Efficacy and safety of adult human bone marrow-derived, cultured, pooled, allogeneic mesenchymal stromal cells (Stempeucel®): preclinical and clinical trial in osteoarthritis of the knee joint

Abstract

Background: Osteoarthritis (OA) is a common and debilitating chronic degenerative disease of the joints. Currently, cell-based therapy is being explored to address the repair of damaged articular cartilage in the knee joint.

Methods: The in vitro differentiation potential of adult human bone marrow-derived, cultured, pooled, allogeneic mesenchymal stromal cells (Stempeucel®) was determined by differentiating the cells toward the chondrogenic lineage and quantifying sulfated glycosaminoglycan (sGAG). The mono-iodoacetate (MIA)-induced preclinical model of OA has been used to demonstrate pain reduction and cartilage formation. In the clinical study, 60 OA patients were randomized to receive different doses of cells (25, 50, 75, or 150 million cells) or placebo. Stempeucel® was administered by intra-articular (IA) injection into the knee joint, followed by 2 ml hyaluronic acid (20 mg). Subjective evaluations-visual analog scale (VAS) for pain, intermittent and constant osteoarthritis pain (ICOAP), and Western Ontario and McMaster Universities Osteoarthritis (WOMAC-OA) index-were performed at baseline and at 1, 3, 6, and 12 months of follow-up. Magnetic resonance imaging of the knee was performed at baseline, and at 6 and 12 months follow-up for cartilage evaluation.

Results: Stempeucel® differentiated into the chondrogenic lineage in vitro with downregulation of Sox9 and upregulation of Col2A genes. Furthermore, Stempeucel® differentiated into chondrocytes and synthesized a significant amount of sGAG (30 ± 1.8 μg/μg GAG/DNA). In the preclinical model of OA, Stempeucel® reduced pain significantly and also repaired damaged articular cartilage in rats. In the clinical study, IA administration of Stempeucel® was safe, and a trend towards improvement was seen in the 25-million-cell dose group in all subjective parameters (VAS, ICOAP, andWOMAC-OA scores), although this was not statistically significant when compared to placebo. Adverse events were predominant in the higher dose groups (50, 75, and 150 million cells). Knee pain and swelling were the most common adverse events. The whole-organ magnetic resonance imaging score of the knee did not reveal any difference from baseline and the placebo group.

Conclusion: Intra-articular administration of Stempeucel® is safe. A twenty-five-million-cell dose may be the most effective among the doses tested for pain reduction. Clinical studies with a larger patient population are required to demonstrate a robust therapeutic efficacy of Stempeucel® in OA.

Trial registration: Clinicaltrials.gov NCT01453738 . Registered 13 October 2011.

Keywords: Cell therapy; Mesenchymal stromal cells; Osteoarthritis.

Fig. 1

CONSORT flow chart showing the number of patients randomized, followed-up, and analyzed. M million cells, Cell Stempeucel®, mITT modified intention to treat

Fig. 2

Quantification of gene expression and sGAG. Quantitative mRNA expression of a SOX9 and b Col2A in the control (white bar) and chondrogenically differentiated Stempeucel® (black bar) by real-time PCR analysis (n = 6). c Sulfated glycosaminoglycan (sGAG) content in the control (white bar) and chondrogenically differentiated Stempeucel® (black bar) by DMMB dye-binding assay. The sGAG values were normalized to the DNA content in the control and chondrogenically differentiated Stempeucel® (n = 6). Results are represented as mean with SEM

Fig. 3

Effect of intra-articular injection of Stempeucel® on pain reduction and cartilage repair in an osteoarthritic rat model. a The effect of Stempeucel® on pain reduction at week 0 (before cell injection), and at weeks 4, 8, and 12 after cell injection. Data are presented as mean ± SEM. *P < 0.05, ***P < 0.001 versus hyaluronic acid (HA)-treated group. b Photomicrographs of representative joint sections of femoral condyle stained with H&E at 4 (a–e), 8 (f–j), and 12 weeks (k–o) after Stempeucel® treatment. Osteoarthritic changes, such as loss of chondrocytes (*), loss of cartilage (vertical arrow), and fibrillation (thin arrow) are evident in vehicle-treated and HA-treated joints. Proliferation of chondrocytes (thick arrow), regeneration, and repair of cartilage tissue was evident in Stempeucel®-treated groups. Scale bars = 100 μm, magnification 10×. H high dose of Stempeucel®, L Low dose of Stempeucel®, MIA mono-iodoacetate, ns not significant

Fig. 4

Histological evaluation of Safranin-O stained joint sections. a Photomicrographs of representative joint specimens of femoral condyle stained with Safranin-O at 4 (a–e), 8 (f–j), and 12 weeks (k–o) after Stempeucel® treatment. Loss of articular surface, roughening of cartilage and reduced staining of Safranin-O (thin arrow) were observed in vehicle- and HA-treated joints. Strongly stained Safranin-O-positive cartilage (thick arrow) with increased numbers of chondrocytes was seen in the Stempeucel®-treated groups. Scale bars = 100 μm, magnification 10×. b Sulfated glycosaminoglycan (GAG) fraction intensity was measured from histological images of Safranin-O-stained sections at weeks 4, 8, and 12. The intensity of Safranin-O staining is represented graphically, and the data are represented as mean ± SEM. At 12 weeks, the Stempeucel®-treated groups (both low (L) and high (H) dose) showed a significant improvement in the sGAG content compared to the disease control (mono-iodoacetate; MIA) and hyaluronic acid (HA)-treated groups. *P < 0.05, *** P < 0.001. ns not significant

Fig. 5

Visual analog scale values. Data are presented as mean ± SD. 1 M, 3 M, 6 M, and 12 M = 1, 3, 6, and 12 months, respectively; C1 cohort 1, C2 cohort 2, M million cells, P placebo, VAS visual analog scale

Fig. 6

WOMAC results. WOMAC a, b composite, c, d pain, e, f stiffness, and g, h physical function (PF) results are shown for cohorts 1 (a, c, e and g) and 2 (b, d, f, and h). Data are presented as mean ± SD. 1 M, 3 M, 6 M, and 12 M = 1, 3, 6, and 12 months, respectively; C1 cohort 1, C2 cohort 2, M million cells, P placebo, WOMAC Western Ontario and McMaster Universities

Fig. 7

ICOAP results. ICOAP a, b total, c, d constant pain, and e, f intermittent pain results are shown for cohorts 1 (a, c, and e) and 2 (b, d, and f). Data are presented as mean ± SD. 1 M, 3 M, 6 M, and 12 M = 1, 3, 6, and 12 months, respectively; C1 cohort 1, C2 cohort 2, ICOAP intermittent and constant osteoarthritis pain, M million cells, P placebo