Nanoscalar modifications to polymeric tissue engineering scaffolds: Effect on cellular behavior

Polymeric scaffolds provide a surface that can facilitate cell growth and tissue morphogenesis. Of particular interest is the role of nanoscalar features on cell behavior. Nanoscale topographies can be generated on two-dimensional polymeric substrates via reactive ion etching. The magnitude and morphology of the resultant surfaces can be tailored by varying the gas media, etching time and power used. Nanofibrillar surfaces were produced on polyethylene terephthalate films via oxygen-plasma etching. These nanofibrils were dimensionally similar to collagen fibers. Cells cultured on nanofibrillar surfaces were shown to have a disrupted cytoskeleton, lower levels of cell-substrate signaling, reduced strength of adhesion and an inhibition of lipid droplet coalescence. The results suggest that cells can detect nanoscalar surface topographies and alter their function in response to these environmental stimuli.;While nanofibrillar surfaces can be considered pseudo-three dimensional, they cannot produce 3-D cell structures. Thus truly three dimensional scaffolds must be fabricated to determine the role of nanoscalar fibers on cell organization and function. Electrospinning was employed to generate 3-D meshes of polycaprolactone, a common biodegradable polymer. These nonwoven meshes were comprised of 500 nm fibers with an average pore size of 5 mum. In addition to forming mats of nonwoven fibers, electrospinning technology can also produce tubular scaffolds. These tubular scaffolds were seeded with human vascular smooth muscle cells and cultured for two days. After 2 days in culture, cells assumed a helical orientation around the lumen of the tube, an architecture which closely mimics natural blood vessels. Thus electrospun scaffolds facilitate the growth and organization of cell populations in a manner which imitates the natural tissue.