Reendothelialization of Acellular Adipose Flaps under Mimetic Physiological Dynamic Conditions

The extensive soft-tissue defects resulting from trauma and tumors pose a prevalent challenge in clinical practice, characterized by a high incidence rate. Autologous tissue flap transplantation, considered the gold standard for treatment, is associated with various drawbacks, including the sacrifice of donor sources, postoperative complications, and limitations in surgical techniques, thereby impeding its widespread applicability. The emergence of tissue-engineered skin flaps, notably the acellular adipose flap (AAF), offers potential alternative solutions. However, a critical concern confronting large-scale tissue-engineered skin flaps currently revolves around the reendothelialization of internal vascular networks. In our study, we have developed an AAF utilizing perfusion decellularization, demonstrating excellent physical properties. Cytocompatibility experiments have confirmed its cellular safety, and cell adhesion experiments have revealed spatial specificity in facilitating endothelial cells adhesion within the adipose flap scaffold. Using a novel mimetic physiological fluid shear stress setting, endothelial cells were dynamically inoculated and cultured within the acellular vascular network of the pedicled AAF in our research. Histological and gene expression analyses have shown that the mimetic physiological fluid dynamic model significantly enhanced the reendothelialization of the AAF. This innovative platform of acellular adipose biomaterials combined with hydrodynamics may offer valuable insights for the design and manufacturing of 3D vascularized tissue constructs, which can be applied to the repair of extensive soft-tissue defects. Impact Statement This study investigated reendothelialization of the acellular adipose flap (AAF) using 2D and 3D culture models in vitro. Under 2D conditions, AAF regulated endothelial cells morphology with spatial differences. A 3D mimetic physiological hydrodynamics culture model was constructed to investigate the AAF reendothelialization. Exposure of endothelial cells to physiologically fluid shear stress improved the AAF reendothelialization and increased the expression of the extracellular matrix-integrins-cytoskeleton pathway. Conversely, exposure to nonphysiological hydrodynamics and static environments decreased the reendothelialization. These findings suggest that the platform of AAF combined with physiological hydrodynamics can be applied to construct vascularized tissues to repair large-scale soft-tissue defects.