(247a) Aligned, 3D, and Electrically Conductive Multicompartment Collagen-Glycosaminoglycan Scaffolds for Musculotendinous Tissue Engineering

Skeletal muscle makes up 40-45% of total body mass and consists of 3D, highly aligned, and electrically excitable muscle fibers. Skeletal muscle has an innate ability to recover from minor injuries. However, this inherent regenerative limit is exceeded during volumetric muscle loss (VML) injuries due to the traumatic loss and damage of large amounts of muscle tissue. Biomaterial-based tissue engineering is an emerging research area due to the lack of effective treatment methods for VML injuries. However, fabricating biomaterials combining 3D structural alignment and electrical conductivity found in native skeletal muscle is challenging. Additionally, muscle injuries are accompanied by damage to the musculotendinous junction due to incongruencies in both biomechanical and biochemical tissue properties at the interface. We developed collagen-glycosaminoglycan scaffolds with an aligned microporous structure using a directional freeze-drying approach. ‘Muscle’ and ‘tendon’ compartments with a smooth interface mimicking the native interface are made by layering type I collagen suspension with and without conductive polymer particles respectively. Poly(3,4-ethylenedioxythiophene) (PEDOT) particles were synthesized and incorporated in type I collagen suspension to make the muscle compartment of the scaffold electrically conductive. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) techniques showed the successful formation of scaffolds with longitudinally aligned micropores due to directional freeze-drying and uniform distribution of conductive PEDOT particles respectively. C2C12 myoblasts and 3T3 fibroblasts cultured on muscle and tendon compartments respectively showed significantly increased metabolic activity (measured non-destructively using an alamarBlue assay) over 7 days of culture. Next, we attempted to further enhance scaffold bioactivity by investigating the role of glycosaminoglycans (GAGs) in regulating muscle cell behavior. GAGs are linear polysaccharides present in ECM which regulate myogenesis and growth factor sequestration. Scaffolds with different GAGs (hyaluronic acid, chondroitin sulfate, and heparin) of increasing sulfation levels were evaluated to understand their effect on cell metabolic activity and differentiation. Scaffolds with heparin (highest sulfation level) exhibited higher values of cell metabolic activity and staining for myosin heavy chain (MHC), a marker of myogenic differentiation. Ongoing work is characterizing multicompartment scaffold mechanical properties, electrical conductivity, and ability to support differentiation of multiple cell types.