Research
Our research investigates the structure-function relationship of the extracellular matrix (ECM) in skeletal muscle mechanics and regeneration. We focus particularly on diseases associated with fibrosis, which is a pathological buildup of ECM. This occurs in many neuromuscular and chronic diseases including muscular dystrophy and cerebral palsy. While function and regeneration are impaired in fibrosis, they do not scale with the amount of fibrotic scar. We go beyond the content to study how ECM architecture controls muscle mechanical function and stem cell-based regeneration in health and disease. Our goal is to develop therapies to engineer ECM architecture in vivo to restore muscle’s regenerative potential in fibrotic disease.
PROJECT 1: Define Properties of ECM Architecture in Fibrosis and Their Effect on Mechanics
Many forms of injury cause muscle to become fibrotic and stiff, restricting joint mobility and function. While fibrosis is typically quantified simply by collagen content, this parameter does not correlate well with functional muscle stiffness. We characterize unique aspects of collagen architecture in fibrotic muscle, including cross-linking, density, and alignment. Densely packed and highly cross-linked collagen is known to have dramatically higher stiffness than loosely packed lightly cross-linked collagen. Having established cross-linking as a signature of muscular dystrophy, we study the types of cross-links that are altered in fibrosis and how they contribute to muscle stiffness. Perhaps the most critical contribution of collagen architecture to passive stiffness is collagen alignment and are at the forefront measuring collagen alignment in skeletal muscle. Our current evidence using both polarized light microscopy and second harmonic generation imaging in conjunction with skeletal muscle mechanics shows collagen misalignment corresponds to the changes in muscle stiffness in fibrotic muscles.
PROJECT 2: Define How Muscle Stem Cells are Controlled by ECM Architecture
The ECM and its architecture can provide cues to stem cells directing them to proliferate, migrate, or differentiate. A healthy ECM architecture supports these processes towards regeneration, but in fibrosis may promote scar tissue formation. We engineer novel matrices to recapitulate the fibrotic architectural properties observed in healthy and diseased skeletal muscle.These substrates will then be used to test the ability of resident muscle stem cells to proliferate, migrate, and differentiate directly on and through these matrices. We evaluate these key functions of stem cells using a variety of techniques including, live cell microscopy, immunofluorescent imaging, RNA profiling, DNA damage assessment, as well as the ability to form contractile micro-muscles.
PROJECT 3: Manipulate ECM architecture as a anti-fibrotic therapy in Skeletal Muscle
Defining parameters of ECM architecture and the mechanisms by which they impair muscle function and regeneration will lead to the identification of novel anti-fibrotic therapeutic targets. While much current research is focused on blocking collagen synthesis, our efforts will focus on manipulating collagen architecture in fibrotic muscle. Inhibiting cross-linking has the potential to increase collagen proteolysis and thus decrease collagen. We investigate both the prevention of fibrosis as well as the ability to reverse the formation of scar tissue in muscle by treating regimes beginning both before and after the onset of fibrosis. We are developing and evaluating additional potential therapies using this framework to target ECM architecture, making use of CRISPR-Cas technology to engineer cells and whole organisms to manipulate the expression of ECM components and ECM modifying enzymes.These pre-clinical studies will facilitate translational research that help bring the most promising of these therapies to patients.