Volumetric muscle loss (VML) usually occurs following traumatic injury and results in a composite loss of muscle mass. These injuries manifest in decreased strength and functional impairments. Clinically, these injuries often heal with fibrosis, as opposed to skeletal muscle regeneration. Current existing therapeutic options are also insufficient for VML treatment, and complications are often associated with surgical repair including nerve injury, excessive immune response, infection, scarring, and limitations of tissue graft supply. Indeed, natural healing and surgical procedures are inefficient in restoring the functionality of injured muscles, resulting in a poor quality of life. Therefore, developing clinically relevant three-dimensional (3D) tissue using patient-specific genetically identical cells has emerged as a potential solution to address the above issues. To achieve this aim, there are two existing main challenges. The first challenge is obtaining large amounts of patient-specific genetically identical cells. The use of human pluripotent stem cells (hiPSCs) differentiated to the muscle lineage represents a promising candidate to build upon personalized therapy. However, directing the differentiation of hiPSCs to the muscle fate along with reproducible differentiation schemes has proven to be challenging. The second challenge is developing a highly organized and vascularized 3D skeletal muscle tissue to maintain the viability of cells inside thick tissue constructs via engineered vessel networks. Furthermore, the fabricated tissues have to strongly integrate into injured site via surgical methods. To address these challenges, we plan to develop a suturable 3D vascularized muscle tissue from hiPSC-derived myogenic precursor cells (hiPSC-MPCs) embedded in biomaterials using bioprinting techniques. We will optimize the recently developed protocols allowing efficient production of functional myofibers from hiPSCs in hydrogels with tunable mechanical properties and degradable profiles, which mimic the extracellular matrix (ECM) of native skeletal muscle tissue. To create biomimetic vascularized muscle constructs, a multi-material embedded bioprinting technique will be used to precisely control the positions of the vascular network and aligned muscle fibers with biologically relevant architectures. With the conventional bioprinting system, it is difficult to precisely control the materials? position in Z directions to create freestanding hydrogel architectures. Also, to achieve prolonged retention of implants into the injured site and to improve muscle regeneration, a muscle growth factor (IGF-1) laden suturable graft will be developed. hiPSC-MPCs-laden constructs will be printed on the suturable graft consisting of IGF-1-laden PGS/GelMA substrates using electrospinning.
Traumatic and non-traumatic musculoskeletal disorders are responsible for substantial morbidity, pain and disability, affecting athletes, soldiers, active working people and the elder population. We propose to generate suturable 3D vascularized muscle tissues from human pluripotent stem cells derived myogenic precursor cells (iPSC-MPCs) embedded in biomimetic biomaterials using advanced bioprinting techniques. The successful development of this technology will be applicable to other areas of regenerative medicine and can potentially be utilized for the treatment of skeletal muscle loss.
