Ex Vivo Preservation of Porcine Vascularized Composite Soft Tissue Allografts.

Introduction: The aim of this study was to evaluate ex vivo perfusion (EVP) for vascularized composite tissue preservation. We hypothesized that EVP could maintain allografts in near-physiologic conditions for ≥ 24 h.

Methods: Twenty superior epigastric artery perforator-based abdominal flaps were procured from 10 Yorkshire pigs. Flaps were preserved for 12 h (n = 5) or 24 h (n = 5) using EVP with an oxygenated colloid solution containing HBOC-201 oxygen carrier (HbO₂ Therapeutics, Souderton, PA). Contralateral flaps were cold storage controls (4°C) (n = 10). Hemodynamics, temperature, gases, metabolites, electrolytes, indocyanine green (ICG) angiography, and weight were analyzed. Biopsies were taken every 6 h for histology.

Results: Ischemia time was 16 ± 6 min. There were no significant differences between the 12 h EVP and 24 h EVP groups at perfusion end for the following parameters: MAP (p = 0.63), pH (p = 0.77), pO2 (p = 0.20), venous pCO₂ (p = 0.22), lactate (p = 0.28), creatine kinase (p = 0.89), or myoglobin (p = 0.95). Electrolytes were also comparable at perfusion termination: sodium (p = 0.31), potassium (p = 0.61), and calcium (p = 0.29). After 12 h, flaps in the 24 h EVP group demonstrated a significant weight decrease (-4.5% [-4.6%, -4.1%] weight change), compared to the 12 h EVP group (1.2% [-1.1%, 1.6%] weight change) (p = 0.03). At perfusion end, weight did not differ from baseline between the 24 h EVP (2.3% [0%, 3%]) and 12 h EVP groups (p = 0.37). SCS flap weight was unchanged from baseline at 12 h (p = 0.954) and 24 h (p = 0.616). ICG revealed well-perfused flaps. H&E staining revealed preserved skin architecture without histopathological changes.

Conclusion: EVP preserved flaps for 24 h within physiologic parameters and without development of edema. EVP may extend preservation time for VCAs.