The new 'spin' on vascular tissue engineering

Over the years there has been considerable effort to develop biomedical textiles for applications ranging from tissue engineering scaffolds to vascular grafts to wound dressings and hemostatic bandages. Biomedical textiles used for such applications must meet many criteria, among which are the following: the material must be biocompatible and function without interrupting other physiological processes and the textile production method must be reproducible and allow for a wide range of shapes and sizes such that the morphological and mechanical properties of the textile are sufficient for the intended use. The method of electrospinning is a simple fabrication process that achieves the goals of many biomedical textiles. Our lab has successfully electrospun the biodegradable polymers poly(glycolic acid) (PGA), poly(lactic acid) (PLA), polycaprolactone (PCL), and polydioxanone (PDS) as well as natural polymers including collagen (types I, II, III and IV), elastin, fibrinogen, hemoglobin, and myoglobin. In addition, blends and copolymers of these synthetic and/or natural polymers have also been electrospun to develop novel biomedical textiles, including tissue engineering scaffolds. vascular grafts, wound dressings, and hemostatic bandages (U.S. and International Patents Pending). The majority of these structures are comprised of fibers ranging in diameter from 80 nm to 1.5 microns. The fiber diameters are controllable via electrospinning solution concentration, and the mechanical properties of the scaffolds are controllable via fiber diameter and fiber orientation. With various compositions, fiber dimensions, and fiber orientations, the mechanical properties and degradation rates of the electrospun textiles can be tailored. Cellular/tissue interactions have been shown to be dependent on the characteristics of the electrospun scaffolds with composition and fiber diameter as the dominant variables. The results from all this preliminary work are very promising in that the ideal biomedical textile may be customized for a specific application using this technology leading to the ultimate goal of biomimicking extracellular matrix, in particular for vascular tissue engineering. Data to date regarding our work fabricating and testing electrospun scaffolds for completely tissue engineered blood vessels (in vitro tissue engineering) and bioresorbable vascular grafts (in vivo tissue engineering) will be presented.