Intra-articular injections of expanded mesenchymal stem cells with and without addition of platelet-rich plasma are safe and effective for knee osteoarthritis

Purpose: To compare the effectiveness and safety of intra-articular injections of autologous expanded mesenchymal stromal stem cells alone (MSCs), or in combination with platelet-rich plasma (MSCs + PRP), in patients with knee osteoarthritis. Methods: Eighteen patients (57.6 ± 9.6 years) with radiographic symptomatic knee osteoarthritis (Dejour grades II–IV) were randomized to receive intra-articular injections of MSCs (n = 9) or MSCs + PRP (n = 9). Injections were performed 2–3 weeks after bone marrow aspiration (± 80–100 ml) which was obtained from both posterior iliac crests. Results: The Knee Injury and Osteoarthritis Outcome Score (KOOS) improved significantly throughout the 12 months for both groups (p < 0.05). No statistically significant differences between groups were found in KOOS subscales and global score improvements at 12-month end-point (n.s.). The MSCs group showed significant improvements in the pain, function and daily living activities, and sports and recreational activities subscales (p < 0.05). Similarly, the MSCs + PRP group showed significant improvements in the pain, function and daily living activities and quality of life subscales (p < 0.05). The average number of fibroblast colony forming units (CFU-F) was 56.8 + 21.9 for MSCs group and 50.7 ± 21.7 for MSCs + PRP group. Minimal adverse effects were seen in both groups (10 adverse events, in 5 patients). Conclusions: Intra-articular injections of expanded MSCs alone or in combination with PRP are safe and have a beneficial effect on symptoms in patients with symptomatic knee osteoarthritis. Adding PRP to the MSCs injections did not provide additional benefit. These results are encouraging and support the recommendation of this minimally invasive procedure in patients with knee osteoarthritis, without requiring hospitalization. The CFU-F results may be used as reference for future research. Level of evidence: Prospective cohort study, Level II.