Smooth muscle cell-like support cells accelerate the autologous endothelialization of a polyurethane scaffold for vascular engineering

The endothelialization of vascular scaffolds, such as small-diameter grafts, has long been an obstacle in the tissue engineering field. The absence of an abundant and expandable autologous endothelial cell source, and of a viable strategy to facilitate their rapid growth, have prevented clinical adoption of endothelialized grafts. At the same time, the importance of a confluent endothelium and mechanisms to prevent graft occlusion have been recognized. Here, we report on the rapid, patient-derived endothelialization of a non-protein coated, biocompatible, and degradable polyurethane scaffold, on which adipose tissue-derived endothelial cells are co-cultured with adipose tissue-derived stromal cells, having a smooth muscle cell-like phenotype. The co-cultured endothelia are characterized using proteomic, genomic, biochemical, and histologic analyses, which demonstrate that they maintain a functional phenotype, as well as fewer inflammatory characteristics than endothelial cells cultured without support cells. Importantly, we also show that this co-culture with endothelial cells does not compromise the differentiated, contractile phenotype of, or extracellular matrix production by, the pre-differentiated support cells. Furthermore, we demonstrate that the differentiated smooth muscle cell phenotype, when combined with human monocytes, best recapitulates the protein composition of human arteries, particularly in terms of elastin production. Overall, we demonstrate the production of a patient-derived, confluent endothelium within a vascular scaffold while recapitulating the natural features key to arterial function, namely mature supporting cells, and a physiologically relevant extracellular matrix. STATEMENT OF SIGNIFICANCE: For small-diameter (< 6 mm) tissue-engineered vascular grafts, it has been recognized that having a confluent endothelium on the graft's lumen, and mimicking the arterial structure and mechanical properties present in the body, are both essential for success. Our work demonstrates the ability to produce a tissue-engineered scaffold that recapitulates critical elements of an artery's in vivo structure and is composed entirely of autologous, fat-derived cells on a degradable, biocompatible polymer. Furthermore, it shows the potential to produce a stable, confluent endothelium, maintain the differentiated character of the co-cultured supporting cells, and synthesize an appropriate extracellular matrix, all of which are key to the graft's ability to respond to physiological cues and remain unobstructed upon implant.