Skeletal muscle tissue is often required in reconstructive surgery following trauma or resection due to cancer, and the long-term goal of the applicants' research is to regenerate functional craniofacial skeletal muscle. The role of direct mechanical stimulation of damaged muscle tissue has largely been ignored in tissue engineering and regenerative medicine efforts to date, in spite of the clear mechanical role and responsiveness of muscle. We have recently demonstrated that cyclic mechanical compression dramatically enhances muscle regeneration, leading to rapid recovery following serious injury in a mouse model of combined direct muscle injury and ischemia. While the mechanism(s) underlying these effects remain unclear, the impact of mechanical stimulation on regeneration correlates to alterations in immune cell infiltration of the muscle; further, direct manipulation of local immune cell activity at the injury site enhances functional muscle regeneration. The specific hypothesis guiding this application is that cyclic mechanical strain imposed via a soft robotic device enhances muscle regeneration via alteration of the immune cell repertoire at the injury site. The hypothesis will be addressed with the following aims: 1. Optimize the regime of mechanical stimulation applied to injured muscle via the development of a new soft robotic system that allows one to simultaneously treat multiple animals in parallel with control over the amplitude, frequency, and duration of stimulation. 2. Delineate the mechanism(s) underlying the mechanically-driven regeneration, focusing on the role of immune cells in the damaged tissue. 3. Reconstitute a similar profile of immune cell activity without mechanical stimulation, and study the impact on muscle regeneration. The successful completion of these aims will lead to a new strategy for the regeneration and return to function of damaged muscle tissue. This work will have significant relevance in craniofacial reconstructive surgery, and also apply to the regeneration of muscle throughout the body. In a broader sense, the concepts explored in this proposal are likely to be broadly applicable to other tissues and organs in the body.

Many patients required the replacement of skeletal muscle lost to disease or trauma, and this project will explore the ability of mechanical stimulation to regenerate lost muscle tissue. Soft robotic devices developed in this project to apply mechanical stimulation could provide a simple, inexpensive and non-invasive means to treat patients suffering from muscle loss.