Centimeter-Scale Self-Assembling Tendon Organoids Drive Tissue Regeneration

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.