Muscle strains are produced by indirect injury to muscle caused by excessive stretch or tension. The most common strains occur at the myotendinous junction, which is the weakest link within the muscle. Typical findings of muscle strains are seen in injuries of the hamstrings and pectoralis major muscles. In one study, hamstring strains accounted for 50% of the strain injuries in sprinters. Rupture of the pectoralis major muscle is an uncommon sports-related injury, but it is increasing in frequency.
University of Michigan researchers have developed a process to fabricate three-dimensional (3-D) skeletal muscle constructs co-cultured with either engineered or self-organized tendon constructs. This process creates constructs with robust myotendinous junctions (MTJs) that when tested withstood tensile loading beyond the physiological strain range. The muscle-tendon constructs are successfully characterized by both structural features and by protein expression patterns that resemble neonatal MTJs in vivo. In addition, these engineered 3-D nerve–muscle constructs display functional neuromuscular junctions that can be electrically stimulated to contract via the neural extensions projecting from the construct.
Applications and Advantages
- Muscle strain injury repair.
- 3-dimensional engineered muscle constructs tend to fail at their attachment points when subjected to prolonged tension, however these engineered MTJs withstand tensile loading beyond physiological strain range.