DPSCs Attenuate Experimental Progressive TMJ Arthritis by Inhibiting the STAT1 Pathway

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.

Application of dental pulp stem cells for bone regeneration

Bone defects resulting from severe trauma, tumors, inflammation, and other factors are increasingly prevalent. Stem cell-based therapies have emerged as a promising alternative. Dental pulp stem cells (DPSCs), sourced from dental pulp, have garnered significant attention owing to their ready accessibility and minimal collection-associated risks. Ongoing investigations into DPSCs have revealed their potential to undergo osteogenic differentiation and their capacity to secrete a diverse array of ontogenetic components, such as extracellular vesicles and cell lysates. This comprehensive review article aims to provide an in-depth analysis of DPSCs and their secretory components, emphasizing extraction techniques and utilization while elucidating the intricate mechanisms governing bone regeneration. Furthermore, we explore the merits and demerits of cell and cell-free therapeutic modalities, as well as discuss the potential prospects, opportunities, and inherent challenges associated with DPSC therapy and cell-free therapies in the context of bone regeneration.

Mesenchymal Stromal Cells Derived from Dental Tissues: Immunomodulatory Properties and Clinical Potential

Mesenchymal stem/stromal cells (MSCs) are multipotent cells located in different areas of the human body. The oral cavity is considered a potential source of MSCs because they have been identified in several dental tissues (D-MSCs). Clinical trials in which cells from these sources were used have shown that they are effective and safe as treatments for tissue regeneration. Importantly, immunoregulatory capacity has been observed in all of these populations; however, this function may vary among the different types of MSCs. Since this property is of clinical interest for cell therapy protocols, it is relevant to analyze the differences in immunoregulatory capacity, as well as the mechanisms used by each type of MSC. Interestingly, D-MSCs are the most suitable source for regenerating mineralized tissues in the oral region. Furthermore, the clinical potential of D-MSCs is supported due to their adequate capacity for proliferation, migration, and differentiation. There is also evidence for their potential application in protocols against autoimmune diseases and other inflammatory conditions due to their immunosuppressive capacity. Therefore, in this review, the immunoregulatory mechanisms identified at the preclinical level in combination with the different types of MSCs found in dental tissues are described, in addition to a description of the clinical trials in which MSCs from these sources have been applied.

Delivery of dental pulp stem cells by an injectable ROS-responsive hydrogel promotes temporomandibular joint cartilage repair via enhancing anti-apoptosis and regulating microenvironment

Temporomandibular joint (TMJ) cartilage repair poses a considerable clinical challenge, and tissue engineering has emerged as a promising solution. In this study, we developed an injectable reactive oxygen species (ROS)-responsive multifunctional hydrogel (RDGel) to encapsulate dental pulp stem cells (DPSCs/RDGel in short) for the targeted repair of condylar cartilage defect. The DPSCs/RDGel composite exhibited a synergistic effect in the elimination of TMJ OA (osteoarthritis) inflammation via the interaction between the hydrogel component and the DPSCs. We first demonstrated the applicability and biocompatibility of RDGel. RDGel encapsulation could enhance the anti-apoptotic ability of DPSCs by inhibiting P38/P53 mitochondrial apoptotic signal in vitro. We also proved that the utilization of DPSCs/RDGel composite effectively enhanced the expression of TMJOA cartilage matrix and promoted subchondral bone structure in vivo. Subsequently, we observed the synergistic improvement of DPSCs/RDGel composite on the oxidative stress microenvironment of TMJOA and its regulation and promotion of M2 polarization, thereby confirmed that M2 macrophages further promoted the condylar cartilage repair of DPSCs. This is the first time application of DPSCs/RDGel composite for the targeted repair of TMJOA condylar cartilage defects, presenting a novel and promising avenue for cell-based therapy.

Anti-inflammatory effect of dental pulp stem cells

Dental pulp stem cells (DPSCs) have received a lot of attention as a regenerative medicine tool with strong immunomodulatory capabilities. The excessive inflammatory response involves a variety of immune cells, cytokines, and has a considerable impact on tissue regeneration. The use of DPSCs for controlling inflammation for the purpose of treating inflammation-related diseases and autoimmune disorders such as supraspinal nerve inflammation, inflammation of the pulmonary airways, systemic lupus erythematosus, and diabetes mellitus is likely to be safer and more regenerative than traditional medicines. The mechanism of the anti-inflammatory and immunomodulatory effects of DPSCs is relatively complex, and it may be that they themselves or some of the substances they secrete regulate a variety of immune cells through inflammatory immune-related signaling pathways. Most of the current studies are still at the laboratory cellular level and animal model level, and it is believed that through the efforts of more researchers, DPSCs/SHED are expected to be transformed into excellent drugs for the clinical treatment of related diseases.

Revolutionizing orofacial pain management: the promising potential of stem cell therapy

Orofacial pain remains a significant health issue in the United States. Pain originating from the orofacial region can be composed of a complex array of unique target tissue that contributes to the varying success of pain management. Long-term use of analgesic drugs includes adverse effects such as physical dependence, gastrointestinal bleeding, and incomplete efficacy. The use of mesenchymal stem cells for their pain relieving properties has garnered increased attention. In addition to the preclinical and clinical results showing stem cell analgesia in non-orofacial pain, studies have also shown promising results for orofacial pain treatment. Here we discuss the outcomes of mesenchymal stem cell treatment for pain and compare the properties of stem cells from different tissues of origin. We also discuss the mechanism underlying these analgesic/anti-nociceptive properties, including the role of immune cells and the endogenous opioid system. Lastly, advancements in the methods and procedures to treat patients experiencing orofacial pain with mesenchymal stem cells are also discussed.

Managing Temporomandibular Joint Osteoarthritis by Dental Stem Cell Secretome

The potential therapeutic role of the Dental Pulp Stem Cells Secretome (SECR) in a rat model of experimentally induced Temporomandibular Joint (TMJ) Osteoarthritis (OA) was evaluated. Proteomic profiling of the human SECR under specific oxygen tension (5% O2) and stimulation with Tumor Necrosis Factor-alpha (TNF-α) was performed. SECR and respective cell lysates (CL) samples were collected and subjected to SDS-PAGE, followed by LC-MS/MS analysis. The identified proteins were analyzed with Bioinformatic tools. The anti-inflammatory properties of SECR were assessed via an in vitro murine macrophages model, and were further validated in vivo, in a rat model of chemically-induced TMJ-OA by weekly recording of the head withdrawal threshold, the food intake, and the weight change, and radiographically and histologically at 4- and 8-weeks post-treatment. SECR analysis revealed the presence of 50 proteins that were enriched and/or statistically significantly upregulated compared to CL, while many of those proteins were involved in pathways related to "extracellular matrix organization" and "immune system". SECR application in vitro led to a significant downregulation on the expression of pro-inflammatory genes (MMP-13, MMP-9, MMP-3 and MCP-1), while maintaining an increased expression of IL-10 and IL-6. SECR application in vivo had a significant positive effect on all the clinical parameters, resulting in improved food intake, weight, and pain suppression. Radiographically, SECR application had a significant positive effect on trabecular bone thickness and bone density compared to the saline-treated group. Histological analysis indicated that SECR administration reduced inflammation, enhanced ECM and subchondral bone repair and regeneration, thus alleviating TMJ degeneration.

Targeted delivery of miR125a-5p and human Factor VIII attenuates molecular mediators of hemophilic arthropathy

Hemophilic arthropathy (HA) due to repeated bleeding into the joint cavity is a major cause of morbidity in patients with hemophilia. The molecular mechanisms contributing to this condition are not well characterized. MicroRNAs (miRs) are known to modulate the phenotype of multiple joint diseases such as osteoarthritis (OA) and rheumatoid arthritis (RA). Since miR125a is known to modulate disease progression in OA and RA, we performed a targeted screen of miR125a-5p and its target genes in a murine model of chronic HA. A digital PCR analysis demonstrated significant downregulation of miR125a-5p (2-fold vs control joint). Further molecular evaluation revealed elevated expression of the immunological markers STAT1 (7.6-fold vs control joint) and TRAF6 (10.6 fold vs control joint), which are direct targets of miR125a-5p. We then studied the impact of targeted overexpression of miR125a-5p using an Adeno-associated virus (AAV) vector in modulating the molecular mediators of HA. AAV5-miR125a vectors were administered intra-articularly either alone or in combination with a low dose of AAV8-based human factor 8 (F8) gene in a murine model of HA. We observed significantly increased expression of miR125a-5p in AAV5-miR125a administered mice (~12 fold vs injured joint) or in combination with AAV8-F8 vectors (~44 fold vs injured joint). The activity assay revealed ~17 %-20 % FVIII levels in mice that received low dose liver-directed F8 gene therapy. Further immunohistochemical analysis, demonstrated a decrease in inflammatory markers (STAT1 and TRAF6) and cartilage-degrading matrix metalloproteinases (MMPs) 3, 9, 13 in the joints of treated animals. These data highlight the crucial role of miR125a-5p in the development of HA.

Targeting transcription factors for therapeutic benefit in rheumatoid arthritis

Rheumatoid arthritis (RA) is a destructive inflammatory autoimmune disease that causes pain and disability. Many of the currently available drugs for treating RA patients are aimed at halting the progression of the disease and alleviating inflammation. Further, some of these treatment options have drawbacks, including disease recurrence and adverse effects due to long-term use. These inefficiencies have created a need for a different approach to treating RA. Recently, the focus has shifted to direct targeting of transcription factors (TFs), as they play a vital role in the pathogenesis of RA, activating key cytokines, chemokines, adhesion molecules, and enzymes. In light of this, synthetic drugs and natural compounds are being explored to target key TFs or their signaling pathways in RA. This review discusses the role of four key TFs in inflammation, namely NF-κB, STATs, AP-1 and IRFs, and their potential for being targeted to treat RA.

Comparison of Biological Properties and Clinical Application of Mesenchymal Stem Cells from the Mesoderm and Ectoderm

Since the discovery of mesenchymal stem cells (MSCs) in the 1970s, they have been widely used in the treatment of a variety of diseases because of their wide sources, strong differentiation potential, rapid expansion in vitro, low immunogenicity, and so on. At present, most of the related research is on mesoderm-derived MSCs (M-MSCs) such as bone marrow MSCs and adipose-derived MSCs. As a type of MSC, ectoderm-derived MSCs (E-MSCs) have a stronger potential for self-renewal, multidirectional differentiation, and immunomodulation and have more advantages than M-MSCs in some specific conditions. This paper analyzes the relevant research development of E-MSCs compared with that of M-MSCs; summarizes the extraction, discrimination and culture, biological characteristics, and clinical application of E-MSCs; and discusses the application prospects of E-MSCs. This summary provides a theoretical basis for the better application of MSCs from both ectoderm and mesoderm in the future.

Immunomodulatory Mechanism and Potential Application of Dental Pulp-Derived Stem Cells in Immune-Mediated Diseases

Dental pulp stem cells (DPSCs) are mesenchymal stem cells (MSCs) derived from dental pulp tissue, which have high self-renewal ability and multi-lineage differentiation potential. With the discovery of the immunoregulatory ability of stem cells, DPSCs have attracted much attention because they have similar or even better immunomodulatory effects than MSCs from other sources. DPSCs and their exosomes can exert an immunomodulatory ability by acting on target immune cells to regulate cytokines. DPSCs can also migrate to the lesion site to differentiate into target cells to repair the injured tissue, and play an important role in tissue regeneration. The aim of this review is to summarize the molecular mechanism and target cells of the immunomodulatory effects of DPSCs, and the latest advances in preclinical research in the treatment of various immune-mediated diseases, providing new reflections for their clinical application. DPSCs may be a promising source of stem cells for the treatment of immune-mediated diseases.

Dental Pulp Stem Cell-Derived Exosomes Alleviate Mice Knee Osteoarthritis by Inhibiting TRPV4-Mediated Osteoclast Activation

Osteoarthritis (OA) is a degenerative disease that causes chronic pain and joint swelling and even disables millions of patients. However, current non-surgical treatment for OA can only relieve pain without obvious cartilage and subchondral bone repair. Mesenchymal stem cell (MSC)-secreted exosomes have promising therapeutic effects on knee OA, but the efficacy of MSC-exosome therapy is not well determined, and the mechanisms involved are still unclear. In this study, we isolated dental pulp stem cell (DPSC)-derived exosomes by ultracentrifugation and determined the therapeutic effects of a single intra-articular injection of DPSC-derived exosomes in a mice knee OA model. The results showed that the DPSC-derived exosomes effectively improved abnormal subchondral bone remodeling, inhibited the occurrence of bone sclerosis and osteophytes, and alleviated cartilage degradation and synovial inflammation in vivo. Moreover, transient receptor potential vanilloid 4 (TRPV4) was activated during the progression of OA. Enhanced TRPV4 activation facilitated osteoclast differentiation, and TRPV4 inhibition blocked this process in vitro. DPSC-derived exosomes repressed osteoclast activation in vivo by inhibiting TRPV4 activation. Our findings demonstrated that a topical, single injection of DPSC-derived exosomes is a potential strategy for knee OA treatment, and that the exosomes regulated osteoclast activation by TRPV4 inhibition, which may act as a promising target for clinical OA treatment.

Global Trends and Future Research Directions for Temporomandibular Disorders and Stem Cells

Temporomandibular disorder (TMD) is an umbrella term used to describe various conditions that affect temporomandibular joints, masticatory muscles, and associated structures. Although the most conservative and least invasive treatment is preferable, more invasive therapies should be employed to refractory patients. Tissue engineering has been presented as a promising therapy. Our study aimed to investigate trends and point out future research directions on TMD and stem cells. A comprehensive search was carried out in the Web of Science Core Collection (WoS-CC) in October 2022. The bibliometric parameters were analyzed through descriptive statistics and graphical mapping. Thus, 125 papers, published between 1992 and 2022 in 65 journals, were selected. The period with the highest number of publications and citations was between 2012 and 2022. China has produced the most publications on the subject. The most frequently used keywords were "cartilage", "temporomandibular joint", "mesenchymal stem cells", and "osteoarthritis". Moreover, the primary type of study was in vivo. It was noticed that using stem cells to improve temporomandibular joint repair and regeneration is a significant subject of investigation. Nonetheless, a greater understanding of the biological interaction and the benefits of using these cells in patients with TMD is required.

Recent Advances in Animal Models, Diagnosis, and Treatment of Temporomandibular Joint Osteoarthritis

Temporomandibular joint osteoarthritis (TMJOA) is a gradual degenerative jaw joint condition. Until recent years, TMJOA is still relatively unrecognized and ineffective to be treated. Appropriate animal models with reliable detection methods can help researchers understand the pathophysiology of TMJOA and find therapeutic options. In this study, we summarized common animal models of TMJOA created by chemical, surgical, mechanical, and genetical approaches. The relevant pathological symptoms and induction mechanisms were outlined. In addition, different pathological indicators, furthermore, emerging therapeutic regimens, such as intra-articular drug delivery and tissue engineering-based approaches to treat TMJOA based on these animal models, were summarized and updated. Understanding the physiology and pathogenesis of the TMJOA, together using various ways to diagnose the TMJOA, were elaborated, including imaging techniques, molecular techniques for detecting inflammatory cytokines, histochemical staining, and histomorphometry measures. A more reliable diagnosis will enable the development of new prevention and more effective treatment strategies and thereby improve the quality of life of TMJOA patients. Impact statement Temporomandibular joint osteoarthritis (TMJOA) affects 8 to 16 percent of the population worldwide. However, TMJOA is still relatively unrecognized and ineffective to be treated in the clinic. Appropriate animal models with reliable diagnostic methods can help researchers understand the pathophysiology of TMJOA and find therapeutic options. We herein summarized common animal models of TMJOA and various ways to diagnose the TMJOA. More importantly, emerging therapeutic regimens to treat TMJOA based on these animal models were summarized. With the aid of strategies listed, more effective treatment strategies will be developed and thereby improve the life quality of TMJOA patients.

Extracellular vesicles in osteoarthritis of peripheral joint and temporomandibular joint

Osteoarthritis (OA) is a disabling disease with significant morbidity worldwide. OA attacks the large synovial joint, including the peripheral joints and temporomandibular joint (TMJ). As a representative of peripheral joint OA, knee OA shares similar symptoms with TMJ OA. However, these two joints also display differences based on their distinct development, anatomy, and physiology. Extracellular vesicles (EVs) are phospholipid bilayer nanoparticles, including exosomes, microvesicles, and apoptotic bodies. EVs contain proteins, lipids, DNA, micro-RNA, and mRNA that regulate tissue homeostasis and cell-to-cell communication, which play an essential role in the progression and treatment of OA. They are likely to partake in mechanical response, extracellular matrix degradation, and inflammatory regulation during OA. More evidence has shown that synovial fluid and synovium-derived EVs may serve as OA biomarkers. More importantly, mesenchymal stem cell-derived EV shows a therapeutic effect on OA. However, the different function of EVs in these two joints is largely unknown based on their distinct biological characteristic. Here, we reviewed the effects of EVs in OA progression and compared the difference between the knee joint and TMJ, and summarized their potential therapeutic role in the treatment of OA.

Protective Actions in Apical Periodontitis: The Regenerative Bioactivities Led by Mesenchymal Stem Cells

Resulting from bacterial infection, apical periodontitis (AP) is a common inflammatory disease of the periapical region of the tooth. The regeneration of the destroyed periapical alveolar bone and the surrounding periodontium tissues has long been a difficult task in clinical practice. These lesions are closely related to pathogen invasion and an overreactive immune response. It is worth noting that the protective healing process occurs simultaneously, in which mesenchymal stem cells (MSCs) have a crucial function in mediating the immune system and promoting regeneration. Here, we review the recent studies related to AP, with a focus on the regulatory network of MSCs. We also discuss the potential therapeutic approaches of MSCs in inflammatory diseases to provide a basis for promoting tissue regeneration and modulating inflammation in AP. A deeper understanding of the protective action of MSCs and the regulatory networks will help to delineate the underlying mechanisms of AP and pave the way for stem-cell-based regenerative medicine in the future.

Strategies to Convert Cells into Hyaline Cartilage: Magic Spells for Adult Stem Cells

Damaged hyaline cartilage gradually decreases joint function and growing pain significantly reduces the quality of a patient’s life. The clinically approved procedure of autologous chondrocyte implantation (ACI) for treating knee cartilage lesions has several limits, including the absence of healthy articular cartilage tissues for cell isolation and difficulties related to the chondrocyte expansion in vitro. Today, various ACI modifications are being developed using autologous chondrocytes from alternative sources, such as the auricles, nose and ribs. Adult stem cells from different tissues are also of great interest due to their less traumatic material extraction and their innate abilities of active proliferation and chondrogenic differentiation. According to the different adult stem cell types and their origin, various strategies have been proposed for stem cell expansion and initiation of their chondrogenic differentiation. The current review presents the diversity in developing applied techniques based on autologous adult stem cell differentiation to hyaline cartilage tissue and targeted to articular cartilage damage therapy.

ALPK1 Aggravates TMJOA Cartilage Degradation via NF-κB and ERK1/2 Signaling

Temporomandibular joint osteoarthritis (TMJOA) is a common degenerative joint disease without effective intervention strategies. Previous research implied that alpha-kinase 1 (ALPK1) is involved in the inflammatory responses of gout, a chronic arthritis. Herein, we found the main distribution of ALPK1 in a proliferative layer of condylar cartilage and marrow cavity of subchondral bone, as well as a lining layer of synovial tissues in human temporomandibular joint. Moreover, the expression of ALPK1 was augmented in degraded condylar cartilage of monosodium iodoacetate (MIA)-induced TMJOA mice. After MIA induction, ALPK1 knockout mice exhibited attenuated damage of cartilage and subchondral bone, as well as synovitis, as compared with wide type mice. In contrast, intra-articular administration of recombinant human ALPK1 aggravated the pathology of MIA-induced TMJOA. Furthermore, ex vivo study demonstrated that ALPK1 exacerbated chondrocyte catabolism by upregulating matrix metalloproteinase 13 and cyclooxygenase 2 by activating NF-κB (nuclear factor-kappaB) signaling and suppressed anabolism by downregulating aggrecan by inhibiting ERK1/2 (extracellular signal-regulated kinase 1/2) in articular chondrocytes. Taken together, ALPK1 exacerbates the degradation of condylar cartilage during TMJOA through the NF-κB and ERK1/2 signaling pathway. This study provides a new insight regarding the role of ALPK1 during TMJOA pathology.

Stem cells to reverse aging

ABSTRACT

As human life expectancy continues to increase and the birth rate continues to decline, the phenomenon of aging is becoming more prominent worldwide. Therefore, addressing the problems associated with global aging has become a current research focus. The main manifestations of human aging are structural degeneration and functional decline of aging tissues and organs, quality of life decline, decreased ability to resist diseases, and high incidence rates of a variety of senile degenerative diseases. Thus far, no ideal treatments have been found. Stem cell (SC) therapies have broad application prospects in the field of regenerative medicine due to the inherent biological characteristics of SCs, such as their plasticity, self-renewal, and multidirectional differentiation potential. Thus, SCs could delay or even reverse aging. This manuscript reviews the causes of human aging, the biological characteristics of SCs, and research progress on age reversal.

Omega 3 polyunsaturated fatty acids: Potential anti-inflammatory effect in a model of ovariectomy and temporomandibular joint arthritis induction in rats

OBJECTIVE

To evaluate the effect of polyunsaturated fatty acid-type omega 3 (ω3) on the temporomandibular joint (TMJ) of ovariectomized rats (OVX) with rheumatoid arthritis (RA).

DESIGN

Rheumatoid arthritis was induced using complete Freund's adjuvant and type II bovine collagen injected at the base of the tail. Twenty-four adult female rats were treated by gavage and divided into four groups: G1: Sham, treated with 0.9% NaCl; G2: OVX, treated with 0.9% NaCl; G3: OVX+RA treated with 0.9% NaCl; G4: OVX+RA+ω3 treated with omega 3 (300 mg/kg/day). The induction of rheumatoid arthritis in groups G3 and G4 was performed 21 days after OVX, treatments were started 15 days after the induction of rheumatoid arthritis, maintained for 7 days, and killed. Bilateral TMJs were removed and assigned to morphometric analysis by micro-computed tomography and immunoassay to assess levels of cytokines IL-1β, IL-6, TNF-α, and IL-10.

RESULTS

Higher levels of inflammatory cytokines were found in the G2 and G3 (P < 0.05) and anti-inflammatory cytokines in the G1 and G4. TMJ analysis by micro-computed tomography showed a higher percentage of bone volume (median - interquartile deviation) in G1 (96.2-1.1) than in the G2 (91.5-2.0, P = 0.0374) and G3 (85.1-5.2, P = 0.0001) but showed no statistically significant differences with the G4 (93.1-1.7, P = 0.79).

CONCLUSIONS

Omega 3 successfully reduced TMJ damage in rats caused by ovariectomy and induced rheumatoid arthritis, and is a promising alternative for bone repair and attenuation of inflammatory processes.

Role of osteoclast differentiation in the occurrence of osteoarthritis of temporomandibular joint

OBJECTIVES

This study aimed to explore the role of osteoclast differentiation in the occurrence of temporomandibular joint osteoarthritis (TMJOA).

METHODS

A mouse TMJOA model was constructed. Micro-CT was used to observe the changes in condylar bone during the development of TMJOA. Hematoxylin-eosin (HE) staining was used to observe the histological structure changes of the condyle of TMJOA mice. Tartrate resistant acid phosphatase (TRAP) staining was used to observe the presence of osteoclasts in TMJOA joint tissue. The synovial fluid of patients with TMJ-OA was collected to determine the effect on osteoclast differentiation.

RESULTS

Micro-CT revealed that the condyle of the TMJOA group had the most obvious damage in the second and third weeks, and the shape of the condyles also changed in a beak-like manner. HE staining showed that the condyle cartilage and subchondral bone structure of TMJOA mice were disordered in the second week. TRAP tissue staining showed that the number of osteoclasts of the TMJOA group obviously increased in the second week. Results of cell experiments showed that the number of osteoclast differentiation significantly increased after stimulation of synovial fluid from TMJOA patients, and the cell volume increased.

CONCLUSIONS

TMJOA animal models and TMJOA patient synovial cell experiments could induce osteoclast differentiation, indicating that osteoclast differentiation plays an important role in TMJOA occurrence.

Research progress on tissue engineering in repairing tempomandibular joint

Temporomandibular joint osteoarthritis (TMJOA) is mainly manifested as perforation of temporomandibular joint disc (TMJD) and destruction of condylar osteochondral complex (COCC). In recent years, tissue engineering technology has become one of the effective strategies in repairing this damage. With the development of scaffold material technology, composite scaffolds have become an important means to optimize the performance of scaffolds with the combined advantages of natural materials and synthetic materials. The gelling method with the minimally invasive concept can greatly solve the problems of surgical trauma and material anastomosis, which is beneficial to the clinical transformation of temporomandibular joint tissue engineering. Extracellular matrix scaffolds technology can solve the problem of scaffold source and maximize the simulation of the extracellular environment, which provides an important means for the transformation of temporo joint tissue engineering to animal level. Due to the limitation of the source and amplification of costal chondrocytes, the use of mesenchymal stem cells from different sources has been widely used for temporomandibular joint tissue engineering. The fibrochondral stem cells isolated from surface layer of articular cartilage may provide one more suitable cell source. Transforming growth factor β superfamily, due to its osteochondrogenesis activity has been widely used in tissue engineering, and platelet-rich derivative as a convenient preparation of compound biological factor, gradually get used in temporomandibular joint tissue engineering. With the deepening of research on extracellular microenvironment and mechanical stimulation, mesenchymal stem cells, exosomes and stress stimulation are increasingly being used to regulate the extracellular microenvironment. In the future, the combination of complex bioactive factors and certain stress stimulation may become a trend in the temporomandibular joint tissue engineering research. In this article, the progress on tissue engineering in repairing COCC and TMJD, especially in scaffold materials, seed cells and bioactive factors, are reviewed, so as to provide information for future research design and clinical intervention.

microRNA-935-modified bone marrow mesenchymal stem cells-derived exosomes enhance osteoblast proliferation and differentiation in osteoporotic rats

AIMS

The involvement of several microRNAs (miRNAs) in osteogenic differentiation has been indicated recently. Also, exosomes, derived from different cells, could shuttle specific miRNAs to other cell systems. Nevertheless, the effect and mechanism of microRNA-935 (miR-935)-containing exosomes in osteoblasts remain basically unclear. The current work was set to inspect the relevance of bone marrow mesenchymal stem cells (BMSCs)-derived exosomes (BMSC-exo) carrying miR-935 to osteoporotic rats.

METHODS

The extracted BMSCs and purchased osteoblasts were cultured, followed by exosome isolation and identification. After cell grouping, osteoblasts were co-cultured with BMSCs. CCK-8, alizarin red staining as well as ALP staining were performed to detect osteoblast proliferation and activity. The binding connection between miR-935 and signal transducer and activator of transcription 1 (STAT1) was measured by dual-luciferase reporter gene assays. The expression profiles of miR-935, STAT1 and osteoblast-related proteins were assessed by RT-qPCR and Western blot. A rat model with osteoporosis was induced, and the BMD, BV/TV, Tb.N, Tb.Th and Tb.Sp values in rat bone tissues were observed by Micro-CT.

RESULTS

BMSC-exo inhibited STAT1 levels by the delivery of miR-935 into osteoblasts, while STAT1 silencing promoted ALP activity in osteoblasts and mineralized nodules. STAT1 was identified as a target gene of miR-935. Moreover, in vivo experiments showed that in ovariectomized rats, silencing of miR-935 significantly reduced BMD, BV/TV, Tb.N, Tb.Th and increased Tb.Sp.

CONCLUSION

BMSC-exo carry miR-935 to promote osteoblast proliferation and differentiation through targeting STAT1.

Recent update on craniofacial tissue engineering

The craniofacial region consists of several different tissue types. These tissues are quite commonly affected by traumatic/pathologic tissue loss which has so far been traditionally treated by grafting procedures. With the complications and drawbacks of grafting procedures, the emerging field of regenerative medicine has proved potential. Tissue engineering advancements and the application in the craniofacial region is quickly gaining momentum although most research is still at early in vitro/in vivo stages. We aim to provide an overview on where research stands now in tissue engineering of craniofacial tissue; namely bone, cartilage muscle, skin, periodontal ligament, and mucosa. Abstracts and full-text English articles discussing techniques used for tissue engineering/regeneration of these tissue types were summarized in this article. The future perspectives and how current technological advancements and different material applications are enhancing tissue engineering procedures are also highlighted. Clinically, patients with craniofacial defects need hybrid reconstruction techniques to overcome the complexity of these defects. Cost-effectiveness and cost-efficiency are also required in such defects. The results of the studies covered in this review confirm the potential of craniofacial tissue engineering strategies as an alternative to avoid the problems of currently employed techniques. Furthermore, 3D printing advances may allow for fabrication of patient-specific tissue engineered constructs which should improve post-operative esthetic results of reconstruction. There are on the other hand still many challenges that clearly require further research in order to catch up with engineering of other parts of the human body.

Serine Metabolism Controls Dental Pulp Stem Cell Aging by Regulating the DNA Methylation of p16

To investigate the characteristics and molecular events of dental pulp stem cells (DPSCs) for tissue regeneration with aging, we isolated and analyzed the stem cells from human exfoliated deciduous teeth (SHED) and permanent teeth of young (Y-DPSCs) and old (A-DPSCs) adults. Results showed that the stemness and osteogenic differentiation capacity of DPSCs decreased with aging. The RNA sequencing results showed that glycine, serine, and threonine metabolism was one of the most enriched gene clusters among SHED, Y-DPSCs, and A-DPSCs, according to analysis based on the Kyoto Encyclopedia of Genes and Genomes. The expression of serine metabolism-related enzymes phosphoserine aminotransferase 1 (PSAT1) and phosphoglycerate (PHGDH) decreased in A-DPSCs and provided less methyl donor S-adenosylmethionine (SAM) for DNA methylation, leading to the hypomethylation of the senescence marker p16 (CDNK2A). Furthermore, the proliferation and differentiation capacity of Y-DPSCs and SHED decreased after PHGDH siRNA treatment, which reduced the level of SAM. Convincingly, the ratios of PSAT1-, PHGDH-, or proliferating cell nuclear antigen-positive cells in the dental pulp of old permanent teeth were less than those in the dental pulp of deciduous teeth and young permanent teeth. In summary, the stemness and differentiation capacity of DPSCs decreased with aging. The decreased serine metabolism in A-DPSCs upregulated the expression of p16 via attenuating its DNA methylation, resulting in DPSC aging. Our finding indicated that serine metabolism and 1 carbon unit participated in stem cell aging, which provided new direction for stem cell aging study and intervention.

Dental Tissue-Derived Human Mesenchymal Stem Cells and Their Potential in Therapeutic Application

Human mesenchymal stem cells (hMSCs) are multipotent cells, which exhibit plastic adherence, express specific cell surface marker spectrum, and have multi-lineage differentiation potential. These cells can be obtained from multiple tissues. Dental tissue-derived hMSCs (dental MSCs) possess the ability to give rise to mesodermal lineage (osteocytes, adipocytes, and chondrocytes), ectodermal lineage (neurocytes), and endodermal lineages (hepatocytes). Dental MSCs were first isolated from dental pulp of the extracted third molar and till now they have been purified from various dental tissues, including pulp tissue of permanent teeth and exfoliated deciduous teeth, apical papilla, periodontal ligament, gingiva, dental follicle, tooth germ, and alveolar bone. Dental MSCs are not only easily accessible but are also expandable in vitro with relative genomic stability for a long period of time. Moreover, dental MSCs have exhibited immunomodulatory properties by secreting cytokines. Easy accessibility, multi-lineage differentiation potential, and immunomodulatory effects make dental MSCs distinct from the other hMSCs and an effective tool in stem cell-based therapy. Several preclinical studies and clinical trials have been performed using dental MSCs in the treatment of multiple ailments, ranging from dental diseases to nondental diseases. The present review has summarized dental MSC sources, multi-lineage differentiation capacities, immunomodulatory features, its potential in the treatment of diseases, and its application in both preclinical studies and clinical trials. The regenerative therapeutic strategies in dental medicine have also been discussed.

Anti-Inflammatory Effect of Adipose-Derived Stromal Vascular Fraction on Osteoarthritic Temporomandibular Joint Synoviocytes

BACKGROUND

Osteoarthritis (OA) in the temporomandibular joint (TMJ) in the TMJ (TMJ-OA) is difficult to treat, and new alternative treatments are needed. Recently, adipose-derived stem cells (ASCs) have been introduced as a promising cell source because of their anti-inflammatory effects. However, the cost and availability of these cells limited broader applications of stem cell therapy. Thus, Thus, stromal vascular fraction (SVF) containing sufficient amount of ASCs at low cost can be an alternative. In this study, we aimed to demonstrate the use of uncultured, optimally isolated SVF for the treatment of TMJ-OA.

METHODS

First, we optimized the method of isolation to harvest high-quality SVFs with a large yield of ASCs. Then, we analyzed the quantity of ASCs in the SVF and performed characterization of stem cell homology. Subsequently, to evaluate the anti-inflammatory effect of high-quality SVF, an in vitro study was performed to assess the expression patterns of inflammatory cytokines including prostaglandin E₂ (PGE₂), IL-6, and CXCL8/IL-8, COX2, TNF, IFN, CCL2/MCP-1 and CCL5/RANTES in co-culture with synoviocytes derived from the synovial fluid in the TMJ-OA patients.

RESULTS

The SVF containing approximately 32% ASCs was isolated via the our optimized isolation method. The SVF significantly down-regulated certain inflammatory cytokines such as PGE2, CXCL8/IL-8 in TMJ-OA tissue-derived synoviocytes.

CONCLUSION

Although further study is needed, our study suggests that transplantation of adipose tissue-derived SVF cells might be a feasible and a novel therapeutic option for TMJ-OA in the future.