TRANSPLANTATION OF ALLOGENEIC HEPATOCYTES WITHOUT IMMUNOSUPPRESSION -LONG-TERM SURVIVAL

Background. Hepatocyte transplantation could be an alternative to whol e liver transplantation. Allogeneic hepatocytes are rejected if transp lanted without immunosuppression. The aim of this study was to transpl ant allogeneic hepatocytes in the peritoneum and to protect them from rejection by encapsulation in a new semipermeable membrane. Methods. R at hepatocytes were encapsulated in hydrogel-based hollow fibers, obta ined from AN69 copolymer, before being transplanted into the peritoneu m of rats. Outcome of allogeneic hepatocytes encapsulated in hollow fi bers was compared with that of syngeneic hepatocytes encapsulated in h ollow fibers, with that of free allogeneic hepatocytes, and with allog eneic hepatocytes encapsulated in hollow fibers left open. Cell viabil ity was assessed by erythrosin exclusion, structure by electron micros copy, and function by albumin release. Results. Up to 90 days, viabili ty of allogeneic hepatocytes in hollow fibers was greater than 80%. Th e structure remained normal at electron microscopy. Albumin release wa s 16.5 +/- 0.3 mu g/24 hr/10(6) hepatocytes (day 15), 14.2 +/- 2.0 mu g/24 hr/106 hepatocytes (day 30), 8.8 +/- 0.1 mu g/24 hr/10(6) hepatoc ytes (day 60), and 11.4 +/- 0.3 mu g/24 hr/10(6) hepatocytes (day 90). Free hepatocytes and hepatocytes in hollow fibers left open did not s urvive at day 15.Conclusions. Viability and function of encapsulated a llogeneic hepatocytes were maintained up to 90 days after transplantat ion, without immunosuppression.