts, however, the overall impact on animal well-being was minimal, and support the continued study of intestinal transplantation for clinical application.