Extracorporeal Perfusion in Porcine Models: A Narrative Review of Preservation Strategies and Translational Barriers in Free Tissue Flap Reconstruction

Background: Extracorporeal perfusion (ECP) offers a physiologic alternative to static cold storage (SCS) for preserving free tissue flaps, yet its application in porcine musculocutaneous models remains variable. This narrative review synthesizes experimental parameters across published porcine ECP studies to identify trends in flap viability, biochemical stability, and replantation outcomes. Methods: A targeted search of PubMed and Google Scholar identified 678 studies related to ECP, porcine models, and free flap preservation. After screening, 13 met inclusion criteria and 7 were selected for data extraction based on methodological similarity. Results: Most studies used rectus abdominis flaps in Dutch Landrace pigs. Perfusion durations ranged from several hours to 24 hours, and post-replantation follow-up ranged from 12 hours-14 days. Histidine-tryptophan-ketoglutarate (HTK) and University of Wisconsin (UW) perfusates generally outperformed SCS in reducing lactate, creatinine kinase, and histologic injury. Apoptotic (casp3, TNFRS10a) and inflammatory markers (IL1B, NFKBIZ) showed inconsistent trends. HTK perfusion often increased flap weight, though edema scores were comparable across groups. Replantation models revealed variable ischemia‑reperfusion injury, including one study where ECP-preserved limbs showed greater injury than SCS controls. A hyperbaric warm perfusion system prolonged viability and delayed tissue rejection compared to SCS. Sampling intervals varied widely, complicating comparisons. Conclusion: Overall, porcine ECP models show potential to extend flap viability, but heterogeneity in perfusion protocols, sampling strategies, and outcomes measures limits generalizability. Standardized sampling, adipose-inclusive models, and larger cohorts are needed to refine ECP for reconstructive applications.