Ex Vivo Preservation of Porcine Vascularized Composite Soft Tissue Allografts

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.

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.

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.

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