Evaluation of dynamic change in regenerated tendons in a mouse model

Area of Science:

• Regenerative medicine
• Biomaterials science
• Orthopedic research

Background:

• Tendon regeneration involves secreted tendon gel transforming into tendon tissue under traction.
• The film model method is used to study this in vitro process.
• Understanding early mechanical properties is crucial for tendon healing.

Purpose of the Study:

• To investigate the association between mechanical properties of regenerating tendon gel and time.
• To analyze the transformation of tendon gel into tendon under mechanical force.
• To evaluate histological maturation alongside mechanical changes.

Main Methods:

• Adult male ddY mice were used, with 30 specimens collected on days 10, 15, and 20 post-transection.
• Tendon gel specimens were subjected to a 0.00245 N traction force for 24 hours.
• Video recording measured extension over time; histological examination used H&E staining and Bonar's scale for maturity.

Main Results:

• Day 10 specimens showed significant stretching (0.43%) over 12 hours, unlike day 15 and 20 specimens (0.03%).
• Day 15 and 20 specimens exhibited immediate stretching and greater histological maturity (scores 3.9 and 4.8) compared to day 10 (1.6).
• Statistical analysis confirmed significant differences (P < 0.017) in mechanical strain and maturity between day 10 and later time points.

Conclusions:

• Tendon gel demonstrates physiological and histological maturation on or after day 15.
• Mechanical strength increases significantly after day 15 compared to day 10.
• Early mechanical properties and histological development are time-dependent during tendon regeneration.