Preconditioning Improves Engineered Muscle Contraction

The ability of scientists to engineer muscle tissue in the laboratory would solve several major hurdles in reconstructive surgery, including the ability to repair traumatic injuries and to replace muscle tissue that is excised along with tumors. New research from our lab suggests that a device to “exercise” or precondition engineered muscle in the lab prior to implantation may help make laboratory-engineered muscle a reality.

Reporting in Tissue Engineering, Part A, we’ve found that preconditioning engineered muscle can significantly improve its contractility and suitability for clinical use. Primary muscle cells were isolated from human muscle and multiplied in the laboratory. These cells were seeded onto strands of collagen, a biodegradable connective material, and exposed to cyclic unidirectional stretching and relaxation in a system known as a bioreactor. The goal of this process is to enhance cellular organization and accelerate tissue maturation.

The tissue was implanted in mice, where it continued to develop. After three weeks, the tissue was capable of generating contractile responses that was 10 percent of the force observed in native tissue. In contrast, engineered muscle that hadn’t been pre-conditioned generated a force of only 1 percent.

This study demonstrates the importance of bioreactor preconditioning in the lab to accelerate skeletal muscle tissue organization, maturation and function of muscle tissue once it is implanted.

(Cyclic mechanical preconditioning improves engineered muscle contraction. Moon du G, Christ G, Stitzel JD, Atala A, Yoo JJ. Tissue Eng Part A. 2008 Apr;14(4):473-82.)