DSC analysis of cryopreservation on the structure of porcine aortic biograft as a function of storage time

The utilization of cryopreserved human allografts is a recommended option in the septic vascular surgical field, if autologous graft is not available. These grafts are subjected to deep freezing and stored at − 80 °C until further utilization. The goal of our investigation was to determine the effect of cryopreservation on the structure of vessel wall as a function of storage time, using freshly excised porcine aortic grafts. The samples were subjected to deep freezing and cryopreservation at − 80 °C. Following immediately, 1, 2, 4, 6, 8 and 12 weeks after cryopreservation, differential scanning calorimetry (DSC) and routine histological examination were performed, comparing the structure of frozen grafts to fresh, native aortic wall. Light microscopy evaluation did not show significant changes in the structure of aortic wall at different time points; however, DSC measurements demonstrated a systematic decrease in the thermal stability up to the 6th week and then improvement and stabilization regarding this parameter till the 12th week. Our histological data suggest that cryopreservation causes only minor alteration in the microstructure of fibres in the first three months; thus, the utilization of deep-freeze biological grafts with this short storage time could give favourable outcome.