Intra-articular injection of mesenchymal stem cells in treating knee osteoarthritis: a systematic review of animal studies

Extracellular vesicles derived from mesenchymal stem cells mediate extracellular matrix remodeling in osteoarthritis through the transport of microRNA-29a

BACKGROUND

Knee osteoarthritis (KOA) is a common orthopedic condition with an uncertain etiology, possibly involving genetics and biomechanics. Factors like changes in chondrocyte microenvironment, oxidative stress, inflammation, and immune responses affect KOA development. Early-stage treatment options primarily target symptom relief. Mesenchymal stem cells (MSCs) show promise for treatment, despite challenges. Recent research highlights microRNAs (miRNAs) within MSC-released extracellular vesicles that can potentially promote cartilage regeneration and hinder KOA progression. This suggests exosomes (Exos) as a promising avenue for future treatment. While these findings emphasize the need for effective KOA progression management, further safety and efficacy validation for Exos is essential.

AIM

To explore miR-29a's role in KOA, we'll create miR-29a-loaded vesicles, testing for early treatment in rat models.

METHODS

Extraction of bone marrow MSC-derived extracellular vesicles, preparation of engineered vesicles loaded with miR-29a using ultrasonication, and identification using quantitative reverse transcription polymerase chain reaction; after establishing a rat model of KOA, rats were randomly divided into three groups: Blank control group injected with saline, normal extracellular vesicle group injected with normal extracellular vesicle suspension, and engineered extracellular vesicle group injected with engineered extracellular vesicle suspension. The three groups were subjected to general behavioral observation analysis, imaging evaluation, gross histological observation evaluation, histological detection, and immunohistochemical detection to compare and evaluate the progress of various forms of arthritis.

RESULTS

General behavioral observation results showed that the extracellular vesicle group and engineered extracellular vesicle group had better performance in all four indicators of pain, gait, joint mobility, and swelling compared to the blank control group. Additionally, the engineered extracellular vesicle group had better pain relief at 4 wk and better knee joint mobility at 8 wk compared to the normal extracellular vesicle group. Imaging examination results showed that the blank control group had the fastest progression of arthritis, the normal extracellular vesicle group had a relatively slower progression, and the engineered extracellular vesicle group had the slowest progression. Gross histological observation results showed that the blank control group had the most obvious signs of arthritis, the normal extracellular vesicle group showed signs of arthritis, and the engineered extracellular vesicle group showed no significant signs of arthritis. Using the Pelletier gross score evaluation, the engineered extracellular vesicle group had the slowest progression of arthritis. Results from two types of staining showed that the articular cartilage of rats in the normal extracellular vesicle and engineered extracellular vesicle groups was significantly better than that of the blank control group, and the engineered extracellular vesicle group had the best cartilage cell and joint surface condition. Immunohistochemical detection of type II collagen and proteoglycan showed that the extracellular matrix of cartilage cells in the normal extracellular vesicle and engineered extracellular vesicle groups was better than that of the blank control group. Compared to the normal extracellular vesicle group, the engineered extracellular vesicle group had a better regulatory effect on the extracellular matrix of cartilage cells.

CONCLUSION

Engineered Exos loaded with miR-29a can exert anti-inflammatory effects and maintain extracellular matrix stability, thereby protecting articular cartilage, and slowing the progression of KOA.

Irisin: An unveiled bridge between physical exercise and a healthy brain

AIMS

Physical exercise has been widely recognized for its positive effects on health and well-being. Recently, the impact of exercise on the nervous system has gained attention, with evidence indicating improvements in attention, memory, neurogenesis, and the release of "happiness hormones." One potential mediator of these benefits is Irisin, a myokine induced by exercise that can cross the blood-brain barrier, reduce neuroinflammation, and counteract neurodegeneration. The objective of this study is to conduct a systematic review of animal trials to summarize the neuroprotective effects of Irisin injection in mitigating neuroinflammation and neurodegeneration.

MATERIALS AND METHODS

Two independent reviewers screened three databases (PubMed, Embase, and Google Scholar) in November 2022. Animal studies assessing the neuroprotective effects of Irisin in mitigating neuroinflammation or counteracting neurodegeneration were included. The methodological quality of the included studies was assessed using SYRCLE's Risk of Bias tool.

KEY FINDINGS

Twelve studies met the inclusion criteria. Irisin injection in rodents significantly reduced neuroinflammation, cytokine cascades, and neurodegeneration. It also protected neurons from damage and apoptosis, reduced oxidative stress, blood-brain barrier disruption, and neurobehavioral deficits following disease or injury. Various mechanisms were suggested to be responsible for these neuroprotective effects. Most of the included studies presented a low risk of bias based on SYRCLE's Risk of Bias tool. Irisin injection demonstrated the potential to alleviate neuroinflammation and counteract neurodegeneration in rodent models through multiple pathways. However, further research is needed to fully understand its mechanism of action and its potential applications in clinical practice and drug discovery.

Regenerative Medicine Applied to Musculoskeletal Diseases in Equines: A Systematic Review

Musculoskeletal injuries in horses have a great economic impact, predominantly affecting tendons, ligaments, and cartilage, which have limited natural regeneration. Cell therapy, which uses mesenchymal stem cells due to their tissue differentiation properties and anti-inflammatory and immunoregulatory effects, aims to restore damaged tissue. In this manuscript, we performed a systematic review using the Parsifal tool, searching the PubMed and Web of Science databases for articles on regenerative medicine for equine musculoskeletal injuries. Our review covers 17 experimental clinical studies categorized by the therapeutic approach used: platelet-rich plasma, conditioned autologous serum, mesenchymal stem cells, and secretome. These therapies reduce healing time, promote regeneration of fibrocartilaginous tissue, improve cellular organization, and improve joint functionality and sustainability. In conclusion, regenerative therapies using platelet-rich plasma, conditioned autologous serum, equine mesenchymal stem cells, and the emerging field of the secretome represent a promising and highly effective approach for the treatment of joint pathologies in horses, implying a valuable advance in equine healthcare.

Integrin α10β1-Selected Mesenchymal Stem Cells Reduce Pain and Cartilage Degradation and Increase Immunomodulation in an Equine Osteoarthritis Model

OBJECTIVE

Integrin α10β1-selected mesenchymal stem cells (integrin α10-MSCs) have previously shown potential in treating cartilage damage and osteoarthritis (OA) in vitro and in animal models in vivo. The aim of this study was to further investigate disease-modifying effects of integrin α10-MSCs.

DESIGN

OA was surgically induced in 17 horses. Eighteen days after surgery, horses received 2 × 107 integrin α10-MSCs intra-articularly or were left untreated. Lameness and response to carpal flexion was assessed weekly along with synovial fluid (SF) analysis. On day 52 after treatment, horses were euthanized, and carpi were evaluated by computed tomography (CT), MRI, histology, and for macroscopic pathology and integrin α10-MSCs were traced in the joint tissues.

RESULTS

Lameness and response to carpal flexion significantly improved over time following integrin α10-MSC treatment. Treated horses had milder macroscopic cartilage pathology and lower cartilage histology scores than the untreated group. Prostaglandin E2 and interleukin-10 increased in the SF after integrin α10-MSC injection. Integrin α10-MSCs were found in SF from treated horses up to day 17 after treatment, and in the articular cartilage and subchondral bone from 5 of 8 treated horses after euthanasia at 52 days after treatment. The integrin α10-MSC injection did not cause joint flare.

CONCLUSION

This study demonstrates that intra-articular (IA) injection of integrin α10-MSCs appears to be safe, alleviate pathological changes in the joint, and improve joint function in an equine post-traumatic osteoarthritis (PTOA) model. The results suggest that integrin α10-MSCs hold promise as a disease-modifying osteoarthritis drug (DMOAD).

Controlled-Release Hydrogel Microspheres to Deliver Multipotent Stem Cells for Treatment of Knee Osteoarthritis

Osteoarthritis (OA) is the most common form of joint disease affecting articular cartilage and peri-articular tissues. Traditional treatments are insufficient, as they are aimed at mitigating symptoms. Multipotent Stromal Cell (MSC) therapy has been proposed as a treatment capable of both preventing cartilage destruction and treating symptoms. While many studies have investigated MSCs for treating OA, therapeutic success is often inconsistent due to low MSC viability and retention in the joint. To address this, biomaterial-assisted delivery is of interest, particularly hydrogel microspheres, which can be easily injected into the joint. Microspheres composed of hyaluronic acid (HA) were created as MSC delivery vehicles. Microrheology measurements indicated that the microspheres had structural integrity alongside sufficient permeability. Additionally, encapsulated MSC viability was found to be above 70% over one week in culture. Gene expression analysis of MSC-identifying markers showed no change in CD29 levels, increased expression of CD44, and decreased expression of CD90 after one week of encapsulation. Analysis of chondrogenic markers showed increased expressions of aggrecan (ACAN) and SRY-box transcription factor 9 (SOX9), and decreased expression of osteogenic markers, runt-related transcription factor 2 (RUNX2), and alkaline phosphatase (ALPL). In vivo analysis revealed that HA microspheres remained in the joint for up to 6 weeks. Rats that had undergone destabilization of the medial meniscus and had overt OA were treated with empty HA microspheres, MSC-laden microspheres, MSCs alone, or a control vehicle. Pain measurements taken before and after the treatment illustrated temporarily decreased pain in groups treated with encapsulated cells. Finally, the histopathological scoring of each group illustrated significantly less OA damage in those treated with encapsulated cells compared to controls. Overall, these studies demonstrate the potential of using HA-based hydrogel microspheres to enhance the therapeutic efficacy of MSCs in treating OA.

Comparative Effects of Intra-Articular versus Intravenous Mesenchymal Stromal Cells Therapy in a Rat Model of Osteoarthritis by Destabilization of Medial Meniscus

Transplanted mesenchymal stromal cells (MSCs) exhibit a robust anti-inflammatory and homing capacity in response to high inflammatory signals, as observed in studies focused on rheumatic diseases that target articular cartilage (AC) health. However, AC degradation in osteoarthritis (OA) does not necessarily coincide with a highly inflammatory joint profile. Often, by the time patients seek medical attention, they already have damaged AC. In this study, we examined the therapeutic potential of a single bone marrow MSC transplant (2 × 106 cells/kgbw) through two different routes: intra-articular (MSCs-IAt) and intravenous (MSCs-IVt) in a preclinical model of low-grade inflammatory OA with an established AC degeneration. OA was induced through the destabilization of the medial meniscus (DMM) in female Wistar Kyoto rats. The animals received MSCs 9 weeks after surgery and were euthanized 4 and 12 weeks post-transplant. In vivo and ex vivo tracking of MSCs were analyzed via bioluminescence and imaging flow cytometry, respectively. Cytokine/chemokine modulation in serum and synovial fluid was measured using a multiplex panel. AC degeneration was quantified through histology, and hindlimb muscle balance was assessed with precision weighing. To our knowledge, we are the first group to show the in vivo (8 h) and ex vivo (12 h) homing of cells to the DMM-OA joint following MSCs-IVt. In the case of MSCs-IAt, the detection of cellular bioluminescence at the knee joint persisted for up to 1 week. Intriguingly, intra-articular saline injection (placebo-IAt) resulted in a worse prognosis of OA when compared to a non-invasive control (placebo-IVt) without joint injection. The systemic cytokines/chemokines profile exhibited a time-dependent variation between transplant routes, displaying a transient anti-inflammatory systemic response for both MSCs-IVt and MSCs-IAt. A single injection of MSCs, whether administered via the intra-articular or intravenous route, performed 9 weeks after DMM surgery, did not effectively inhibit AC degeneration when compared to a non-invasive control.

Therapeutic potential of senolytic agent quercetin in osteoarthritis: A systematic review and meta-analysis of preclinical studies

BACKGROUND

Quercetin, a natural flavonoid, has shown promise as a senolytic agent for various degenerative diseases. Recently, its protective effect against osteoarthritis (OA), a representative age-related disease of the musculoskeletal system, has attracted much attention. The aim of this study is to summarize and analyze the current literature on the effects of quercetin on OA cartilage in in vivo preclinical studies.

METHODS

The Medline (via/using PubMed), Embase, and Web of Science databases were searched up to March 10th, 2023. Risk of bias and the qualitative assessment including mechanisms of all eligible studies and a meta-analysis of cartilage histological scores among the applicable studies was performed.

RESULTS

A total of 12 in vivo animal studies were included in this systematic review. A random-effects meta-analysis was performed on six studies using the Osteoarthritis Research Society International (OARSI) scoring system, revealing that quercetin significantly improved OA cartilage OARSI scores (SMD, -6.30 [95% CI, -9.59 to -3.01]; P = 0.0002; heterogeneity: I2 = 86%). The remaining six studies all supported quercetin's protective effects against OA during disease and aging.

CONCLUSIONS

Quercetin has shown beneficial effects on cartilage during OA across animal species. Future double-blind randomized controlled clinical trials are needed to verify the efficacy of quercetin in the treatment of OA in humans.

Potential of secretome of human fetal cartilage progenitor cells as disease modifying agent for osteoarthritis

AIMS

Osteoarthritis (OA) is caused by an imbalance in the synthesis and degradation of cartilage tissue by chondrocytes. Therefore, a therapeutic agent for OA patients that can positively affect both synthesis and degradation is needed. However, current nonsurgical treatments for OA can barely achieve satisfactory long-term outcomes in cartilage repair. Human fetal cartilage progenitor cells-secretome (ShFCPC) has shown potent anti-inflammatory and tissue-repair effects; however, its underlying mechanisms and effects on OA have rarely been systematically elucidated. This study aims to analyze and evaluate the potency of ShFCPC in modifying OA process.

MAIN METHODS

Herein, secreted proteins enriched in ShFCPC have been characterized, and their biological functions both in vitro and in vivo in an OA model are compared with those of human bone marrow-derived mesenchymal stem cells-secretome (ShBMSC) and hyaluronan (HA).

KEY FINDINGS

Secretome analysis has shown that ShFCPC is significantly enriched with extracellular matrix molecules involved in many effects of cellular processes required for homeostasis during OA progression. Biological validation in vitro has shown that ShFCPC protects chondrocyte apoptosis by suppressing the expression of inflammatory mediators and matrix-degrading proteases and promotes the secretion of pro-chondrogenic cytokines in lipopolysaccharide-induced coculture of human chondrocytes and SW982 synovial cells compared with ShBMSC. Moreover, in a rat OA model, ShFCPC protects articular cartilage by reducing inflammatory cell infiltration and M1/M2 macrophage ratio in the synovium, which directly contributes to an increase in immunomodulatory atmosphere and enhances cartilage repair compared to ShBMSC and HA.

SIGNIFICANCE

Our findings support clinical translations of ShFCPC as a novel agent for modifying OA process.

The effects of losartan or angiotensin II receptor antagonists on cartilage: a systematic review

OBJECTIVE

The aim of this study is to analyze the latest evidence on the effects of losartan or Ang II receptor antagonists on cartilage repair, with a focus on their clinical relevance.

DESIGN

The PubMed, Embase, and Cochrane Library databases were searched up to November 12th 2021 to evaluate the effects of losartan or Ang II receptor antagonists on cartilage repair in in vitro studies and in vivo animal studies. Study design, sample characteristics, treatment type, duration, and outcomes were analyzed. The risk of bias and the quality of the eligible studies were assessed using the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) risk of bias assessment tool and Collaborative Approach to Meta-Analysis and Review of Animal Data from Experimental Studies (CAMARADES).

RESULTS

A total of 12 studies were included in this systematic review. Of the 12 eligible studies, two studies were in vitro human studies, three studies were in vitro animal studies, one study was an in vitro human and animal study, and six studies were in vivo animal studies. The risk bias and quality assessments were predominantly classified as moderate. Since meta-analysis was difficult due to differences in treatment type, dosage, route of administration, and method of outcome assessment among the eligible studies, qualitative evaluation was conducted for each study.

CONCLUSIONS

Both in vitro and in vivo studies provide evidence to demonstrate beneficial effects of Ang II receptor antagonists on osteoarthritis and cartilage defect models across animal species.

Intraarticular Injections of Mesenchymal Stem Cells in Knee Osteoarthritis: A Review of Their Current Molecular Mechanisms of Action and Their Efficacy

More than 10% of the world's population suffers from osteoarthritis (OA) of the knee, with a lifetime risk of 45%. Current treatments for knee OA pain are as follows: weight control; oral pharmacological treatment (non-steroidal anti-inflammatory drugs, paracetamol, opioids); mechanical aids (crutches, walkers, braces, orthotics); therapeutic physical exercise; and intraarticular injections of corticosteroids, hyaluronic acid, and platelet-rich plasma (PRP). The problem is that such treatments usually relieve joint pain for only a short period of time. With respect to intraarticular injections, corticosteroids relieve pain for several weeks, while hyaluronic acid and PRP relieve pain for several months. When the above treatments fail to control knee pain, total knee arthroplasty (TKA) is usually indicated; however, although a very effective surgical technique, it can be associated with medical and postoperative (surgery-related) complications. Therefore, it seems essential to look for safe and effective alternative treatments to TKA. Recently, there has been much research on intraarticular injections of mesenchymal stem cells (MSCs) for the management of OA of the knee joint. This article reviews the latest information on the molecular mechanisms of action of MSCs and their potential therapeutic benefit in clinical practice in patients with painful knee OA. Although most recent publications claim that intraarticular injections of MSCs relieve joint pain in the short term, their efficacy remains controversial given that the existing scientific information on MSCs is indecisive. Before recommending intraarticular MSCs injections routinely in patients with painful knee OA, more studies comparing MSCs with placebo are needed. Furthermore, a standard protocol for intraarticular injections of MSCs in knee OA is needed.

Harnessing hyaluronic acid for the treatment of osteoarthritis: A bibliometric analysis

Background: Osteoarthritis (OA) is a common disease which usually occurs in middle-aged and elderly people. Hyaluronic acid (HA) has been widely used to treat OA and related researches on the efficacy and safety of HA in the treatment of OA have been published. Therefore, the purpose of this research was to investigate the subject characteristics of harnessing HA for the treatment of OA and to analyse the relevant trends and hotspots by using a bibliometric approach.

Methods: The articles published from 1 January 2002 to 31 December 2021 were searched in the Web of Science Core Collection (WoSCC) and the relevant information of HA for the treatment of OA was extracted after screening. Then, a total of 2438 publications were analysed by using Microsoft Excel, CiteSpace 5.8.R3, VOSviewer 1.6.18 and the Online Analysis Platform of Literature Metrology (http://bibliometric.com/).

Results: A total of 2438 articles were finally included for analysis. The number of publications increased year by year. A total of 83 coutries and 3319 institutions published 2438 manuscripts in the field of use HA for the treatment of OA. The most productive country was United States with total 689 publications and League of European Research Universities Leru (Belgium) was the leading institution with total 126 publicatios. In terms of authors, the most prominent author was KrausVB, who published 28 papers with the highest H-index (19). In addition, Osteoarthritis and Cartilage had the highest number of publications (152 articles) and the highest number of citations (6450 citations). The co-cited references analysis indicated that the article published by McAlindon in 2014 had the most highest number of citations (91co-citations). What’s more, most research hotspots focused on the efficacy and safety of HA, and regenerative medicine researches such as platelet-rich plasma (PRP) and mesenchymal stem cells (MSCs) have attracted more and more attentions of researchers.

Conclusion: This study visually analyzed the historical evolution and future trends of HA for the treatment of OA, and discussed the research priorities. At present, there are still different views on the efficacy of HA for the treatment of OA. Gradually, research hotspots of this field have focused on the regenerative medicine.

Intra-Articular Injections of Allogeneic Mesenchymal Stromal Cells vs. High Molecular Weight Hyaluronic Acid in Dogs With Osteoarthritis: Exploratory Data From a Double-Blind, Randomized, Prospective Clinical Trial

This double-blind, randomized, prospective clinical trial was conducted to obtain exploratory data comparing the efficacy of intra-articular allogeneic mesenchymal stem/stromal cells (MSC) to high molecular weight hyaluronic acid (HA) for the treatment of pain associated with canine osteoarthritis (OA). Objective gait analysis (%Body Weight Distribution, %BWD), accelerometry, clinical metrology instruments and veterinary exams were used as outcome measures during various time points throughout the 48-week study period. Fourteen dogs with elbow or coxofemoral OA were enrolled and assigned in a 2:1 ratio to the treatment groups. Each patient received a set of two injections 4 weeks apart. Self-limiting joint flare was observed in seven patients, with six of these in the MSC group. Ten patients completed all follow-up appointments. Both treatment groups showed evidence of mild improvement following the treatment, but the results were inconsistent among the various outcome measures assessed. Overall, dogs enrolled in the HA group showed greater improvement compared to the MSC group. The primary outcome measure, %BWD, showed evidence of improvement, when compared to baseline values, at 36 weeks after injection for the HA group only (p = 0.048, estimated difference: 4.7). Similarly, when treatment groups were compared, evidence of a difference between treatment groups (with the HA-group showing greater improvement) were identified for weeks 24 and 36 (p = 0.02 and 0.01, respectively). The small sample size of this exploratory study does not allow firm conclusions. However, until studies with larger sample sizes are available, the current literature combined with our data do not support the clinical use of intra-articular MSC therapy over high molecular weight HA for the treatment of canine OA at this time.

Human integrin α10β1-selected mesenchymal stem cells home to cartilage defects in the rabbit knee and assume a chondrocyte-like phenotype

BACKGROUND

Mesenchymal stem cells (MSCs) have shown promising results in stimulating cartilage repair and in the treatment of osteoarthritis (OA). However, the fate of the MSCs after intra-articular injection and their role in cartilage regeneration is not clear. To address these questions, this study investigated (1) homing of labeled human adipose tissue derived integrin α10β1-selected MSCs (integrin α10-MSCs) to a cartilage defect in a rabbit model and (2) the ability of the integrin α10-MSCs to differentiate to chondrocytes and to produce cartilage matrix molecules in vivo.

DESIGN

Integrin α10-MSCs were labeled with superparamagnetic iron oxide nanoparticles (SPIONs) co-conjugated with Rhodamine B to allow visualization by both MRI and fluorescence microscopy. A cartilage defect was created in the articular cartilage of the intertrochlear groove of the femur of rabbits. Seven days post-surgery, labeled integrin α10-MSCs or vehicle were injected into the joint. Migration and distribution of the SPION-labeled integrin α10-MSCs was evaluated by high-field 9.4 T MRI up to 10 days after injection. Tissue sections from the repair tissue in the defects were examined by fluorescence microscopy.

RESULTS

In vitro characterization of the labeled integrin α10-MSCs demonstrated maintained viability, proliferation rate and trilineage differentiation capacity compared to unlabeled MSCs. In vivo MRI analysis detected the labeled integrin α10-MSCs in the cartilage defects at all time points from 12 h after injection until day 10 with a peak concentration between day 1 and 4 after injection. The labeled MSCs were also detected lining the synovial membrane at the early time points. Fluorescence analysis confirmed the presence of the labeled integrin α10-MSCs in all layers of the cartilage repair tissue and showed co-localization between the labeled cells and the specific cartilage molecules aggrecan and collagen type II indicating in vivo differentiation of the MSCs to chondrocyte-like cells. No adverse effects of the α10-MSC treatment were detected during the study period.

CONCLUSION

Our results demonstrated migration and homing of human integrin α10β1-selected MSCs to cartilage defects in the rabbit knee after intra-articular administration as well as chondrogenic differentiation of the MSCs in the regenerated cartilage tissue.

Management of Knee Osteoarthritis: What Internists Need to Know

Knee osteoarthritis (OA) is a common and morbid condition. No disease-modifying therapies exist; hence the goals of current treatment are to palliate pain and to retain function. OA pain is significantly influenced by the placebo effect. Nonpharmacologic interventions are essential and have been shown to improve outcomes. Canes, unloading braces, and therapeutic heating/cooling may be valuable. Pharmacotherapy options include topical and oral nonsteroidal anti-inflammatory drugs, duloxetine, and periodic intra-articular glucocorticoids and hyaluronans. Opioids, intra-articular stem cells, and platelet-rich plasma are not recommended. Novel targets such as nerve growth factor are under investigation and may be approved soon for OA pain.

Preclinical studies and clinical trials on mesenchymal stem cell therapy for knee osteoarthritis: A systematic review on models and cell doses

AIM

To provide a systematic analysis of the study design in knee osteoarthritis (OA) preclinical studies, focusing on the characteristics of animal models and cell doses, and to compare these to the characteristics of clinical trials using mesenchymal stem cells (MSCs) for the treatment of knee OA.

METHOD

A systematic and comprehensive search was conducted using the PubMed, Web of Science, Ovid, and Embase electronic databases for research papers published in 2009-2020 on testing MSC treatment in OA animal models. The PubMed database and ClinicalTrials.gov website were used to search for published studies reporting clinical trials of MSC therapy for knee OA.

RESULTS

In total, 9234 articles and two additional records were retrieved, of which 120 studies comprising preclinical and clinical studies were included for analysis. Among the preclinical studies, rats were the most commonly used species for modeling knee OA, and anterior cruciate ligament transection was the most commonly used method for inducing OA. There was a correlation between the cell dose and body weight of the animal. In clinical trials, there was large variation in the dose of MSCs used to treat knee OA, ranging from 1 × 10⁶ to 200 × 10⁶ cells with an average of 37.91 × 10⁶ cells.

CONCLUSION

Mesenchymal stem cells have shown great potential in improving pain relief and tissue protection in both preclinical and clinical studies of knee OA. Further high-quality preclinical and clinical studies are needed to explore the dose effectiveness relationship of MSC therapy and to translate the findings from preclinical studies to humans.

A low dose cell therapy system for treating osteoarthritis: In vivo study and in vitro mechanistic investigations

Mesenchymal stem cells (MSCs) can be effective in alleviating the progression of osteoarthritis (OA). However, low MSC retention and survival at the injection site frequently require high doses of cells and/or repeated injections, which are not economically viable and create additional risks of complications. In this study, we produced MSC-laden microcarriers in spinner flask culture as cell delivery vehicles. These microcarriers containing a low initial dose of MSCs administered through a single injection in a rat anterior cruciate ligament (ACL) transection model of OA achieved similar reparative effects as repeated high doses of MSCs, as evaluated through imaging and histological analyses. Mechanistic investigations were conducted using a co-culture model involving human primary chondrocytes grown in monolayer, together with MSCs grown either within 3D constructs or as a monolayer. Co-culture supernatants subjected to secretome analysis showed significant decrease of inflammatory factors in the 3D group. RNA-seq of co-cultured MSCs and chondrocytes using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed processes relating to early chondrogenesis and increased extracellular matrix interactions in MSCs of the 3D group, as well as phenotypic maintenance in the co-cultured chondrocytes. The cell delivery platform we investigated may be effective in reducing the cell dose and injection frequency required for therapeutic applications.

Reprogrammed Synovial Fluid-Derived Mesenchymal Stem/Stromal Cells Acquire Enhanced Therapeutic Potential for Articular Cartilage Repair

OBJECTIVES

Functions of mesenchymal stem/stromal cells (MSCs) are affected by patient-dependent factors such as age and health condition. To tackle this problem, we used the cellular reprogramming technique to epigenetically alter human MSCs derived from the synovial fluid of joints with osteoarthritis (OA) to explore the potential of reprogrammed MSCs for repairing articular cartilage.

MATERIALS AND METHODS

MSCs isolated from the synovial fluid of three patients' OA knees (Pa-MSCs) were reprogrammed through overexpression of pluripotency factors and then induced for differentiation to establish reprogrammed MSC (Re-MSC) lines. We compared the in vitro growth characteristics, chondrogenesis for articular cartilage chondrocytes, and immunomodulatory capacity. We also evaluated the capability of Re-MSCs to repair articular cartilage damage in an animal model with spontaneous OA.

RESULTS

Our results showed that Re-MSCs increased the in vitro proliferative capacity and improved chondrogenic differentiation toward articular cartilage-like chondrocyte phenotypes with increased THBS4 and SIX1 and decreased ALPL and COL10A1, compared to Pa-MSCs. In addition, Re-MSC-derived chondrocytes expressing elevated COL2A and COL2B were more mature than parental cell-derived ones. The enhancement in chondrogenesis of Re-MSC involves the upregulation of sonic hedgehog signaling. Moreover, Re-MSCs improved the repair of articular cartilage in an animal model of spontaneous OA.

CONCLUSIONS

Epigenetic reprogramming promotes MSCs harvested from OA patients to increase phenotypic characteristics and gain robust functions. In addition, Re-MSCs acquire an enhanced potential for articular cartilage repair. Our study here demonstrates that the reprogramming strategy provides a potential solution to the challenge of variation in MSC quality.

Intra-articular Injection of Kartogenin-Enhanced Bone Marrow-Derived Mesenchymal Stem Cells in the Treatment of Knee Osteoarthritis in a Rat Model

BACKGROUND

In this study, we investigated the in vitro and in vivo chondrogenic capacity of kartogenin (KGN)-enhanced bone marrow-derived mesenchymal stem cells (BMSCs) for cartilage regeneration.

PURPOSE

To determine (1) whether functionalized nanographene oxide (NGO) can effectively deliver KGN into BMSCs and (2) whether KGN would enhance BMSCs during chondrogenesis in vitro and in vivo in an animal model.

STUDY DESIGN

Controlled laboratory study.

METHODS

Functionalized NGO with line chain amine-terminated polyethylene glycol (PEG) and branched polyethylenimine (BPEI) were used to synthesize biocompatible NGO-PEG-BPEI (PPG) and for loading hydrophobic KGN molecules noncovalently via π-π stacking and hydrophobic interactions (PPG-KGN). Then, PPG-KGN was used for the intracellular delivery of hydrophobic KGN by simple mixing and co-incubation with BMSCs to acquire KGN-enhanced BMSCs. The chondrogenic efficacy of KGN-enhanced BMSCs was evaluated in vitro. In vivo, osteoarthritis (OA) was induced by anterior cruciate ligament transection in rats. A total of 5 groups were established: normal (OA treated with nothing), phosphate-buffered saline (PBS; intra-articular injection of PBS), PPG-KGN (intra-articular injection of PPG-KGN), BMSCs (intra-articular injection of BMSCs), and BMSCs + PPG-KGN (intra-articular injection of PPG-KGN-preconditioned BMSCs). At 6 and 9 weeks after the surgical induction of OA, the rats received intra-articular injections of PPG-KGN, BMSCs, or KGN-enhanced BMSCs. At 14 weeks after the surgical induction of OA, radiographic and behavioral evaluations as well as histological analysis of the knee joints were performed.

RESULTS

The in vitro study showed that PPG could be rapidly uptaken in the first 4 hours after incubation, reaching saturation at 12 hours and accumulating in the lysosome and cytoplasm of BMSCs. Thus, PPG-KGN could enhance the efficiency of the intracellular delivery of KGN, which showed a remarkably high chondrogenic differentiation capacity of BMSCs. When applied to an OA model of cartilage injuries in rats, PPG-KGN-preconditioned BMSCs contributed to protection from joint space narrowing, pathological mineralization, OA development, and OA-induced pain, as well as improved tissue regeneration, as evidenced by radiographic, weightbearing, and histological findings.

CONCLUSION

Our results demonstrate that KGN-enhanced BMSCs showed markedly improved capacities for chondrogenesis and articular cartilage repair. We believe that this work demonstrates that a multifunctional nanoparticle-based drug delivery system could be beneficial for stem cell therapy. Our results present an opportunity to reverse the symptoms and pathophysiology of OA.

CLINICAL RELEVANCE

The intracellular delivery of KGN to produce BMSCs with enhanced chondrogenic potential may offer a new approach for the treatment of OA.

Intra-articular Injection of Cell-laden 3D Microcryogels Empower Low-dose Cell Therapy for Osteoarthritis in a Rat Model

Intra-articular injection of mesenchymal stem cells (MSCs) in an osteoarthritic joint can help slow down cartilage destruction. However, cell survival and the efficiency of repair are generally low due to mechanical damage during injection and a high rate of cell loss. We, thus, investigated an improved strategy for cell delivery to an osteoarthritic joint through the use of three-dimensional (3D) microcryogels. MSCs were seeded into 3D microcryogels. The viability and proliferation of MSCs in microcryogels were determined over 5 d, and the phenotype of MSCs was confirmed through trilineage differentiation tests and flow cytometry. In Sprague Dawley rats with induced osteoarthritis (OA) of the knee joint, a single injection was made with the following groups: saline control, low-dose free MSCs (1 × 10⁵ cells), high-dose free MSCs (1 × 10⁶ cells), and microcryogels + MSCs (1 × 10⁵ cells). Cartilage degeneration was evaluated by macroscopic examination, micro-computed tomographic analysis, and histology. MSCs grown in microcryogels exhibited optimal viability and proliferation at 3 d with stable maintenance of phenotype in vitro. Microcryogels seeded with MSCs were, therefore, primed for 3 d before being used for in vivo experiments. At 4 and 8 wk, the microcryogels + MSCs and high-dose free MSC groups had significantly higher International Cartilage Repair Society macroscopic scores, histological evidence of more proteoglycan deposition and less cartilage loss accompanied by a lower Mankin score, and minimal radiographic evidence of osteoarthritic changes in the joint compared to the other two groups. In conclusion, intra-articular injection of cell-laden 3D microcryogels containing a low dose of MSCs can achieve similar effects as a high dose of free MSCs for OA in a rat model. Primed MSCs in 3D microcryogels can be considered as an improved delivery strategy for cell therapy in treating OA that minimizes cell dose while retaining therapeutic efficacy.

Management of Knee Osteoarthritis: What Internists Need to Know

Knee osteoarthritis (OA) is a common and morbid condition. No disease-modifying therapies exist; hence the goals of current treatment are to palliate pain and to retain function. OA is significantly influenced by the placebo effect. Nonpharmacologic interventions are essential and have been shown to improve outcomes. Canes, unloading braces, and therapeutic heating/cooling may be valuable. Pharmacotherapy options include topical and oral nonsteroidal anti-inflammatory drugs, duloxetine, and periodic intra-articular glucocorticoids and hyaluronans. Opioids, intra-articular stem cells, and platelet-rich plasma are not recommended. Novel targets such as nerve growth factor are under investigation and may be approved soon for OA pain.

Clinical-Grade Human Embryonic Stem Cell-Derived Mesenchymal Stromal Cells Ameliorate the Progression of Osteoarthritis in a Rat Model

Mesenchymalstem cell (MSC)-based therapy is being increasingly explored in preclinical and clinical studies as a regenerative method for treating osteoarthritis (OA). However, the use of primary MSCs is hampered by a number of limitations, including donor heterogeneity and inconsistent cell quality. Here, we tested the therapeutic potential of embryonic stem cell-derived MSCs (ES-MSCs) in anOA rat model. ES-MSCs were generated and identified by morphology, trilineage differentiation and flow cytometry. Sprague Dawley rats were treated with either a single dose (10⁶ cells/rat) of ES-MSCs or with three doses spaced one week apart for each dose, starting at four weeks after anterior cruciate ligament transectionto induce OA. Cartilage quality was evaluated at 6 and 10 weeks after treatment with behavioral analysis, macroscopic examination, and histology. At sixweeks after treatment, the groups treated with both single and repeated doses of ES-MSCs had significantly better modified Mankin scores and International Cartilage Repair Society (ICRS) macroscopic scores in the femoral condyle compared to the control group. At 10 weeks after treatment, the repeated doses group had a significantly better ICRS macroscopic scores in the femoral condyle compared to the single dose and control groups. Histological analysis also showed more proteoglycan and less cartilage loss, along with lower Mankin scores in the repeated doses group. In conclusion, treatment with multiple injections of ES-MSCs can ameliorate OA in a rat model. TheES-MSCs have potential to be considered as a regenerative therapy for OA, and can provide an infinite cellular source.

Stem cell transplantation for the treatment of osteochondral defects of the knee: Operative technique for a single-stage transplantation procedure using bone marrow-derived mesenchymal stem cells

BACKGROUND

Autologous chondrocyte implantation (ACI) is a NICE-approved technique to regenerate hyaline cartilage in chondral and osteochondral defects (OCDs). The drawbacks of ACI include that it requires a two-stage approach, involves a lengthy rehabilitation process and is expensive. Bone marrow harvest with mesenchymal stem cell transplantation using a single-stage procedure and an accelerated rehabilitation programme has been developed to overcome this. The aim of this paper is to describe the surgical technique for stem cell transplantation of the knee for OCDs with reference to case examples.

METHODS

The surgical technique for stem cell transplantation of the knee for OCDs is described, with reference to three cases. Magnetic resonance imaging was performed at six months postoperatively.

RESULTS

The surgical technique is described in this paper. The three patient cases described all improved clinically with reduced pain and improved function at a minimum of six months follow-up.

CONCLUSIONS

Stem cell transplantation has the potential to produce favourable outcomes for patients with osteochondral defects of the knee. This single-stage approach and accelerated rehabilitation is associated with reduced financial costs. A long-term prospective study of this technique is currently underway at our institution and randomised controlled trials are planned to demonstrate the effectiveness over other techniques.

Emerging pharmaceutical therapies for osteoarthritis

The prevalence of osteoarthritis (OA) and the burden associated with the disease are steadily increasing worldwide, representing a major public health challenge for the coming decades. The lack of specific treatments for OA has led to it being recognized as a serious disease that has an unmet medical need. Advances in the understanding of OA pathophysiology have enabled the identification of a variety of potential therapeutic targets involved in the structural progression of OA, some of which are promising and under clinical investigation in randomized controlled trials. Emerging therapies include those targeting matrix-degrading proteases or senescent chondrocytes, promoting cartilage repair or limiting bone remodelling, local low-grade inflammation or Wnt signalling. In addition to these potentially disease-modifying OA drugs (DMOADs), several targets are being explored for the treatment of OA-related pain, such as nerve growth factor inhibitors. The results of these studies are expected to considerably reshape the landscape of OA management over the next few years. This Review describes the pathophysiological processes targeted by emerging therapies for OA, along with relevant clinical data and discussion of the main challenges for the further development of these therapies, to provide context for the latest advances in the field of pharmaceutical therapies for OA.

Adipose stem cells exhibit mechanical memory and reduce fibrotic contracture in a rat elbow injury model

Fibrosis is driven by a misdirected cell response causing the overproduction of extracellular matrix and tissue dysfunction. Numerous pharmacological strategies have attempted to prevent fibrosis but have attained limited efficacy with some detrimental side effects. While stem cell treatments have provided more encouraging results, they have exhibited high variability and have not always improved tissue function. To enhance stem cell efficacy, we evaluated whether mechanical memory could direct cell response. We hypothesized that mechanically pre-conditioning on a soft matrix (soft priming) will delay adipose-derived stem cell (ASC) transition to a pro-fibrotic phenotype, expanding their regenerative potential, and improving healing in a complex tissue environment. Primary ASCs isolated from rat and human subcutaneous fat exhibited mechanical memory, demonstrated by a delayed cell response to stiffness following two weeks of soft priming including decreased cell area, actin coherency, and extracellular matrix production compared to cells on stiff substrates. Soft primed ASCs injected into our rat model of post-traumatic elbow contracture decreased histological evidence of anterior capsule fibrosis and increased elbow range-of-motion when evaluated by joint mechanics. These findings suggest that exploiting mechanical memory by strategically controlling the culture environment during cell expansion may improve the efficacy of stem cell-based therapies targeting fibrosis.

Systematic review of extracellular vesicle-based treatments for lung injury: are EVs a potential therapy for COVID-19?

Severe COVID-19 infection results in bilateral interstitial pneumonia, often leading to acute respiratory distress syndrome (ARDS) and pulmonary fibrosis in survivors. Most patients with severe COVID-19 infections who died had developed ARDS. Currently, ARDS is treated with supportive measures, but regenerative medicine approaches including extracellular vesicle (EV)-based therapies have shown promise. Herein, we aimed to analyse whether EV-based therapies could be effective in treating severe pulmonary conditions that affect COVID-19 patients and to understand their relevance for an eventual therapeutic application to human patients. Using a defined search strategy, we conducted a systematic review of the literature and found 39 articles (2014–2020) that reported effects of EVs, mainly derived from stem cells, in lung injury models (one large animal study, none in human). EV treatment resulted in: (1) attenuation of inflammation (reduction of pro-inflammatory cytokines and neutrophil infiltration, M2 macrophage polarization); (2) regeneration of alveolar epithelium (decreased apoptosis and stimulation of surfactant production); (3) repair of microvascular permeability (increased endothelial cell junction proteins); (4) prevention of fibrosis (reduced fibrin production). These effects were mediated by the release of EV cargo and identified factors including miRs-126, −30b-3p, −145, −27a-3p, syndecan-1, hepatocyte growth factor and angiopoietin-1. This review indicates that EV-based therapies hold great potential for COVID-19 related lung injuries as they target multiple pathways and enhance tissue regeneration. However, before translating EV therapies into human clinical trials, efforts should be directed at developing good manufacturing practice solutions for EVs and testing optimal dosage and administration route in large animal models.

Intra-articular delivery of umbilical cord-derived mesenchymal stem cells temporarily retard the progression of osteoarthritis in a rat model

AIM

Mesenchymal stem cell (MSC)-based therapy is being explored in treating osteoarthritis (OA). Human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) are least reported. In this study, we investigated the effects of single intra-articular injections of hUC-MSCs on a rat OA model.

METHOD

hUC-MSCs were isolated from the Wharton's jelly of the human umbilical cord and identified. Eighteen Sprague-Dawley rats were used for the OA model. All rats were divided into 3 groups: hyaluronic acid (HA)+MSCs (n = 6), HA (n = 6), and control group (n = 6). One by 10⁶ hUC-MSCs in 100 μL HA, 100 μL HA or 100 μL saline were injected into the knee joint 4 weeks post-surgery as a single dose. Cartilage degeneration was evaluated at 6 and 12 weeks after treatment with macroscopic examination, micro-computed tomography analysis, behavioral analysis, and histology.

RESULTS

At 6 weeks, the HA + MSCs group had a significantly better International Cartilage Repair Society score in the femoral condyle compared to the HA and control groups. Histological analysis also showed more proteoglycan and less cartilage loss, with lower modified Mankin score in the HA + MSCs group. However, at 12 weeks there were no significant differences between groups from macroscopic examination and histological analysis. Subchondral bone sclerosis of the medial femoral condyle and behavioral tests showed no significant differences between groups at 6 and 12 weeks.

CONCLUSION

These findings indicate that single injection of hUC-MSCs can have temporary effects on decelerating the progression of cartilage degeneration in OA rats, but may not inhibit OA progression in the long-term.

Repairing effects of glucosamine sulfate in combination with etoricoxib on articular cartilages of patients with knee osteoarthritis

Purpose

To evaluate the repairing effects of glucosamine sulfate combined with etoricoxib on articular cartilages of patients with knee osteoarthritis (KOA).

Methods

A total of 106 KOA patients were randomly divided into control (n = 40) and experimental groups (n = 66) and treated with etoricoxib alone and glucosamine sulfate plus etoricoxib, respectively. Changes in WOMAC score and clinical efficacy were observed. The synovial fluid was extracted. Bone metabolism indices, growth factors, inflammatory factors, matrix metalloproteinases (MMPs), and NO-induced apoptosis-related factors were measured by ELISA. JNK and Wnt5a mRNA levels were determined using RT-PCR.

Results

After treatment, the total WOMAC scores of both groups significantly declined (P < 0.05), being lower in experimental group. The total effective rate of experimental group was higher (P < 0.05). BGP and OPG levels rose, especially in experimental group (P < 0.05). CTX-II, COMP, and RANKL levels decreased, particularly in experimental group (P < 0.05). TGF-β, IGF-1, and FGF-2 levels increased, especially in experimental group (P < 0.05). Both groups, particularly experimental group, had decreased levels of IL-1β, IL-17, IL-18, TNF-α, MMP-3, MMP-9, and MMP-13 (P < 0.05). JNK and Wnt5a mRNA levels of both groups dropped, which were lower in experimental group (P < 0.05). NO and LPO levels reduced, being lower in experimental group. SOD level rose, especially in experimental group (P < 0.05).

Conclusion

Glucosamine sulfate plus etoricoxib can repair the articular cartilages of KOA patients. Probably, JNK and Wnt5a are downregulated to inhibit the secretion of MMPs through lowering the levels of inflammatory factors, thereby delaying cartilage matrix degradation. NO-induced chondrocyte apoptosis may be suppressed via the SOD pathway.

Integrin α10β1-Selected Mesenchymal Stem Cells Mitigate the Progression of Osteoarthritis in an Equine Talar Impact Model

BACKGROUND

Early intervention with mesenchymal stem cells (MSCs) after articular trauma has the potential to limit progression of focal lesions and prevent ongoing cartilage degeneration by modulating the joint environment and/or contributing to repair. Integrin α10β1 is the main collagen type II binding receptor on chondrocytes, and MSCs that are selected for high expression of the α10 subunit have improved chondrogenic potential. The ability of α10β1-selected (integrin α10^high) MSCs to protect cartilage after injury has not been investigated.

PURPOSE

To investigate integrin α10^high MSCs to prevent posttraumatic osteoarthritis in an equine model of impact-induced talar injury.

STUDY DESIGN

Controlled laboratory study.

METHODS

Focal cartilage injuries were created on the tali of horses (2-5 years, n = 8) by using an impacting device equipped to measure impact stress. Joints were treated with 20 × 10⁶ allogenic adipose-derived α10^high MSCs or saline vehicle (control) 4 days after injury. Synovial fluid was collected serially and analyzed for protein content, cell counts, markers of inflammation (prostaglandin E2, tumor necrosis factor α) and collagen homeostasis (procollagen II C-propeptide, collagen type II cleavage product), and glycosaminoglycan content. Second-look arthroscopy was performed at 6 weeks, and horses were euthanized at 6 months. Joints were imaged with radiographs and quantitative 3-T magnetic resonance imaging. Postmortem examinations were performed, and India ink was applied to the talar articular surface to identify areas of cartilage fibrillation. Synovial membrane and osteochondral histology was performed, and immunohistochemistry was used to assess type I and II collagen and lubricin. A mixed effect model with Tukey post hoc and linear contrasts or paired t tests were used, as appropriate.

RESULTS

Integrin α10^high MSC-treated joints had less subchondral bone sclerosis on radiographs (P = .04) and histology (P = .006) and less cartilage fibrillation (P = .04) as compared with control joints. On gross pathology, less India ink adhered to impact sites in treated joints than in controls, which may be explained by the finding of more prominent lubricin immunostaining in treated joints. Prostaglandin E2 concentration in synovial fluid and mononuclear cell synovial infiltrate were increased in treated joints, suggesting possible immunomodulation by integrin α10^high MSCs.

CONCLUSION

Intra-articular administration of integrin α10^high MSCs is safe, and evidence suggests that the cells mitigate the effects of joint trauma.

CLINICAL RELEVANCE

This preclinical study indicates that intra-articular therapy with integrin α10^high MSCs after joint trauma may be protective against posttraumatic osteoarthritis.

Stem Cell Treatment for Knee Articular Cartilage Defects and Osteoarthritis

PURPOSE OF REVIEW

To review the current basic science and clinical literature on mesenchymal stem cell (MSC) therapy for articular cartilage defects and osteoarthritis of the knee.

RECENT FINDINGS

MSCs derived from bone marrow, adipose, and umbilical tissue have the capacity for self-renewal and differentiation into the chondrocyte lineage. In theory, MSC therapy may help restore cartilage focally or diffusely where nascent regenerative potential in the intra-articular environment is limited. Over the last several years, in vitro and animal studies have elucidated the use of MSCs in isolation as injectables, in combination with biological delivery media and scaffolding, and as surgical adjuvants for cartilage regeneration and treatment of knee degenerative conditions. More recently, clinical and translational literature has grown more convincing from early descriptive case series to randomized controlled trials showing promise in efficacy and safety. Studies describing MSC for knee cartilage regeneration applications are numerous and varied in quality. Future research directions should include work on elucidating optimal cell concentration and dosing, as well as standardization in methodology and reporting in prospective trials. Backed by promise from in vitro and animal studies, preliminary clinical evidence on MSC therapy shows promise as a nonoperative therapeutic option or an adjuvant to existing surgical cartilage restoration techniques. While higher quality evidence to support MSC therapy has emerged over the last several years, further refinement of methodology will be necessary to support its routine clinical use.

Synovium-Derived Mesenchymal Stem/Stromal Cells and their Promise for Cartilage Regeneration

Adult tissues are reservoirs of rare populations of cells known as mesenchymal stem/stromal cells (MSCs) that have tissue-regenerating features retained from embryonic development. As well as building up the musculoskeletal system in early life, MSCs also replenish and repair tissues in adult life, such as bone, cartilage, muscle, and adipose tissue. Cells that show regenerative features at least in vitro have been identified from several connective tissues. Bone marrow and adipose tissue are the most well recognized sources of MSCs that are already used widely in clinical practice. Regenerative medicine aims to exploit MSCs and their tissue regeneration even though the underlying mechanisms for their beneficial effects are largely unknown. Despite many studies that have used various tissue-derived MSCs, the most effective tissue source for orthopedic procedures still remains to be identified. Another question that needs to be addressed is how to evaluate autologous MSCs (i.e., patient derived). Previous studies have suggested the features of bone-marrow-derived MSCs can differ widely between individuals, and can be changed in particular in patients suffering from some forms of degenerative disorder, such as osteoarthritis. The synovium is a thin membrane that protects the synovial joints, and it is a rich source of MSCs that show great potential for regenerative medicine. Here, we review synovium-derived MSCs from reports on basic and clinical studies. We discuss their potential to treat cartilage defects caused by either degeneration or trauma, and what needs to be done in further research toward their better exploitation for joint regeneration.

Global research trends in stem cells for osteoarthritis: a bibliometric and visualized study

AIM

There have been increased interests in the use of stems cells in the research of osteoarthritis (OA). The present study aimed to investigate the global status and trends in this field.

METHOD

Publications related to stem cells search in OA from 1994 to 2017 were retrieved from the Science Citation Index-Expanded Web of Science. The source data were studied and indexed using a bibliometric methodology. For visualized study, VOS viewer software was used to conduct bibliographic coupling, co-authorship, co-citation and co-occurrence analysis and to analyze the publication trends in stem cells for OA research.

RESULT

A total of 1933 articles were included. The relative research interests and number of publications were globally increasing per year. The USA made the highest contributions to the global research with the most citations and the highest H-index. The journal Osteoarthritis and Cartilage had the highest publication number. The Tokyo Medical and Dental University, University of Pittsburgh and Shanghai Jiaotong University were the most contributive institutions. Studies could be divided into four clusters: mechanism study, animal study, clinical trials and tissue engineering. The clinical studies were predicted to be the next popular topic in this field.

CONCLUSION

The number of publications about stem cells for OA would be increasing based on the current global trends. The USA was the largest contributor in this field. Most efforts could be put into clinical studies involving mesenchymal stem cells for OA, which may be the next hot spots in OA and stem cells research.

Tissue Engineering in Osteoarthritis: Current Status and Prospect of Mesenchymal Stem Cell Therapy

Osteoarthritis (OA) is the most common form of arthritis. Over the last 20 years, attempts have been made to regenerate articular cartilage to overcome the limitations of conventional treatments. As OA is generally associated with larger and diffuse involvement of articular surfaces and alteration of joint homeostasis, a tissue engineering approach for cartilage regeneration is more difficult than in simple chondral defects. Autologous and allogeneic mesenchymal stem cells (MSCs) have rapidly emerged as investigational products for cartilage regeneration. This review outlines points to consider in MSC-based approaches for OA treatment, including allogeneic MSCs, sources of MSCs, dosages, feasibility of multiple injections, indication according to severity of OA lesion and patient age, and issues regarding implantation versus injection. We introduce possible mechanisms of action of implanted or injected MSCs as well as the immunological aspects of MSC therapy and provide a summary of clinical trials of MSCs in the treatment of OA. Given current knowledge, it is too early to draw conclusions on the ultimate effectiveness of intra-articular application of MSCs in terms of regenerative effects. Further radiological and histological data will be needed, with a larger pool of patients, before this question can be answered.

Intra-articular implantation of autologous bone marrow-derived mesenchymal stromal cells to treat knee osteoarthritis: a randomized, triple-blind, placebo-controlled phase 1/2 clinical trial

BACKGROUND

The intra-articular implantation of mesenchymal stromal cells (MSCs) as a treatment for knee osteoarthritis (OA) is an emerging new therapy. In this study, patients with knee OA received intra-articular implantations of autologous bone marrow-derived MSCs. We sought to assess the safety and efficacy of this implantation.

MATERIALS AND METHODS

This was a phase 1/2 single-center, triple-blind, randomized controlled trial (RCT) with a placebo control. The subjects consisted of patients with knee OA randomly assigned to either an intra-articular implantation of MSCs (40 × 10⁶ cells) or 5 mL normal saline (placebo). Patients were followed up for 6 months after the implantations. The pain level and function improvements for patient-reported outcomes were assessed based on a visual analog scale (VAS), Western Ontario and McMaster Universities Arthritis Index (WOMAC) and its subscales, walking distance, painless walking distance, standing time and knee flexion compared with the placebo group at 3 and 6 months following the implantations.

RESULTS

Overall, 43 patients (Kellgren-Lawrence grades 2, 3 and 4) were assigned to either the MSCs (n = 19) or placebo (n = 24) group. Patients who received MSCs experienced significantly greater improvements in WOMAC total score, WOMAC pain and physical function subscales and painless walking distance compared with patients who received placebo. There were no major adverse events attributed to the MSC therapy.

CONCLUSION

This randomized, triple-blind, placebo-controlled RCT demonstrated the safety and efficacy of a single intra-articular implantation of 40 × 10⁶ autologous MSCs in patients with knee OA. Intra-articular implantation of MSCs provided significant and clinically relevant pain relief over 6 months versus placebo and could be considered a promising novel treatment for knee OA. We propose that further investigations should be conducted over an extended assessment period and with a larger cohort.