Cellular Cytosolic Energy Replenishment Increases Vascularized Composite Tissue Tolerance to Extended Cold Ischemia...

Area of Science:

• Transplantation immunology
• Regenerative medicine
• Surgical innovation

Background:

• Vascularized composite allotransplantation (VCA) is crucial for treating severe injuries but limited by short allograft cold ischemia times (CIT).
• Current hypothermic preservation protocols restrict CIT to under 4 hours, hindering routine clinical application.
• Novel strategies are needed to extend allograft preservation and improve VCA outcomes.

Purpose of the Study:

• To investigate the efficacy of active cellular adenosine-5`-triphosphate (ATP) replenishment using energy delivery vehicles (ATPv) in extending allograft tolerance to cold ischemia.
• To evaluate the impact of ATPv on composite tissue viability and structural integrity after prolonged cold storage.

Main Methods:

• A rat hind limb model was used for in-situ perfusion with University of Wisconsin (UW) solution, with or without ATPv, and with or without oxygen supplementation.
• Perfused hind limbs underwent static cold storage at 4°C for 12, 16, or 24 hours.
• Tissue histology and lysate studies assessed microvascular damage, myocyte integrity, and nucleus density.

Main Results:

• ATPv-enhanced perfusion significantly increased myocyte nucleus density compared to controls (13 vs. 8 nuclei/field, P < .004).
• Oxygenation of perfusion solutions did not significantly impact nucleus density.
• Prolonged cold storage completely degraded RNA, precluding its use as a viability marker.

Conclusions:

• Active cellular ATP replenishment via ATPv enhances composite tissue tolerance to extended cold ischemia times.
• This approach shows promise for improving VCA allograft preservation.
• Further research is needed to identify reliable biomarkers for assessing composite tissue viability during static cold storage.