Factors affecting outcomes of intra-articular injection of autologous, culture-expanded, adipose-derived mesenchymal stem cells in knee osteoarthritis

BACKGROUND: This study aims to assess the outcomes of intra-articular injection of adipose-derived mesenchymal stem cells (ADMSC) in osteoarthritis (OA) of knee joint up to 3-year follow-up and evaluate possible factors related to the outcomes. METHODS: This was a prospective observational follow-up of participants from the ADMSC treatment arm of a prior phase III clinical trial. A total of 104 patients were assessed through the follow-up study for 3 years after ADMSC injection. We assessed the WOMAC and VAS for pain at 1-, 2-, and 3-year post-injection and compared with baseline values. Minimal clinically important difference (MCID) was calculated, and the proportion of patients achieving MCID was evaluated at each time point. Finally, we assessed which factors may affect the outcome. RESULTS: Significant improvements in WOMAC and VAS scores were observed after ADMSC injection, with these benefits sustained throughout the 1-, 2-, and 3-year follow-up. The proportion achieving MCID slightly decreased over time without statistical significance. Significant factors affecting the favorable outcomes were lower body mass index (BMI) (<25), higher baseline clinical scores up to 3 years after the injection. Other variables did not show the significant relation. CONCLUSIONS: Intra-articular injection of autologous, culture-expanded ADMSC in patient with knee OA was sustained improvements observed up to 3 years in terms of WOMAC and VAS values. Moreover, patient BMI and baseline WOMAC were related to the outcomes after a single injection. Patient condition including severity of pain may affect the effect of ADMSC injection in OA knee. Clinical trial registration number: NCT04427930. This study was retrospectively registered.