Bioresorbable fiber reinforced hydrogel scaffold for cartilage tissue regeneration

Melt electrowriting (MEW) is an innovative additive manufacturing technology utilized for producing fibrous three-dimensional structures for tissue engineering and regenerative medicine applications. While polycaprolactone (PCL) is the predominant polymer employed in MEW, its limited elasticity and slow degradation rate restrict its effectiveness in tissue regeneration. This study investigates the printability of medical-grade poly(L-lactide-co-caprolactone) (PLCL), which has a faster degradation rate, resulting in MEW PLCL scaffolds characterized by uniform fiber diameter, regular layer stacking, and customizable pore sizes. At a pore size of 500μm, the PLCL scaffolds exhibit superior mechanical properties, with a tensile strength of 22.4 MPa and an elastic modulus of 72.6 MPa. Additionally, compared with PCL scaffolds of the same pore size, PLCL scaffolds promote sustained cell proliferation, along with the upregulation of SOX9 and Col II and the downregulation of MMP7. These results indicate enhanced chondrocyte proliferation and increased synthesis of cartilage-specific matrix. When comparing pore sizes of 300μm and 500μm, PLCL-500 scaffolds support continuous cell proliferation even at lower cell densities. In contrast, PLCL-300 scaffolds promote initial cell adhesion but demonstrate a decline in proliferation after day 3. This constraint downregulates anabolic markers (SOX9, collagen II, Aggrecan) and upregulates matrix-degrading enzyme MMP7, primarily caused by excessive cell packing and compromised nutrient diffusion within scaffolds. Furthermore, the gelatin methacryloyl (GelMA) hydrogel is reinforced by PLCL-500 scaffolds, optimizing their mechanical properties and bioactivity. The composite scaffold exhibits an elongation at break of 1000% and a tensile strength of 0.5 MPa. Importantly, cell viability remains above 90%, with chondrocytes maintaining a spherical phenotype and establishing networks by day 14, accompanied by increased sulfated glycosaminoglycan (sGAG) deposition. This research clarifies the relationships among scaffold dimension, component, mechanical properties, and chondrogenesis, offering a promising strategy for cartilage tissue engineering applications.