Cryopreserved small-diameter arterial allografts for arterial by-pass procedures: an experimental study

The search of small-caliber vascular prosthesis for myocardial revascularization and arterial reconstruction has led to an investigation of cryopreserved arterial allografts in a sheep model. Carotid arteries with an internal diameter of 4 mm and length of 10 cm were harvested from donor sheep and soaked immediately in a cold saline solution. Nine arteries were cryopreserved in a nutrient media containing 10% DMSO as cryoprotectant and then were stored in a liquid nitrogen vapor at -150 degrees C to -170 degrees C. In recipient sheep from different species, arterial substitution of a 10 cm segment of carotid artery was realised by implantation of fresh (n = 9) or cryopreserved (n = 9) carotid artery allografts. After 3 months, the allografts were harvested. In both groups: 7/9 were patent at the time of explantation. Components of arterial allograft rejection were observed in most fresh and cryopreserved arteries: intimal thickening with cell proliferation was seen in fresh (3/7) and cryopreserved (4/8) arteries; Loss of smooth muscle medial cells was constant; Adventitia was involved by a marked inflammatory reaction. A non cellular fibrous intimal thickening and presence of large medial calcifications were essentially observed in cryopreserved arteries. In conclusion, these results show that at three months post implantation, there is little difference in the outcome of fresh and cryopreserved arterial allografts. Cryopreservation does not reduce the apparent antigenicity of small diameter arterial allografts.