The fate of the freeze-preserved xenograft: an experimental study on rabbits, cats, and dogs.

: Freeze-preserved allografts have been used successfully in patients for vascular peripheral replacement, dialysis, and chemotherapy. Freezing of veins seems to decrease or abolish antigenicity by decreasing the viable cellular components of the grafts. To confirm its acceptance and consequently, the high patency rates of freeze-preserved vein grafts, we inserted segments of human veins preserved at -80 degrees Centigrade as arterial substitutes into rabbits, cats, and dogs and studied the morphological changes of these xenografts up to 2 years. In all the groups, the patency rate was satisfactory. In rabbits and dogs, the cellular inflammatory reaction around the grafts and suture lines disappeared after a few weeks; the endothelium was reconstructed at 2 months and a poorly differentiated cellular fibro-collagenous wall with prominent hyalin matrix was observed. In cats, however, the histio-lymphocytic infiltrate persisted in functioning grafts up to 2 years associated with adjacent prominent vascular and nerve proliferation. It is suggested that this inflammatory reaction has no deleterious effect on the graft; on the contrary, it promotes its neovascularisation and innervation. The cat proved to be a good animal model for vascular surgical experiments. Our study proved the poor antigenicity of freeze-preserved venous xenograft. It could, in the future, be used for human arterial substitutes.