Introduction: Lack of enough space for safe closure after transplantation leads to the use of fascia and abdominal wall grafts to overcome this problem. Little is known about the immunogenicity of fascial transplants. We have been using an experimental model of fascia transplants in rabbits for the last 4 years. Here we show the results of a subset of 9 pig to rabbit xenotransplants.

Methods: Fascia procurement: a midline abdominal incision in the pig served for a 3 x1 cm fascial graft procurement. The graft was kept at 4ºC in serum (7) or glutaraldehyde (G) (2) and transplanted 24 h later in the rabbits, removing a similar size fascial tissue. Macroscopic examination was also done.

Blood from pigs and rabbits was drawn, and fascial biopsies at 0,14,28 and 90 days, and rabbit spleen after sacrifice.

Donor specific antibodies (DSA) determination was performed by flow cytometry crossmatch (FCM-XM), using F(ab ')2 Donkey Anti-Rabbit IgG PE as secondary antibody. The mean fluorescence intensity ratio (ΔMFI) was calculated as the difference of the test serum MFI with respect to the negative serum (unimmunized rabbit) MFI. ΔMFI> 100 was considered positive. Additionally, a functional assay of cytotoxic capacity was performed in the positive sera by complement-dependent cytotoxicity (CDC-XM).

Results: There were not appropriate blood samples from 2 rabbits. One rabbit died of diarrhea on POD 16. All the transplants had an important reaction at 1 month, with seroma or graft detachment. At 3 months, the G grafts maintained an important reaction, but the other were integrated except one that had a big ventral hernia.

Flow cytometry results were positive in all the surviving rabbits at 30 days, except in those with G treated grafts. At 60 days, 4/4 had negative results (2 of them G treated). The antibodies showed cytotoxic activity by CDC-XM test in all serum tested (3 rabbits).

Conclusions: All the xenografts showed important immune reactivity at 1 month, but this decreased after 3 months, and tissue integration was observed at 3 months except in those treated with G. In this model, the immune reaction seem to decrease after the first month, with good integration of the graft in the majority of animals after 3 months. The G solution used had some other components that could explain the tissue reaction.