Effect of an Atelocollagen-Loaded Hyaluronic Acid-Based Porous Scaffold on Healing in a Rabbit Model of Chronic Rotator Cuff Tear.

Abstract

High re-tear rates following rotator cuff repair are largely due to poor tendon-to-bone healing and fibrotic tissue formation. Hyaluronic acid (HA) and atelocollagen have demonstrated potential for improving tendon healing, but their injectable forms suffer from rapid diffusion and limited retention at the repair site. An atelocollagen-loaded HA porous scaffold would demonstrate excellent structural, mechanical, and biological properties in vitro and promote superior tendon healing in a rabbit model of chronic rotator cuff tear. Controlled laboratory study. The porous HA scaffold was synthesized via cryogelation and reinforced with VICRYL mesh. In vitro characterization included macroporosity (∼100-200 μm), swelling behavior, compressive strength under cyclic loading and pore interconnectivity. Atelocollagen loading and retention were assessed through injection and agitation tests, while biocompatibility was evaluated using C2C12 myoblasts in a transwell culture system. For in vivo analysis, 32 rabbits underwent bilateral chronic supraspinatus tendon detachment and delayed repair, and were randomized into 4 groups: (A) saline injection, (B) HA scaffold only, (C) atelocollagen injection and (D) atelocollagen-loaded HA scaffold. At 12 weeks post-repair, histological scoring, gene expression and biomechanical testing were performed. The porous scaffold exhibited high mechanical resilience, stable atelocollagen retention within macropores, and excellent biocompatibility with no cytotoxic effects. VICRYL reinforcement enabled firm suture retention without tearing, confirming surgical applicability. In vivo, Group D demonstrated significantly greater collagen fiber density (p = .041) and higher tendon stiffness (42.2 ± 7.5 N/mm; p = .005) compared to other groups. Load-to-failure values were highest in Group D but not statistically significant. No significant differences were observed in gene expression among groups at 12 weeks. The atelocollagen-loaded HA porous scaffold offers a structurally stable, biocompatible platform capable of sustained therapeutic delivery. It significantly enhanced collagen organization and mechanical strength in a chronic rotator cuff tear model, supporting its potential as an effective adjunct to tendon repair.