Aims. The purpose of our study was to determine whether mesenchymal stem cells (MSCs) are an effective and safe therapeutic agent for the treatment of knee osteoarthritis (OA), owing to their cartilage regeneration potential. Methods. We searched PubMed, Embase, and the Cochrane Library, with keywords including “knee osteoarthritis” and “mesenchymal stem cells”, up to June 2019. We selected randomized controlled trials (RCTs) that explored the use of MSCs to treat knee OA. The visual analogue scale (VAS), Western Ontario and McMaster University Osteoarthritis Index (WOMAC), adverse events, and the whole-organ MRI score (WORMS) were used as the primary evaluation tools in the studies. Our meta-analysis included a subgroup analysis of cell dose and cell source. Results. Seven trials evaluating 256 patients were included in the meta-analysis. MSC treatment significantly improved the VAS (mean difference (MD), –13.24; 95% confidence intervals (CIs) –23.28 to –3.20, p = 0.010) and WOMAC (MD, –7.22; 95% CI –12.97 to –1.47, p = 0.010). The low-dose group with less than 30 million cells showed lower p-values for both the VAS and WOMAC. Adipose and umbilical cord–derived stem cells also had lower p-values for pain scores than those derived from bone marrow. Conclusion. Overall, MSC-based cell therapy is a relatively safe treatment that holds great potential for OA, evidenced by a positive effect on pain and knee function. Using low-dose (25 million) and adipose-derived stem cells is likely to achieve better results, but further research is needed. Cite this article: Bone Joint Res 2020;9(10):719–728

Stem cells are defined by their potential for self-renewal and the ability to differentiate into numerous cell types, including cartilage and bone cells. Although basic laboratory studies demonstrate that cell therapies have strong potential for improvement in tissue healing and regeneration, there is little evidence in the scientific literature for many of the available cell formulations that are currently offered to patients. Numerous commercial entities and ‘regenerative medicine centres’ have aggressively marketed unproven cell therapies for a wide range of medical conditions, leading to sometimes indiscriminate use of these treatments, which has added to the confusion and unpredictable outcomes. The significant variability and heterogeneity in cell formulations between different individuals makes it difficult to draw conclusions about efficacy. The ‘minimally manipulated’ preparations derived from bone marrow and adipose tissue that are currently used differ substantially from cells that are processed and prepared under defined laboratory protocols. The term ‘stem cells’ should be reserved for laboratory-purified, culture-expanded cells. The number of cells in uncultured preparations that meet these defined criteria is estimated to be approximately one in 10 000 to 20 000 (0.005% to 0.01%) in native bone marrow and 1 in 2000 in adipose tissue. It is clear that more refined definitions of stem cells are required, as the lumping together of widely diverse progenitor cell types under the umbrella term ‘mesenchymal stem cells’ has created confusion among scientists, clinicians, regulators, and our patients. Validated methods need to be developed to measure and characterize the ‘critical quality attributes’ and biological activity of a specific cell formulation. It is certain that ‘one size does not fit all’ – different cell formulations, dosing schedules, and culturing parameters will likely be required based on the tissue being treated and the desired biological target. As an alternative to the use of exogenous cells, in the future we may be able to stimulate the intrinsic vascular stem cell niche that is known to exist in many tissues. The tremendous potential of cell therapy will only be realized with further basic, translational, and clinical research. Cite this article: Bone Joint J 2019;101-B:361–364

Background. Stem cell based intervertebral disc (IVD) regeneration is quickly moving towards clinical applications. However, many aspects need to be investigated to routinely translate this therapy to clinical applications, in particular, the most efficient way to deliver cell to the IVD. Cells are commonly delivered to the IVD through the annulus fibrosus (AF) injection. However, recent studies have shown serious drawbacks of this approach. As an alternative we have described and tested a new surgical approach to the IVD via the endplate-pedicles (transpedicular approach). The Purpose of the study was to test MSCs/hydrogel transplantation for IVD regeneration in a grade IV preclinical model of IDD on large size animals via the transpeducular approach with cell dose escalation. Methods. Adult sheep (n=18) underwent bone marrow aspiration for autologous MSC isolation and expansion. MSC were suspended in autologous PRP and conjugated with Hyaluronic Acid and Batroxobin at the time of transplant (MSCs/hydrogel). Nucleotomy was performed via the transpedicular approach in four lumbar IVDs and that were injected with 1) hydrogel, 2) Low doses of MSC/hydrogel, 3) High doses of MSC/hydrogel, 4) no injection (CTRL). The endplate tunnel was sealed using a polyurethane scaffold. X-ray and MRI were performed at baseline and 1,3,6,12 months. Disc macro- and micro-morphology were analysed at each time point. Results. The MRI index showed a significant decrease in the untreated group, the disc injected with hydrogel and those injected with low MSC dose compared to healthy discs in all time points. The discs treated with high dose of MSC showed maintenance of the MRI index compared to the healthy disc. Morphologically, the grade of degeneration evaluated using the were in agreement with the grades observed at the MRI. Conclusions. An effective dose of autologous MSC (1−107 cell/ml) delivered via the alternative transpedicular approach regenerates the NP in a preclinical model of grade IV IDD maintaining the AF intact This preclinical study has high translational value as large animal model with the long fallow up were used, MSCs were expanded in GMP facility simulating the clinical scenario, and the hydrogel were composed of clinically available drags and materials

Summary Statement. This study explores the therapeutic use of MSCs to enhance ligament healing from an immuno-modulatory perspective. We report improved healing with MSC treatment, but inconsistent effects on inflammatory markers. Introduction. Mesenchymal stem cell (MSC) use continues to hold untapped potential as a therapeutic agent because: 1) MSCs have the ability to differentiate into several different connective tissues such as cartilage, bone, muscle and fat (1–3), and 2) MSCs can modulate immune and inflammatory responses that affect healing (4, 5). This paradigm shift from differentiation to immune modulation is being studied for different applications (6). Several studies suggest MSCs decrease inflammation by reducing pro-inflammatory cytokines and changing the macrophage phenotype from M1 (classically-activated) to M2 (alternatively-activated) (7–10). However, their immune-modulatory effects within a healing ligament remain unexplored. MSCs can behave differently depending on the tissue and healing environment they encounter, which leads to our interest in MSC immune-modulation in healing ligaments. Methods. Forty-four rats underwent bilateral MCL transection. Days 5 and 14 healing were examined comparing two cell doses (1×10. 6. MSCs or 4×10. 6. MSCs). At the time of surgery, fluorescently-labeled rat MSCs (passage 8–10) were injected into the right MCL, while the left MCL served as a control for normal healing. MCLs were collected at the different time points and processed with immunohistochemistry (n=12). Type 1 macrophages (M1) and type 2 macrophages (M2) were quantified spatially within the healing ligaments. Twelve rats with MSC injections underwent mechanical testing. A multiplex cytokine reader measured 10 different cytokines in the healing ligaments at days 5 and 14. Results. MSCs were detected solely in the healing region and healing region edges at Days 5 and 14 in both dose groups using fluorescence microscopy. At day 5, the higher dose of cells produced significant M2 changes throughout the ligament. There were more M2′s (p=.05) in the distal and proximal healing regions of the normal healing ligament compared to the MSC injection group. There were significant changes in both the low dose and high dose groups at day 14. Fewer M1′s were found in the ends (p=.01) and throughout the MCL (p=.04) in the low dose group. M2′s were decreased in the ends (p=.04), but only in the ligaments that received the higher dose of MSCs. Cytokine analysis showed a greater amount of pro-inflammatory cytokines in the high dose MSC group at Day 5 (IL-1β, IL-2, and Interferon-Y) compared to controls, along with increased IL-12 at Day 14. The low dose MSC injection group demonstrated increased strength with an average failure load of 26.4N compared to 20.9N in the control group (p=.03). Low dose ligaments also exhibited increased stiffness with an average of 12.2 N/mm compared to 10.0 N/mm (p=.01) in control ligaments. Discussion. MSCs improved healing when applied at an appropriate dose as shown by improved mechanical properties at day 14. Interestingly, the smaller dose of 1 million cells proved more successful than the larger dose of 4 million cells. MSCs also affected the cytokine profile and macrophage phenotype at both healing time points, but not always as expected with regard to inflammatory cells and cytokines

Objectives

Traumatic brachial plexus injury causes severe functional impairment of the arm. Elbow flexion is often affected. Nerve surgery or tendon transfers provide the only means to obtain improved elbow flexion. Unfortunately, the functionality of the arm often remains insufficient. Stem cell therapy could potentially improve muscle strength and avoid muscle-tendon transfer. This pilot study assesses the safety and regenerative potential of autologous bone marrow-derived mononuclear cell injection in partially denervated biceps.

We evaluated the efficacy of Escherichia coli-derived recombinant human bone morphogenetic protein-2 (E-BMP-2) in a mini-pig model of spinal anterior interbody fusion. A total of 14 male mini-pigs underwent three-level anterior lumbar interbody fusion using polyether etherketone (PEEK) cages containing porous hydroxyapatite (HA). Four groups of cages were prepared: 1) control (n = 10 segments); 2) 50 μg E-BMP-2 (n = 9); 3) 200 μg E-BMP-2 (n = 10); and 4) 800 μg E-BMP-2 (n = 9). At eight weeks after surgery the mini-pigs were killed and the specimens were evaluated by gross inspection and manual palpation, radiological evaluation including plain radiographs and micro-CT scans, and histological analysis. Rates of fusion within PEEK cages and overall union rates were calculated, and bone formation outside vertebrae was evaluated. One animal died post-operatively and was excluded, and one section was lost and also excluded, leaving 38 sites for assessment. This rate of fusion within cages was 30.0% (three of ten) in the control group, 44.4% (four of nine) in the 50 μg E-BMP-2 group, 60.0% (six of ten) in the 200 μg E-BMP-2 group, and 77.8% (seven of nine) in the 800 μg E-BMP-2 group. Fusion rate was significantly increased by the addition of E-BMP-2 and with increasing E-BMP-2 dose (p = 0.046). In a mini-pig spinal anterior interbody fusion model using porous HA as a carrier, the implantation of E-BMP-2-loaded PEEK cages improved the fusion rate compared with PEEK cages alone, an effect that was significantly increased with increasing E-BMP-2 dosage.

Cite this article: Bone Joint J 2013;95-B:217–23.

Cytokine mediated activation of osteoclasts can lead to peri-implant osteolysis and aseptic loosening. The aim of this study was to determine the IL-1β and TNFα mRNA cytokine expression profile of human macrophages when stimulated with polyethylene particles using relative quantitative real-time polymerase chain reaction (rqRT-PCR). Human peripheral blood monocytes or human monocytes from the cell line THP-1 were used in this study. rqRT-PCR conditions were optimized by stimulating human macrophages with 200ng/ml lipopolysaccharide (LPS). The median CV% value for duplicate measures was 12.6 (range 4.5–54). Stimulation assays were performed using unfractionated endotoxin-free commercial polyethylene particles (median size 7μm); or fractionated particles (size range 0.1–1.2μm). Human macrophages were stimulated with high dose unfractionated polyethylene particles at 0, 3500 or 10500 mm. 3. /cell or with fractionated polyethylene particles at 0 and 100mm. 3. /cell at time points 0 and 3 hours. Low dose unfractionated polyethylene stimulation was performed on THP-1 cells at 0, 50, 100, 1000 and 10000 mm. 3. /cell. In all experiments LPS stimulation was used as a positive control. RNA was extracted and rqRT-PCR was performed using standard techniques. High dose unfractionated polyethylene stimulation did not result in a significant difference in cytokine mRNA levels between groups. Using fractionated polyethylene, a small increase in IL-1β mRNA was identified (21% versus maximal stimulation using LPS). Low dose unfractionated polyethylene stimulation of THP-1 cells demonstrated dose dependent decreases in TNFα and IL-1β mRNA expression that was not due to inhibition of RNA extraction or a decrease of cell viability. Endotoxin-free polyethylene particles do not appear to be a major stimulus for IL-1β and TNFα mRNA production as measured by rqRT-PCR. We did observe a small positive effect on IL-1β mRNA expression using a fractionated polyethylene stimulus. However it remains unclear whether this effect is due to fractionation of particles into the submicron range or is due to introduction of endotoxin during the filtration process