Fabrication of Aligned Polycaprolactone Nanofibrillar Bundles to Control Cell-Mediated Collagen Deposition in Engineered Cartilage.

The structural anisotropy of collagen is essential for the function of tissues such as articular cartilage, yet current biofabrication strategies fail to reproduce this hierarchical organization. Melt electrowriting (MEW) is widely used to fabricate mechanically stable polycaprolactone (PCL) scaffolds for reinforcing hydrogels in cartilage tissue engineering, but these constructs typically develop randomly organized collagen networks during chondrogenic differentiation, both in vitro and in vivo. Here, we introduce melt electrofibrillation (MEF), a variation of MEW, as a promising strategy to produce nanofibrillar PCL scaffolds with defined architectures for cartilage tissue engineering. We demonstrate that MEF PCL scaffolds promote enhanced cellular alignment and retention while consistently guiding the organization of a collagen type II-rich extracellular matrix. As a result, MEF provides a tunable, printable scaffold for directing organized cartilage matrix formation. This approach represents a significant step toward engineering biomimetic cartilage and potentially other aligned, collagen-rich tissues with controlled structural organization.