A Composite Microsphere/Nanofiber Controlled Release System for Fibrous Tissue Engineering

Fibrous tissues are characterized by a dense, ordered collagenous structure that defines their unique and anisotropic mechanical properties. These properties are critical for tissue function, and are compromised in instances of injury and tissue degeneration. To improve repair, engineering methods based on electrospinning have produced aligned and anisotropic scaffolds composed of biodegradable nanofibers that can serve as templates for new tissue formation [1]. For example, the slow degrading polyester, poly(ε-caprolactone) (PCL) can be formed into aligned arrays that direct cell alignment and ordered ECM deposition, with construct mechanical properties that increase with time [2]. We have further modified these structural templates via the fabrication of multi-polymer composites, with different mechanical properties and degradation profiles provided by different component materials [3]. For example, inclusion of a sacrificial poly-ethylene oxide (PEO) fiber element, followed by its removal (via hydration) increases the porosity of the remaining PCL network and expedites cell infiltration [4].