Rafael Correia Cavalcante

The temporomandibular joint (TMJ) relies on specialized progenitor cells for tissue maintenance and repair. We characterized TMJ-derived progenitor cells in mice and investigated the role of Evc2-mediated Hedgehog signaling. Progenitor cells from the anterior TMJ exhibited greater colony-forming capacity and an elongated morphology, while posterior cells were cuboidal, highlighting regional heterogeneity. TMJ-derived progenitors demonstrated multipotency, differentiating into osteogenic and chondrogenic lineages. Gli1-expressing, slow-cycling cells localized to the ligament attachment regions, initially accumulating there and not overlapping with specialized cells (Col1⁺ cells). Conditional Evc2 disruption in Gli1-expressing cells paradoxically augmented expression of Gli1 and mechanosensors (Yap, Wwtr1, Piezo1), and produced more confluent, rapidly expanding colonies. We hypothesize that these colonies are primarily composed of transit amplifying cells (TACs), which may proliferate robustly but face challenges in terminal differentiation. These results reveal critical roles for EVC2 and regional progenitor cell diversity in TMJ regenerative biology and suggest that targeting cell signaling and mechanical factors may inform novel strategies for TMJ disorder therapies.

Maintaining the native morphology and characteristic staining patterns of dissected tissues is critical for histological analysis. Reliable preservation enables accurate assessment of structural integrity and cellular components, which is fundamental to identifying viable avenues for tissue regeneration and improving clinical outcomes. Acknowledging the constraints of conventional paraffin embedding, we propose an alternative method employing gelatin as an embedding medium. Gelatin is a natural, water-soluble protein derived from collagen, known for its biocompatibility. As a hydrogel, it provides a supportive matrix that closely mimics the natural extracellular matrix of soft tissues facilitating excellent preservation of structural and molecular features during the histological process. Here we demonstrate that this strategy offers superior support for fragile tissues, including fibrocartilage and hyaline cartilage across various anatomical sites, such as the temporomandibular joint, the knee joint, the long bone growth plate, and the intervertebral disc. To assess the maintenance of tissue morphology and matrix composition, histological sections were subjected to various staining techniques, including hematoxylin and eosin, Masson’s trichome, safranin O, immunofluorescence, and von Kossa staining. Gelatin embedding resulted in superior maintenance of fibrocartilage architecture, as evidenced by histological evaluation. In addition, quantification of safranin O staining showed significantly greater glycosaminoglycan content in gelatin-embedded samples.

The temporomandibular joint (TMJ), essential for jaw movements, is susceptible to osteoarthritis, impacting a significant portion of the population. This study introduces an innovative genetic mouse model to explore TMJ development, maintenance, and interactions with the mechanical environment. We exploited Evc2/Limbin conditional KO (Evc2 cKO) mice, specifically targeting neural crest cell-derived tissues (Wnt1Cre), to observe TMJ development. Disruption of Evc2 in neural crest cells contributed to morphological changes in the TMJ growth plate cartilage layers, predisposing the joint components to defects. Condyle defective regions presented a unique environment composed of cartilage, bone, stem cells, and an augmented polymorphic layer. Our findings further revealed that the Evc2 cKO mice presented TMJ components degeneration clinically like those observed in human TMJ-osteoarthritis (OA). Mandible condyle gene expression analysis showed augmented expression of general inflammatory and OA markers. Supplying the mice with regular chow worsens the phenotype, but soft chow fed partially rescued both condyle morphology and intra-articular space. The data suggest that changes in the loading environment critically affect the integrity and functionality of the TMJ, with direct implications for its preservation and disease management.

Bone, cartilage, and their composites in various joints are the most important components that form the skeletal structure and enable motion and movements of the body. Their disease and/or loss are most debilitating and afflict millions of Americans, reducing productivity and deteriorating quality of life. Due to limited treatments, scientists, engineers, and clinical doctors are investigating new tissue engineering solutions. In tissue engineering approaches, scaffolds are artificially designed temporary matrices that accommodate stem/progenitor cells and provide both physical and biological signals to guide cell differentiation and 3D tissue regeneration but eventually degrade and leave behind regenerated functional tissues or organs. Therefore, scaffolds often substantially benefit from mimicking certain features of the natural extracellular matrix (ECM) and designing certain engineered features to facilitate cell repopulation, mass transportation, and mechanical and biological cues for cells to regenerate tissue. This review article focuses on the design, synthesis, fabrication, and functionalization of nanofibrous materials to mimic the ECM, deliver biological signals, and integrate various engineering design features such as pore shape, size, connectivity, tissue architectures, and anatomic tissue/organ shapes to guide 3D tissue regeneration. In addition to biological and physical principles of scaffold design and fabrication, we also provide several examples of specific applications of these advanced nanofibrous scaffolds for bone, cartilage, and their associated composite tissue regeneration in osteochondral defects. We also discuss the interdisciplinary and multidisciplinary nature of these research directions, the importance of collaborations across disciplines, and the perspectives of future developments in the field.

The temporomandibular joint (TMJ) is unique in both developmental origin and functional maintenance. The role of bone morphogenic protein (BMP) signaling in endochondral ossification has been widely investigated but not in the context of the TMJ. We employed a histomorphometric analysis approach to understand how augmented BMP signaling in the cranial neural crest affects the postnatal development of the TMJ. Our analysis showed that cartilage length in the mandibular condyle was reduced in Wnt1 Cre;caBmpr1a mice before the weaning stage (P17). However, following weaning, the mandibular condylar cartilage showed recovered length (P28 and P42). Furthermore, the changes in cartilage length coincide with alterations in cell death in the superficial region of the mandibular condyle. These results suggest that BMP signaling influences chondrocyte cell death and TMJ development in a timepoint-specific manner.

More than 500,000 bone grafting procedures are performed annually in the USA. Considering the significant limitations of available bone grafts, we previously invented a phase-separation technology to generate nanofibrous poly(l-lactic acid) (PLLA) scaffolds that mimic the bone matrix collagen in nanofiber geometry and enhance bone regeneration. Here we report the development of nanofibrous scaffolds with covalently attached synthetic peptides that mimic native collagen peptides to activate the two main collagen receptors in bone cells, discoidin domain receptor 2 (DDR2) and β1 integrins. We synthesized a PLLA-based graft-copolymer to enable covalent peptide conjugation via a click reaction. Using PLLA and the graft-copolymer, we developed 3D scaffolds with interconnected pores and peptides-containing nanofibers to activate DDR2 and β1 integrins of osteogenic cells. The degradation rate and mechanical properties of the scaffolds are tunable. The peptides-decorated nanofibrous scaffolds demonstrated 7.8 times more mineralized bone regeneration over the control scaffolds without the peptides in a critical-sized bone defect regeneration model after 8 weeks of implantation, showing a synergistic effect of the two peptides. This study demonstrates the power of scaffolds to mimic ECM at both nanometer and molecular levels, activating cell surface receptors to liberate the innate regenerative potential of host stem/progenitor cells.

Purpose To assess oral health-related quality of life (OHRQoL) in patients requiring orthognathic surgery, and evaluate if depression, temporomandibular disorders (TMD), and genetic polymorphisms in interleukin-6 (IL6) influence their OHRQoL. Methods A total of 132 individuals included in three different groups. Two groups were composed by patients with dentofacial deformity (DFD) Class II (n = 44) or Class III (n = 44) malocclusions, requiring orthognathic surgery. The control group (n = 44) included individuals without DFD. Patients from all groups were evaluated in preoperative appointments to assessOHRQoL, TMD, and genetic polymorphisms in IL6. OHRQoL was assessed using the 14-item Oral Health Impact Profile (OHIP-14). TMD and depression were assessed using Research Diagnostic Criteria for Temporomandibular Disorders protocol. The genetic polymorphisms rs1800795 and rs1800796 in IL6 were assessed through genomic DNA using real-time polymerase chain reaction. Results OHIP-14 scores were increased in patients with depression, myofascial pain, and inflammatory temporomandibular joint alterations in the right side, regardless of sex and DFD group. Individual homozygous CC in rs1800795 had increased values in domains “social disability” and “handicap” of the OHIP-14 compared with those who were homozygous GG. Individual heterozygous CG in the rs1800796 demonstrated increased values in domain “psychological discomfort” compared with those homozygous for CC and GG. Conclusion In individuals requiring orthognathic surgery, depression, TMD, and genetic polymorphisms in IL6 contribute to negative impact on OHRQoL. These physical and emotional conditions, together with biological pathways, should receive more attention in treatment plans, in order to improve the patients’ quality of life.

Objective: To evaluate if temporomandibular disorders (TMDs) are associated with genetic polymorphisms in ESR1 and ESR2, which are genes encoding oestrogen receptor alpha (ERα) and beta (ERβ). Also, we included an animal model to check if ERα and ERβ are expressed in the temporomandibular joint (TMJ) during adolescence. Materials and methods: A total of 139 teenagers and 93 adults were diagnosed according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMDs). The DNA was collected and the markers ESR1 and ERS2 were genotyped. Additionally, immunohistochemistry was performed in TMJ tissues from female Wistar rats during puberty. All data were submitted to statistical analysis with confidence interval of 95%. Results: Teenagers presented more disc displacement and arthralgia than adults (p < .05). The genetic polymorphism rs1256049 in ESR2 was associated with disc displacement (p = .040; OR = 10.50/95%CI 1.17–98.74) and arthralgia (p = .036; OR = 7.20/95%CI 1.10–46.88) in adults. The ERα and ERβ are expressed in rat TMJ tissues. Conclusions: We provide evidence that ESR2 is associated with TMD and could be a genetic marker for this condition in adult women. Furthermore, oestrogens receptors are presented in TMJ of adolescent female rats.