关键词: 肩袖补片, 外消旋聚乳酸, I型胶原, 静电纺丝, 恒应力退火, 生物医用纺织品, 肩袖肌腱修复

Abstract:

Objective Rotator cuff repairs continue to face significant clinical challenges due to high retear rates, primarily resulting from poor tendon healing and insufficient mechanical support during the regeneration process. This study aims to develop an advanced biomimetic scaffold that combines synthetic polymers with natural extracellular matrix components to create a functional patch that enhances both biological integration and mechanical stability at the repair site, thereby potentially improving clinical outcomes in rotator cuff reconstruction.

Method The as-received poly(D,L-lactic acid) (PDLLA)/type I collagen composite fibrous patch was prepared by electrospinning a blend solution. The thermally as-annealed patch was subsequently obtained by controlled heat treatment. The patches were characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), universal mechanical testing, and in vitro cell assays to evaluate their morphology, chemical composition, hydrophilicity, mechanical properties, wet-state stability, and cytocompatibility.

Results Both the as-received and as-annealed patches exhibited well-defined three-dimensional fibrous networks with interconnected pores, featuring a hierarchical structure containing both nanoscale and microscale fibers. The porosity measurements confirmed highly porous architectures exceeding 80%, which provides an optimal environment for cell infiltration and nutrient transport. Successful incorporation of type I collagen within the PDLLA matrix was confirmed by FT-IR spectroscopy, demonstrating characteristic collagen absorption bands. This integration significantly enhanced the surface hydrophilicity of the inherently hydrophobic PDLLA polymer, as evidenced by substantially reduced water contact angles. The thermal annealing treatment profoundly improved the patch's performance in wet conditions. After 14 d aqueous incubation, the as-annealed patch demonstrated remarkable structural preservation compared to the as-received patch. Quantitative analysis revealed that the fiber orientation retention increased by 50% (p<0.001), while the area shrinkage decreased by 39.3% (p<0.01). Mechanical characterization showed that the annealing process effectively maintained structural integrity under hydration, with the as-annealed patch exhibiting 31.21% higher fracture strength (p<0.05) and 84.53% greater elastic modulus (p<0.05) than the as-received patch after the same incubation period. Furthermore, biological assessment confirmed excellent cytocompatibility of the as-annealed patch, with cell proliferation rates consistently exceeding 80% throughout the 7 d culture period.

Conclusion The thermally annealed PDLLA/type I collagen composite fibrous patch proposed demonstrates comprehensive advantages including significantly enhanced wet-state stability, superior mechanical retention under physiological conditions, and excellent cytocompatibility. These improved characteristics address critical requirements for rotator cuff repair applications, where maintaining structural integrity and promoting biological integration are essential for successful healing. The annealing strategy effectively stabilizes the fiber architecture against hydration-induced collapse while preserving the beneficial effects of collagen incorporation on biological activity. The patch's biomimetic composition, combining synthetic polymer durability with natural protein bioactivity, along with its optimized structural properties, positions it as a promising candidate for clinical application in tendon repair. Future work should focus on in vivo validation using appropriate animal models to further investigate the patch's regenerative performance and long-term fate in biological environments, as well as exploration of its potential for delivering therapeutic agents to further enhance the healing process.

Key words: rotator cuff repair patch, poly(D, L-lactic acid), type I collagen, electrospinning, constant-stress annealing synergy, medical textiles, rotator cuff tendon repair