Short-term supercooling enables prolonged suspended animation of murine neonates

Time plays a central role in mediating survival in trauma; the first 60-minute window following traumatic injury is known as the "golden hour". Subzero non-freezing or 'supercooling' (SC) has been successfully applied to extend organ preservation in similar time-sensitive context of transplantation. However, no studies have attempted to extend the preservation of whole mammals with this approach. In this study, murine neonates are exposed to standard cryoanesthesia (CA) at 0-4 °C for 12 min, and to extended preservation comparing 30 min of CA with 30 min of SC at -6 °C and Fresh controls. Both 30 min groups are divided into groups receiving i.p. dexamethasone or sham saline injections. Upon recovery, neonates received modified APGAR scores, and survivors underwent frequent weighing and neurobehavioral assessments after weaning. Neonates subjected to SC 30 min demonstrated significantly improved recovery and survival rates compared to CA 30 min. Supercooled neonates showed robust recovery, achieving high APGAR scores post-storage, and exhibited normal long-term physical and neurobehavioral development. Notably, dexamethasone administration post-supercooling, aimed at alleviating respiratory distress, did not yield additional survival benefits. These preclinical findings highlight the feasibility of supercooling for prolonging suspended animation in mammalian organisms, and may inform future translational research in trauma management and advanced neonatal interventions. Further studies in larger animal models are warranted to evaluate this potential.