Mechanical properties of arteries cryopreserved at -80 degrees C and -150 degrees C

A new protocol for cryopreservation of arteries frozen at -80 degrees C was compared to the reference protocol for cryopreservation at -150 degrees C and to freshly harvested arteries. The aim of the study is to evaluate both protocols as global procedures to freeze and thaw arteries commonly used in tissue banks. Changes in mechanical properties of rabbit common carotid arteries were studied. Vascular segments were tested in vitro under dynamics loading conditions. Pressure and diameter were recorded simultaneously by a high fidelity transducer and an echotracking device, respectively. The pressure-diameter relationship was fitted by the arctangent Langewouters' model and the arterial thickness was derived from histological measurements. Histological sections showed that the fresh and -80 degrees C groups were less damaged by hemodynamic load and histological preparation than the -150 degrees C group (p<0.05). No differences between fresh and cryopreserved arteries regarding the structural (diameter, intimal-media thickness) and mechanical parameters (distensibility, circumferential stress, elastic modulus) were found. The isobaric circumferential stress was reduced in frozen arteries. These results demonstrate that the cryopreservation at -80 degrees C preserves the histological structure and mechanical properties better than the cryopreservation at -150 degrees C, suggesting that the new cryopreservation protocol at -80 degrees C is a method of choice for treating vessel replacement in vascular surgery.