Skeletal muscle tissue damage costs the US government hundreds of billions of dollars annually, and there are currently no suitable tissue replacements for skeletal muscle. In addition, there is great potential to use skeletal muscle as a scalable actuator system, covering wide length scales, frequencies, and force regimes. Hence, the interest in soft robotics and regenerative medicine methods to engineer skeletal muscle has increased in recent years. The challenges to generate a functional muscle strip are typical to those of tissue engineering, where common issues such as cell source, material scaffold, bioreactor method or configuration play key roles. Specifically, it is important to translate myogenesis knowledge into engineering constructs by examining the impact of the cell microenvironment on growth, alignment, fusion, and differentiation of skeletal muscle cells. The motivation behind this thesis was to generate a contractile 3D skeletal muscle construct utilizing biochemical and physical cues to guide muscle cell differentiation and maturation. Such a construct is expected to play an important role in medical applications and the development of soft robotics. To do this, 3D, swollen hydrogels were chosen to provide tailorable platforms that support cellular activities to similar extents as native matrices.

We utilized an engineered bio-functionalized poly(ethylene glycol)-(PEG)-hydrogel with maleimide (MAL) cross-linking reaction chemistry that gels rapidly with high reaction efficiency under cytocompatible reaction conditions. To develop an effective soft biomaterial for the development of an aligned, functional muscle construct, we (i) screened hydrogel properties for differentiation, (ii) recreated alignment of skeletal muscle cells, (iii) determined effective generated force upon action of an external agonist. The impact of this study will be significant in the construction of biological machines while providing a unique regenerative solution for skeletal muscle tissue repair and regeneration.