Emerging intra-articular drug delivery systems for the temporomandibular joint

Controlled Release of Human Dental Pulp Stem Cell-Derived Exosomes from Hydrogels Attenuates Temporomandibular Joint Osteoarthritis

Temporomandibular joint osteoarthritis (TMJOA) is a painful inflammatory condition that limits mouth opening. Cell-derived exosomes, which have anti-inflammatory effects, are emerging as a treatment for TMJOA. Injection of dental pulp stem cells (DPSCs), which secrete exosomes, can moderate tissue damage in a rat model of TMJOA. However, injected exosomes are quickly cleared, necessitating repeated injections for therapeutic efficacy. Here, vinyl sulfone-modified hyaluronic acid (HA-VS) hydrogels, suitable for encapsulating exosomes are formulated. HA-VS hydrogels degrade in the presence of hyaluronidase and allow for the release of beads of similar size to exosomes over 3 to 6 days. In a rat model of TMJOA, injection of exosomes or exosomes within HA-VS hydrogels significantly attenuated damage-mediated subchondral bone loss as determined by micro-computed tomography, and reduced inflammatory and tissue damage scores as assessed by histology. Overall, DPSCs-derived exosomes attenuated joint damage, but treatment with exosomes within HA-VS hydrogels shows additional protective effects on subchondral bone maintenance and integrity. These findings confirm the protective effects of DPSCs-derived exosomes in moderating tissue damage in TMJOA and suggest that combining exosomes with HA hydrogels can further promote their therapeutic effects.

Can intra-articular daidzein injection reduce oxidative damage and early osteoarthritis in a rabbit temporomandibular joint model?

BACKGROUND

Oxidative damage and inflammatory cytokines in osteoarthritis (OA) exacerbate the disease course. Daidzein (DZ) has antioxidant and anti-inflammatory effects. This study evaluated the early histopathological effects of intra-articular daidzein injection on experimentally induced osteoarthritis in rabbit TMJs.

METHODS

The predictor variable was intra-articular injection of DZ or a saline control. 50 µl of 3 mg/mL MIA solution was injected into the right TMJ of 16 New Zealand rabbits to induce experimental OA. One rabbit was sacrificed after 4 weeks to confirm the formation of the OA model and the OA model was obtained. The remaining 15 rabbits were randomly divided into 2 groups: an experimental group (9 rabbits) and a control group (6 rabbits). On days 1, 7, 14, and 21; 50 µl of saline solution was applied to the right TMJ of the control group and 50 µl daidzein solution (1.8 mg/ml) was applied to the right TMJ to the experimental group. After one week from the date of the last injection, the rabbits were sacrificed, and histopathological and biochemical evaluations were performed. The Shapiro-Wilk test was used to evaluate whether the variables in the study conformed to normal distribution. Mean ± SD (standard deviation) or median (interquartile range (IQR)) was used to show the descriptive statistics of the variables. T-test and Mann Whitney U test were used to compare the control and experimental groups for biochemical changes. The chi-square test was used to show the distribution of histopathological changes variables obtained within the scope of the study based on control and experimental groups. A P-value < 0.05 was considered significant for all evaluations.

RESULTS

There were 8 and 6 animate treated with DZ and saline, respectively. There was no statistically significant difference between groups in articular cartilage (p = 0.3), osteochondral junction (p = 0.3), subchondral bone structure (p = 1.0) or chondrocyte appearance (p = 0.4). The experimental group showed significantly lower mean values for Total Oxidant Status (TOS) (p = 0.002) and Oxidative Stress Index (OSI) (p = 0.007).

CONCLUSIONS

An intra-articular DZ injection appears to show limited reduction of oxidative damage and early OA in the rabbit TMJ. DZ might represent a promising natural compound with beneficial effects in the management of TMJ-OA.

Recent advancements in microspheres mediated targeted delivery for therapeutic interventions in osteoarthritis

Osteoarthritis (OA), affecting around 240 million people globally is a major threat. Currently, available drugs only treat the symptoms of OA; they cannot reverse the disease's progression. The delivery of drugs to afflicted joints is challenging because of poor vasculature of articular cartilage results in their less bioavailability and quick elimination from the joints. Recently approved drugs such as KGN and IL-1 receptor antagonists also encounter challenges because of inadequate formulations. Therefore, microspheres could be a potential player for the intervention of OA owing to its excellent physicochemical properties. This review primarily focuses on microspheres of distinct biomaterials acting as cargo for drugs and biologicals via different delivery routes in the effective management of OA. Microspheres can improve the efficacy of therapeutics by targeting strategies at specific body locations. This review also highlights clinical trials conducted in the last few decades.

Intra-Articular Injection of Adipose-Derived Stromal Vascular Fraction in Osteoarthritic Temporomandibular Joints: Study Design of a Randomized Controlled Clinical Trial

INTRODUCTION

Temporomandibular joint (TMJ) osteoarthritis is a degenerative disease of the TMJ. It is characterized by progressive degradation of the extracellular matrix components of articular cartilage, with secondary inflammatory components leading to pain in the temporomandibular region and reduced mouth opening. Current treatments do not halt disease progression, hence the need for new therapies to reduce inflammation and, consequently, improve symptoms. The aim of our randomized controlled clinical trial protocol is to investigate the efficacy of adjuvant intra-articular injections of autologous tissue-like stromal vascular fraction (tSVF), compared to arthrocentesis alone, in reducing pain and improving mouth opening in TMJ osteoarthritis patients.

MATERIALS AND METHODS

The primary endpoint analysis will consist of the visual analogue scale (VAS) for pain. The secondary endpoint analyses will include maximal interincisal mouth opening measurements; assessment of oral health and mandibular function based on the oral health impact profile (OHIP) questionnaire and mandibular functional impairment questionnaire (MFIQ); complications during the follow up; synovial cytokine analysis at baseline and after 26 weeks; and nucleated cells and tSVF (immuno)histochemistry analyses of the intervention group.

DISCUSSION

Our randomized clinical trial protocol will be applied to evaluate the efficacy of a new promising tSVF injection therapy for TMJ osteoarthritis. The safety of intra-articular injections of tSVF has been proven for knee osteoarthritis. However, since a tSVF injection is considered a heterologous application of cell therapy, the regulatory requirements are strict, which makes medical ethical approval challenging.

Hyaluronic acid injections for pain relief and functional improvement in patients with temporomandibular disorders: An umbrella review of systematic reviews

BACKGROUND

Temporomandibular disorders (TMD) are the main cause of chronic facial pain, and intra-articular (IA) injections of hyaluronic acid (HA) are commonly performed.

OBJECTIVES

This umbrella review of systematic reviews aimed at analysing the effectiveness of HA injections on pain and functional outcomes in patients affected by TMD.

METHODS

PubMed, Cochrane Library and PEDro were systematically searched from inception until 17 January 2023 to identify systematic reviews evaluating the effects on pain and functional outcomes of HA IA injections. PROSPERO registration number: CRD42022382586.

RESULTS

Out of 316 papers suitable for title/abstract screening, 18 articles were included in the umbrella review. Thirteen studies included only randomized controlled clinical trials (RCTs). The included systematic reviews reported no statistically significant differences between HA and corticosteroids, whereas platelet derivates seem to have good results in pain relief. The literature did not show severe adverse events, except for mild pain in the site of injection. Concerning the quality assessment of the 18 systematic reviews, 2 (11.11%) had a high quality, 3 (16.67%) a moderate quality, 7 (38.89%) a low quality and 6 (33.33%) a critically low quality.

CONCLUSIONS

Taken together, findings of this umbrella review showed intriguing effects of IA HA injections in terms of reduction of pain intensity and improvement of functioning in patients affected by TMD. Furthermore, there is no agreement on the effectiveness of a combination of arthrocentesis or arthroscopy with IA HA injections. Although the literature showed these positive results after IA HA injections, the overlapping of primary studies in the systematic reviews included might have affect our results, such as the very low quality of the papers. Thus, further RCTs are needed to confirm the efficacy of IA injections of HA on pain relief in patients with TMD.

Applications of Hydrogels in Drug Delivery for Oral and Maxillofacial Diseases

Oral and maxillofacial diseases have an important impact on local function, facial appearance, and general health. As a multifunctional platform, hydrogels are widely used in the biomedical field due to their excellent physicochemical properties. In recent years, a large number of studies have been conducted to adapt hydrogels to the complex oral and maxillofacial environment by modulating their pore size, swelling, degradability, stimulus-response properties, etc. Meanwhile, many studies have attempted to use hydrogels as drug delivery carriers to load drugs, cytokines, and stem cells for antibacterial, anticancer, and tissue regeneration applications in oral and maxillofacial regions. This paper reviews the application and research progress of hydrogel-based drug delivery systems in the treatment of oral and maxillofacial diseases such as caries, endodontic diseases, periodontal diseases, maxillofacial bone diseases, mucosal diseases, oral cancer, etc. The characteristics and applications of hydrogels and drug-delivery systems employed for the treatment of different diseases are discussed in order to provide a reference for further research on hydrogel drug-delivery systems in the future.

Accurate Diagnosis and Treatment of Painful Temporomandibular Disorders: A Literature Review Supplemented by Own Clinical Experience

Introduction

Temporomandibular disorders (TMD) is a multifactorial group of musculoskeletal disorders often with combined etiologies that demand different treatment plans. While pain is the most common reason why patients decide to seek help, TMD is not always painful. Pain is often described by patients as a headache, prompting patients to seek the help of neurologists, surgeons, and ultimately dentists. Due to the unique characteristics of this anatomical area, appropriate diagnostic tools are needed, as well as therapeutic regimens to alleviate and/or eliminate the pain experienced by patients. Aim of the Study. The aim of this study is to collect and organize information on the diagnosis and treatment of pain in TMD, through a review of the literature supplemented by our own clinical experience. Material and Methods. The study was conducted by searching scientific databases PubMed, Scopus, and Google Scholar for documents published from 2002-2022. The following keywords were used to build the full list of references: TMD, pain, temporomandibular joint (TMJ), TMJ disorders, occlusal splint, relaxing splints, physiotherapy TMD, pharmacology TMD, natural therapy TMD, diagnostic criteria for TMD, and DC/TMD. The literature review included 168 selected manuscripts, the content of which was important for pain diagnosis and clinical treatment of TMD.

Results

An accurate diagnosis of TMD is the foundation of appropriate treatment. The most commonly described treatments include physiotherapy, occlusal splints therapy, and pharmacological treatment tailored to the type of TMD.

Conclusions

Based on the literature review and their own experience, the authors concluded that there is no single ideal form of pain therapy for TMD. Treatment of TMD should be based on a thorough diagnostic process, including the DC/TMD examination protocol, psychological evaluation, and cone beam computer tomography (CBCT) imaging. Following the diagnostic process, once a diagnosis is established, a treatment plan can be constructed to address the patient's complaints.

Evaluation of the efficiency of hyaluronic acid, PRP and I-PRF intra-articular injections in the treatment of internal derangement of the temporomandibular joint: A prospective study

This study aimed to evaluate the clinical effects of hyaluronic acid (HA), platelet-rich plasma (PRP), and platelet-rich fibrin (I-PRF) injections in the internal derangement of the temporomandibular joint. Adult patients who had failed to respond to nonsurgical treatment were were included in the study. The patients were divided into three treatment groups according to the given substance: 1) HA administration three times in a row on a weekly basis, 2) a single dose of PRP, or 3) a single dose of I-PRF. Clinical assessment was performed preoperatively and 6 and 12 months after the treatment, including maximal mouth opening (MMO) and pain level (Visual Analog Scale). Low and high molecular weight (HA_L, HA_H) hyaluronic acid forms were also compared. 68 adult patients, with a total of 109 joints were included in the study. The mean age was 53 ± 16 years. The statistical analysis showed a significant improvement in MMO in the HA group (p < 0.01). The pain level significantly decreased in all treatment groups (p_HA,PRP,I-PRF<0.01). Comparing HA_L and HA_H forms, no significant difference was found in the evaluation of MMO and VAS values. Within the limitations of the study it seems that due to the similar effects of HA and the autologous blood substances, the platelet concentrates should be preferred in the intra-articular treatment in order to reduce the risk of possible adverse effects.

Comparison of chemical-induced temporomandibular osteoarthritis rat models (monosodium iodoacetate versus collagenase type II) for the study of prolonged drug delivery systems

OBJECTIVE

To compare two agents that can induce a rat model of temporomandibular joint osteoarthritis (TMJOA) by chemical induction: monosodium iodoacetate (MIA) and collagenase type 2 (Col-2). We wished to ascertain the best agent for assessing drug-delivery systems (DDSs).

METHOD

Male Wistar rats underwent intra-articular injection with MIA or Col-2. They were manipulated for 30 days. The head withdrawal threshold (HWT), immunohistological assessment, and positron emission tomography (PET) were used to evaluate the relevance of our models.

RESULTS

For both the MIA and Col-2 groups, pain persisted for 30 days after injection. Change in the HWT showed that Col-2 elicited a strong action initially that decreased progressively. MIA had a constant action upon pain behavior. Histology of TMJ tissue from both groups showed progressive degradation of TMJ components.

CONCLUSIONS

MIA and Col-2 induced orofacial pain by their local chemical action on TMJs. However, based on a prolonged and greater sustained effect on the pain threshold, persistent histological changes, and imaging results, MIA appeared to be more suitable for creation of a rat model of TMJOA for the study of DDSs.

The Biomimetics of Mg2+-Concentration-Resolved Microenvironment for Bone and Cartilage Repairing Materials Design

With the increase in population aging, the tendency of osteochondral injury will be accelerated, and repairing materials are increasingly needed for the optimization of the regenerative processes in bone and cartilage recovery. The local environment of the injury sites and the deficiency of Mg2+ retards the repairing period via inhibiting the progenitor osteogenesis and chondrogenesis cells’ recruitment, proliferation, and differentiation, which results in the sluggish progress in the osteochondral repairing materials design. In this article, we elucidate the Mg2+-concentration specified effect on the cell proliferation, osteochondral gene expression, and differentiation of modeling chondrocytes (extracted from New Zealand white rabbit) and osteoblasts (MC3T3-E1). The concentration of Mg2+ in the culture medium affects the proliferation, chondrogenesis, and osteogenesis: (i) Appropriate concentrations of Mg2+ promote the proliferation of chondrocytes (1.25−10.0 mM) and MC3T3-E1 cells (2.5−30.0 mM); (ii) the optimal concentration of Mg2+ that promotes the gene expression of noncalcified cartilage is 15 mM, calcified cartilage 10 mM, and subchondral bone 5 mM, respectively; (iii) overdosed Mg2+ leads to the inhibition of cell activity for either chondrocytes (>20 mM) or osteoblasts (>30 mM). The biomimetic elucidation for orchestrating the allocation of gradient concentration of Mg2+ in accordance of the physiological condition is crucial for designing the accurate microenvironment in osteochondral injury defects for optimization of bone and cartilage repairing materials in the future.

A comparison of the outcomes following intra-articular steroid injection alone or arthrocentesis alone in the management of internal derangement of the temporomandibular joint

CONTEXT

One of the main causes of chronic facial pain is temporomandibular disorders (TMDs) which may turn out to be a major cause for disability. The two types of treatment strategies may be undertaken to counter temporomandibular joint (TMJ) disorders, namely conservative management and surgical intervention. Surgical management can be classified into invasive open methods and minimally invasive procedures such as arthrocentesis, intra-articular steroid injection, and arthroscopy.

AIMS

The aim of this study is to compare the efficacy of Kenacort (Triamcinolone) as an intra-articular corticosteroid injection and arthrocentesis for lysis and lavage, for the treatment of the temporomandibular joint disorders.

SUBJECTS AND METHODS

Twenty patients with internal derangement of temporomandibular joint (IDTMJ) not responding to conservative management and meeting the inclusion criteria randomly underwent either intra-articular steroid injection or arthrocentesis and the results of the two procedures were evaluated and compared.

STATISTICAL ANALYSIS USED

Unpaired t-test, repeated-measures ANOVA. A value of P < 0.05 is considered to be statistically significant.

RESULTS AND CONCLUSION

Both procedures turned out to be successful in reducing pain and improving mouth opening, both in a short-term and a long-term use. Upon comparison in our series of patients, arthrocentesis was noted to be a better treatment modality in the long term for the management of IDTMJ.

Poly ε-Caprolactone Nanoparticles for Sustained Intra-Articular Immune Modulation in Adjuvant-Induced Arthritis Rodent Model

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disorder with synovitis and articular pathology as its primary expositions. Leflunomide (Lfd) is an anti-rheumatic drug that is effective in the treatment of RA, but displays severe side effects upon prolonged systemic administration. Local therapy might represent a promising strategy to treat rheumatoid arthritis without eliciting systemic adverse effects. In this study, leflunomide-loaded poly(ε-caprolactone) nanoparticles (Lfd-NPs) were prepared and assessed as a local drug delivery system capable of alleviating RA-associated inflammation. Lfd-NPs were optimized using the Quality by Design (QbD) approach, applying a 32 full factorial design. In vitro drug release from NPs was examined in simulated synovial fluid. In addition, the in vivo efficacy of Lfd-NPs was evaluated in the Adjuvant Induced Arthritis (AIA) rodent model. Sustained drug release in simulated synovial fluid was observed for up to 168 h. A gradual reduction in paw volume and knee diameter was observed over the course of treatment, indicating the regression of the disease. In addition, significant reductions in serum proinflammatory markers and cytokines, including the C-reactive protein (CRP), rheumatoid factor (RF), TNF-α, IL1-β, and IL-6, were verified upon treatment with Lfd-NPs, suggesting the modulation of immune responses at the pathological site. Most importantly, no remarkable signs of toxicity were observed in Lfd-NP-treated animals. Collectively, intra-articularly administered Lfd-NPs might represent a potential therapeutic alternative to systemically administered drugs for the treatment of rheumatoid arthritis, without eliciting systemic adverse effects.

Systematic review of studies on drug-delivery systems for management of temporomandibular-joint osteoarthritis

INTRODUCTION

Temporomandibular-joint osteoarthritis (TMJOA) management is a major challenge. Minimally invasive therapies (based mainly on injections) have been developed to increase local efficacy and limit adverse systemic effects. However, the requirement for repeat injections due to a short duration of action and expensive healthcare costs have pushed researchers to develop, via tissue engineering, drug-delivery systems (DDSs). In this literature systematic review, we aim to provide an overview of studies that tested DDSs on a TMJOA model.

MATERIAL AND METHODS

We searched on PubMed for articles published from November 1965 to March 2021 on DDSs using a TMJOA model. We highlighted the different DDSs and the active molecule employed. Route of drug administration, model type, test duration, and efficacy duration were assessed. To evaluate the quality of each study, a protocol bias was tested using QUADAS-2™.

RESULTS

Of the 10 studies that were full text-screened, four used a poly(lactic-co-glycolic acid)-based delivery system. The other DDSs employed chitosan-based hydrogels, microneedles patches, nanostructured lipid carriers, or poloxamer micelles. Hyaluronic acid, nonsteroidal anti-inflammatory drugs, and analgesics were used as active molecules in five studies. The main way to administer DDSs was intra-articular injection and the most used model was the rat.

DISCUSSION

Various DDSs and active molecules have been studied on a TMJOA model that could aid TMJOA management. Further works using longer test durations are necessary to validate these advances.

EtoGel for Intra-Articular Drug Delivery: A New Challenge for Joint Diseases Treatment

Ethosomes^® have been proposed as potential intra-articular drug delivery devices, in order to obtain a longer residence time of the delivered drug in the knee joint. To this aim, the conventional composition and preparation method were modified. Ethosomes^® were prepared by using a low ethanol concentration and carrying out a vesicle extrusion during the preparation. The modified composition did not affect the deformability of ethosomes^®, a typical feature of this colloidal vesicular topical carrier. The maintenance of sufficient deformability bodes well for an effective ethosome^® application in the treatment of joint pathologies because they should be able to go beyond the pores of the dense collagen II network. The investigated ethosomes^® were inserted in a three-dimensional network of thermo-sensitive poloxamer gel (EtoGel) to improve the residence time in the joint. Rheological experiments evidenced that EtoGel could allow an easy intra-articular injection at room temperature and hence transform itself in gel form at body temperature into the joint. Furthermore, EtoGel seemed to be able to support the knee joint during walking and running. In vitro studies demonstrated that the amount of used ethanol did not affect the viability of human chondrocytes and nanocarriers were also able to suitably interact with cells.

Temporomandibular joint injections in dogs with temporomandibular joint pain: 11 cases (2015-2019)

OBJECTIVES

To describe and evaluate the clinical application of temporomandibular joint injections using betamethasone and ropivacaine in German Shepherd dogs suffering from non-odontogenic orofacial pain due to temporomandibular dysplasia and/or osteoarthritis.

MATERIALS AND METHODS

Outcomes in dogs presented with clinical signs of non-odontogenic orofacial pain associated to temporomandibular joint dysplasia and/or arthritis and treated with a temporomandibular joint injection were retrospectively-prospectively evaluated.

RESULTS

The overall clinical signs free period ranged between 25 to 1579 days, with an average of 461 days. The clinical signs free period for temporomandibular joint osteoarthritis scores 1, 2 and 3 were on average 659 days (180-1579 days), 134 days (42-355 days) and 723 days (25-1377 days), respectively. Similarly the temporomandibular dysplasia scores 1, 2 and 3 were on average 306 days (26-1579 days), 1377 days and 669 days (25-1429 days) respectively. Those dogs in which only one side was injected the clinical signs free period average was 639 days (25-1578 days), compared with dogs in which both temporomandibular joints were injected showing a clinical signs free period average of 378 days (42-1377 days).

CLINICAL SIGNIFICANCE

The temporomandibular joint injection technique proved to be feasible with a decent outcome in dogs suffering from non-odontogenic orofacial pain associated with temporomandibular joint osteoarthritis and/or dysplasia. Further randomised studies are required to confirm the effectiveness of this intervention.

Short-Term Effects of Intra-Articular Hyaluronic Acid Administration in Patients with Temporomandibular Joint Disorders

The study described in this paper was conducted to assess the short-term outcomes of intra-articular administration of hyaluronic acid in patients with symptoms of temporomandibular joint disorders. A group of 40 patients suffering from temporomandibular joint disorders underwent a series of hyaluronic acid intra-articular injections. Questionnaires and clinical examinations were conducted to assess stress exposure of the subjects and to evaluate short-term treatment outcomes, i.e., reducing joint and muscle pain and increasing the mobility of the mandible. A weak positive correlation between stress exposure and pain was observed. As a result of treatment, 61% of subjects revealed a total reduction of muscle pain, while joint pain completely resolved in 88% of patients. Mandibular mobility increased by 11%, 31%, 9%, and 11% regarding opening, protrusive, and lateral right and left movements, respectively. The study confirms the short-term effectiveness of intra-articular administration of hyaluronic acid on reducing joint and muscle pain in patients with articular disc displacement. The treatment positively affected the mobility of the mandible in all directions. The verification of late treatment effects of hyaluronic acid viscosupplementation requires the continuation of the research.

Advances in nanomedicine for the treatment of ankylosing spondylitis

Ankylosing spondylitis (AS) is a complex disease characterized by inflammation and ankylosis primarily at the cartilage-bone interface. The disease is more common in young males and risk factors include both genetic and environmental. While the pathogenesis of AS is not completely understood, it is thought to be an immune-mediated disease involving inflammatory cellular infiltrates, and human leukocyte antigen-B27. Currently, there is no specific diagnostic technique available for this disease; therefore conventional diagnostic approaches such as clinical symptoms, laboratory tests and imaging techniques are used. There are various review papers that have been published on conventional treatment approaches, and in this review work, we focus on the more promising nanomedicine-based treatment modalities to move this field forward.

Remaining Hurdles for Tissue-Engineering the Temporomandibular Joint Disc

The temporomandibular joint (TMJ) disc, a fibrocartilaginous structure between the mandible and temporal bone, is implicated in temporomandibular disorders (TMDs). TMDs symptomatically affect approximately 25% of the population, of which 70% have internal derangement of the disc. Treatments lack efficiency, motivating novel therapies, including tissue-engineering toward TMJ disc regeneration. Recent developments in scaffold-based or scaffold-free approaches, cell sources, and biochemical and mechanical stimulation have resulted in constructs exhibiting native tissue mechanics. Safety and efficacy of tissue-engineered implants have shown promising results in orthotopic animal studies. However, many hurdles need to be overcome in tissue-engineering approaches, and clinical and regulatory pathways. Future studies present an opportunity for clinicians and researchers to work together toward safe and effective clinical trials.

Change of site of intra-articular injection of hypertonic dextrose resulted in different effects of treatment

Most minimally invasive treatments for dysfunction of the temporomandibular joint (TMJ) are empirical, and aimed at the painful trigger points with the purpose of preventing muscular spasm and restoring normal function. In this prospective study I investigated whether the choice of site of injection of hypertonic dextrose affected the benefits of treatment of internal derangement and pain. I studied 72 patients with pain and clicking as a result of dysfunction of the TMJ. Patients were divided into four groups with four separate sites for intra-articular injection. Dextrose was injected into the superior joint space, inferior joint space, retrodiscal tissue, and anterior capsule injection. Results showed that the retrodiscal site was the most effective for reducing clicking and subsequently improving derangement, while the inferior joint space was the best site for the relief of pain, and the extracapsular site should be used in cases of hypermobility. In conclusion, the injection site should be selected according to the symptoms being treated, and could be used as an adjunct to other sites to improve outcome.

Intra-articular biomaterials-assisted delivery to treat temporomandibular joint disorders

The temporomandibular joint disorder, also known as myofascial pain syndrome, is considered one of the prevalent chronic pain diseases caused by muscle inflammation and cartilage degradation in head and neck, and thus influences even biopsychosocial conditions in a lifetime. There are several current treatment methodologies relieving inflammation and preventing degradation of the joint complex. One of the promising non-surgical treatment methods is an intra-articular injection of drugs such as corticosteroids, analgesics, and anti-depressants. However, the side effects of drugs due to frequent injections and over-doses, including dizziness, dry mouth, and possible drug dependency are considered limitations. Thus, the delivery of therapeutic molecules through the use of nano/microparticles is currently considered as a promising strategy primarily due to the controlled release. This review highlights the nano/microparticle systems for effective intra-articular therapeutics delivery to prevent cartilage degradation and protect subchondral bone in a temporomandibular joint.

Temporomandibular Joint Regenerative Medicine

The temporomandibular joint (TMJ) is an articulation formed between the temporal bone and the mandibular condyle which is commonly affected. These affections are often so painful during fundamental oral activities that patients have lower quality of life. Limitations of therapeutics for severe TMJ diseases have led to increased interest in regenerative strategies combining stem cells, implantable scaffolds and well-targeting bioactive molecules. To succeed in functional and structural regeneration of TMJ is very challenging. Innovative strategies and biomaterials are absolutely crucial because TMJ can be considered as one of the most difficult tissues to regenerate due to its limited healing capacity, its unique histological and structural properties and the necessity for long-term prevention of its ossified or fibrous adhesions. The ideal approach for TMJ regeneration is a unique scaffold functionalized with an osteochondral molecular gradient containing a single stem cell population able to undergo osteogenic and chondrogenic differentiation such as BMSCs, ADSCs or DPSCs. The key for this complex regeneration is the functionalization with active molecules such as IGF-1, TGF-β1 or bFGF. This regeneration can be optimized by nano/micro-assisted functionalization and by spatiotemporal drug delivery systems orchestrating the 3D formation of TMJ tissues.

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.

Chitosan-Based Thermosensitive Hydrogel for Controlled Drug Delivery to the Temporomandibular Joint

Intra-articular injections of hyaluronic acid (HA) and corticosteroids have been extensively used in treating temporomandibular disorders. However, rapid clearance from the site of injection is a major concern that is commonly managed by frequent dosing, which is not without complications. This study aimed to determine the suitability of thermosensitive chitosan-based hydrogels for intra-articular controlled release of drugs in the rabbit temporomandibular joint (TMJ). A series of hydrogels were prepared using different chitosan (Ch) to β-glycerophosphate (β-GP) ratios. The gelation time, swelling ratio, the shape, and surface morphology of the prepared gels were investigated to select the formulation with optimum characteristics. The left TMJ in 13 adult male New Zealand white rabbits was injected with 0.2 mL of Chitosan/β-glycerophosphate/HA while the right TMJ was injected with 0.2 mL of control solution of HA. Hyaluronic acid concentrations in experimental and control groups were measured using Hyaluronan Quantikine Enzyme-Linked Immunosorbent Assay Kit. In vitro characterization showed that both the Ch:β-GP ratio and incorporation of HA had a significant effect on gelation time, degree of swelling, and surface morphology of the hydrogels. No morphological changes were observed in the joints in both groups. The mean concentration of HA in the experimental joints after 7 days (1339.79 ± 244.98 μg/g) was significantly higher than that in the control (474.52 ± 79.36 μg/g). In conclusion, the chitosan-based thermosensitive hydrogel can be considered as a promising controlled drug release system to the TMJ in a rabbit model that would potentially overcome many of the current limitations of intra-articular formulations.

Development and optimization of self-assembling nanosystem for intra-articular delivery of indomethacin

Osteoarthritis is a propagated debilitating condition affecting patients' quality of life. Intra-articular injection approach was investigated as a localized treatment strategy providing: site-specific delivery, decreased side effects and, increased patient compliance. A 3² full factorial experimental design was employed to prepare the indomethacin-loaded self-assembling nanosystems (SANS). The surfactant (Poloxamer 407/Tetronic 90R4) ratio and the poly(lactic-co-glycolic acid) (PLGA) concentration significantly affected encapsulation efficiency and drug release (p<0.05). The optimized formula was subjected to modification by addition of different proteoglycans, as a compensatory treatment, to improve its pharmacological properties. The modified SANS, containing glucosamine (150mg), was selected for in-vivo studies as it had a sustained drug release profile and a small particle size (173.90nm). The effect of the optimized SANS, with or without PLGA, was compared with the modified formula containing glucosamine and, with the drug suspension on the arthritic knee joints of rats. It was found that the formulation containing PLGA and glucosamine showed significantly higher reduction in both, knee diameter and TNF-α levels, compared to other groups. Furthermore, all SANS showed histological improvement in the cellularity of the synovial membranes and joints. Our results indicate that SANS containing PLGA and glucosamine is capable of treating arthritic joints.

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.

Cationic PLGA/Eudragit RL nanoparticles for increasing retention time in synovial cavity after intra-articular injection in knee joint

Positively surface-charged poly(lactide-co-glycolide) (PLGA)/Eudragit RL nanoparticles (NPs) were designed to increase retention time and sustain release profile in joints after intra-articular injection, by forming micrometer-sized electrostatic aggregates with hyaluronic acid, an endogenous anionic polysaccharide found in high amounts in synovial fluid. The cationic NPs consisting of PLGA, Eudragit RL, and polyvinyl alcohol were fabricated by solvent evaporation technique. The NPs were 170.1 nm in size, with a zeta potential of 21.3 mV in phosphate-buffered saline. Hyperspectral imaging (CytoViva(®)) revealed the formation of the micrometer-sized filamentous aggregates upon admixing, due to electrostatic interaction between NPs and the polysaccharides. NPs loaded with a fluorescent probe (1,1'-dioctadecyl-3,3,3',3' tetramethylindotricarbocyanine iodide, DiR) displayed a significantly improved retention time in the knee joint, with over 50% preservation of the fluorescent signal 28 days after injection. When DiR solution was injected intra-articularly, the fluorescence levels rapidly decreased to 30% of the initial concentration within 3 days in mice. From these findings, we suggest that PLGA-based cationic NPs could be a promising tool for prolonged delivery of therapeutic agents in joints selectively.

Temporomandibular disorders: a review of etiology, clinical management, and tissue engineering strategies

Temporomandibular disorders (TMD) are a class of degenerative musculoskeletal conditions associated with morphologic and functional deformities that affect up to 25% of the population, but their etiology and progression are poorly understood and, as a result, treatment options are limited. In up to 70% of cases, TMD are accompanied by malpositioning of the temporomandibular joint (TMJ) disc, termed "internal derangement." Although the onset is not well characterized, correlations between internal derangement and osteoarthritic change have been identified. Because of the complex and unique nature of each TMD case, diagnosis requires patient-specific analysis accompanied by various diagnostic modalities. Likewise, treatment requires customized plans to address the specific characteristics of each patient's disease. In the mechanically demanding and biochemically active environment of the TMJ, therapeutic approaches that can restore joint functionality while responding to changes in the joint have become a necessity. One such approach, tissue engineering, which may be capable of integration and adaptation in the TMJ, carries significant potential for the development of repair and replacement tissues. The following review presents a synopsis of etiology, current treatment methods, and the future of tissue engineering for repairing and/or replacing diseased joint components, specifically the mandibular condyle and TMJ disc. An analysis of native tissue characterization to assist clinicians in identifying tissue engineering objectives and validation metrics for restoring healthy and functional structures of the TMJ is followed by a discussion of current trends in tissue engineering.

Liposomal formulation of chondroitin sulfate enhances its antioxidant and anti-inflammatory potential in L929 fibroblast cell line

Liposomes have the capacity to be used as efficient, biodegradable and nontoxic carriers of bioactive molecules and are able to better control their delivery at the site of interest. The objective of this study was to obtain and characterize an appropriate liposomal formulation of the bioactive molecule chondroitin sulfate (CS) for its use in the local treatment of inflammatory and degenerative disorders, specifically osteoarthritis (OA). Empty liposomes (L) and CS-entrapping liposomes (L-CS) were prepared by thin film hydration method followed by sonication and extrusion. They were characterized in terms of size, polydispersity index and ζ-potential by dynamic light scattering (DLS) and morphology by transmission electron microscopy. The effect of L-CS formulation on viability and morphology of mouse fibroblast cells and its biologic activity in hydrogen peroxide-stimulated cells were compared to those of L, non-encapsulated CS and a mixture of L and CS (L + CS). Our results demonstrated a high biocompatibility of L-CS and a more efficient cell protection against oxidative damage using L-CS treatment than CS or L + CS treatment. Also, L-CS exhibited a higher anti-inflammatory activity than CS in stimulated cells by reducing the level of IL-8 and TNF-α proinflammatory cytokines. The overall results suggest that the delivery of CS in liposomal formulation could improve its therapeutic potential in intra-articular treatment of OA.

Histological assessment of intra-articular versus intra-peritoneal betamethasone L.A on tempromandibular joint arthritis in rat

BACKGROUND

Pain and dysfunction of the tempromandibular joint (TMJ) are major clinical problems, especially, in arthritis. The aim of this study was to compare the effect of intra-articular (IA) versus intra-peritoneal (IP) injection of betamethasone long acting on TMJ arthritis in rat.

MATERIALS AND METHODS

In this experimental study, an inflammation in the left TMJ of 29 rats was induced by injection of complete Freund's adjuvant. After 1 week, rats were divided into 5 groups: Group A: Rats of this group were not treated (n = 5); groups B, C: Rats were injected with a single dose of ½ mg/kg betamethasone L.A IA (n = 6); groups D, E: Rats received a single dose of ½ mg/kg betamethasone L.A IP (n = 6). Rats in groups B and D after 1 week, and in groups C, E and A, at 4 weeks after drug injection were sacrificed. Severity of inflammation was scored from 1 to 11 according to synovial hyperplasia, vascularity, fibrin deposits, and synovial adhesion. Results were analyzed by using Kruskal-Wallis and Mann-Whitney (P < 0/05 was considered significant).

RESULTS

Significant differences were existed between groups B, D (P = 0/004) and groups C, E (P = 0/002). The least severity of Inflammation and also evidence of resorbtion in condylar head was seen in group C.

CONCLUSION

The best therapeutic response was seen with IA injection of betamethasone L.A in comparison with IP injection.

Intra-articular controlled release of anti-inflammatory siRNA with biodegradable polymer microparticles ameliorates temporomandibular joint inflammation

We investigated the in vivo therapeutic efficacy of an intra-articular controlled release system consisting of biodegradable poly(dl-lactic-co-glycolic acid) (PLGA) microparticles (MPs) encapsulating anti-inflammatory small interfering RNA (siRNA), together with branched poly(ethylenimine) (PEI) as a transfecting agent, in a rat model of painful temporomandibular joint (TMJ) inflammation. The in vivo effects of PLGA MP dose and siRNA-PEI polyplex delivery were examined via non-invasive meal pattern analysis and by quantifying the protein level of the siRNA target as well as of several downstream inflammatory cytokines. Controlled release of siRNA-PEI from PLGA MPs significantly reduced inflammation-induced changes in meal patterns compared to untreated rats with inflamed TMJs. These changes correlated to decreases in tissue-level protein expression of the siRNA target to 20-50% of the amount present in the corresponding control groups. Similar reductions were also observed in the expression of downstream inflammatory cytokines, e.g. interleukin-6, whose tissue levels in the siRNA-PEI PLGA MP groups were 50% of the values for the corresponding controls. This intra-articular sustained release system has significant implications for the treatment of severe TMJ pain, and also has the potential to be readily adapted and applied to mitigate painful, chronic inflammation in a variety of conditions.

Micro- and Nano-Carrier Mediated Intra-Articular Drug Delivery Systems for the Treatment of Osteoarthritis

The objective of this paper is to provide readers with current developments of intra-articular drug delivery systems. In recent years, although the search for a clinically successful ideal carrier is ongoing, sustained-release systems, such as polymeric micro- and nanoparticles, liposomes, and hydrogels, are being extensively studied for intra-articular drug delivery purposes. The advantages associated with long-acting preparations include a longer effect of the drug in the action site and a reduced risk of infection due to numerous injections consequently. This paper discusses the recent developments in the field of intra-articular sustained-release delivery systems for the treatment of osteoarthritis.

Controlled release of anti-inflammatory siRNA from biodegradable polymeric microparticles intended for intra-articular delivery to the temporomandibular joint

PURPOSE

As the next step in the development of an intra-articular controlled release system to treat painful temporomandibular joint (TMJ) inflammation, we developed several biodegradable poly(DL-lactic-co-glycolic acid) (PLGA)-based microparticle (MP) formulations encapsulating a model anti-inflammatory small interfering RNA (siRNA) together with branched poly(ethylenimine) (PEI) as a transfecting agent. The effect of siRNA loading and N:P ratio on the release kinetics of siRNA-PEI polyplexes was determined, and the size and N:P ratio of the polyplexes released over time was characterized.

METHODS

Polyplex-loaded PLGA MPs were prepared using an established double emulsion technique. Increasing the pH of the release samples enabled siRNA-PEI dissociation and subsequent measurement of the release of each component over 28 days. Polyplex diameter was measured for all release samples and compared to freshly prepared siRNA-PEI under simulated physiologic conditions.

RESULTS

Systematic variation of siRNA loading and N:P ratio resulted in distinct siRNA and PEI release profiles. Polyplex diameter remained constant despite large variations in the relative amounts of siRNA and PEI. Excess PEI was sequestered through complexation with 500-1,000 nm diameter PLGA MP-derived particles, including small MPs and PLGA degradation products.

CONCLUSIONS

These PLGA MP formulations show exciting potential as the first intra-articular TMJ controlled release system.

Intra-articular microparticles for drug delivery to the TMJ

This study describes the in vivo biocompatibility of intra-articular poly(DL-lactic-co-glycolic acid) (PLGA) microparticle (MP) formulations in the rat temporomandibular joint (TMJ). To our knowledge, this is the first intra-articular microparticle-based drug delivery system for the TMJ. The impact of PLGA MP concentration on rat TMJ function was quantified via computerized meal pattern analysis; in this non-invasive technique, previously validated markers of TMJ pain or nociception (specifically, meal duration and food intake) were recorded by computer-monitored pellet feeders. Bilateral intra-articular injection of 15, 30, or 50 mg/mL PLGA MPs had no impact on meal duration or food intake over 6 days, compared with controls that did not receive injections. Histological analysis showed that the MPs were retained within the synovial lining. These findings indicate that the PLGA MPs described herein are biocompatible and suitable for intra-articular delivery to the rat TMJ, a finding that has significant implications for the improvement of TMJ therapeutics.