Tendon Extracellular Matrix Promotes Myotendinous Junction Protein Expression in Engineered Muscle Tissue under Both...

Area of Science:

• Musculoskeletal research
• Tissue engineering
• Bioreactor technology

Background:

• Crosstalk between muscle and tendon is crucial for musculoskeletal health but remains understudied.
• In vitro models are needed to investigate the myotendinous junction (MTJ) function and repair.
• Engineered muscle tissues offer a platform to study MTJ under controlled conditions.

Purpose of the Study:

• To culture engineered muscle tissues in a novel bioreactor under static and dynamic conditions.
• To evaluate the expression of myotendinous junction-specific proteins (paxillin and type XXII collagen).
• To investigate the influence of different biomaterials (type I collagen and tendon-derived extracellular matrix) on protein expression.

Main Methods:

• C2C12 myoblasts were cultured in type I collagen or tendon-derived extracellular matrix (tECM) hydrogels.
• Engineered tissues were stabilized for 10 days, followed by 2-4 weeks of cyclic mechanical stimulation (3 hours/day).
• Protein expression of paxillin and type XXII collagen was analyzed.

Main Results:

• Mechanical stimulation significantly increased paxillin expression in tECM hydrogels compared to type I collagen hydrogels after 2 and 4 weeks.
• Tendon-derived extracellular matrix hydrogels showed higher increases in paxillin expression under mechanical stimulation (62% at 2 weeks, 31-57% at 4 weeks).
• Type XXII collagen expression was also modulated by both hydrogel material and mechanical stimulation.

Conclusions:

• The novel bioreactor and engineered muscle-tendon unit effectively model the muscle-tendon microenvironment.
• Mechanical strain is a key regulator of myotendinous junction protein expression in engineered tissues.
• This model holds promise for studying muscle-tendon interactions and MTJ formation/maintenance.