Accelerating vascular graft development: Adipose-derived stem cells and PODS® (Polyhedrin delivery system with tissue-specific growth factors) – Enhanced 3D bioprinting for functional blood vessels

Abstract

Advancing bioprinted vascular grafts for clinical applications faces the challenge of obtaining sufficient functional endothelial cells and smooth muscle cells essential for the biofabrication of blood vessels. Accurate placement of these cells is crucial for optimal performance. Tissue engineering, particularly with adipose-derived stem cells (ADSCs), offers promising solutions. In this approach, ADSCs were cultivated and differentiated into endothelial cells (dECs) in vitro using VEGF-165 PODS® (Polyhedrin Delivery System), while smooth muscle cells (dSMCs) were differentiated in situ within the outer layer of the 3D bioprinted vessel using TGF-β1 PODS® with bioink VascuBiomatrixTM. The effect of PODS® on production of differentiated Endothelial Cells (dECs) and Smooth Muscle Cells (dSMCs) was validated through flow cytometry, immunocytochemical staining, and RT-PCR, using cell specific markers, as well as immunolabeling for extracellular collagen I and elastin. This confirmed that cells within the vessel walls retained their phenotype and secreted human extracellular matrix (ECM) components. Scanning electron microscopy (SEM) confirmed the vessels' morphology and dimensions, and tensile testing and burst pressure tests assessed mechanical properties. In vivo compatibility was evaluated by blood hemocompatibility and the CAM (Ex Ovo chorioallantoic membrane) assay. Results confirmed the successful fabrication of a bilayer blood vessel structure with smooth muscle cells and an endothelial lining, exhibiting adequate physiological properties. Hemocompatibility and in vivo CAM assays demonstrated low platelet adhesion, improved biocompatibility, and angiogenic properties. These findings suggest that integrating ADSCs and bioink for 3D bioprinting provides a practical solution for fabricating functional small-diameter vascular grafts. This study advances vascular tissue engineering through the combination of stem cells, growth factor delivery systems, and bioprinting technology.