Three-dimensionally printed biological machines powered by skeletal muscle

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 111; no. 28; pp. 10125 - 10130
• Main Authors: Cvetkovic, Caroline, Raman, Ritu, Chan, Vincent, Williams, Brian J., Tolish, Madeline, Bajaj, Piyush, Sakar, Mahmut Selman, Asada, H. Harry, Saif, M. Taher A., Bashir, Rashid
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 15-07-2014; National Acad Sciences
• Subjects: Animals; Bioengineering; Biological Sciences; Biomimetics; Bioprinting; Cell Line; Cells; Collagen Type I - chemistry; Collagens; Design engineering; Electrical stimulation; Hydrogels; Insulin-Like Growth Factor I - chemistry; Locomotion; Machinery; Mammals; Mice; Muscle tissues; Muscle, Skeletal; Muscles; Physical Sciences; Signal transduction; Simulation; Skeletal muscle; Tissue engineering; bioactuator; stereolithography
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1401577111

Combining biological components, such as cells and tissues, with soft robotics can enable the fabrication of biological machines with the ability to sense, process signals, and produce force. An intuitive demonstration of a biological machine is one that can produce motion in response to controllable external signaling. Whereas cardiac cell-driven biological actuators have been demonstrated, the requirements of these machines to respond to stimuli and exhibit controlled movement merit the use of skeletal muscle, the primary generator of actuation in animals, as a contractile power source. Here, we report the development of 3D printed hydrogel “bio-bots” with an asymmetric physical design and powered by the actuation of an engineered mammalian skeletal muscle strip to result in net locomotion of the bio-bot. Geometric design and material properties of the hydrogel bio-bots were optimized using stereolithographic 3D printing, and the effect of collagen I and fibrin extracellular matrix proteins and insulin-like growth factor 1 on the force production of engineered skeletal muscle was characterized. Electrical stimulation triggered contraction of cells in the muscle strip and net locomotion of the bio-bot with a maximum velocity of ∼156 μm s ⁻¹, which is over 1.5 body lengths per min. Modeling and simulation were used to understand both the effect of different design parameters on the bio-bot and the mechanism of motion. This demonstration advances the goal of realizing forward-engineered integrated cellular machines and systems, which can have a myriad array of applications in drug screening, programmable tissue engineering, drug delivery, and biomimetic machine design.