Centimeter‐Scale Self‐Assembling Tendon Organoids Drive Tissue Regeneration

Abstract As a cell‐deficient tissue, the scarcity of endogenous stem cells significantly hampers the regeneration of tissue structure and restoration of motor function following tendon injury. To engineer large‐scale transplantable stem cell‐derived organoids in vitro would show tremendous potential in regenerative medicine. Here, by optimizing chemical signals and mimicking tendon extracellular matrix, transplantable tendon organoids exceeding 3 cm in human tissue‐scale dimensions are ultimately developed. This strategy empowers tendon organoids, with high cellular viability, proliferation, tenogenic phenotype, and remarkable enhancements in extracellular matrix (ECM) production enabled self‐assembly. At the single‐cell level, the majority cells in tendon organoids successfully achieve precise tendon‐specific lineage differentiation in vitro while retaining the exceptional regenerative capacity characteristic of fetal tendons. In a tendon defect model, the organoids increase the retention rate of stem cells by 7.9 times at 4 weeks and initiate the formation of a denser repaired tendon with enhanced mechanical properties. Overall, an efficient construction of centimeter‐scale human tendon organoids with superior regenerative potential is achieved, providing a promising strategy for the regenerative medicine.