Effect of in vitro chondrogenic differentiation of autologous mesenchymal stem cells on cartilage and subchondral cancellous bone repair in osteoarthritis of temporomandibular joint

Mesenchymal Stem Cell-Based Therapies for Temporomandibular Joint Repair: A Systematic Review of Preclinical Studies

Temporomandibular disorders (TMDs) are a heterogeneous group of musculoskeletal and neuromuscular conditions involving the temporomandibular joint (TMJ), masticatory muscles, and associated structures. Mesenchymal stromal/stem cells (MSCs) have emerged as a promising therapy for TMJ repair. This systematic review aims to consolidate findings from the preclinical animal studies evaluating MSC-based therapies, including MSCs, their secretome, and extracellular vesicles (EVs), for the treatment of TMJ cartilage/osteochondral defects and osteoarthritis (OA). Following the PRISMA guidelines, PubMed, Embase, Scopus, and Cochrane Library databases were searched for relevant studies. A total of 23 studies involving 125 mice, 149 rats, 470 rabbits, and 74 goats were identified. Compliance with the ARRIVE guidelines was evaluated for quality assessment, while the SYRCLE risk of bias tool was used to assess the risk of bias for the studies. Generally, MSC-based therapies demonstrated efficacy in TMJ repair across animal models of TMJ defects and OA. In most studies, animals treated with MSCs, their derived secretome, or EVs displayed improved morphological, histological, molecular, and behavioral pain outcomes, coupled with positive effects on cellular proliferation, migration, and matrix synthesis, as well as immunomodulation. However, unclear risk in bias and incomplete reporting highlight the need for standardized outcome measurements and reporting in future investigations.

In vitro differentiation of human induced pluripotent stem cells into temporomandibular joint disc like cells

Temporomandibular joint discs (TMJ discs) are unable to repair themselves in disease states, while induced stem cell differentiation is a common method to repair tissue defects. Nowadays, kinds of stem cells are attempted for tissue regeneration of TMJ disc, but these methods have several downsides, which limit their wide application. The proliferation and differentiation ability of human induced pluripotent stem cells (hiPSC) provides a new research direction for TMJ disc tissue regeneration. In this study, we investigated the feasibility of induced differentiation of hiPSC into TMJ disc cells in vitro and the differentiation efficiency of different methods to clarify the possibility and conditions of hiPSC application in TMJ disc tissue engineering. We collected sheep TMJ disc cells cultures for adding in hiPSC culture environment and treated hiPSC by both direct induction and Transwell co-culture for 7 days, 14 days and 21 days. The secretion of extracellular matrix in TMJ disc cells was detected by Sirius Red and Safranin O staining. Collagen Ⅰ and Collagen Ⅱ were qualitatively detected by immunohistochemical staining. The expression of extracellular matrix genes (type I collagen (COL1A1), type II collagen(COL2), glycosaminoglycan (GAG)), chondrogenic differentiation gene SOX9 and pluripotency gene OCT4 were detected by RT-qPCR. Our results showed that hiPSC had the ability to differentiate to TMJ disc cells by direct induction in TMJ disc cell culture medium and by Transwell co-culture method. The highest degree of differentiation was observed after 14 days of direct induction, while Transwell co-culture showed significant differentiation at different times and with different major directions. Meanwhile, Transwell co-culture not only differentiates hiPSC but also promotes the growth and proliferation of TMJ disc cells. Our study is valuable to investigate the possibility of differentiation of hiPSC toward TMJ disc cells and to determine the time of differentiation. It provides new ideas for the selection of seed cells for TMJ disc tissue engineering.

Degenerative Disorder of the Temporomandibular Joint Treated With Autologous Bone Marrow-Derived Stem Cells Using the Regentime Technique: A Case Report

Temporomandibular joint (TMJ) disease is a type of degenerative musculoskeletal disorder that leads to morphological and functional abnormalities. It has a poorly understood progression with numerous independent and interrelated factors, which makes it difficult for the available treatment options to meet long-term demands.  We present the case of a 37-year-old woman who suffered from excruciating pain in the right temporomandibular joint, associated with limited mandibular movement. She was found to have imaging features of TMJ disorder. She underwent the Regentime procedure which uses autologous bone marrow-derived stem cells that are partially differentiated and redirected to the targeted tissue. Clinical follow-up showed total clinical recovery.

A new frontier in temporomandibular joint osteoarthritis treatment: Exosome-based therapeutic strategy

Temporomandibular joint osteoarthritis (TMJOA) is a debilitating degenerative disease with high incidence, deteriorating quality of patient life. Currently, due to ambiguous etiology, the traditional clinical strategies of TMJOA emphasize on symptomatic treatments such as pain relief and inflammation alleviation, which are unable to halt or reverse the destruction of cartilage or subchondral bone. A number of studies have suggested the potential application prospect of mesenchymal stem cells (MSCs)-based therapy in TMJOA and other cartilage injury. Worthy of note, exosomes are increasingly being considered the principal efficacious agent of MSC secretions for TMJOA management. The extensive study of exosomes (derived from MSCs, synoviocytes, chondrocytes or adipose tissue et al.) on arthritis recently, has indicated exosomes and their specific miRNA components to be potential therapeutic agents for TMJOA. In this review, we aim to systematically summarize therapeutic properties and underlying mechanisms of MSCs and exosomes from different sources in TMJOA, also analyze and discuss the approaches to optimization, challenges, and prospects of exosome-based therapeutic strategy.

Applications of Biotechnology to the Craniofacial Complex: A Critical Review

Background: Biotechnology shows a promising future in bridging the gap between biomedical basic sciences and clinical craniofacial practice. The purpose of the present review is to investigate the applications of biotechnology in the craniofacial complex. Methods: This critical review was conducted by using the following keywords in the search strategy: “biotechnology”, “bioengineering”, “craniofacial”, “stem cells”, “scaffolds”, “biomarkers”, and ”tissue regeneration”. The databases used for the electronic search were the Cochrane Library, Medline (PubMed), and Scopus. The search was conducted for studies published before June 2022. Results: The applications of biotechnology are numerous and provide clinicians with the great benefit of understanding the etiology of dentofacial deformities, as well as treating the defected areas. Research has been focused on craniofacial tissue regeneration with the use of stem cells and scaffolds, as well as in bioinformatics with the investigation of growth factors and biomarkers capable of providing evidence for craniofacial growth and development. This review presents the biotechnological opportunities in the fields related to the craniofacial complex and attempts to answer a series of questions that may be of interest to the reader. Conclusions: Biotechnology seems to offer a bright future ahead, improving and modernizing the clinical management of cranio-dento-facial diseases. Extensive research is needed as human studies on this subject are few and have controversial results.

Autologous Stem Cells Transplants in the Treatment of Temporomandibular Joints Disorders: A Systematic Review and Meta-Analysis of Clinical Trials

This systematic review aims to analyze the outcomes of the treatment of temporomandibular joint (TMJ) articular pain (AP) and restricted maximum mouth opening (MMO) with intra-articular administration of mesenchymal stem cells (MSCs). The inclusion criteria allowed primary studies involving AP and/or MMO pre-treatment and post-intervention values. Medical databases that were covered by ACM Digital, BASE, EBSCOhost, Google Scholar, PubMed, Scopus, and Web of Science engines were searched. The risk of bias was assessed with RoB 2 and ROBINS-I tools. The results were tabulated, plotted, and analyzed for regression. A total of 5 studies involving 51 patients/69 TMJs were identified, and 4 studies on 50 patients/67 TMJs were synthesized. Interventions were each time effective in decreasing AP and increasing MMO in a 6-month follow-up period by an average of about 85% and over 40%, respectively. Regression analysis showed a good fit of the logarithmic model for AP relief (5.8 − 0.8 ln x; R² = 0.90) and MMO increase (33.5 + 2.4 ln x; R² = 0.89). The results for AP and MMO were based on 3 studies in 39 patients and 4 studies in 50 patients, respectively, all at high risk of bias. The intra-articular administration of MSCs to TMJs, based on weak evidence, may be highly effective in reducing AP and improving MMO. This study received no funding.

An updated view on Temporomandibular Joint degeneration: insights from the cell subsets of mandibular condylar cartilage

The high prevalence of temporomandibular joint osteoarthritis (TMJOA), which causes joint dysfunction, indicates the need for more effective methods for treatment and repair. Mandibular condylar cartilage (MCC), a typical fibrocartilage that experiences degenerative changes during the development of TMJOA, has become a research focus and therapeutic target in recent years. MCC is composed of four zones of cells at various stages of differentiation. The cell subsets in MCC exhibit different physiological and pathological characteristics during development and in TMJOA. Most studies of TMJOA are mainly concerned with gene regulation of pathological changes. The corresponding treatment targets with specific cell subsets in MCC may provide more accurate and reliable results for cartilage repair and TMJOA treatment. In this review, we summarized the current research progress on the cell subsets of MCC from the perspective of MCC development and degeneration. We hope to provide a reference for further exploration of the pathological process of TMJOA and improvement of TMJOA treatment.

Mesenchymal Stromal Cell Transplantation Induces Regeneration of Large and Full-Thickness Cartilage Defect of the Temporomandibular Joint

OBJECTIVE

Cartilage damage (CD) in the temporomandibular joint (TMJ) continues being a major problem in maxillofacial field. Evidence suggests that cellular therapy may be used for repairing CD in the TMJ.

DESIGN

A murine model of condyle CD (CCD) was generated in the TMJ to evaluate the capacity of mesenchymal stromal cells (MSCs) to induce cartilage regeneration in CCD. A large CCD was surgically created in a condyle head of the TMJ of C57BL/6 mice. Human MSC embedded into preclotted platelet-rich plasma (PRP) were placed on the surface of CCD. As controls, untreated CCD and exposed TMJ condyle (sham) were used. After 6 weeks, animals were sacrificed, and each mandibular condyle was removed and CCD healing was assessed macroscopically and histologically.

RESULTS

Macroscopic observation of CCD treated with MSC showed the presence of cartilage-like tissue in the CCD site. Histological analysis showed a complete repair of the articular surface with the presence of cartilage-like tissue and subchondral bone filling the CCD area. Chondrocytes were observed into collagen and glycosaminoglycans extracellular matrix filling the repaired tissue. There was no evidence of subchondral bone sclerosis. Untreated CCD showed denudated osteochondral lesions without signs of cartilage repair. Histological analysis showed the absence of tissue formation over the CCD.

CONCLUSIONS

Transplantation of MSC induces regeneration of TMJ-CCD. These results provide strong evidence to use MSC as potential treatment in patients with cartilage lesions in the TMJ.

Enhanced Circadian Clock in MSCs-Based Cytotherapy Ameliorates Age-Related Temporomandibular Joint Condyle Degeneration

Aging has been proven to be one of the major causes of temporomandibular joint (TMJ) disability and pain in older people. Peripheral circadian rhythms play a crucial role in endochondral ossification and chondrogenesis. However, the age-related alterations of circadian clock in TMJ structures are seldom reported. In the current study, TMJ condyles were extracted from young (4-month-old), middle-aged (10-month-old), and old-aged (20-month-old) adults to detect the morphology and circadian oscillation changes in TMJ condyles with aging. The transcriptome profile of Bmal1-deleted bone-marrow mesenchymal stem cells (BMSCs) and controls were explored to reveal the circadian-related differences at the molecular level. Furthermore, the reparative effects of Bmal1-overexpressed BMSCs-based cytotherapy in aged TMJ condyles were investigated in vitro and in vivo. Aged TMJ condyles displayed damaged tissue structure and an abolished circadian rhythm, accompanied by a progressively decreasing chondrogenesis capability and bone turnover activities. The deletion of Bmal1 significantly down-regulated chondrogenesis-related genes Prg4, Sox9, and Col7a1. Bmal1-overexpressed BMSCs presented improved migration capability ex vivo and attenuated age-related TMJ condylar degeneration in vivo. These data demonstrate the crucial role of circadian timing in the maintenance of osteochondral homeostasis, and indicate the potential clinical prospects of circadian-modified MSCs therapy in tissue regeneration.

Chondrogenic Potential of Human Dental Pulp Stem Cells Cultured as Microtissues

Several tissue engineering stem cell-based procedures improve hyaline cartilage repair. In this work, the chondrogenic potential of dental pulp stem cell (DPSC) organoids or microtissues was studied. After several weeks of culture in proliferation or chondrogenic differentiation media, synthesis of aggrecan and type II and I collagen was immunodetected, and SOX9, ACAN, COL2A1, and COL1A1 gene expression was analysed by real-time RT-PCR. Whereas microtissues cultured in proliferation medium showed the synthesis of aggrecan and type II and I collagen at the 6^th week of culture, samples cultured in chondrogenic differentiation medium showed an earlier and important increase in the synthesis of these macromolecules after 4 weeks. Gene expression analysis showed a significant increase of COL2A1 after 3 days of culture in chondrogenic differentiation medium, while COL1A1 was highly expressed after 14 days. Cell-cell proximity promotes the chondrogenic differentiation of DPSCs and important synthesis of hyaline chondral macromolecules.

3D printed gelatin-genipin scaffolds for temporomandibular joint cartilage regeneration

Gelatin has emerged as a biocompatible polymer with high printability in scaffold-based tissue engineering. The aim of the current study was to investigate the potential of genipin-crosslinked 3D printed gelatin scaffolds for temporomandibular joint (TMJ) cartilage regeneration. Crosslinking with genipin increased the stability and mechanical properties, without any cytotoxic effects. Chondrogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBMSC) on the scaffolds were compared to cell pellets and spheres. Although hBMSC seeded scaffolds showed a lower expression of chondrogenesis-related genes compared to cell pellets and spheres, they demonstrated a significantly reduced expression of collagen (COL) 10, suggesting a decreased hypertrophic tendency. After 21 days, staining with Alcian blue and immunofluorescence for SOX9 and COL1 confirmed the chondrogenic differentiation of hBMSC on genipin-crosslinked gelatin scaffolds. In summary, 3D printed gelatin-genipin scaffolds supported the viability, attachment and chondrogenic differentiation of hBMSC, thus, demonstrating potential for TMJ cartilage regeneration applications.

GABARAP ameliorates IL-1β-induced inflammatory responses and osteogenic differentiation in bone marrow-derived stromal cells by activating autophagy

Bone mesenchymal stem cells (BMSCs) are the most commonly investigated progenitor cells in bone defect repair and osteoarthritis subchondral bone regeneration; however, these studies are limited by complex inflammatory conditions. In this study, we investigated whether pro-autophagic γ-aminobutyric acid receptor-associated protein (GABARAP) promotes BMSCs proliferation and osteogenic differentiation by modulating autophagy in the presence or absence of interleukin-1 beta (IL-1β) in vitro. The expression levels of all relevant factors were evaluated by qRT-PCR or western blotting where appropriate. BMSCs differentiation were assessed by Alizarin Red, alkaline phosphatase, safranin O, and Oil Red O staining. Furthermore, the interactions between autophagy and osteogenic differentiation were investigated by co-treatment with the autophagy inhibitor 3-methyladenine (3-MA). As the results, we found that treatment with recombinant human His6-GABARAP protein promoted cell proliferation, inhibited apoptosis, and reduced ROS generation by increasing autophagic activity, particularly when co-cultured with IL-1β. Moreover, His6-GABARAP could effectively increase the osteogenic differentiation of BMSCs. The expression levels of inflammatory factors were significantly decreased by His6-GABARAP treatment, whereas its protective effects were attenuated by 3-MA. This study demonstrates that GABARAP maintains BMSCs survival and strengthens their osteogenic differentiation in an inflammatory environment by upregulating mediators of the autophagy pathway.

BMSC-Derived Small Extracellular Vesicles Induce Cartilage Reconstruction of Temporomandibular Joint Osteoarthritis via Autotaxin-YAP Signaling Axis

Background: Temporomandibular joint osteoarthritis (TMJOA) seriously affects the health of patients, and the current treatments are invasive and only used for advanced cases. Bone marrow mesenchymal stem cell (BMSC)-derived small extracellular vesicles (BMSC-sEVs) may represent a safer and more effective treatment, but their role in TMJOA has not been elucidated. This study attempted to analyze the cartilage reconstruction effect of BMSC-sEVs on TMJOA and the mechanism underlying this effect.

Methods: BMSC-sEVs were isolated and purified by microfiltration and ultrafiltration and were subsequently characterized by nanoparticle tracking analysis, electron microscopy, and immunoblotting. TMJOA models were established in vivo and in vitro, and hematoxylin–eosin staining, immunohistochemistry, and histological scoring were performed to analyze the histological changes in TMJOA cartilage tissues treated with BMSC-sEVs. The proliferation, migratory capacity, and cell cycle distribution of TMJOA cartilage cells treated with BMSC-sEVs were detected. Furthermore, the related mechanisms were studied by bioinformatic analysis, immunoblotting, and quantitative PCR, and they were further analyzed by knockdown and inhibitor techniques.

Results: The acquisition and identification of BMSC-sEVs were efficient and satisfactory. Compared with the osteoarthritis (OA) group, the condylar tissue of the OA group treated with BMSC-sEV (OA^sEV) showed an increase in cartilage lacuna and hypertrophic cartilage cells in the deep area of the bone under the cartilage. Significantly upregulated expression of proliferating cell nuclear antigen and cartilage-forming factors and downregulated expression of cartilage inflammation-related factors in OA^sEV were observed. In addition, we found higher rates of cell proliferation and migratory activity and alleviated G1 stagnation of the cell cycle of OA^sEV. Autotaxin was found in the BMSC-sEVs, and key factors of the Hippo pathway, Yes-associated protein (YAP), phosphorylated Yes-associated protein (p-YAP), etc. were upregulated in the OA^sEV group. Treatment with BMSC-sEVs after autotaxin knockdown or inhibition no longer resulted in expression changes in cartilage-forming and inflammation-related factors and key factors of the Hippo pathway.

Conclusions: These results suggest that the autotaxin–YAP signaling axis plays an important role in the mechanism by which BMSC-sEVs promote cartilage reconstruction in TMJOA, which may provide guidance regarding their therapeutic applications as early and minimally invasive therapies for TMJOA, and provide insight into the internal mechanisms of TMJOA.

An Update on Mesenchymal Stem Cell-Centered Therapies in Temporomandibular Joint Osteoarthritis

Temporomandibular joint osteoarthritis (TMJOA) is a degenerative disease characterized by cartilage degeneration, disrupted subchondral bone remodeling, and synovitis, seriously affecting the quality of life of patients with chronic pain and functional disabilities. Current treatments for TMJOA are mainly symptomatic therapies without reliable long-term efficacy, due to the limited self-renewal capability of the condyle and the poorly elucidated pathogenesis of TMJOA. Recently, there has been increased interest in cellular therapies for osteoarthritis and TMJ regeneration. Mesenchymal stem cells (MSCs), self-renewing and multipotent progenitor cells, play a promising role in TMJOA treatment. Derived from a variety of tissues, MSCs exert therapeutic effects through diverse mechanisms, including chondrogenic differentiation; fibrocartilage regeneration; and trophic, immunomodulatory, and anti-inflammatory effects. Here, we provide an overview of the therapeutic roles of various tissue-specific MSCs in osteoarthritic TMJ or TMJ regenerative tissue engineering, with an additional focus on joint-resident stem cells and other cellular therapies, such as exosomes and adipose-derived stromal vascular fraction (SVF). Additionally, we summarized the updated pathogenesis of TMJOA to provide a better understanding of the pathological mechanisms of cellular therapies. Although limitations exist, MSC-centered therapies still provide novel, innovative approaches for TMJOA treatment.

The efficacy of mesenchymal stem cells in regenerating structures associated with the temporomandibular joint: A systematic review

OBJECTIVES

The objective of this systematic review is to evaluate the role of mesenchymal stem cells in the regenerative treatment of temporomandibular joint resorption.

DESIGN

Search strategies were performed in the following databases: PubMed/MEDLINE, EMBASE, Cochrane Collaboration Library, and Web of Science. Two independent reviewers selected the included articles using a two-phase process based on the eligibility criteria. The reviewers independently collected the required information from the included articles. The methodological quality of the selected studies was assessed individually.

RESULT

In accordance with the inclusion and exclusion criteria, 703 studies were found and 8 articles were included. Thus, six studies using animal models and two human studies were included in this systematic review.

CONCLUSION

Based on the data of our systematic review, the use of mesenchymal stem cells is a promising method for the repair and regeneration of temporomandibular joint components.

Nanoparticles from Equine Fetal Bone Marrow-Derived Cells Enhance the Survival of Injured Chondrocytes

Simple Summary

Reports on the potential of using mesenchymal stem cells (MSCs) for treating equine degenerative joint diseases have been increasing over the past few years, in spite of limitations such as uncontrolled differentiation, immunogenicity, and tumorigenicity. We elucidated an allogenic alternative, where equine bone marrow-derived cells (BMC)-derived nanoparticles (BMC-NPs) can be used to promote the growth of chondrocytes, and simultaneously reduce their cytokine-induced apoptosis. The role of BMC-NPs in activation of signaling pathway molecules was also established.

Abstract

Recent studies have shown that mesenchymal stem cells (MSCs) can play a restorative role against degenerative joint diseases in horses. The purpose of this study was to investigate whether fetal bone marrow-derived cells (BMC)-derived nanoparticles (BMC-NPs) can stimulate the survival of equine chondrocytes. Equine fetal BMCs were isolated and characterized, and the role of BMC-NPs s in equine chondrocytes undergoing inflammatory cell death was examined. BMCs have several characteristics, such as the potential to differentiate into chondrocytes and osteocytes. Additionally, BMCs expressed immunoregulatory genes in response to treatment with tumor necrosis factor-alpha (TNF-α) and Interleukin 1 beta (IL-1β). We found that BMC-NPs were taken up by equine chondrocytes. Functionally, BMC-NPs promoted the growth of chondrocytes, and reduced apoptosis induced by inflammatory cytokines. Furthermore, we observed that BMC-NPs upregulated the phosphorylation of protein kinase B (Akt) in the presence of IL-1β, and reduced the phosphorylation of TNF-α-induced activation of extracellular signal-regulated kinase 1/2 (ERK1/2) in the chondrocytes. Cumulatively, our study demonstrated that equine fetal BMC-NPs have the potential to stimulate the survival of chondrocytes damaged by inflammatory cytokines. Thus, BMC-NPs may become an alternative cell-free allogenic therapeutic for degenerative joint diseases in horses.

Current and future uses of skeletal stem cells for bone regeneration

The postnatal skeleton undergoes growth, modeling, and remodeling. The human skeleton is a composite of diverse tissue types, including bone, cartilage, fat, fibroblasts, nerves, blood vessels, and hematopoietic cells. Fracture nonunion and bone defects are among the most challenging clinical problems in orthopedic trauma. The incidence of nonunion or bone defects following fractures is increasing. Stem and progenitor cells mediate homeostasis and regeneration in postnatal tissue, including bone tissue. As multipotent stem cells, skeletal stem cells (SSCs) have a strong effect on the growth, differentiation, and repair of bone regeneration. In recent years, a number of important studies have characterized the hierarchy, differential potential, and bone formation of SSCs. Here, we describe studies on and applications of SSCs and/or mesenchymal stem cells for bone regeneration.

Reduction of osteoarthritis severity in the temporomandibular joint of rabbits treated with chondroitin sulfate and glucosamine

Osteoarthritis is a degenerative disease that causes substantial changes in joint tissues, such as cartilage degeneration and subchondral bone sclerosis. Chondroitin sulfate and glucosamine are commonly used products for the symptomatic treatment of osteoarthritis. The aim of the present study was to investigate the effects of these products when used as structure-modifying drugs on the progression of osteoarthritis in the rabbit temporomandibular joint. Thirty-six New Zealand rabbits were divided into 3 groups (n = 12/group): control (no disease); osteoarthritis (disease induction); and treatment (disease induction and administration of chondroitin sulfate and glucosamine). Osteoarthritis was induced by intra-articular injection of monosodium iodoacetate. Animals were killed at 30 and 90 days after initiation of therapy. The treatment was effective in reducing disease severity, with late effects and changes in the concentration of glycosaminoglycans in the articular disc. The results indicate that chondroitin sulfate and glucosamine may have a structure-modifying effect on the tissues of rabbit temporomandibular joints altered by osteoarthritis.

Tissue Engineering and Regenerative Medicine in Craniofacial Reconstruction and Facial Aesthetics

The craniofacial region is anatomically complex and is of critical functional and cosmetic importance, making reconstruction challenging. The limitations of current surgical options highlight the importance of developing new strategies to restore the form, function, and esthetics of missing or damaged soft tissue and skeletal tissue in the face and cranium. Regenerative medicine (RM) is an expanding field which combines the principles of tissue engineering (TE) and self-healing in the regeneration of cells, tissues, and organs, to restore their impaired function. RM offers many advantages over current treatments as tissue can be engineered for specific defects, using an unlimited supply of bioengineered resources, and does not require immunosuppression. In the craniofacial region, TE and RM are being increasingly used in preclinical and clinical studies to reconstruct bone, cartilage, soft tissue, nerves, and blood vessels. This review outlines the current progress that has been made toward the engineering of these tissues for craniofacial reconstruction and facial esthetics.

Extracellular Vesicles from Mesenchymal Stem Cells as Novel Treatments for Musculoskeletal Diseases

Mesenchymal stem/stromal cells (MSCs) represent a promising therapy for musculoskeletal diseases. There is compelling evidence indicating that MSC effects are mainly mediated by paracrine mechanisms and in particular by the secretion of extracellular vesicles (EVs). Many studies have thus suggested that EVs may be an alternative to cell therapy with MSCs in tissue repair. In this review, we summarize the current understanding of MSC EVs actions in preclinical studies of (1) immune regulation and rheumatoid arthritis, (2) bone repair and bone diseases, (3) cartilage repair and osteoarthritis, (4) intervertebral disk degeneration and (5) skeletal muscle and tendon repair. We also discuss the mechanisms underlying these actions and the perspectives of MSC EVs-based strategies for future treatments of musculoskeletal disorders.

Protective effects of extracorporeal shockwave on rat chondrocytes and temporomandibular joint osteoarthritis; preclinical evaluation with in vivo99mTc-HDP SPECT and ex vivo micro-CT

OBJECTIVE

Extracorporeal shockwave therapy (ESWT) has been shown to have chondroprotective effects on arthritic diseases. We investigated the effects of ESWT on temporomandibular joint osteoarthritis (TMJOA) using rat chondrocytes and TMJOA rat models.

DESIGN

Cell viability and expression of pro-inflammatory cytokines, cartilage degradation, and apoptosis markers were measured in control, monosodium iodoacetate (MIA)-treated and ESWT plus MIA-treated chondrocytes in vitro, and intra-articular MIA injection (TMJOA) and ESWT on TMJOA rats in vivo. In vivo^99mTc-hydroxymethylene diphosphonate (HDP) single-photon emission computerized tomography/computerized tomography (SPECT/CT) and ex-vivo micro-CT and histologic examinations were performed in rat models.

RESULTS

ESWT plus MIA-treated chondrocytes showed increased cell viability significantly (P = 0.007), while decreased genetic expression of pro-inflammatory cytokines [tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6); P < 0.001 for each] and cartilage degradation markers [matrix metalloproteinase-3 (MMP3), matrix metalloproteinase-13 (MMP13), and bone morphogenetic protein 7 (BMP7); P < 0.001 for each], and number of apoptotic cells (P < 0.001) compared to MIA-treated chondrocytes. Changes in cytochrome c and cleaved caspase-3 levels relative to procaspase-3 were decreased over MIA-treated chondrocytes. ESWT on TMJOA rat models was associated with a significant decrease in pro-inflammatory and cartilage degradation markers, as demonstrated by real-time PCR and immunohistochemistry stains (P < 0.001 for each). On ^99mTc-HDP SPECT/CT, the ESWT group showed a significantly lower uptake ratio compared to the TMJOA group (P = 0.008). Micro-CT analysis revealed that the ESWT group showed improved structure and bone quality compared to the TMJOA control group.

CONCLUSIONS

ESWT was associated with a protective effect on cartilage and subchondral bone structures of TMJOA by reducing inflammation, cartilage degradation, and chondrocyte apoptosis.

Tissue engineering toward temporomandibular joint disc regeneration

Treatments for temporomandibular joint (TMJ) disc thinning and perforation, conditions prevalent in TMJ pathologies, are palliative but not reparative. To address this, scaffold-free tissue-engineered implants were created using allogeneic, passaged costal chondrocytes. A combination of compressive and bioactive stimulation regimens produced implants with mechanical properties akin to those of the native disc. Efficacy in repairing disc thinning was examined in minipigs. Compared to empty controls, treatment with tissue-engineered implants restored disc integrity by inducing 4.4 times more complete defect closure, formed 3.4-fold stiffer repair tissue, and promoted 3.2-fold stiffer intralaminar fusion. The osteoarthritis score (indicative of degenerative changes) of the untreated group was 3.0-fold of the implant-treated group. This tissue engineering strategy paves the way for developing tissue-engineered implants as clinical treatments for TMJ disc thinning.

Prevalence of clinical manifestations of temporomandibular osteoarthrosis

Introduction. The two compartments, disco-temporal and condilo-discal, which make up the temporo-mandibular joint, fulfill the functions of the stomatognathic system, namely: phonation, mastication and swallowing. The temporo-mandibular degenerative pathology is one of the 5 clinical entities given by the American Academy of Orofacial Pain in 1993. The symptoms are varied, dominated by pain, impaired joint mobility, cracks, sensation of muscle fatigue in the masseter and temporal muscles. Most cases benefit from conservative treatment, consisting of anti-allergic and anti-inflammatory medication, specific orthodontic treatment, electrotherapy (TENS, ultrasound, magnetodiaflux, laser), kinesiotherapy. 2-5% of patients require surgery. Material and method. We performed a retrospective study, over a 9-year period (January 2010-March 2019), in which we included 503 patients who went to the Timisoara Oro-Maxillofacial Surgery Clinic, with a definite diagnosis of temporomandibular algodisfunctional syndrome, of different etiologies, between the ages of 6 and 85 years. We evaluated the etiology of temporomandibular algodisfunctional syndrome, the prevalence of clinical manifestations in temporomandibular osteoarthritis and their evolution after 10 days of conservative treatment. Results and discussions. Pain is present in 100% of cases, the values obtained in these patients with temporomandibular osteoarthritis are between 10 and 40mm. Cracks are present in women in the percentage of 40.8% and 37.9% in men; mobility limitation is found in women in 11% of cases, and in men in 15% of cases. Conclusions. The existence of a protocol for the diagnosis of TM osteoarthritis is essential to establish the treatment plan and prognosis of the disease. The pain from osteoarthritis TM is low intensity, present in all patients; cracks and limiting mobility are present in comparable proportions, regardless of gender. The response to treatment was optimal at 21 days of treatment.

Exosomes of stem cells from human exfoliated deciduous teeth as an anti-inflammatory agent in temporomandibular joint chondrocytes via miR-100-5p/mTOR

Objectives

Temporomandibular joint osteoarthritis (TMJOA) is an inflammatory joint disease. This study investigated whether exosomes (Exos) of stem cells from human exfoliated deciduous teeth (SHEDs) have a therapeutic effect on TMJ inflammation and elucidated the underlying mechanisms.

Materials and methods

SHEDs were verified by flow cytometry. SHED-Exos were identified by western blotting, nanoparticle tracking analysis, and transmission electron microscopy. Western blot and RT-qPCR were performed to verify the anti-inflammatory effects of SHED-Exos. MicroRNA (miRNA) array analysis was conducted to determine the miRNA expression profiles of SHED-Exos, and the key pathways were analyzed. After chondrocytes were treated with an miR-100-5p mimic or rapamycin, relative expression of genes was measured by RT-qPCR and western blotting. A luciferase reporter assay was performed to reveal the molecular role of the exosomal miR-100 target, mTOR.

Results

MiR-100-5p was enriched in the SHED-Exos. Treatment with SHED-Exos suppressed the expression of interleukin-6 (IL-6), IL-8, matrix metalloproteinase 1 (MMP1), MMP3, MMP9, MMP13, and disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5). Chondrocytes treated with the miR-100 mimic showed lower expression of MMP1, MMP9, MMP13, ADAMTS5, and mTOR. In contrast, miR-100 downregulation upregulated the MMPs and mTOR. Rapamycin treatment upregulated miR-100 and downregulated MMPs and ADAMTS5. Furthermore, the luciferase reporter assay demonstrated that miR-100-5p directly targeted the mTOR 3′ untranslated region and that SHED-Exos miR-100-5p repressed mTOR expression.

Conclusions

This study demonstrated that SHED-Exos suppress inflammation in TMJ chondrocytes and may thus be a novel therapeutic agent for TMJ inflammation.

Effect of human adipose-derived regenerative cells on temporomandibular joint healing in immunodeficient rabbits

Increasing research attention has focused on the use of stem cells (SCs) in regenerative and reparative medicine. Adipose-derived regenerative cells (ADRCs) are a relatively cheap and ethical source of SCs. Temporomandibular disorders (TMDs) have been reported with rising incidence over recent decades. The main aims of this study were to evaluate the effects of ADRCs application on the healing of both soft and hard temporomandibular joint (TMJ) tissues, and to assess the possible utilization of ADRCs in TMD treatment. We investigated the effects of human ADRCs on the healing of TMJ defects in immunodeficient rabbits. With no prior cultivation, ADRCs were applied to a surgically created defect in the cartilage of a rabbit TMJ. The healing process and inflammatory response were examined. Our results indicated that ADRCs supported repair processes in soft tissues. However, ADRC treatment induced a significant immune response in both soft and hard tissues, with hard tissues showing a higher level of bone remodelling. Non-differentiated ADRCs can be a promising tool for regenerative medicine of TMJ; however, deeper understanding of their effect on the cellular level is needed.

MSC exosomes alleviate temporomandibular joint osteoarthritis by attenuating inflammation and restoring matrix homeostasis

The efficacy of mesenchymal stem cell (MSC) therapies is increasingly attributed to paracrine secretion, particularly exosomes. In this study, we investigated the role of MSC exosomes in the regulation of inflammatory response, nociceptive behaviour, and condylar cartilage and subchondral bone healing in an immunocompetent rat model of temporomandibular joint osteoarthritis (TMJ-OA). We observed that exosome-mediated repair of osteoarthritic TMJs was characterized by early suppression of pain and degeneration with reduced inflammation, followed by sustained proliferation and gradual improvements in matrix expression and subchondral bone architecture, leading to overall joint restoration and regeneration. Using chondrocyte cultures, we could attribute some of the cellular activities during exosome-mediated joint repair to adenosine activation of AKT, ERK and AMPK signalling. Specifically, MSC exosomes enhanced s-GAG synthesis impeded by IL-1β, and suppressed IL-1β-induced nitric oxide and MMP13 production. These effects were partially abrogated by inhibitors of adenosine receptor activation, AKT, ERK and AMPK phosphorylation. Together, our observations suggest that MSC exosomes promote TMJ repair and regeneration in OA through a well-orchestrated mechanism of action that involved multiple cellular processes to restore the matrix and overall joint homeostasis. This study demonstrates the translational potential of a cell-free ready-to-use exosome-based therapeutic for treating TMJ pain and degeneration.

Tissue Engineering for the Temporomandibular Joint

Tissue engineering potentially offers new treatments for disorders of the temporomandibular joint which frequently afflict patients. Damage or disease in this area adversely affects masticatory function and speaking, reducing patients' quality of life. Effective treatment options for patients suffering from severe temporomandibular joint disorders are in high demand because surgical options are restricted to removal of damaged tissue or complete replacement of the joint with prosthetics. Tissue engineering approaches for the temporomandibular joint are a promising alternative to the limited clinical treatment options. However, tissue engineering is still a developing field and only in its formative years for the temporomandibular joint. This review outlines the anatomical and physiological characteristics of the temporomandibular joint, clinical management of temporomandibular joint disorder, and current perspectives in the tissue engineering approach for the temporomandibular joint disorder. The tissue engineering perspectives have been categorized according to the primary structures of the temporomandibular joint: the disc, the mandibular condyle, and the glenoid fossa. In each section, contemporary approaches in cellularization, growth factor selection, and scaffold fabrication strategies are reviewed in detail along with their achievements and challenges.

The many faces of genetic contributions to temporomandibular joint disorder: An updated review

OBJECTIVES

The aim was to review the literature regarding genetic contributions to temporomandibular joint disorder (TMD) after our 2008 publication.

SETTING AND SAMPLE POPULATION

Literature review.

MATERIAL AND METHODS

PubMed and MEDLINE were used to obtain literature in any language regarding genes and TMD, using the keywords "temporomandibular joint disorder" and "temporomandibular joint dysfunction" for studies published from 2009 to 2017.

RESULTS

In our search, 274 studies were found. We excluded 76 studies from animal models, 22 studies that were in vitro and 120 reports that were not cohort or case-control studies. Of the 274 results, 56 articles were selected for this review. Genes that are suggested to contribute to TMD included the ones related to disc and bone alterations as well as pain sensation.

CONCLUSION

Currently, no evidence of associated genetic variants, which can determine the development of TMD in individuals, could be translated to novel clinical management and public health strategies for patients suffering from TMD.

Aberrant activation of latent transforming growth factor-β initiates the onset of temporomandibular joint osteoarthritis

There is currently no effective medical treatment for temporomandibular joint osteoarthritis (TMJ-OA) due to a limited understanding of its pathogenesis. This study was undertaken to investigate the key role of transforming growth factor-β (TGF-β) signalling in the cartilage and subchondral bone of the TMJ using a temporomandibular joint disorder (TMD) rat model, an ageing mouse model and a Camurati–Engelmann disease (CED) mouse model. In the three animal models, the subchondral bone phenotypes in the mandibular condyles were evaluated by µCT, and changes in TMJ condyles were examined by TRAP staining and immunohistochemical analysis of Osterix and p-Smad2/3. Condyle degradation was confirmed by Safranin O staining, the Mankin and OARSI scoring systems and type X collagen (Col X), p-Smad2/3a and Osterix immunohistochemical analyses. We found apparent histological phenotypes of TMJ-OA in the TMD, ageing and CED animal models, with abnormal activation of TGF-β signalling in the condylar cartilage and subchondral bone. Moreover, inhibition of TGF-β receptor I attenuated TMJ-OA progression in the TMD models. Therefore, aberrant activation of TGF-β signalling could be a key player in TMJ-OA development.

Blocking the activity of a critical growth factor could help treat degenerative disease of the jaw joint, according to experiments in three rodent models. Xuedong Zhou from Sichuan University in Chengdu, China, examined the cartilage and adjoining layer of bone found at the ends of the jawbone in a rat model of temporomandibular joint disorder and in two related mouse models. In all three, the researchers observed tissue abnormalities consistent with what’s seen in humans with osteoarthritis of the jaw joint, a condition with no effective therapeutic options. They showed that transforming growth factor-β, a master regulatory protein, displayed aberrant signalling patterns in these tissues and that blocking this protein’s receptor with a drug attenuated the disease process. The findings help explain what drives jaw joint osteoarthritis — and point to a strategy for treating it.

Synovial fluid‑derived synovial fragments represent an improved source of synovial mesenchymal stem cells in the temporomandibular joint

Surgery-obtained synovium specimens (SSSs) can provide a source of synovial mesenchymal stem cells (SMSCs) for experimental studies. However, these specimens contain diverse tissues, including the intima and subintima; therefore, these SMSCs are not entirely derived from the intima and their cell source is heterogeneous. The present study isolated synovial fragments (SFs) from synovial fluid dilutions extracted from patients with temporomandibular joint (TMJ) osteoarthrosis. Unlike SSSs, SFs, which are membranous and translucent, consist of only several cell layers, indicating the presence of only the intima. In the present study, SF cells (SFCs) and SSS cells (SSSCs) exhibited a homogeneous, fibroblast-like, spindle-shaped morphology after passaging in vitro. Furthermore, both cell types exhibited similar proliferative and differentiation potentials in vitro. However, SFCs exhibited more uniform surface markers compared with SSSCs when analysed by flow cytometry. Taken together, these results indicated that SFs contained a greater amount of unmixed intima than SSSs, and that SFCs exhibited more homogeneous characteristics than SSSCs, thereby offering an improved source of SMSCs in the TMJ.

Mesenchymal Stem Cells for Cartilage Regeneration of TMJ Osteoarthritis

Temporomandibular joint osteoarthritis (TMJ OA) is a degenerative disease, characterized by progressive cartilage degradation, subchondral bone remodeling, synovitis, and chronic pain. Due to the limited self-healing capacity in condylar cartilage, traditional clinical treatments have limited symptom-modifying and structure-modifying effects to restore impaired cartilage as well as other TMJ tissues. In recent years, stem cell-based therapy has raised much attention as an alternative approach towards tissue repair and regeneration. Mesenchymal stem cells (MSCs), derived from the bone marrow, synovium, and even umbilical cord, play a role as seed cells for the cartilage regeneration of TMJ OA. MSCs possess multilineage differentiation potential, including chondrogenic differentiation as well as osteogenic differentiation. In addition, the trophic modulations of MSCs exert anti-inflammatory and immunomodulatory effects under aberrant conditions. Furthermore, MSCs combined with appropriate scaffolds can form cartilaginous or even osseous compartments to repair damaged tissue and impaired function of TMJ. In this review, we will briefly discuss the pathogenesis of cartilage degeneration in TMJ OA and emphasize the potential sources of MSCs and novel approaches for the cartilage regeneration of TMJ OA, particularly focusing on the MSC-based therapy and tissue engineering.

Histological and Immunohistochemical Analyses of Repair of the Disc in the Rabbit Temporomandibular Joint Using a Collagen Template

A previous study demonstrated that the reconstituted type I collagen matrix extracted from rabbit tendons enabled the TMJ disc to regenerate in the rabbit. The aim of this study was to investigate changes in the extracellular matrix (ECM) and mechanisms of regeneration in the TMJ disc. In 36 New Zealand rabbits that underwent a partial discectomy, discs were replaced with reconstituted collagen templates for 3 months. A histological analysis showed that moderate to severe degeneration appeared in partially discectomized joints without implantation. In contrast, discs experienced regeneration of reconstituted collagen template implantation and the joint returned to normal function. Cells in the regenerative tissue expressed ECM, and fibers became regular and compact due to tissue remodeling over time. Reparative cells differentiated into chondroblasts, and showed highly dense pericellular fibers. The morphology and collagen composition of the disc and condyle in the 3-month experimental group were similar to those of normal tissues. In conclusion, the reconstituted collagen template facilitated the regeneration of surgically discectomized discs. Type I and type II collagens play a crucial role in the regeneration of articular discs.

Stem Cells for Temporomandibular Joint Repair and Regeneration

Temporomandibular Disorders (TMD) represent a heterogeneous group of musculoskeletal and neuromuscular conditions involving the temporomandibular joint (TMJ), masticatory muscles and/or associated structures. They are a major cause of non-dental orofacial pain. As a group, they are often multi-factorial in nature and have no common etiology or biological explanations. TMD can be broadly divided into masticatory muscle and TMJ disorders. TMJ disorders are characterized by intra-articular positional and/or structural abnormalities. The most common type of TMJ disorders involves displacement of the TMJ articular disc that precedes progressive degenerative changes of the joint leading to osteoarthritis (OA). In the past decade, progress made in the development of stem cell-based therapies and tissue engineering have provided alternative methods to attenuate the disease symptoms and even replace the diseased tissue in the treatment of TMJ disorders. Resident mesenchymal stem cells (MSCs) have been isolated from the synovia of TMJ, suggesting an important role in the repair and regeneration of TMJ. The seminal discovery of pluripotent stem cells including embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) have provided promising cell sources for drug discovery, transplantation as well as for tissue engineering of TMJ condylar cartilage and disc. This review discusses the most recent advances in development of stem cell-based treatments for TMJ disorders through innovative approaches of cell-based therapeutics, tissue engineering and drug discovery.

The cartilage extracellular matrix as a transient developmental scaffold for growth plate maturation

The cartilage growth plate is a specialized developmental tissue containing characteristic zonal arrangements of chondrocytes. The proliferative and differentiative states of chondrocytes are tightly regulated at all stages including the initial limb bud and rudiment cartilage stages of development, the establishment of the primary and secondary ossification centers, development of the growth plates and laying down of bone. A multitude of spatio-temporal signals, including transcription factors, growth factors, morphogens and hormones, control chondrocyte maturation and terminal chondrocyte differentiation/hypertrophy, cell death/differentiation, calcification and vascular invasion of the growth plate and bone formation during morphogenetic transition of the growth plate. This involves hierarchical, integrated signaling from growth and factors, transcription factors, mechanosensory cues and proteases in the extracellular matrix to regulate these developmental processes to facilitate progressive changes in the growth plate culminating in bone formation and endochondral ossification. This review provides an overview of selected components which have particularly important roles in growth plate biology including collagens, proteoglycans, glycosaminoglycans, growth factors, proteases and enzymes.

RANTES and SDF-1 Are Keys in Cell-based Therapy of TMJ Osteoarthritis

The present study aimed to investigate the therapeutic effect of injections of local bone marrow mesenchymal stem cells (BMSCs) on osteoarthritis (OA) of the temporomandibular joint (TMJ) and to explore the role of stromal cell-derived factor 1 (SDF-1) and regulated on activation, normal T-cell expressed and secreted (RANTES) in this effect. Fundamentally, OA of the TMJ was induced by unilateral anterior crossbite in mice. Exogenous green fluorescent protein-labeled BMSCs (GFP-BMSCs) were weekly injected into the TMJ region for 4, 8, and 12 wk. The reparative effects of exogenous GFP-BMSCs were investigated by morphological observation and micro-computed tomography. The differentiation of GFP-BMSCs in the cartilage was examined by double immunofluorescence of GFPs with type II collagen, and the expression of related factors in the condylar cartilage was quantified by real-time polymerase chain reaction. The role of RANTES and SDF-1 in the therapeutic effect of exogenous BMSCs was examined by both in vitro and in vivo studies. The OA cartilage of the TMJ displays a synchronous increase in SDF-1 and RANTES expression and a higher capability of attracting the migration of GFP-BMSCs. The implanted GFP-BMSCs differentiated into type II collagen-positive cells and reversed cartilage degradation and subchondral bone loss in mice with OA of the TMJ. The migration of GFP-BMSCs towards OA cartilage and the rescuing effect of GFP-BMSC injections were impaired by the inhibitors of C-X-C chemokine receptor type 4 (CXCR4) and C-C chemokine receptor type 1 (CCR1), which are the receptors of SDF-1 and RANTES, respectively. Our data indicated that SDF-1/CXCR4 and RANTES/CCR1 signals are pivotal and function synergistically in the recruitment of GFP-BMSCs towards degraded cartilage in mice OA of the TMJ.

Current understanding of pathogenesis and treatment of TMJ osteoarthritis

Osteoarthritis is a common disease that can cause severe pain and dysfunction in any joint, including the temporomandibular joint (TMJ). TMJ osteoarthritis (TMJOA) is an important subtype in the classification of temporomandibular disorders. TMJOA pathology is characterized by progressive cartilage degradation, subchondral bone remodeling, and chronic inflammation in the synovial tissue. However, the exact pathogenesis and process of TMJOA remain to be understood. An increasing number of studies have recently focused on inflammation and remodeling of subchondral bone during the early stage of TMJOA, which may elucidate the possible mechanism of initiation and progression of TMJOA. The treatment strategy for TMJOA aims at relieving pain, preventing the progression of cartilage and subchondral bone destruction, and restoring joint function. Conservative therapy with nonsteroidal anti-inflammatory drugs, splint, and physical therapy, such as low-energy laser and arthrocentesis, are the most common treatments for TMJOA. These therapies are effective in most cases in relieving the signs and symptoms, but their long-term therapeutic effect on the pathologic articular structure is unsatisfactory. A treatment that can reverse the damage of TMJOA remains unavailable to date. Treatments that prevent the progression of cartilage degradation and subchondral bone damage should be explored, and regeneration for the TMJ may provide the ideal long-term solution. This review summarizes the current understanding of mechanisms underlying the pathogenesis and treatment of TMJOA.

Cartilage regeneration by chondrogenic induced adult stem cells in osteoarthritic sheep model

Objectives

In this study, Adipose stem cells (ADSC) and bone marrow stem cells (BMSC), multipotent adult cells with the potentials for cartilage regenerations were induced to chondrogenic lineage and used for cartilage regenerations in surgically induced osteoarthritis in sheep model.

Methods

Osteoarthritis was induced at the right knee of sheep by complete resection of the anterior cruciate ligament and medial meniscus following a 3-weeks exercise regimen. Stem cells from experimental sheep were culture expanded and induced to chondrogenic lineage. Test sheep received a single dose of 2×10⁷ autologous PKH26-labelled, chondrogenically induced ADSCs or BMSCs as 5 mls injection, while controls received 5 mls culture medium.

Results

The proliferation rate of ADSCs 34.4±1.6 hr was significantly higher than that of the BMSCs 48.8±5.3 hr (P = 0.008). Chondrogenic induced BMSCs had significantly higher expressions of chondrogenic specific genes (Collagen II, SOX9 and Aggrecan) compared to chondrogenic ADSCs (P = 0.031, 0.010 and 0.013). Grossly, the treated knee joints showed regenerated de novo cartilages within 6 weeks post-treatment. On the International Cartilage Repair Society grade scores, chondrogenically induced ADSCs and BMSCs groups had significantly lower scores than controls (P = 0.0001 and 0.0001). Fluorescence of the tracking dye (PKH26) in the injected cells showed that they had populated the damaged area of cartilage. Histological staining revealed loosely packed matrixes of de novo cartilages and immunostaining demonstrated the presence of cartilage specific proteins, Collagen II and SOX9.

Conclusion

Autologous chondrogenically induced ADSCs and BMSCs could be promising cell sources for cartilage regeneration in osteoarthritis.

Effect of self-assembled peptide-mesenchymal stem cell complex on the progression of osteoarthritis in a rat model

PURPOSE

To evaluate the efficacy of mesenchymal stem cells (MSCs) encapsulated in self-assembled peptide (SAP) hydrogels in a rat knee model for the prevention of osteoarthritis (OA) progression.

MATERIALS AND METHODS

Nanostructured KLD-12 SAPs were used as the injectable hydrogels. Thirty-three Sprague Dawley rats were used for the OA model. Ten rats were used for the evaluation of biotin-tagged SAP disappearance. Twenty-three rats were divided into four groups: MSC (n=6), SAP (n=6), SAP-MSC (n=6), and no treatment (n=5). MSCs, SAPs, and SAP-MSCs were injected into the knee joints 3 weeks postsurgery. Histologic examination, immunofluorescent staining, measurement of cytokine levels, and micro-computed tomography analysis were conducted 6 weeks after injections. Behavioral studies were done to establish baseline measurements before treatment, and repeated 3 and 6 weeks after treatment to measure the efficacy of SAP-MSCs.

RESULTS

Concentration of biotinylated SAP at week 1 was not significantly different from those at week 3 and week 6 (P=0.565). Bone mineral density was significantly lower in SAP-MSC groups than controls (P=0.002). Significant differences in terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick-end labeling staining between the control group and all other groups were observed. Caspase-8, tissue inhibitor of metalloproteinases 1, and matrix metalloproteinase 9 were diffusely stained in controls, whereas localized or minimal staining was observed in other groups. Modified Mankin scores were significantly lower in the SAP and SAP-MSC groups than in controls (P=0.001 and 0.013). Although not statistically significant, synovial inflammation scores were lower in the SAP (1.3±0.3) and SAP-MSC (1.3±0.2) groups than in controls (2.6±0.2). However, neither the cytokine level nor the behavioral score was significantly different between groups.

CONCLUSION

Injection of SAP-MSC hydrogels showed evidence of chondroprotection, as measured by the histologic grading and decreased expression of biochemical markers of inflammation and apoptosis. It also lowered subchondral bone mineral density, which can be increased by OA. This suggests that the SAP-MSC complex may have clinical potential to inhibit OA progression.

Synovium fragment-derived cells exhibit characteristics similar to those of dissociated multipotent cells in synovial fluid of the temporomandibular joint

Multipotent mesenchymal stem cells (MSCs) found in the synovial fluid (SFMSCs) of the tempromandibular joint (TMJ) remain poorly understood. During TMJ arthrocentesis, we discovered that synovial fluid collected from some patients with TMJ disorders contained not only SFMSCs but also synovium fragments (SFs). In this study, we attempted to characterize both the SFMSCs and SF-derived cells (SFCs) in order to further understand the role of MSCs in the synovial fluid of the TMJ. The SFs were membranous and translucent and consisted of several cell layers, indicating that their origin was only from the intima. SFCs were obtained by digestion of the SFs and subsequently expanded in vitro. SFMSCs were enriched by centrifugation of the synovial fluid and expanded in vitro. SFCs and SFMSCs displayed a similar fibroblast-like, spindle-shaped morphology, and we observed that some SFMSCs grew out of small tissue masses in culture. Flow cytometric analysis showed that both groups of cells expressed similar surface markers, including CD90, CD44, CD105, and CD73. However, both were negative for Stro-1, CD146, CD45, CD34, CD11b, CD19, and HLA-DR. Immunofluorescent staining showed that both SFs and SFMSCs expressed vascular cell adhesion molecule 1. Both SFCs and SFMSCs could be induced to differentiate down osteogenic, chondrogenic, adipogenic, and neurogenic lineages in vitro. Together, our results indicate that the intima is the most likely tissue origin of SFMSCs in the TMJ. Moreover, the SFs are composed of only intima and thus offer an improved source of synovium-derived MSCs compared to synovium specimens obtained by surgery, which contain both intima and subintima.

Temporomandibular joint osteoarthritis: diagnosis and long-term conservative management: a topic review

Degenerative joint disease (DJD), a common osteoarthritic problem encountered in clinical practice presents as a chronic debilitating disease resulting in altered joint structure due to degradation and loss of articular cartilage, along with changes in the subchondral bone and other soft tissues. DJD is a frequent finding in the Temporomandibular joints (TMJs). Consequently, a good understanding of the use of a diagnostic algorithm will lead to a better control of DJD in the TMJ. The etiopathogenesis of osteoarthritis is complex, and it is associated with multiple risk factors. The condition progresses slowly through different phases with periods of remission and activity finally reaching the burnout phase. Conservative management forms the cornerstone for the treatment of most of these cases. This review attempts to acquaint the dentist with the diagnosis, pathogenesis and general characteristics of the disease while highlighting and updating them with the current conservative treatment algorithms in order to assist in the formulation of a treatment plan for these patients.

New therapeutics in promoting and modulating mandibular growth in cases with mandibular hypoplasia

Children with mandibular growth deficiency may develop airway obstruction. The standard treatment of severe airway obstruction involves invasive procedures such as tracheostomy. Mandibular distraction osteogenesis has been proposed in neonates with mandibular deficiency as a treatment option to avoid tracheostomy procedure later in life. Both tracheostomy and distraction osteogenesis procedures suffer from substantial shortcomings including scarring, unpredictability, and surgical complications. Forward jaw positioning appliances have been also used to enhance mandible growth. However, the effectiveness of these appliances is limited and lacks predictability. Current and future approaches to enhance mandibular growth, both experimental and clinical trials, and their effectiveness are presented and discussed.