Blood Vessels Bioengineered from Induced Pluripotent Stem Cell Derived Mesenchymal Stem Cells and Functional Scaffolds

Background: The development of small-diameter vascular grafts poses a significant challenge in tissue engineering. Despite advances in biofabrication, current vessel mimics lack remodelling and regenerative capabilities. Here, we sought to fabricate patient-specific bioengineered vessels using induced pluripotent stem cells (iPSCs) and functionalised biodegradable scaffolds to produce patient-specific bioengineered vessels. Methods: Human iPSCs were differentiated into mesenchymal stem cells (iMSCs) using SB431542, a TGF-β1 pathway inhibitor. iMSCs were further differentiated into vascular smooth muscle cells (VSMCs) with PDGF-BB and TGF-β1. Human bone marrow derived mesenchymal stem cells (hBM-MSC) from a commercial source were used for optimising differentiation protocols and quality control of iMSCs. Electrospun poly-L-lactide (PLLA) scaffolds coated with silk fibroin were developed for cell adhesion and growth. Both hBM-MSCs and iMSCs were seeded on these scaffolds for in-scaffold differentiation into VSMCs. The cell-laden scaffolds were rolled into tubular structures to scaffolds with ~3 mm inner diameters and ~20 mm in length. Results: Over 34-36 days, iPSCs were differentiated into cells with fibroblast-like morphology (iMSCs) expressing MSC markers CD73, CD90, and CD105, confirmed via immunofluorescence and flow cytometry. Thereafter, hBM-MSCs and iMSCs were successfully differentiating into VSMCs by supplementing media with PDGF-BB and TGF-β1 media over 9 days. Differentiated VSMCs expressed of α-SMA, CNN1, SM22, and MYH-11. Silk fibroin-coated PLLA scaffolds enhanced MSC adhesion and proliferation compared to uncoated scaffolds. The engineered tubular grafts displayed VSMC markers and mechanical properties akin to autologous coronary artery bypass grafting (CABG) grafts. Conclusion: This study developed a versatile method to fabricate tissue-engineered blood vessels using stem cells and silk fibroin-coated scaffolds. The resulting grafts exhibited tunica media-like structures and mechanical properties comparable to autografts used in CABG, showing strong potential for clinical application.