An Intelligent Biorobot for the Regenerative Rehabilitation of Volumetric Muscle Loss Defects - Project Summary Volumetric Muscle Loss (VML) is the most devastating and chronic musculoskeletal injury in which a substantial amount of muscle is lost due to traumatic incidents. The aftermaths of VML are dreadful and excruciatingly painful, leading to poor life quality, suboptimal or completely impaired limb function, or life-long disability. The current standard of care for VML, which includes muscle flap transfer, physical therapy, and bracing, is highly limited in efficacy, challenges patient outcomes, and does not guarantee the complete restoration of functional muscle. The major limitation of tissue-engineered regenerative constructs at a research level is that they cannot adequately reinnervate the newly formed muscle fibers, which is critical in enhancing functional recovery. To address these limitations, the primary goal of this project is to develop and validate the pre-clinical efficacy of a unique Regenerative Rehabilitation (Regen-Rehab) therapy that focuses on forming innervated, vascularized, and functional muscles post-VML injury. Specifically, we propose to develop a regenerative ‘intelligent’ biorobot, i.e., a piezoelectric construct capable of introducing myoblasts and autonomously providing low-level electrical stimulation (E-Stim) with forces generated from regular limb movements to expedite muscle formation. To enhance therapeutic outcomes, we propose integrating a rehabilitation paradigm, i.e., neuromuscular eccentric contraction training (NMET), with our biorobot treatment. We hypothesize that our biorobot will generate piezoelectric E-Stim, i.e., bioelectrical cues, at the injury site by responding to tensile forces caused by limb movements in NMET. These bioelectrical cues will stimulate the myoblasts in the biorobot to form mature muscle fiber and promote axonal sprouting in neighboring axon terminals towards re-innervating the newly formed muscle and enhancing muscle functionality. We have designed two Aims. Aim 1 will focus on developing and optimizing the cell-laden biorobots that mimic skeletal muscle stiffness, generate E-Stim when forces are applied, and help in cell spreading and maturation. We will use state-of-the-art bioprinting to develop the biorobots. We have designed innovative in vitro studies, including a bioreactor that can apply controlled load to the biorobots to generate E-Stim. One of the primary accomplishments of this Aim would be to determine the biorobots that help form neuromuscular junctions (NMJs) in vitro. Aim 2 will focus on determining the pre-clinical efficacy of the biorobot integrated with NMET treatment. For that, we will engraft the biorobots in a rat VML injury model involving 20% muscle loss. We will expose the animals to the NMET rehabilitation paradigm, which involves controlled eccentric contractions by a servo motor and simultaneous peroneal nerve stimulation. One of the primary accomplishments of this Aim would be determining the pre-clinical efficacy of our treatment in enhancing functional recovery in restored muscles. Completing this project will help us establish a clinically translatable Regen-Rehab therapy with a high potential to expedite skeletal muscle restoration and shorten recovery time and suffering in patients who experience excruciating pain and poor quality of life after a VML injury.
