A Bioinspired Ultraporous Nanofiber-Hydrogel Mimic of the Cartilage Extracellular Matrix

A true biomimetic of the cartilage extracellular matrix (ECM) could greatly contribute to our ability to regenerate this tissue in a mechanically demanding, often inflamed environment. Articular cartilage is a composite tissue made of cells and fibrillar proteins embedded in a hydrophilic polymeric meshwork. Here, a polyanionic functionalized alginate is used to mimic the glycosaminoglycan component of the native ECM. To create the fibrillar component, cryoelectrospinning of poly(e-caprolactone) on a −78 °C mandrel, subsequently treated by O2 plasma, is used to create a stable, ultraporous and hydrophillic nanofiber network. In this study, cell-laden, fiber-reinforced composite scaffolds thicker than 1.5 mm can be created by infiltrating a chondrocyte/alginate solution into the fiber mesh, which is then physically cross-linked. The fibrillar component significantly reinforces the chondroinductive, but mechanically weak sulfated alginate hydrogels. This allows the production of a glycosaminoglycan- and collagen type II-rich matrix by the chondrocytes as well as survival of the composite in vivo. To further enhance the system, the electrospun component is loaded with dexamethasone, which protected the cells from an IL-1β-mediated inflammatory insult.