Polyurethanes for engineering vascular graft: A review

The surgical bypass is the gold standard for long-term revascularization. Autologous transplants and synthetic grafts are available for patients. However, the current options persist with a need for more suitable autologous tissue, compliance mismatch, and poor revascularization. Several strategies involving natural and synthetic polymers have been approached by tissue engineering. Polyurethanes are flexible synthetic materials that can overcome challenges associated with mechanical mismatches. Limitations regarding the interaction between tissue and cell have been addressed by authors in several manners, including surface modification, scaffold fabrication, and blending with other materials. This review compiles and describes the trends over the last thirteen years regarding using polyurethanes to design tissue-engineered vascular grafts. We identify that most studies use commercially available polyurethanes and often combine them with bioactive molecules. In addition, surface modification has been shown to improve graft cell-material interaction, and electrospinning is the preferred technique for scaffold fabrication. Most research is executed in vitro models to evaluate biological performance, and the preferred in vivo models are in rats. We also identify a knowledge gap regarding the biomechanical characterization of the novel grafts. Tools like constitutive modeling and finite element analysis can guide the designs to overcome the challenges associated with mechanical behavior. Overall, studies continue supporting polyurethane-based vascular grafts as an alternative. The addressed limitations in the cell-material interaction have provided novel solutions with clinical relevance that should be pushed to the following preclinical and clinical assessment levels.