Muscle-Tendon Units
At the Soft Robotics Lab, we replicate the motile functions of living beings by looking at the relation between architecture and dynamics. In bio-hybrid systems, the relation between mechanical properties of tissue substrates and force output is crucial. Aiming to maximize the force transfer, we recreate optimal interfaces of native tissue by engineering co-culture models of skeletal muscle and tendon tissues.
Living Muscle + Living Tendon Systems
At the SRL, we explore creating biphasic tissues that combine both skeletal muscle and tendon tissue as a strategy to mediate force transfer in complex, dynamic systems. While the in vitro fabrication of muscle and tendon tissues as individual systems has been extensively studied, the development of dual tissue constructs is still an open field for exploration and exciting discovery. In the musculoskeletal system, forces are transmitted from skeletal muscle through tendon tissue to the bones, making the engineering of muscle-tendon units (MTUs) crucial for understanding how force transfer impacts motion in the body. MTU engineering offers significant insights into tissue development and functionality, with applications in fields like biomedicine and robotics.
We use extrusion-based bioprinting to fabricate centimeter-scale muscle-tendon units, where myoblasts and fibroblasts form stable, mature tissues that interface seamlessly. Our constructs exhibited several promising traits, such as a biomimetic architecture at the myotendinous junction with a complex design for mechanical interlocking. Moreover, we focus on generating a gradient of mechanical properties at the tissue interface, which enhances force transmission. In our systems, the tissues display remarkable stability, maintaining mechanical integrity and functional contractility for several weeks. We investigate how co-culturing fibroblasts with myoblasts impacts muscle tissue formation, and development of muscle fibers. Moreover, we use motion analysis to describe how the dynamic functionality of the tissue is distributed in the construct, and how passive and active tissues contribute to the overall system’s motility.
Applications
Our bioprinted Muscle-Tendon Unit platform will allow us to characterize the dynamics of the biological actuators in biomimetic functional designs, and determine the efficiency of force transfer. Our bioprinted MTU opens new possibilities for developing more efficient bio-actuators, and more biofidel models of tissue development under cell co-culture regimes.
Authors Involved
This research was conducted by a collaborative team from the Soft Robotics Lab at ETH Zurich, including:
- Miriam Filippi
- Aiste Balciunaite
- Robert K. Katzschmann