A novel single-step self-assembly approach for the fabrication of tissue-engineered vascular constructs

There is a clinical need for a functional tissue-engineered blood vessel because small-caliber arterial graft (<5 mm) applications are limited by the availability of suitable autologous vessels and suboptimal performances of synthetic grafts. This study presents an analysis of the mechanical properties of tissue-engineered vascular constructs produced using a novel single-step self-assembly approach. Briefly, the tissue-engineered vascular media were produced by culturing smooth muscle cell in the presence of sodium l-ascorbate until the formation of a cohesive tissue sheet. This sheet was then rolled around a tubular support to create a media construct. Alternatively, the tissue-engineered vascular adventitia was produced by rolling a tissue sheet obtained from dermal fibroblasts or saphenous vein fibroblasts. The standard self-assembly approach to obtain the two-layer tissue-engineered vascular constructs comprising both media and adventitia constructs consists of two steps in which tissue-engineered vascular media were first rolled on a tubular support and a tissue-engineered vascular adventitia was then rolled on top of the first layer. This study reports an original alternative method for assembling tissue-engineered vascular constructs comprising both media and an adventitia in a single step by rolling a continuous tissue sheet containing both cell types contiguously. This tissue sheet was produced by growing smooth muscle cells alongside fibroblasts (saphenous vein fibroblasts or dermal fibroblasts) in the same culture dish separated by a spacer, which is removed later in the culture period. The mechanical strength assessed by uniaxial tensile testing, burst pressure measurements, and viscoelastic behavior evaluated by stepwise stress relaxation tests reveals that the new single-step fabrication method significantly improves the mechanical properties of tissue-engineered vascular construct for both ultimate tensile strength and all the viscoelastic moduli.