An Experimental Human DIEP Flap Model to Investigate Preservation Strategies for Vascularized Composite Allografts and Free Flaps.

Recently, preservation approaches such as cytoprotective agents injection, ex vivo machine perfusion, and supercooling have emerged as strategies to enhance long-term preservation of both standard and marginal organs by mitigating ischemic and hypoxic injury. Although encouraging, its application in the field of vascularized composite allotransplantation (VCA) remains largely confined to preclinical research. To date, most studies investigating VCA perfusion strategies have relied on animal models, particularly swine or rodent composites. While these models provide valuable mechanistic insights, their anatomical, immunological, and physiological differences limit reproducibility and translational relevance to human applications. In this protocol, each surgical step required for the procurement of a human deep inferior epigastric perforator (DIEP) flap for preservation studies is described in detail. The perforator is transected above the fascia without any subfascial dissection, yielding a short yet sufficient pedicle for catheterization. This model takes advantage of discarded tissue from standard abdominoplasty procedures, posing no additional risk to the patient. Critical steps are outlined to ensure a functional flap is harvested without prolonging operative time or compromising patient safety. Functional imaging is subsequently performed to confirm flap viability prior to experimental use, and sequential biopsies may be performed to follow tissue integrity. This model is particularly suited for research involving muscle-sparing VCA procedures -- such as partial facial transplantation -- and may also have relevance for the study of autologous free flap preservation.