Spatial Regulators of Skeletal Muscle Regeneration and Disease - Skeletal muscles are responsible for movement, breathing, posture and metabolism. Loss of muscle function via acute injury or chronic neuromuscular disease (NMD) is debilitating to quality of life and is associated with high healthcare burden. In the US, there are over 12 million cases of sprains and strains injuries each year, an estimated 50 million people living with age-related sarcopenia, and another 250,000 with NMDs. My long-term goal is to elucidate the cellular and molecular mechanisms which underlie the muscle repair and develop therapies for chronic muscle disorders. A major barrier in this endeavor is our limited of understanding of the multiplicity of cell types involved during muscle regeneration. Little is known regarding functions of each cell type and how they interact with tissue-resident stem cells to regulate the restoration of muscle function. Thus, tissue cytometry, the mapping of single cells within tissues, is necessary to gain novel insights into cellular interactions during muscle regeneration and in dysregulated disease states. My central hypothesis is that local signaling in the cellular microenvironment regulate the behavior of critical cell types to remodel or repair the tissue. To this, I have optimized a novel multiplexed imaging technology (CODEX) that enables visualizes 40+ antibodies on a single muscle section. In the proposed research, I aim to (i) develop technologies to study cellular interactions using high dimensional imaging data and build a single cell resolution spatial map of the localization, abundance, dynamics, and interactions of 25 cell type within normal muscle regeneration and disease states; (ii) elucidate critical cell types and spatially-localized signaling that determine the proper expansion and differentiation of muscle stem cells; (iii) deep profile the function of M2 macrophages and fibroadipogenic precursors in process of motor neuron and neuromuscular junction remodeling. The training I will receive during the mentored phase of this proposal will be critical for the success of this project. Moreover, application of this systematic approach to study inter-cellular signaling will allow me to achieve academic independence. The proposed experiments in the K99 phase will provide novel insights into the coordinated process of tissue regeneration and will yield candidate signaling molecules with the potential to modulate the function of muscle stem cells. Further, the proposed project for the R00 phase will lead to better understanding of the cellular responses and fundamental mechanisms of motor neuron and neuromuscular junction remodeling, which has significant relevance for nerve injuries and chronic autoimmune neuromuscular diseases.
