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.