Treatment of Partial Growth Arrest Using an In Vitro-generated Scaffold-free Tissue-engineered Construct Derived From Rabbit Synovial Mesenchymal Stem Cells

Background: Injuries to the epiphyseal plate sometimes result in partial growth arrest, which can lead to the development of angular deformities and limb length discrepancies in growing children. The aim of this study was to develop a new treatment for partial growth arrest of the physis. For this purpose, we investigated the feasibility of an in vitro-generated scaffold-free tissue-engineered construct (TEC) derived from synovial mesenchymal stem cells (MSCs) in a rabbit growth arrest model. Methods: An experimental model for growth arrest was created by excising the medial half of the proximal growth plate of tibias from 6-week-old New Zealand White rabbits. Three experimental groups were set to evaluate TEC implantation: group 1, no implantation as controls; group 2, implantation of bone wax as additional controls; and group 3, implantation of TEC in the lesion. Results: In group 1, all damaged growth plates were arrested and angular deformities appeared 4 weeks later. In groups 2 and 3, angular deformities were less than in the control group. Histologic images showed bone bridges developed at the damaged growth plate in group 1. Regeneration of growth plates was recognized in groups 2 and 3. Histologic examination showed greater regeneration of the growth plate in group 3 than in group 2. In addition, MSCs in the TEC differentiated into proliferative and prehypertrophic chondrocyte-like cells. Conclusions: A scaffold-free 3D TEC made using cultured synovium-derived MSCs differentiated into proliferative and prehypertrophic chondrocyte-like cells. Clinical Relevance: The results of this experimental study suggest that scaffold-free 3D TEC made using cultured synovium-derived MSCs can be a new approach for the repair of epiphyseal injury. Clinical effectiveness of a scaffold-free 3D TEC for growth arrest remains to be determined.