Recombinant Human Amelogenin Protein Enhances Tendon-To-Bone Healing in a Rat Rotator Cuff Tear Model

Area of Science:

• Biomaterials Science
• Orthopedic Surgery
• Regenerative Medicine

Background:

• Rotator cuff tears (RCTs) often result in poor tendon-bone enthesis healing, leading to high retear rates after surgical repair.
• Recombinant human amelogenin protein (rHAM+) has previously shown efficacy in regenerating musculoskeletal tissues.

Purpose of the Study:

• To investigate the potential of rHAM+ in promoting the regeneration of biomechanical and structural properties of the tendon-bone enthesis following a full-thickness rotator cuff tear.

Main Methods:

• A full-transection model of the infraspinatus tendon in 75 rats was used.
• Rats were treated with either rHAM+ in a propylene glycol alginate (PGA) carrier or PGA alone.
• Biomechanical and histological analyses were performed at 4 and 8 weeks post-treatment.

Main Results:

• rHAM+ treatment led to full recovery of biomechanical properties by 8 weeks, with tensile strength comparable to unoperated tendons.
• Histological analysis revealed progressive structural improvement with rHAM+, including organized collagen fibers, restored fibrocartilage, and bone ingrowth.
• PGA carrier alone resulted in significantly inferior biomechanical and structural outcomes compared to rHAM+.

Conclusions:

• rHAM+ effectively induces regeneration of biomechanical strength and promotes enthesis maturation in a rat model of rotator cuff tears.
• Amelogenin shows promise as a therapeutic strategy to enhance rotator cuff repair healing and reduce retear incidence.