Chondrogenic potential of electrospun nanofibres for cartilage tissue engineering

Articular cartilage has a heterogeneous structure, comprising elongated cells at the articulating surface and rounded cells elsewhere. This feature poses a complex challenge when fabricating 3D tissue engineering scaffolds able to mimic the native extracellular matrix (ECM) of cartilage for tissue repair and regeneration. Nanofibre scaffolds can provide an ECM-like structure, but are mechanically weak and typically have subcellular pore geometries. In this study, the use of poly(L,D-lactide) (PLDLA) nanofibre coatings on PLDLA microfibres or films (nanofibre composites) to influence bovine chondrocyte behaviour was investigated. It was demonstrated that electrospun nanofibres facilitated the adhesion of chondrocytes and helped to maintain smaller projected cell areas and a rounded cell phenotype, when compared to PLDLA films or microfibres. Random nanofibre composites were associated with the smallest and most rounded cells and aligned nanofibre composites also demonstrated a similar tendency. Quantitative PCR revealed that nanofibres promoted the expression of chondrogenic markers, such as collagen type IIaI and aggrecan, while maintaining low levels of collagen IaI. It was also found, by water contact angle measurement, that nanofibres were significantly more hydrophobic than cast films. The lower wettability of polymeric nanofibres favoured the maintenance of rounded chondrocyte morphology. To our knowledge this is the first study to confirm the positive influence on preserving chondrogenic phenotype and gene expression at the interface of true nano-microfibrous composites by using individual microfibres coated with aligned nanofibres. Such composites can potentially be fabricated into mechanically durable 3D scaffolds with better cell infiltration throughout the scaffolds.