Induced Pluripotent Stem Cell-Derived Small-Diameter Vascular Grafts: Scaffold Design, Immune Engineering, and...

Small-diameter vascular grafts (≤ 6 mm) remain a critical unmet need in cardiovascular surgery, as autologous vessels are unavailable in up to 30% of patients requiring coronary or peripheral bypass. Induced pluripotent stem cells (iPSCs) have emerged as a transformative cell source for tissue-engineered vascular grafts (TEVGs), offering unlimited self-renewal, patient-specific or universal donor potential, and the capacity to generate all vascular cell lineages. Recent breakthroughs-including iPSC-derived grafts achieving 100% patency in allogeneic primate models and the first United States Food and Drug Administration (FDA) approval of an acellular tissue-engineered vessel (SYMVESS, December 2024)-signal that clinical translation is accelerating. This review provides a comprehensive synthesis of the iPSC-to-graft pipeline, encompassing vascular cell differentiation protocols, biomaterial scaffold design, immune engineering strategies for universal grafts, bioreactor maturation, preclinical evaluation, and the evolving clinical-regulatory landscape. We critically evaluate how the convergence of clustered regularly interspaced short palindromic repeats (CRISPR)-based immune editing, advanced biomaterials, and scalable manufacturing is reshaping the field toward off-the-shelf vascular grafts. Finally, we identify remaining challenges in long-term patency, thrombogenicity, and manufacturing scalability, and propose a translational roadmap for the next decade.