In vitro and in vivo grafting of xeno pig fetal liver fragments using ultrafiltration membrane.

Transplantation of xeno fetal liver fragments (FLF) could be an alternative or supplementary therapy for acute and chronic liver failure not resolved by routine medical therapies. However, the xenografts themselves are rejected by the host immune system. To overcome these problems, immunoisolate capsules with various cutoff points, from 50,000 (YM30) to 500,000 (ZM500) were tested for their protective effects on FLF graft survival. In an in vitro study, the capsule with the smallest cutoff size (YM30) had an excellent protective effect on the grafts it contained, and showed the lowest GOT values in the culture supernatant and the normal histological structure. In an in vivo study using rats, the same capsule enabled a FLF graft to survive as long as 21 days, even with severe IgG deposition on and within the graft. In another in vivo study, which used beagle dog, however, it did not improve the natural course of survival of the graft, which had totally degenerated by day 7. In conclusion, 1) Immunocapsules, especially those with the smallest cutoff values, impeded the infiltration of the (xeno) humoral attacking factor, but the blocking effect was not complete, as shown by the immunoglobulin (IgG) deposit on the grafts they contained. 2) The FLFs with capsules survived longer than those without capsules--only in rats, not in beagles. This difference may be attributable to the difference of the extent of humoral or nutritional response to the xenografts.