Qualitative and Quantitative Evaluation of Loose Bodies as a Novel Cell Source for Autologous Chondrocyte Implantation

Background: Autologous chondrocyte implantation (ACI) has recently produced successful outcomes, but donor site morbidity remains an urgent issue to be resolved. Thus, alternative cell sources are highly desirable to minimize donor site morbidity. Purpose: To qualitatively and quantitatively evaluate the potential of loose bodies as a novel cell source for ACI. Study Design: Controlled laboratory study. Methods: Loose bodies were obtained from 10 patients during arthroscopic surgery. They were evaluated by gross appearance and histology and classified into normal, abnormal, and no-cartilage groups. Then, 3-dimensional (3D)-cultured cartilage was prepared using chondrocytes from the loose bodies, and cell proliferation and glycosaminoglycan production in the 3D-cultured cartilage were compared with those from native cartilage obtained from patients who underwent total knee arthroplasty. Finally, expression of 42 genes by primary chondrocytes from the loose bodies was analyzed by chondrocyte gene spatial mapping analysis (CGSMA) and compared with that of reference chondrocytes to visualize their global properties, including ossification and denaturation. Scores for the chondrocyte gene spatial mapping analysis showed that the 3D-cultured cartilage produced from 2 loose bodies exhibited gene expression within the reference range of native cartilage. While 2 of the 10 loose bodies (20%) met the predefined criteria across all 3 evaluations, this proportion increased to 50% (2 of 4) when the analysis was restricted to loose bodies classified in the normal cartilage group. Conclusion: A subset of loose bodies demonstrated matrix-producing capacity without ossification or denaturation, supporting their potential as a cell source for ACI. Clinical Relevance: Appropriately selected loose bodies are a potential cell source for ACI while minimizing donor site morbidity.