Engineering Functional Skeletal Muscle Sheets for Bionic Applications

Description

Engineering skeletal muscle sheet has drawn increasing attention because of its immense potential for repairing impaired muscle or building bionic machines. Spatial patterning cues have been widely used to align muscle precursors to facilitate their fusion and differentiation during myogenesis. Comparing to nano-topographic cues, micropatterning offers superior advantages in reproducing intricate patterns and providing significantly greater length and alignment of myotubes. However, on micropattern, cells were reported with an unexpected, unidirectional slanting angle deviating from the pattern boundary. Such deviation is consistently and independently observed by many groups, but has long been unattended and unexplained. When uncontrolled, it can disorganize muscle fibers, creating significant difficulty when engineering skeletal muscle tissue.Rather than a random, noisy event, recent investigation found that the slanting angle of cell orientation is indeed due to an intrinsic chirality of cells. Here, combining our expertise in cell chirality and pattern formation, we aim at engineering skeletal muscle sheet with scalable, intricate and more importantly, controlled patterns of myotubes. To achieve it, we will first systematically study the chiral orientation of myoblasts on micropatterned stripe during myogenesis (Task 1). The analysis will be based on our developed “outline-etching image segmentation” to extract the orientation of cell nucleus with respect to the micropattern boundaries. Next, we will explore an engineering strategy to guide the direction of myotube formation (Task 2). We will first investigate the possible suppression of cell chirality through image-based analysis of spatial distribution and chiral-biased swirling pattern of actin filaments upon treatment of actin inhibitors. As an alternative plan, we will also design the orientation of micropatterned stripe with a “compensation angle” relative to the desired myotube direction. Compared to the chiral orientation, the compensation angle will be the same amount of deviation but in opposite direction. Thus, when the chiral orientation subsequently emerges, the muscle fiber can be eventually aligned toward the desired direction. Finally, we will guide the formation of functional skeletal myotubes into desired, intricate, and function patterns by either compensating or suppressing the chiral orientation. Moreover, using soft material as the substrate, we will construct skeletal muscle sheets as bionic machines with a central ring lining with rounded myotubes and radial branches with longitudinally aligned myotubes to explore the corresponding locomotion and applications (Task 3). As a new perspective of incorporating the chiral orientation for building muscle pattern, our project would establish the knowledge foundation for tissue engineering in bionic applications.