Coaxial electrohydrodynamic printing of core-shell microfibrous scaffolds with layer-specific growth factors release for enthesis regeneration

Herein, a tri-layered core-shell microfibrous scaffold with layer-specific growth factors (GFs) release is developed using coaxial electrohydrodynamic (EHD) printing for in situ cell recruitment and differentiation to facilitate gradient enthesis tissue repair. SDF-1 is loaded in the shell, while bFGF, TGF-β, and BMP-2 are loaded in the core of the EHD-printed microfibrous scaffolds in a layer-specific manner. Correspondingly, the tri-layered microfibrous scaffolds have a core-shell fiber size of 25.7 ± 5.1 μm, with a pore size sequentially increasing from 81.5 ± 4.6 μm to 173.3 ± 6.9 μm, and to 388.9 ± 6.9 μm for the tenogenic, chondrogenic, and osteogenic instructive layers. A rapid release of embedded GFs is observed within the first 2 days, followed by a faster release of SDF-1 and a slightly slower release of differentiation GFs for approximately four weeks. The coaxial EHD-printed microfibrous scaffolds significantly promote stem cell recruitment and direct their differentiation toward tenocyte, chondrocyte, and osteocyte phenotype in vitro. When implanted in vivo, the tri-layered core-shell microfibrous scaffolds rapidly restored the biomechanical functions and promoted enthesis tissue regeneration with native-like bone-to-tendon gradients. Our findings suggest that the microfibrous scaffolds with layer-specific GFs release may offer a promising clinical solution for enthesis regeneration.