CRYOPRESERVED SMALL-DIAMETER ARTERIAL ALLOGRAFTS FOR ARTERIAL BYPASS PROCEDURES - AN EXPERIMENTAL-STUDY

The search of small-caliber vascular prosthesis for myocardial revascu larization and arterial reconstruction has led to an investigation of cryopreserved arterial allografts in a sheep model. Carotid arteries w ith an internal diameter of 4 mm and length of 10 cm were harvested fr om 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 -15 0 degrees C to -170 degrees C. In recipient sheep from different speci es, arterial substitution of a 10 cm segment of carotid artery was rea lised by implantation of fresh (n = 9) or cryopreserved (n = 9) caroti d 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 cryopr eserved 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 inflam matory reaction. A non cellular fibrous intimal thickening and presenc e of large medial calcifications were essentially observed in cryopres erved 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 redu ce the apparent antigenicity of small diameter arterial allografts.