Bone Marrow Mesenchymal Stromal Cell Treatment in Patients with Osteoarthritis Results in Overall Improvement in Pain and Symptoms and Reduces Synovial Inflammation

Abstract

Patients with late-stage Kellgren-Lawrence knee osteoarthritis received a single intra-articular injection of 1, 10, or 50 million bone marrow mesenchymal stromal cells (BM-MSCs) in a phase I/IIa trial to assess safety and efficacy using a broad toolset of analytical methods. Besides safety, outcomes included patient-reported outcome measures (PROMs): Knee Injury and Osteoarthritis Outcome Score (KOOS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC); contrast-enhanced magnetic resonance imaging (MRI) for cartilage morphology (Whole Organ MRI Scores [WORMS]), collagen content (T2 scores), and synovitis; and inflammation and cartilage turnover biomarkers, all over 12 months. BM-MSCs were characterized by a panel of anti-inflammatory markers to predict clinical efficacy. There were no serious adverse events, although four patients had minor, transient adverse events. There were significant overall improvements in KOOS pain, symptoms, quality of life, and WOMAC stiffness relative to baseline; the 50 million dose achieved clinically relevant improvements across most PROMs. WORMS and T2 scores did not change relative to baseline. However, cartilage catabolic biomarkers and MRI synovitis were significantly lower at higher doses. Pro-inflammatory monocytes/macrophages and interleukin 12 levels decreased in the synovial fluid after MSC injection. The panel of BM-MSC anti-inflammatory markers was strongly predictive of PROMs over 12 months. Autologous BM-MSCs are safe and result in significant improvements in PROMs at 12 months. Our analytical tools provide important insights into BM-MSC dosing and BM-MSC reduction of synovial inflammation and cartilage degradation and provide a highly predictive donor selection criterion that will be critical in translating MSC therapy for osteoarthritis. Stem Cells Translational Medicine 2019;8:746&757.

Keywords: Arthritis; Cellular therapy; Clinical trials; Mesenchymal stem cells; Monocyte; Selectable marker.

Figure 1

Patient‐reported outcomes at baseline and after BM‐MSC injection. (A): Progression in WOMAC (left) and KOOS (right) subscales after BM‐MSG injection. WOMAC scores have been normalized such that higher WOMAC scores are indicative of better outcomes. p values shown for comparisons between baseline and 1‐year follow‐up using Wilcoxon signed‐rank test. (B): Delta in patient‐reported outcome measures (PROMs) relative to baseline. Dotted line indicates minimal clinical important difference threshold of 10. Green indicates 1 million, blue 10 million, and red 50 million BM‐MSC dose group. Error bars indicate SEM. (C): Number of patients from each group (four in each group) having a minimal clinically significant improvement (>10 in delta relative to baseline for each PROM) in each PROMs. Abbreviations: ADL, activity of daily living; KOOS, Knee Injury and Osteoarthritis Outcome Score; QOL, quality of life; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index.

Figure 2

Cartilage and synovitis composite scores over 12 months. (A): Cartilage morphology does not change after mesenchymal stromal cell (MSC) treatment. Fold change relative to baseline is shown. n = 4 for each MSC dose. (B): Synovitis score (shown as fold change relative to baseline) differs slightly between doses. n = 4 for 50 and n = 3 for 10 and 1 million MSC dose. No significant differences were found between baseline and 1‐year follow‐up.

Figure 3

Changes in plasma, serum, and urine biomarkers after mesenchymal stromal cell (MSC) injection. (A): Plasma HA and COMP. (B): Serum C1‐2C. (C): Urine CTXII and C2C. (A–C): Data are shown as fold change relative to baseline (before MSC injection) at 2, 6, 12, 24, and 48 weeks after MSC treatment. Error bars represent SEM. Blue line, 1 million MSC dose; green line, 10 million MSC dose; red line, 50 million MSC dose. Statistics related to this figure are shown in Table 1. No significant differences were seen using pairwise comparisons of baseline versus 12 months; thus, no statistics are shown on the graphs. Abbreviations: C1‐2C, collagen type I and II cleavage; C2C, cleavage product specific to type II collagen; COMP, cartilage oligomeric matrix protein; CTXII, C‐terminal crosslinked telopeptide type II collagen; HA, hyaluronan.

Figure 4

Synovial fluid changes 3 months after MSC treatment. (A): Only a few of the factors characterized in SF changed after MSC treatment. Fold change in SF soluble factors concentration after MSC treatment is displayed; dotted line indicates levels at baseline. Friedman test with Dunn's test as post hoc was used for identifying significant changes (n = 7). (B, C): Levels of adiponectin (B) and IL12p40 (C) in SF decrease after MSC treatment (n = 7). (D): Levels of VEGF increase after MSC treatment (n = 7). (E): Pro‐inflammatory CD14 + CD16+ monocyte/macrophages tend to decrease after MSC treatment (n = 5). (B–E): p values shown for Wilcoxon signed‐rank test. Abbreviations: CCL1, chemokine (C‐C motif) ligand 1; HGF, hepatocyte growth factor; IL, interleukins; MCP‐1, monocyte chemoattractant protein 1; MMP, matrix metalloproteinases; MSC, mesenchymal stromal cell; PGE2, prostaglandin; TIMP, tissue inhibitor of metalloproteinases; VEGF, vascular endothelial growth factor.

Figure 5

Licensed MSC anti‐inflammatory gene and protein expression is donor‐dependent. (A): Gene expression profile of interferon‐gamma (IFN‐γ) licensed mesenchymal stromal cells (MSCs) and secreted TSG‐6 levels by tumor necrosis factor‐licensed MSCs; markers analyzed indicated under each column and patient number indicated in each row. (B): PCA of IFN‐γ licensed MSC gene expression profile. Plot shows each patient MSC plotted with the two first PCs and identified for the dose at which it was used in the clinical study. Percentage shown next to PC‐1 and PC‐2 on axis labels indicate the contribution of each PC to the variance. (C): Contribution of each gene to PC‐1. (D): PC‐1 of each patient MSC showing high variability between donors. Abbreviations: HGF, hepatocyte growth factor; IDO, indoleamine 2,3 dioxygenase; IL, interleukins; PC, principal component; PCA, principal component analysis; PD‐L1, programmed death‐ligand 1; PGE2, prostaglandin; TGF‐β, transforming growth factor beta; TSG‐6, tumor necrosis factor alpha stimulated gene.