Regulation of cellular infiltration into tissue engineering scaffolds composed of submicron diameter fibrils produced by electrospinning

We characterize the infiltration of interstitial cells into tissue engineering scaffolds prepared with electrospun collagen, electrospun gelatin, electrospun poly(glycolic) acid (PGA), electrospun poly(lactic) acid (PLA), and an electrospun PGA/PLA co-polymer. Electrospinning conditions were optimized to produce non-woven tissue engineering scaffolds composed of individual fibrils less than 1000 nm in diameter. Each of these materials was then electrospun into a cylindrical construct with a 2 mm inside diameter with a wall thickness of 200-250 μm. Electrospun scaffolds of collagen were rapidly, and densely, infiltrated by interstitial and endothelial cells when implanted into the interstitial space of the rat vastus lateralis muscle. Functional blood vessels were evident within 7 days. In contrast, implants composed of electrospun gelatin or the bio-resorbable synthetic polymers were not infiltrated to any great extent and induced fibrosis. Our data suggests that topographical features, unique to the electrospun collagen fibril, promote cell migration and capillary formation.