Grant: Research Tools and Instruments

Background: Muscle stem cell (MuSC) quiescence, as well as all stages of skeletal muscle regeneration are controlled by complex signals from the extracellular matrix (ECM). Importantly, deregulated ECM signals leading to MuSC dysfunction contribute significantly to disease pathogenesis in conditions such as muscular dystrophy and age-related muscle loss. Due to their dependence on microenvironmental signals ex-vivo culture of MuSCs is challenging and represents a significant hurdle for the field. Once removed from their tissue microenvironment and extracellular matrix (ECM) scaffold, MuSCs quickly lose their self-renewal capacity and become terminally committed to differentiation. Traditional culture models for MuSC-derived cells make use of a thin layer of homogeneous coating typically consisting of a single ECM molecule (e.g. Laminin or Collagen) in rigid 2D plastic dishes. Thus, these culture paradigms lack tree-dimensional context, do not reiterate the complexity of the native ECM, and do not mimic the biomechanical properties of skeletal muscle tissue. Complementing four different NSERC supported projects, our teams (Bentzinger, Grandbois, and Boudreault) pursue approaches to circumvent these limitations and engineer improved tissue culture paradigms for MuSC-derived cells. Here, we request a device that will allow us to characterize the elasticity of skeletal muscle tissue and hydrogels to engineer ECM-based 3D culture models mimicking physiological or pathological mechanical properties. Device: The Mach-1 v500css mechanical tester produced by the Canadian company Biomomentum has unique features allowing for compression/tension, shear, torsion testing based on up to four machine-driven displacement stages (linear or rotational) enabling high-throughput indexation, 3D profilometry, mechanical 3D indentation/thickness mapping. Objectives: This proposal revolves around four main lines of investigation: I&II) Engineering of hydrogels derived from decellularized skeletal muscle ECM whose elasticity can be adapted using intercalated polyethylene glycol (PEG) for 3D MuSC culture and as grafts for muscle injury (Bentzinger). III) Adhesion molecule micropatterning to study cell-cell interactions and develop spatially defined culture models using 2D and 3D PEG hydrogels (Grandbois). IV) Screening and engineering of ECM derived adhesion peptide motifs for MuSC culture in functionalized 2D and 3D hydrogel substrates with physiological biomechanic characteristics (Boudreault). Relevance of the proposed work: The Mach-1 mechanical tester will help to shed light on the complex molecular interplay stem cell-ECM interactions and help to device MuSC culture models with optimized biomechanical properties. In the long run the availability of optimized culture paradigms for MuSCs will enable the identification of therapeutic targets and compounds for muscle wasting conditions accompanied by regenerative dysfunction.