Cell Therapy in Osteonecrosis: How Can We Target and Improve the Number of Cells for Better Clinical Results?

Symptomatic osteonecrosis related to corticosteroids has a high risk of progression to collapse in absence of treatment. The purpose of this study was to evaluate the results of cell therapy grafting of the hip in patients with osteonecrosis and to compare the results with the type of cells, the number of cells and the cause of osteonecrosis. We investigated the impact of mesenchymal stem cell (MSC) therapy on treating bilateral human hip osteonecrosis, analyzing 908 cases. The study assesses factors like tissue source and cell count, comparing repair and clinical results with various cell therapies. The research emphasizes bone repair according to pre-treatment conditions and the specificities of cell therapy in osteonecrosis repair, indicating a potential for improved bone repair strategies in hips with collapse and without femoral head collapse. The examined the impact on bone repair of tissue source (autologous bone marrow concentrate, allogeneic expanded, autologous expanded), cell quantity (from none in core decompression alone to millions in cell therapy), and osteonecrosis stage and volume influence. Both pre-operative and post-operative MRIs and a follow-up of over five years. The analysis divided these patients into seven groups based on match control treatment variations in bilateral hip osteonecrosis, primarily investigating the outcomes. Younger patients (<30 years) demonstrated significantly better repair volumes, particularly in stage II lesions than older counterparts. Additionally, bone repair volume increased with the number of implanted MSCs up to 1,000,000, beyond which no additional benefits were observed. No significant difference was observed in repair outcomes between different sources of MSCs (BMAC, allogenic, or expanded cells). The study also highlighted that a ‘washing effect’ was beneficial, particularly for larger-volume osteonecrosis. A partial bone repair was the more frequent event observed, while total bone repair of osteonecrosis was possible but less frequent. The volume and stage of osteonecrosis, alongside the number of injected cells, significantly affected treatment outcomes. The study provides comprehensive insights into the effectiveness and variables influencing the use of mesenchymal stem cells in treating human hip osteonecrosis. It emphasizes the potential of cell therapy while acknowledging the complexity and variability of results based on factors like age, cell count, and disease stage.