Macroporous Three-dimensional Aligned Biomimetic Collagen/silk Scaffold For Functional Shoulder Repair

Massive rotator cuff tear is one of the most common shoulder injuries, often resulting in pain and physical debilitation. Current commercial products, such as allograft or other tissue decellularized matrices can’t provide appropriate pore size, porosity, inductivity and sufficient mechanical strength to facilitate cell infiltration and tendon remodeling. The aim of this study is to develop an advanced 3D aligned collagen/silk scaffold (ACS) by modifying the arrangement of collagen fibers within our basic scaffold. ACS had similar structure as natural tendon with superior mechanical characteristics. Through ectopic transplantation studies, the optimal collagen concentration required for sustaining stable macro-structure conducive for cellular infiltration was determined. Within in vitro culture, tendon stem/progenitor cells (TSPCs) displayed spindle-shaped morphology, and were well-aligned on ACS as early as 24 hours. TSPCs formed intercellular contacts and deposited extracellular matrix after 7 days. With the in vivo rotator cuff repair model, the regenerative tendon of the BCS group displayed more native microstructures with larger diameter collagen fibrils that had better alignment and mechanical properties after 8 and 12 weeks post-surgery. In conclusion, these findings demonstrate the positive efficacy of the macroporous 3D aligned biomimetic scaffold in facilitating tendon regeneration, and its practical applications for tendon tissue engineering.