Advances in Achilles Tendon Tissue Engineering: Integrating Cells, Scaffolds, and Mechanical Loading for Functional Regeneration.

Achilles tendon injuries are among the most frequent and debilitating musculoskeletal conditions, often resulting in incomplete healing and functional deficits. Conventional repair techniques primarily restore structural continuity but rarely achieve full biomechanical or histological regeneration. Recent advances in tissue engineering have introduced innovative strategies combining biomimetic scaffolds, cellular therapy, growth factors, and mechanical loading to promote regenerative rather than fibrotic repair. This review summarises the current understanding of Achilles tendon biology and healing mechanisms, with a focus on the integration of stem cell technologies, scaffold design, and mechanobiological conditioning. Various scaffold systems, including natural, synthetic, hybrid, and hydrogel-based constructs, are evaluated for their biocompatibility, mechanical performance, and tenoinductive potential. Preclinical studies demonstrate that mesenchymal stem cell (MSC)-loaded scaffolds exhibit significantly enhanced biomechanical outcomes in tendon defect models, including improved tensile strength, organized collagen I deposition and aligned fibre architecture in repaired constructs. While preclinical results are promising, clinical translation remains limited by regulatory, economic, and methodological challenges. Future research should prioritise standardised protocols, long-term functional outcomes, and interdisciplinary collaboration.