Enhancing Vascularized Composite Allograft Supercooling Preservation: A Multifaceted Approach with CPA Optimization, Thermal Tracking, and Stepwise Loading Techniques.

Vascularized composite allografts (VCAs) present unique challenges in transplant medicine, owing to their complex structure and vulnerability to ischemic injury. Innovative preservation techniques are crucial for extending the viability of these grafts, from procurement to transplantation. This study addresses these challenges by integrating cryoprotectant agent (CPA) optimization, advanced thermal tracking, and stepwise CPA loading strategies within an ex vivo rodent model. CPA optimization focused on various combinations, identifying those that effectively suppress ice nucleation while mitigating cytotoxicity. Thermal dynamics were monitored using invasive thermocouples and non-invasive FLIR imaging, yielding detailed temperature profiles crucial for managing warm ischemia time and optimizing cooling rates. The efficacy of stepwise CPA loading versus conventional flush protocols demonstrated that stepwise (un)loading significantly improved arterial resistance and weight change outcomes. In summary, this study presents comprehensive advancements in VCA preservation strategies, combining CPA optimization, precise thermal monitoring, and stepwise loading techniques. These findings hold potential implications for refining transplantation protocols and improving graft viability in VCA transplantation.

Sub-Zero Non-Freezing of Vascularized Composite Allografts Preservation in Rodents.

Ischemia is a major limiting factor in Vascularized Composite Allotransplantation (VCA) as irreversible muscular injury can occur after as early as 4-6 hours of static cold storage (SCS). Organ preservation technologies have led to the development of storage protocols extending rat liver ex vivo preservation up to 4 days. Development of such a protocol for VCAs has the added challenge of inherent ice nucleating factors of the graft, therefore this study focused on developing a robust protocol for VCA supercooling. Rodent partial hindlimbs underwent subnormothermic machine perfusion (SNMP) with several loading solutions, followed by cryoprotective agent (CPA) cocktail developed for VCAs. Storage occurred in suspended animation for 24h and VCAs were recovered using SNMP with modified Steen. This study shows a robust VCA supercooling preservation protocol in a rodent model. Further optimization is expected to allow for its application in a transplantation model, which would be a breakthrough in the field of VCA preservation.