The Leiden ex vivo human growth plate model in severe tall stature: a proof-of-concept study

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ABSTRACT Background Viable human growth plate (GP) tissue is rarely available for translational research, limiting direct investigation of human longitudinal bone growth and pediatric growth disorders. In this proof-ofconcept study, we aimed to determine feasibility to establish a clinically integrated ex vivo human growth plate model using tissue obtained during routine percutaneous epiphysiodesis (PE) procedures in adolescents treated for extreme tall stature or leg length difference due to trauma. Methods Growth plate tissue and cells were collected during PE and processed using protocols adapted from established methods of human osteoarthritic cartilage collection within the RAAK study. Collected tissues and three-dimensional cartilage pellets generated from isolated cells were assessed by histology. Proliferation of GP-derived chondrocytes was compared with osteoarthritis-derived articular chondrocytes. Results Across consecutive surgical procedures, viable GP tissue could be obtained reproducibly including the node of Ranvier, with only few samples failing to yield cells and no contamination. Isolated GP chondrocytes expanded successfully in two-dimensional culture and showed a stronger early proliferative response compared with RAAK-derived chondrocytes. In addition, GP-derived cells formed threedimensional organoids and histology confirmed cartilage-like matrix deposition supporting their capacity to generate neo-cartilage tissue in vitro . Conclusion This study demonstrates feasibility to obtain, culture, and functionally assess viable human growth plate tissue from routine PE surgery. As such, the Leiden ex vivo human growth plate model provides a unique platform to study local mechanisms of endochondral bone growth, link genetic determinants of height to functional growth plate biology, and support future therapeutic research in pediatric growth disorders.