Hierarchical scaffolds amalgamating bFGF-immobilized fibrous yarn bundles with cryogel tube for tendon tissue...

Tissue engineering is a promising strategy for repairing damaged tendons. The tendon tissue engineering scaffold should have a hierarchical structure similar to that of tendon and provide adequate mechanical stiffness and strength. To address this need, we twisted aligned gelatin/polycaprolactone/heparin microfibers into a fibrous yarn (GPHY). Basic fibroblast growth factor (bFGF) was attached to the yarn by binding with heparin, which acts as a biochemical cue for seeded tenocytes. The FGF-GPHY bundle was then combined with a macroporous gelatin/hyaluronic acid cryogel tube (GHCT) intended to prevent postoperative adhesion. This tubular bFGF-GPHY@GHCT composite scaffold can offer biochemical cues from released bFGF, as well as biophysical cues derived from its anisotropic fiber architectures or from uniaxial cyclic tensile loading in dynamic cell culture in a bioreactor. We conducted a thorough characterization of the scaffold's properties and its interaction with rabbit tenocytes in vitro, demonstrating its promising effectiveness and potential applications. Mechanical stimulation can significantly enhance the proliferation rates of tenocytes and help maintain their tenogenic phenotype. The cell/scaffold constructs also exhibited improved mechanical properties. In a rabbit Achilles tendon defect model, dynamically cultured cell/scaffold constructs demonstrated an impressive ability to regenerate tendon tissues, yielding histological properties comparable to those of native tendons. Creating a hierarchical bFGF-GPHY@GHCT scaffold that mimics tendon structure and effectively combines biochemical and biophysical cues could be a successful strategy for repairing tendon defects.