Multi-Scale Mechanics of Cryopreserved Human Arterial Allografts Across a Six-Month Period

Operating under septic conditions poses significant challenges in vascular surgery. Infection is a serious risk when handling synthetic vessel prostheses and is one of the most dreaded complications. In the event of graft infection, an infection-resistant alternative is necessary. Cryopreserved vascular allografts offer a suitable alternative to replace an infected vessel or a section of a synthetic graft. However, there are no international guidelines for the preparation, storage, and thawing of such vessel grafts. Here, we aimed to investigate the mechanical properties of human cryopreserved arteries across multiple scales, ranging from nanonewton to newton forces and identify the optimal cryogenic storage duration. Human arterial allograft samples were frozen in a slow, controlled process and stored at -80 °C. One native and four cryopreserved samples were examined during a six-month-long period. Dimethyl-sulphoxide was used as a cryoprotectant. The mechanical properties of fresh and stored samples were explored in uniaxial ring tests and nanoindentation. We found no significant changes in the multi-scale mechanical properties during the examination period. Our results indicate that the cryopreserved vascular allografts are mechanically stable for up to six months under cryogenic conditions; hence, they represent ideal samples in vascular surgery.