Chemical Optimization for Functional Ligament Tissue Engineering.

Electrospun materials are widely used for functional tissue engineering for its robust production and biomimetic properties. Several issues persist, however, including heterogeneous cell distribution, insufficient matrix elaboration/accumulation, and limited construct size. We took three synergistic approaches to address these issues by modifying the chemical microenvironment for the seeded cells. Instead of the commonly used fibronectin, we demonstrated that type I collagen (COL) coating, facilitated by polydopamine treatment, promoted cell infiltration into the fibrous scaffold and resulted in homogeneous distribution in one week. Sequential treatment with fibroblast growth factor and transforming growth factor-β after cell infiltration enhanced cell proliferation and matrix deposition, with increased lysyl oxidase and decreased matrix metalloproteinase-1 expressions. Finally, lamination of the fibrous sheets with fibrin gel not only increased construct size, but further stimulated COL deposition and improved construct mechanical functionalities in combination with sequential growth factor supplementation. These soluble and insoluble chemical optimizations encouraged rapid and robust construct development for a functional engineered ligament graft and can be adapted for the engineering of other tissues. Impact Statement Ligament and tendon injuries are some of the most common orthopedic injuries with long-term repercussions. Tissue engineered grafts provide a promising alternative to autograft and allografts. We present in this study robust and synergistic chemical optimization approaches for the functional engineering of ligament grafts. Moreover, these approaches can be adapted for a variety of other tissues to improve homogeneous construct development.