Telehealth Utilization in Oral Medicine and Oral and Maxillofacial Surgery

Objectives: The objectives of this retrospective study were to analyze telehealth utilization for two specialty care practices: oral medicine (OM) and oral and maxillofacial surgery (OMFS) during the first 2 years of the pandemic, its impact as a new treatment modality and on participating providers, as well as identify the type of patient visit that most readily adopted telehealth. Methods: Retrospective study of patients who sought specialty services, OM and OMFS, at an outpatient clinic in a university health system setting between March 1, 2019, and February 28, 2022. Source data were obtained from Epic, an electronic medical record application. Data were graphed using Tableau and Microsoft Excel software. Statistical analysis was performed utilizing chi-squared test and analysis of variance (ANOVA). Results: OMFS utilized telehealth 12% of the time, and OM 8% of the time. The majority (87%) of telehealth visits were for return patients (RPs). Compared with the first year of the pandemic, there was a decrease in the number of telehealth visits in the second year (p = 0.0001). As of August 2022, new patient (NP) telehealth encounters have largely returned to prepandemic levels (0-1.5%), whereas RP telehealth visits remained at an average level of 11.4% (9.4-12.4%). Surveyed providers consider telehealth as an effective complement to in-person care and will continue its use (4.2/5 Likert scale). Conclusions: Telehealth has become a viable pathway of care for OM and OMFS who previously did not utilize the remote platform to deliver healthcare. As a new treatment modality, telehealth is perceived as impactful in increasing access to specialty care by participating providers. NP visits are now almost completely in person, but telehealth continues for RPs. Ongoing demand for telehealth highlights urgency to develop appropriate standards and effective remote diagnostic/monitoring tools to maximize telehealth's capability to leverage finite health care resources and increase access to specialty care.

Potential Application of Orofacial MSCs in Tissue Engineering Nerve Guidance for Peripheral Nerve Injury Repair

Injury to the peripheral nerve causes potential loss of sensory and motor functions, and peripheral nerve repair (PNR) remains a challenging endeavor. The current clinical methods of nerve repair, such as direct suture, autografts, and acellular nerve grafts (ANGs), exhibit their respective disadvantages like nerve tension, donor site morbidity, size mismatch, and immunogenicity. Even though commercially available nerve guidance conduits (NGCs) have demonstrated some clinical successes, the overall clinical outcome is still suboptimal, especially for nerve injuries with a large gap (≥ 3 cm) due to the lack of biologics. In the last two decades, the combination of advanced tissue engineering technologies, stem cell biology, and biomaterial science has significantly advanced the generation of a new generation of NGCs incorporated with biological factors or supportive cells, including mesenchymal stem cells (MSCs), which hold great promise to enhance peripheral nerve repair/regeneration (PNR). Orofacial MSCs are emerging as a unique source of MSCs for PNR due to their neural crest-origin and easy accessibility. In this narrative review, we have provided an update on the pathophysiology of peripheral nerve injury and the properties and biological functions of orofacial MSCs. Then we have highlighted the application of orofacial MSCs in tissue engineering nerve guidance for PNR in various preclinical models and the potential challenges and future directions in this field.

Targeted inhibition of eIF5Ahpu suppresses tumor growth and polarization of M2-like tumor-associated macrophages in oral cancer

Eukaryotic initiation factor 5A2 (eIF5A2) is overexpressed in many types of cancer, and spermidine-mediated eIF5A hypusination (eIF5Ahpu) appears to be essential to most of eIF5A's biological functions, including its important role in regulating cancer cell proliferation, epithelial-mesenchymal transition (EMT), and cancer stem cell (CSC) properties as well as immune cell functions. Here we investigated the role of eIF5Ahpu in the growth of oral squamous cell carcinoma cells (OSCCs) and OSCC-induced polarization of M2-like tumor-associated macrophages (TAMs). TCGA dataset analysis revealed an overall upregulation in the mRNA expression of eIF5A2 and several key enzymes involved in polyamine (PA) metabolism in HNSCC, which was confirmed by Western blot and IHC studies. Blocking eIF5Ahpu by GC-7 but not the upstream key enzyme activities of PA metabolism, remarkably inhibited cell proliferation and the expression of EMT- and CSC-related genes in OSCC cells. In addition, blocking eIF5Ahpu robustly inhibited OSCC-induced M2-like TAM polarization in vitro. More Importantly, blocking eIF5Ahpu dramatically retarded tumor growth and infiltration/polarization of M2-like TAM in a syngeneic orthotopic murine tongue SCC model. Thus, eIF5Ahpu plays dual functions in regulating tumor cell growth and polarization of M2-TAMs in OSCC.

Sagittal and Vertical Changes of the Maxilla after Surgically Assisted Rapid Palatal Expansion: A Systematic Review and Meta-Analysis

Surgically assisted rapid palatal expansion (SARPE) is often performed to correct the transverse deficiency in the maxilla for skeletally mature patients. However, there is little consensus on the sagittal and vertical displacement of the maxilla after SARPE. This systematic review aims to analyze the position changes of the maxilla in the sagittal and vertical dimensions after the completion of SARPE. Registered with PROSPERO (registration number: CRD42022312103), this study complied with the 2020 PRISMA guideline and was conducted on 21 January 2023. Original studies were screened from MEDLINE (PubMed), Elsevier (SCOPUS), and Cochrane, and supplemented by hand-searching. Cephalometric changes of skeletal vertical and sagittal measurements were the focus. A fixed-effects model was applied in R for meta-analysis. After applying inclusion and exclusion criteria, seven articles were included in the final review. Four studies had a high risk of bias, and the other three had a medium risk of bias. Meta-analysis revealed that the SNA angle increased by 0.50° ± 0.08° (95% confidence interval, 0.33° to 0.66°), and the SN-PP angle increased by 0.60° ± 0.09° (95% confidence interval, 0.41° to 0.79°) after SARPE. In summary, the maxilla displayed statistically significant forward and clockwise downward movement after SARPE. However, the amounts were small and might not be clinically significant. Due to the high risk of bias of included studies, our results must be taken cautiously. Future studies are needed to discern the effects of direction and angulation of the osteotomies of SARPE on the displacement of the maxilla.

DPSC-Derived Extracellular Vesicles Promote Rat Jawbone Regeneration

Repair and functional reconstruction of large jawbone defects remain one of the challenges in the field of head and neck surgery. The recent progress in tissue engineering technologies and stem cell biology has significantly promoted the development of regenerative reconstruction of jawbone defects. The multiple trophic activities of extracellular vesicles (EVs) produced by mesenchymal stem cells (MSCs) may play a critical role in their therapeutic effects. Accumulating evidence has shown the promise of dental pulp stem cells (DPSCs) in bone regeneration, but less is known about the regenerative effects of DPSC-EVs on jawbone defects. The purpose of this study is to explore the osteogenic effects of DPSC-EVs on jawbone marrow-derived MSCs (JB-MSCs) in vitro and their osteoinductive effects in a mandibular bone defect model in rats. Our results showed that JB-MSCs could efficiently uptake DPSC-EVs, which in turn significantly promoted the expression of osteogenic genes, such as runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP), and osteocalcin (OCN), as well as the osteogenic differentiation capability of JB-MSCs. Meanwhile, we found that the pro-osteogenic effect in vitro induced by DPSC-EVs was comparable to that induced by BMP-2 (bone morphogenetic protein 2), currently the only Food and Drug Administration-approved osteoinductive growth factor. In vivo, animals that were locally treated with DPSC-EVs laden with a commercially available collagen membrane exhibited a relatively fast wound closure and increased new bone density at the mandible defects. Our results provide evidence for the osteogenic and osteoinductive effects of DPSC-EVs on jawbone regeneration. Due to the accessibility, rapid proliferation, and osteogenic propensity of DPSCs, DPSC-EVs may represent a safe cell-free therapeutic approach for craniofacial bone regeneration.

Quality of life in patients with oral potentially malignant disorders: oral lichen planus and oral epithelial dysplasia

OBJECTIVE

The aim of this study was to evaluate and compare quality of life (QoL) parameters in patients with oral potential malignant disorders (OPMDs), namely, oral lichen planus (OLP) and oral epithelial dysplasia (OED).

STUDY DESIGN

A cross-sectional study was completed at the oral maxillofacial surgery/oral medicine practices at University of Pennsylvania. Patients with clinical and histopathologic confirmation of OLP or OED from January to June 2021 were included in the study. The primary predictor variable was the OPMD type. The primary outcome variable was the score of 3 separate surveys: the Chronic Oral Mucosal Disease Questionnaire-26 (COMDQ-26), Oral Potential Malignant Disorder QoL Questionnaire (OPMDQoL), and Hospital Anxiety and Depression Scale. Multiple linear regression was used to determine independent predictors of increased/decreased questionnaire scores.

RESULTS

The final study sample consisted of 100 patients:53 patients had OLP (53.0%), 39 patients had OED (39.0%), and 8 patients had OLP with OED (8.0%). Relative to OED, OLP added 15.7 points to the COMDQ-26 survey score (P < .001). Relative to OED, OLP added 8.9 points to the OPMDQoL survey score (P = .003).

CONCLUSIONS

Oral lichen planus shows significantly poorer QoL specifically within the COMD-26 and OPMDQoL questionnaires, compared with OED. Additionally, patients with OPMDs aged 40 to 64 years were independently associated with higher COMD-26 scores compared with older patients (>65 years).

Asymmetric Maxillary Expansion Introduced by Surgically Assisted Rapid Palatal Expansion: A Systematic Review

PURPOSE

A commonly reported complication of surgically assisted rapid palatal expansion (SARPE) that has not been explored extensively is uneven expansion between left and right sides, which requires secondary surgery for correction. This systematic review aims to analyze the prevalence and potential causes of asymmetric expansion in the transverse dimension after SARPE to guide the clinical practice.

METHODS

Electronic databases and manual search were used to search for original articles published on SARPE on March 11, 2022. Original human studies that recorded the number and percentage of asymmetric expansion after two-piece SARPE were included. The 2020 Preferred Reporting Items for Systemic Reviews and Meta-Analyses guideline was implemented for the quality assessment and data analysis of the included articles. The study was registered at the International Prospective Register of Systematic Reviews under the number CRD42022300782.

RESULTS

After applying inclusion and exclusion criteria, 13 articles were included in the final review. The risk of bias was high in 8 studies and medium in the other 5 studies. Overall, the prevalence of asymmetric expansion in the transverse dimension (different amount of expansion between left and right sides) was 7.52%, with 12.90% of patients involved receiving a second surgery for correction. Expander design did not significantly affect the rate of asymmetry expansion. Pterygomaxillary fissure release significantly increased the rate of asymmetry expansion (11.02% vs 5.08%, P < .001). In comparison, lateral nasal wall osteotomy (4.26% vs 14.77%, P < .001) and release of the nasal septum (5.22% vs 17.15%, P < .001) significantly lowered the rate of asymmetry expansion, respectively.

CONCLUSIONS

Asymmetric dentoskeletal expansion between left and right sides is a common complication of SARPE procedures, mostly caused by variations in surgical cuts. However, the risk of bias in currently available publications is high. Further studies are warranted to fully understand the causes of asymmetric expansion.

Implantation of a nerve protector embedded with human GMSC-derived Schwann-like cells accelerates regeneration of crush-injured rat sciatic nerves

BACKGROUND

Peripheral nerve injuries (PNIs) remain one of the great clinical challenges because of their considerable long-term disability potential. Postnatal neural crest-derived multipotent stem cells, including gingiva-derived mesenchymal stem cells (GMSCs), represent a promising source of seed cells for tissue engineering and regenerative therapy of various disorders, including PNIs. Here, we generated GMSC-repopulated nerve protectors and evaluated their therapeutic effects in a crush injury model of rat sciatic nerves.

METHODS

GMSCs were mixed in methacrylated collagen and cultured for 48 h, allowing the conversion of GMSCs into Schwann-like cells (GiSCs). The phenotype of GiSCs was verified by fluorescence studies on the expression of Schwann cell markers. GMSCs encapsulated in the methacrylated 3D-collagen hydrogel were co-cultured with THP-1-derived macrophages, and the secretion of anti-inflammatory cytokine IL-10 or inflammatory cytokines TNF-α and IL-1β in the supernatant was determined by ELISA. In addition, GMSCs mixed in the methacrylated collagen were filled into a nerve protector made from the decellularized small intestine submucosal extracellular matrix (SIS-ECM) and cultured for 24 h, allowing the generation of functionalized nerve protectors repopulated with GiSCs. We implanted the nerve protector to wrap the injury site of rat sciatic nerves and performed functional and histological assessments 4 weeks post-surgery.

RESULTS

GMSCs encapsulated in the methacrylated 3D-collagen hydrogel were directly converted into Schwann-like cells (GiSCs) characterized by the expression of S-100β, p75NTR, BDNF, and GDNF. In vitro, co-culture of GMSCs encapsulated in the 3D-collagen hydrogel with macrophages remarkably increased the secretion of IL-10, an anti-inflammatory cytokine characteristic of pro-regenerative (M2) macrophages, but robustly reduced LPS-stimulated secretion of TNF-1α and IL-1β, two cytokines characteristic of pro-inflammatory (M1) macrophages. In addition, our results indicate that implantation of functionalized nerve protectors repopulated with GiSCs significantly accelerated functional recovery and axonal regeneration of crush-injured rat sciatic nerves accompanied by increased infiltration of pro-regenerative (M2) macrophages while a decreased infiltration of pro-inflammatory (M1) macrophages.

CONCLUSIONS

Collectively, these findings suggest that Schwann-like cells converted from GMSCs represent a promising source of supportive cells for regenerative therapy of PNI through their dual functions, neurotrophic effects, and immunomodulation of pro-inflammatory (M1)/pro-regenerative (M2) macrophages.

Potential application of dental stem cells in regenerative reconstruction of oral and maxillofacial tissues: a narrative review

Background and Objective:

Methods:

Key Content and Findings:

Conclusions:

Gingiva-Derived Mesenchymal Stem Cells: Potential Application in Tissue Engineering and Regenerative Medicine - A Comprehensive Review

A unique subpopulation of mesenchymal stem cells (MSCs) has been isolated and characterized from human gingival tissues (GMSCs). Similar to MSCs derived from other sources of tissues, e.g. bone marrow, adipose or umbilical cord, GMSCs also possess multipotent differentiation capacities and potent immunomodulatory effects on both innate and adaptive immune cells through the secretion of various types of bioactive factors with immunosuppressive and anti-inflammatory functions. Uniquely, GMSCs are highly proliferative and have the propensity to differentiate into neural cell lineages due to the neural crest-origin. These properties have endowed GMSCs with potent regenerative and therapeutic potentials in various preclinical models of human disorders, particularly, some inflammatory and autoimmune diseases, skin diseases, oral and maxillofacial disorders, and peripheral nerve injuries. All types of cells release extracellular vesicles (EVs), including exosomes, that play critical roles in cell-cell communication through their cargos containing a variety of bioactive molecules, such as proteins, nucleic acids, and lipids. Like EVs released by other sources of MSCs, GMSC-derived EVs have been shown to possess similar biological functions and therapeutic effects on several preclinical diseases models as GMSCs, thus representing a promising cell-free platform for regenerative therapy. Taken together, due to the easily accessibility and less morbidity of harvesting gingival tissues as well as the potent immunomodulatory and anti-inflammatory functions, GMSCs represent a unique source of MSCs of a neural crest-origin for potential application in tissue engineering and regenerative therapy.

Exosomes from TNF-α-treated human gingiva-derived MSCs enhance M2 macrophage polarization and inhibit periodontal bone loss

Mesenchymal stem cell (MSC)–derived exosome plays a central role in the cell-free therapeutics involving MSCs and the contents can be customized under disease-associated microenvironments. However, optimal MSC-preconditioning to enhance its therapeutic potential is largely unknown. Here, we show that preconditioning of gingival tissue-derived MSCs (GMSCs) with tumor necrosis factor-alpha (TNF-α) is ideal for the treatment of periodontitis. TNF-α stimulation not only increased the amount of exosome secreted from GMSCs, but also enhanced the exosomal expression of CD73, thereby inducing anti-inflammatory M2 macrophage polarization. The effect of GMSC-derived exosomes on inflammatory bone loss were examined by ligature-induced periodontitis model in mice. Local injection of GMSC-derived exosomes significantly reduced periodontal bone resorption and the number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts, and these effects were further enhanced by preconditioning of GMSCs with TNF-α. Thus, GMSC-derived exosomes also exhibited anti-osteoclastogenic activity. Receptor activator of NF-κB ligand (RANKL) expression was regulated by Wnt5a in periodontal ligament cells (PDLCs), and exosomal miR-1260b was found to target Wnt5a-mediated RANKL pathway and inhibit its osteoclastogenic activity. These results indicate that significant ability of the TNF-α-preconditioned GMSC-derived exosomes to regulate inflammation and osteoclastogenesis paves the way for establishment of a therapeutic approach for periodontitis.

Tissue Engineered Bands of Büngner for Accelerated Motor and Sensory Axonal Outgrowth

Following peripheral nerve injury comprising a segmental defect, the extent of axon regeneration decreases precipitously with increasing gap length. Schwann cells play a key role in driving axon re-growth by forming aligned tubular guidance structures called bands of Büngner, which readily occurs in distal nerve segments as well as within autografts - currently the most reliable clinically-available bridging strategy. However, host Schwann cells generally fail to infiltrate large-gap acellular scaffolds, resulting in markedly inferior outcomes and motivating the development of next-generation bridging strategies capable of fully exploiting the inherent pro-regenerative capability of Schwann cells. We sought to create preformed, implantable Schwann cell-laden microtissue that emulates the anisotropic structure and function of naturally-occurring bands of Büngner. Accordingly, we developed a biofabrication scheme leveraging biomaterial-induced self-assembly of dissociated rat primary Schwann cells into dense, fiber-like three-dimensional bundles of Schwann cells and extracellular matrix within hydrogel micro-columns. This engineered microtissue was found to be biomimetic of morphological and phenotypic features of endogenous bands of Büngner, and also demonstrated 8 and 2× faster rates of axonal extension in vitro from primary rat spinal motor neurons and dorsal root ganglion sensory neurons, respectively, compared to 3D matrix-only controls or planar Schwann cells. To our knowledge, this is the first report of accelerated motor axon outgrowth using aligned Schwann cell constructs. For translational considerations, this microtissue was also fabricated using human gingiva-derived Schwann cells as an easily accessible autologous cell source. These results demonstrate the first tissue engineered bands of Büngner (TE-BoBs) comprised of dense three-dimensional bundles of longitudinally aligned Schwann cells that are readily scalable as implantable grafts to accelerate axon regeneration across long segmental nerve defects.

Extracellular Vesicles of GMSCs Alleviate Aging-Related Cell Senescence

Healthy aging is a complex biological process with progressive accumulation of senescent cells characterized by stable cell cycle arrest, resulting in impaired homeostasis, regenerative potential, and gradual functional decline in multiple tissues and organs, whereby the aberrant activation of mammalian target of rapamycin (mTOR) signaling networks plays a central role. Herein, we explored the effects of extracellular vesicles (EVs) released by gingiva-derived mesenchymal stem cells (GMSC-EVs) on oxidative stress-induced cellular senescence in human endothelial cells and skin fibroblasts and their antiaging potentials. Our results showed that GMSC-EVs robustly abrogated oxidative stress-induced upregulation in the expression of cellular senescence-related genes, such as β-galactosidase, p21, p53, and γH2AX, and mTOR/pS6 signaling pathway, in human umbilical vein endothelial cells (HUVECs) and skin fibroblasts. Meanwhile, GMSC-EVs restored oxidative stress-induced impairment in proliferation and tube formation by HUVECs. Systemic administration of GMSC-EVs attenuated aging-associated elevation in the expression levels of p21, mTOR/pS6, interleukin 6, and tumor necrosis factor α in skin and heart tissues of aged mice. These findings suggest that GMSC-EVs could be a potential alternative source of cell-free product for attenuation of aging-related skin and vascular dysfunctions due to their potent inhibitory effects on oxidative stress-induced cellular senescence in endothelial cells and skin fibroblasts.

Utility of decellularised urinary bladder extracellular matrix in full mucosalisation of a post-oncological maxillectomy defect

This report highlights the utility of MatriStem Surgical Matrix Thick UBM™ (rebranded as Gentrix® ACell, Inc), a decellularised urinary bladder extracellular matrix in the reconstruction of a post-oncological maxillectomy defect. In utilising this biological construct to serve as a biological dressing, our patient underwent complete mucosalisation of his surgical site without the development of an oroantral fistula and with adequate maxillary vestibule to allow for definitive oral rehabilitation with a removable partial denture.

Oral Mucositis: An Update on Innate Immunity and New Interventional Targets

Oral mucositis (OM), a common debilitating toxicity associated with chemo- and radiation therapies, is a significant unmet clinical need for head and neck cancer patients. The biological complexities of chemoradiotherapy-induced OM involve interactions among disrupted tissue structures, inflammatory infiltrations, and oral microbiome, whereby several master inflammatory pathways constitute the complicated regulatory networks. Oral mucosal damages triggered by chemoradiotherapy-induced cell apoptosis were further exacerbated by the amplified inflammatory cascades dominantly governed by the innate immune responses. The coexistence of microbiome and innate immune components in oral mucosal barriers indicates that a signaling hub coordinates the interaction between environmental cues and host cells during tissue and immune homeostasis. Dysbiotic shifts in oral microbiota caused by cytotoxic cancer therapies may also contribute to the progression and severity of chemoradiotherapy-induced OM. In this review, we have updated the mechanisms involving innate immunity-governed inflammatory cascades in the pathobiology of chemoradiotherapy-induced OM and the development of new interventional targets for the management of this severe morbidity in head and neck cancer patients.

Considerations in the evaluation and management of oral potentially malignant disorders during the COVID-19 pandemic

Aim

The COVID‐19 pandemic has resulted in society experiencing unprecedented challenges for health care practitioners and facilities serving at the frontlines of this pandemic. With regard to oral cancer, there is a complete absence of literature regarding the long‐term impact of pandemics on patients with oral potentially malignant disorders (OPMDs). The objective of this article is to put forth an institutional multidisciplinary approach for the evaluation and management of OPMDs.

Methods

A multidisciplinary approach was put formalized within our institution to risk stratify patients based on need for in‐person assessment vs telehealth assessment during the COVID‐19 pandemic.

Results

With judicious risk stratification of patients based on clinical features of their OPMD and with consideration of ongoing mitigation efforts and regional pandemic impact, providers are able to safely care for their patients.

Conclusions

The COVID‐19 pandemic has required health care practitioners to make novel decisions that are new to us with development of creative pathways of care that focused on patient safety, mitigation efforts, and clinical management of disease processes. The care of patients with OPMDs requires special considerations especially as patients at high risk for severe COVID‐19 illness are also higher risk for the development of OPMDs.

Oral Rehabilitation of Patients Sustaining Orofacial Injuries: The UPenn Initiative

Tissue injuries in the oral and maxillofacial structures secondary to trauma, warfare, ablative cancer, and benign tumor surgery result in significant losses of speech, masticatory and swallowing functions, aesthetic deformities, and overall psychological stressors and compromise. Optimal oral rehabilitation remains a formidable challenge and an unmet clinical need due to the influence of multiple factors related to the physiologic limitations of tissue repair, the lack of site and function-specific donor tissues and constructs, and an integrated team of multidisciplinary professionals. The advancements in stem cell biology, biomaterial science, and tissue engineering technologies, particularly the 3-dimensional bioprinting technology, together with digital imaging and computer-aided design and manufacturing technologies, have paved the path for personalized/precision regenerative medicine. At the University of Pennsylvania, we have launched the initiative to integrate multidisciplinary health professionals and translational/clinical scientists in medicine, dentistry, stem cell biology, tissue engineering, and regenerative medicine to develop a comprehensive, patient-centered approach for precision and personalized reconstruction, as well as oral rehabilitation of patients sustaining orofacial tissue injuries and defects, especially oral cancer patients.

Trainee Contribution Is Not Associated With Citation Frequency: A Retrospective Study

PURPOSE

Publication citation frequency is a measure of scientific influence. The purpose of this study was to measure the association between trainee involvement in publications and citation frequency.

MATERIALS AND METHODS

A retrospective cohort study of the Journal of Oral and Maxillofacial Surgery from January to December 2010 was conducted. For each included publication, the study topic and design were recorded. The primary predictor variable was trainee involvement (yes or no). For the purpose of our study, the term "trainee" encompassed dental students, graduate (non-dental) students, oral and maxillofacial surgery residents, and non-oral and maxillofacial surgery residents, as indicated by author affiliations listed in each article. The outcome variable was the number of citations accumulated between 2010 and 2017. Descriptive statistics were computed. Analyses of variance were performed to compare citation distribution among study types and designs. Student t tests and χ² tests were performed.

RESULTS

The sample consisted of 111 publications, of which 85 (76.6%) had at least 1 trainee author. Among all publications, the mean number of citations was significantly different across study designs (P = .03), with case reports earning the lowest number of citations on average (mean, 14.9 citations). Trainee publications had significantly different distributions of study topics (P = .02) and designs (P < .01). Among publications with a trainee author, the most common topic was pathology (37%) and the most common study design was a case report (45%). Despite the higher proportion of case reports, the mean number of citations between trainee (mean, 30.4 citations) and non-trainee (mean, 30.5 citations) publications was not significantly different (P = .99).

CONCLUSIONS

Including trainees does not alter the citation frequency of the articles published in the Journal of Oral and Maxillofacial Surgery. This finding is encouraging to both academic surgeons and their trainees, as a higher volume of students and residents can be engaged in research while preserving the influence of the published works.

SIS-ECM Laden with GMSC-Derived Exosomes Promote Taste Bud Regeneration

Oral cancer has a high annual incidence rate all over the world, and the tongue is the most frequently affected anatomic structure. The current standard care is ablative surgery of malignant neoplasm, followed by tongue reconstruction with free flap. However, such reconstructive modalities with postsurgery radiotherapy or chemotherapy can hardly support the functional recovery of the tongue-particularly, functional taste bud regeneration-in reconstructed areas, thus seriously affecting patients' prognosis and life quality. Using a critical-sized tongue defect model in rats, we show that combinatory transplantation of small intestinal submucosa-extracellular matrix (SIS-ECM) with gingival mesenchymal stem cells (GMSCs) or their derivative exosomes promoted tongue lingual papillae recovery and taste bud regeneration as evidenced by increased expression of CK14, CK8, and markers for type I, II, and III taste bud cells (NTPdase 2, PLC-β2, and AADC, respectively). In addition, our results indicate that GMSCs or their derivative exosomes could increase BDNF expression, a growth factor that plays an important role in the proliferation and differentiation of epithelial basal progenitor cells into taste bud cells. Meanwhile, we showed an elevated expression level of Shh-which is essential for development, homeostasis, and maintenance of the taste bud organ-in wounded areas of the tongue among animals treated with GMSC/SIS-ECM or exosome/SIS-ECM as compared with SIS-ECM control. Moreover, our data show that GMSCs or their derivative exosomes promoted innervation of regenerated taste buds, as evidenced by elevated expressions of neurofilament and P2X₃ at the injury areas. Together, our findings indicate that GMSC/SIS-ECM and exosome/SIS-ECM constructs can facilitate taste bud regeneration and reinnervation with promising potential application in postsurgery tongue reconstruction of patients with tongue cancer.

Letermovir for prophylaxis of cytomegalovirus in allogeneic hematopoietic stem cell recipients

Letermovir is a new antiviral agent with activity against human cytomegalovirus (CMV). Letermovir works as an inhibitor of the CMV DNA terminase complex which further inhibits viral DNA processing and packaging. Letermovir is available both orally and intravenously in 480-mg and 240-mg dosage forms, and is approved for use in the prophylaxis of CMV infection and disease in CMV-seropositive recipients of allogeneic hematopoietic stem cell transplant (HSCT) over the age of 18. The recommended dose is 480 mg p.o./i.v. once daily initiated between day 0 through day 28 post-allogeneic HSCT and continued through day 100 post-transplantation; the dose should be reduced to 240 mg daily if coadministered with cyclosporine. Letermovir is metabolized primarily by hepatic OATP1B1/3 and is not recommended for patients with severe hepatic impairment (Child-Pugh class C). Renal dosage adjustments are not warranted until a creatinine clearance (CrCl) of less than 10 mL/min; however, serum creatinine should be monitored when administered to patients with a CrCl of less than 50 mL/min. Cross-resistance with other useful antiviral agents in the treatment of CMV has not been observed. Additionally, letermovir is active against DNA polymerase inhibitor-resistant viral strains. Letermovir has shown promising clinical efficacy and is generally well tolerated, thus providing a favorable new option in the prophylaxis of CMV infection and disease.

EGF induces epithelial-mesenchymal transition and cancer stem-like cell properties in human oral cancer cells via promoting Warburg effect

"Warburg effect", the enhanced glycolysis or aerobic glycolysis, confers cancer cells the ability to survive and proliferate even under stressed conditions. In this study, we explored the role of epidermal growth factor (EGF) in orchestrating Warburg effect, the epithelial-mesenchymal transition (EMT) process, and the acquisition of cancer stem-like cell properties in human oral squamous cell carcinoma (OSCC) cells. Our results showed that EGF induces EMT process in OSCC cells, which correlates with the acquisition of cancer stem-like properties, including the enrichment of CD44+/CD24- population of cancer cells and an increased expression of CSC-related genes, aldehyde dehydrogenase-1 (ALDH1) and Bmi-1. We also showed that EGF concomitantly enhanced L-lactate production, while blocking glycolysis by 2-deoxy-D-glucose (2-DG) robustly reversed EGF-induced EMT process and CSC-like properties in OSCC cells. Mechanistically, we demonstrated that EGF promoted EMT process and CSC generation through EGFR/PI3K/HIF-1α axis-orchestrated glycolysis. Using an orthotopic tumor model of human OSCC (UM-SCC1) injected in the tongue of BALB/c nude mice, we showed that treatment with 2-DG in vivo significantly inhibited the metastasis of tumor cells to the regional cervical lymph nodes and reduced the expression of ALDH1 and vimentin in both in situ tumors and tumor cell-invaded regional lymph nodes. Taken together, these findings have unveiled a new mechanism that EGF drives OSCC metastasis through induction of EMT process and CSC generation, which is driven by an enhanced glycolytic metabolic program in OSCC cells.

Neural Crest Stem-Like Cells Non-genetically Induced from Human Gingiva-Derived Mesenchymal Stem Cells Promote Facial Nerve Regeneration in Rats

Non-genetic induction of somatic cells into neural crest stem-like cells (NCSCs) is promising for potential cell-based therapies for post-traumatic peripheral nerve regeneration. Here, we report that human gingiva-derived mesenchymal stem cells (GMSCs) could be reproducibly and readily induced into NCSCs via non-genetic approaches. Compared to parental GMSCs, induced NCSC population had increased expression in NCSC-related genes and displayed robust differentiation into neuronal and Schwann-like cells. Knockdown of the expression of Yes-associated protein 1 (YAP1), a critical mechanosensor and mechanotransducer, attenuated the expression of NCSC-related genes; specific blocking of RhoA/ROCK activity and non-muscle myosin II (NM II)-dependent contraction suppressed YAP1 and NCSC-related genes and concurrently abolished neural spheroid formation in NCSCs. Using a rat model of facial nerve defect, implantation of NCSC-laden nerve conduits promoted functional regeneration of the injured nerve. These promising findings demonstrate that induced NCSCs derived from GMSCs represent an easily accessible and promising source of neural stem-like cells for peripheral nerve regeneration.

The neuroprotective effect of nicotine in Parkinson's disease models is associated with inhibiting PARP-1 and caspase-3 cleavage

Clinical evidence points to neuroprotective effects of smoking in Parkinson’s disease (PD), but the molecular mechanisms remain unclear. We investigated the pharmacological pathways involved in these neuroprotective effects, which could provide novel ideas for developing targeted neuroprotective treatments for PD. We used the ETC complex I inhibitor methylpyridinium ion (MPP⁺) to induce cell death in SH-SY5Y cells as a cellular model for PD and found that nicotine inhibits cell death. Using choline as a nicotinic acetylcholine receptor (nAChR) agonist, we found that nAChR stimulation was sufficient to protect SH-SY5Y cells against cell death from MPP⁺. Blocking α7 nAChR with methyllycaconitine (MLA) prevented the protective effects of nicotine, demonstrating that these receptors are necessary for the neuroprotective effects of nicotine. The neuroprotective effect of nicotine involves other pathways relevant to PD. Cleaved Poly (ADP-ribose) polymerase-1 (PARP-1) and cleaved caspase-3 were decreased by nicotine in 6-hydroxydopamine (6-OHDA) lesioned mice and in MPP⁺-treated SH-SY5Y cells. In conclusion, our data indicate that nicotine likely exerts neuroprotective effects in PD through the α7 nAChR and downstream pathways including PARP-1 and caspase-3. This knowledge could be pursued in future research to develop neuroprotective treatments for PD.

Applications of Mesenchymal Stem Cells in Oral and Craniofacial Regeneration

The field of tissue engineering and regenerative medicine has been rapidly expanded through multidisciplinary integration of research and clinical practice in response to unmet clinical needs for reconstruction of dental, oral, and craniofacial structures. The significance of the various types of stem cells, specifically mesenchymal stem cells derived from the orofacial tissues, ranging from dental pulp stem cells to periodontal ligament stem cells to mucosa/gingiva has been thoroughly investigated and their applications in tissue regeneration are outlined in this article.

Mesenchymal Stromal Cell-Derived Interleukin-6 Promotes Epithelial-Mesenchymal Transition and Acquisition of Epithelial Stem-Like Cell Properties in Ameloblastoma Epithelial Cells

Epithelial-mesenchymal transition (EMT), a biological process associated with cancer stem-like or cancer-initiating cell formation, contributes to the invasiveness, metastasis, drug resistance, and recurrence of the malignant tumors; it remains to be determined whether similar processes contribute to the pathogenesis and progression of ameloblastoma (AM), a benign but locally invasive odontogenic neoplasm. Here, we demonstrated that EMT- and stem cell-related genes were expressed in the epithelial islands of the most common histologic variant subtype, the follicular AM. Our results revealed elevated interleukin (IL)-6 signals that were differentially expressed in the stromal compartment of the follicular AM. To explore the stromal effect on tumor pathogenesis, we isolated and characterized both mesenchymal stromal cells (AM-MSCs) and epithelial cells (AM-EpiCs) from follicular AM and demonstrated that, in in vitro culture, AM-MSCs secreted a significantly higher level of IL-6 as compared to the counterpart AM-EpiCs. Furthermore, both in vitro and in vivo studies revealed that exogenous and AM-MSC-derived IL-6 induced the expression of EMT- and stem cell-related genes in AM-EpiCs, whereas such effects were significantly abrogated either by a specific inhibitor of STAT3 or ERK1/2, or by knockdown of Slug gene expression. These findings suggest that AM-MSC-derived IL-6 promotes tumor-stem like cell formation by inducing EMT process in AM-EpiCs through STAT3 and ERK1/2-mediated signaling pathways, implying a role in the etiology and progression of the benign but locally invasive neoplasm. Stem Cells 2017;35:2083-2094.

Induction of Salivary Gland-Like Cells from Dental Follicle Epithelial Cells

The dental follicle (DF), most often associated with unerupted teeth, is a condensation of ectomesenchymal cells that surrounds the tooth germ in early stages of tooth development. In the present study, we aim to isolate epithelial stem-like cells from the human DF and explore their potential differentiation into salivary gland (SG) cells. We demonstrated the expression of stem cell-related genes in the epithelial components of human DF tissues, and these epithelial progenitor cells could be isolated and ex vivo expanded in a reproducible manner. The human DF-derived epithelial cells possessed clonogenic and sphere-forming capabilities, as well as expressed a panel of epithelial stem cell-related genes, thus conferring stem cell properties (hDF-EpiSCs). When cultured under in vitro 3-dimensional induction conditions, hDF-EpiSCs were capable to differentiate into SG acinar and duct cells. Furthermore, transplantation of hDF-EpiSC-loaded native de-cellularized rat parotid gland scaffolds into the renal capsule of nude mice led to the differentiation of transplanted hDF-EpiSCs into salivary gland-like cells. These findings suggest that hDF-EpiSCs might be a promising source of epithelial stem cells for the development of stem cell-based therapy or bioengineering SG tissues to repair/regenerate SG dysfunction.

A Gingiva-Derived Mesenchymal Stem Cell-Laden Porcine Small Intestinal Submucosa Extracellular Matrix Construct Promotes Myomucosal Regeneration of the Tongue

In the oral cavity, the tongue is the anatomic subsite most commonly involved by invasive squamous cell carcinoma. Current treatment protocols often require significant tissue resection to achieve adequate negative margins and optimal local tumor control. Reconstruction of the tongue while preserving and/or restoring its critical vocal, chewing, and swallowing functions remains one of the major challenges in head and neck oncologic surgery. We investigated the in vitro feasibility of fabricating a novel combinatorial construct using porcine small intestinal submucosa extracellular matrix (SIS-ECM) and human gingiva-derived mesenchymal stem cells (GMSCs) as a GMSC/SIS-ECM tissue graft for the tongue reconstruction. We developed a rat model of critical-sized myomucosal defect of the tongue that allowed the testing of therapeutic effects of an acellular SIS-ECM construct versus a GMSC/SIS-ECM construct on repair and regeneration of the tongue defect. We showed that the GMSC/SIS-ECM construct engrafted at the host recipient site, promoted soft tissue healing, and regenerated the muscular layer, compared to the SIS-ECM alone or nontreated defect controls. Furthermore, our results revealed that transplantation of the GMSC/SIS-ECM construct significantly increased the expression of several myogenic transcriptional factors and simultaneously suppressed the expression of type I collagen at the wounded area of the tongue. These compelling findings suggest that, unlike the tongue contracture and fibrosis of the nontreated defect group, transplantation of the combinatorial GMSC/SIS-ECM constructs accelerates wound healing and muscle regeneration and maintains the overall tongue shape, possibly by both enhancing the function of endogenous skeletal progenitor cells and suppressing fibrosis. Together, our findings indicate that GMSC/SIS-ECM potentially served as a myomucosal graft for tongue reconstruction postsurgery of head and neck cancer.

Loss of Notch3 Signaling Enhances Osteogenesis of Mesenchymal Stem Cells from Mandibular Torus

Mandibular torus (MT) is a common intraoral osseous outgrowth located on the lingual surface of the mandible. Histologic features include hyperplastic bone consisting of mature cortical and trabecular bone. Some theories on the etiology of MT have been postulated, such as genetic factors, masticatory hyperfunction, trauma, and continued growth, but the underlying mechanism remains largely unknown. In this study, we investigated the potential role of mesenchymal stem cells (MSCs) derived from human MT in the pathogenesis of bone outgrowth. We demonstrated that MT harbored a distinct subpopulation of MSCs, with enhanced osteogenic and decreased adipogenic differentiation capacities, as compared with their counterparts from normal jaw bone. The increased osteogenic differentiation of mandibular torus MSCs was associated with the suppression of Notch3 signaling and its downstream target genes, Jag1 and Hey1, and a reciprocal increase in the transcriptional activation of ATF4 and NFATc1 genes. Targeted knockdown of Notch3 expression by transient siRNA transfection promoted the expression of osteogenic transcription factors in normal jaw bone MSCs. Our data suggest that the loss of Notch3 signaling may contribute partly to bone outgrowth in MT, as mediated by enhanced MSC-driven osteogenic differentiation in the jaw bone.

Neural Progenitor-Like Cells Induced from Human Gingiva-Derived Mesenchymal Stem Cells Regulate Myelination of Schwann Cells in Rat Sciatic Nerve Regeneration

Regeneration of peripheral nerve injury remains a major clinical challenge. Recently, mesenchymal stem cells (MSCs) have been considered as potential candidates for peripheral nerve regeneration; however, the underlying mechanisms remain elusive. Here, we show that human gingiva‐derived MSCs (GMSCs) could be directly induced into multipotent NPCs (iNPCs) under minimally manipulated conditions without the introduction of exogenous genes. Using a crush‐injury model of rat sciatic nerve, we demonstrate that GMSCs transplanted to the injury site could differentiate into neuronal cells, whereas iNPCs could differentiate into both neuronal and Schwann cells. After crush injury, iNPCs, compared with GMSCs, displayed superior therapeutic effects on axonal regeneration at both the injury site and the distal segment of the injured sciatic nerve. Mechanistically, transplantation of GMSCs, especially iNPCs, significantly attenuated injury‐triggered increase in the expression of c‐Jun, a transcription factor that functions as a major negative regulator of myelination and plays a central role in dedifferentiation/reprogramming of Schwann cells into a progenitor‐like state. Meanwhile, our results also demonstrate that transplantation of GMSCs and iNPCs consistently increased the expression of Krox‐20/EGR2, a transcription factor that governs the expression of myelin proteins and facilitates myelination. Altogether, our findings suggest that transplantation of GMSCs and iNPCs promotes peripheral nerve repair/regeneration, possibly by promoting remyelination of Schwann cells mediated via the regulation of the antagonistic myelination regulators, c‐Jun and Krox‐20/EGR2. Stem Cells Translational Medicine2017;6:458–470

Visible red and infrared light alters gene expression in human marrow stromal fibroblast cells

OBJECTIVES

This study tested whether or not gene expression in human marrow stromal fibroblast (MSF) cells depends on light wavelength and energy density.

MATERIALS AND METHODS

Primary cultures of isolated human bone marrow stem cells (hBMSC) were exposed to visible red (VR, 633 nm) and infrared (IR, 830 nm) radiation wavelengths from a light emitting diode (LED) over a range of energy densities (0.5, 1.0, 1.5, and 2.0 Joules/cm2) Cultured cells were assayed for cell proliferation, osteogenic potential, adipogenesis, mRNA and protein content. mRNA was analyzed by microarray and compared among different wavelengths and energy densities. Mesenchymal and epithelial cell responses were compared to determine whether responses were cell type specific. Protein array analysis was used to further analyze key pathways identified by microarrays.

RESULT

Different wavelengths and energy densities produced unique sets of genes identified by microarray analysis. Pathway analysis pointed to TGF-beta 1 in the visible red and Akt 1 in the infrared wavelengths as key pathways to study. TGF-beta protein arrays suggested switching from canonical to non-canonical TGF-beta pathways with increases to longer IR wavelengths. Microarrays suggest RANKL and MMP 10 followed IR energy density dose-response curves. Epithelial and mesenchymal cells respond differently to stimulation by light suggesting cell type-specific response is possible.

CONCLUSIONS

These studies demonstrate differential gene expression with different wavelengths, energy densities and cell types. These differences in gene expression have the potential to be exploited for therapeutic purposes and can help explain contradictory results in the literature when wavelengths, energy densities and cell types differ.

DPSCs from Inflamed Pulp Modulate Macrophage Function via the TNF-α/IDO Axis

Human dental pulp stem cells (DPSCs) can be isolated from inflamed pulp derived from carious teeth with symptomatic irreversible pulpitis (I-DPSCs), which possess stemness and multidifferentiation potentials similar to DPSCs from healthy pulp. Since macrophages-essential cell players of the pulpal innate immunity-can regulate pulpal inflammation and repair, the authors investigated the immunomodulatory effects of DPSCs/I-DPSCs on macrophage functions and their underlying mechanisms. Similar to DPSCs, I-DPSCs were capable of colony-forming efficiency and adipogenic and osteo/dentinogenic differentiation under in vitro induction conditions. I-DPSCs also expressed a similar phenotypic profile of mesenchymal stem cell markers, except a relatively higher level of CD146 as compared with DPSCs. Coculture of DPSCs or I-DPSCs with differentiated THP-1 cells, the human monocyte cell line, markedly suppressed tumor necrosis factor α (TNF-α) secretion in response to stimulation with lipopolysaccharides (LPS) and/or nigericin. However, unlike TNF-α, the secreted level of interleukin 1β was not affected by coculture with DPSCs or I-DPSCs. Furthermore, DPSC/I-DPSC-mediated inhibition of TNF-α secretion by macrophages was abolished by pretreatment with 1-methyl-D-tryptophan, a specific inhibitor of indoleamine-pyrrole 2,3-dioxygenase (IDO), but not by NSC-398, a specific inhibitor of COX-2, suggesting IDO as a mediator. Interestingly, IDO expression was significantly augmented in macrophages and mesenchymal stromal cells in inflamed human pulp tissues. Collectively, these findings show that I-DPSCs, similar to DPSCs, possess stem cell properties and suppress macrophage functions via the TNF-α/IDO axis, thereby providing a physiologically relevant context for their innate immunomodulatory activity in the dental pulp and their capability for pulp repair.

Targeting Cancer Stem Cells in Oral Cancer

The concept of tumor development driven by a unique subpopulation of cancer stem cells (CSCs), or the CSCs hypothesis, may help to explain the high mortality, low response to treatment and tendency of developing multiple tumors in oral cancer. We will review current knowledge of the CSCs hypothesis in oral cancer and the traits displayed by CSCs, focusing on the resistance to therapy and attempts being made to treat oral cancer by specifically targeting CSCs.

Bisphosphonate Induces Osteonecrosis of the Jaw in Diabetic Mice via NLRP3/Caspase-1-Dependent IL-1β Mechanism

Diabetes mellitus is an established risk factor associated with bisphosphonate-related osteonecrosis of the jaw (BRONJ). Sustained activation of Nod-like receptor (NLR) family, pyrin domain-containing protein 3 (NLRP3) inflammasome contributes to the persistent inflammation and impaired cutaneous wound healing in diabetic mice and human. We have recently demonstrated a compelling linkage between M1 macrophages and BRONJ conditions in both murine and human diseases. The aim of this study was to determine whether NLRP3 inflammasome activation is involved in BRONJ development in diabetic mice. We showed an increased incidence of delayed oral wound healing and bone necrosis of extraction sockets in db/db mice compared with those in nondiabetic db/+ controls, which correlated with an elevated expression of NLRP3, caspase-1, and IL-1β in macrophages residing at local wounds. Constitutively, bone marrow-derived macrophages from db/db mice (db/db BMDMs) secrete a relatively higher level of IL-1β than those from db/+ mice (db/+ BMDMs). Upon stimulation by NLRP3 activators, the secretion of IL-1β by db/db BMDMs was 1.77-fold higher than that by db/+ BMDMs (p < 0.001). Systemic treatment of mice with zoledronate (Zol), a nitrogen-containing bisphosphonate, resulted in a 1.86- and 1.63-fold increase in NLRP3/caspase-1-dependent IL-1β secretion by db/+ and db/db BMDMs, respectively, compared with BMDMs derived from nontreated mice (p < 0.001). Importantly, systemic administration of pharmacological inhibitors of NLRP3 activation improved oral wound healing and suppressed BRONJ formation in db/db mice. Mechanistically, we showed that supplementation with intermediate metabolites of the mevalonate pathway, inhibitors of caspase-1 and NLRP3 activation, an antagonist for P2X7 R, or a scavenger of reactive oxygen species (ROS), robustly abolished Zol-enhanced IL-1β release from macrophages in response to NLRP3 activation (p < 0.001). Our findings suggest that diabetes-associated chronic inflammatory response may have contributed to impaired socket wound healing and rendered oral wound susceptible to the development of BRONJ via NLRP3 activation in macrophages.

Ossifying fibroma tumor stem cells are maintained by epigenetic regulation of a TSP1/TGF-β/SMAD3 autocrine loop

Abnormal stem cell function makes a known contribution to many malignant tumors, but the role of stem cells in benign tumors is not well understood. Here, we show that ossifying fibroma (OF) contains a stem cell population that resembles mesenchymal stem cells (OFMSCs) and is capable of generating OF-like tumor xenografts. Mechanistically, OFMSCs show enhanced TGF-β signaling that induces aberrant proliferation and deficient osteogenesis via Notch and BMP signaling pathways, respectively. The elevated TGF-β activity is tightly regulated by JHDM1D-mediated epigenetic regulation of thrombospondin-1 (TSP1), forming a JHDM1D/TSP1/TGF-β/SMAD3 autocrine loop. Inhibition of TGF-β signaling in OFMSCs can rescue their abnormal osteogenic differentiation and elevated proliferation rate. Furthermore, chronic activation of TGF-β can convert normal MSCs into OF-like MSCs via establishment of this JHDM1D/TSP1/TGF-β/SMAD3 autocrine loop. These results reveal that epigenetic regulation of TGF-β signaling in MSCs governs the benign tumor phenotype in OF and highlight TGF-β signaling as a candidate therapeutic target.

Selective orexin 2 receptor antagonism blocks cue-induced reinstatement, but not nicotine self-administration or nicotine-induced reinstatement

The orexinergic system has been implicated in a number of behaviors, including reward and incentive motivation. Orexin 1 receptor antagonism has been reported to reduce drug self-administration, conditioned place preference, and reinstatement in rodents, but the role of the orexin 2 receptor is unclear. Here we evaluated the impact of the novel and selective orexin 2 receptor antagonist, 2-SORA 18, on motivation for nicotine as measured by responding on a progressive ratio schedule, as well as cue-induced reinstatement of a response previously associated with nicotine reward, and nicotine-induced reinstatement. 2-SORA 18 demonstrated selective effects on these behaviors. Specifically, doses up to 60 mg/kg 2-SORA 18 were without significant effect on nicotine self-administration or nicotine-induced reinstatement, but doses as low as 15 mg/kg 2-SORA 18 completely blocked cue-induced reinstatement. These findings indicate that orexin 2 receptor antagonism might have utility for attenuating relapse, particularly for patients sensitive to environmental stimuli associated with drug taking.

Antiresorptive drug-related osteonecrosis of the jaw

Nitrogen-containing and non-nitrogen-containing bisphosphonates have been implicated in the development of osteonecrosis of the jaw (ONJ), a condition termed bisphosphonate-related OHJ. Other antiresorptive drugs have been implicated in the development of OHJ, hence the new term antiresorptive drug-related ONJ. The underlying pathogenesis remains unclear, and no definite diagnosis or cure has been established for this debilitating condition. This article reviews some of the most common antiresorptive drugs with their associated risks of ONJ and the current understanding of the pathogenesis ONJ, and summarizes current clinical guidelines.

Bowman birk inhibitor concentrate and oral leukoplakia: a randomized phase IIb trial

Oral premalignancy serves as an ideal model for study of chemopreventive agents. Although 13-cis-retinoic acid showed reversal of oral premalignancy, toxicity, and reversal of clinical response after cessation of therapy obviated its widespread use. A search for nontoxic agents with cancer preventive activity led us to evaluate Bowman Birk Inhibitor (BBI) formulated as BBI Concentrate (BBIC). We previously reported encouraging results in a phase IIa trial of BBIC in patients with oral leukoplakia with measurable clinical responses and favorable biomarker changes. On the basis of these results, we undertook a randomized, placebo controlled phase IIb trial with patients receiving BBIC or placebo for 6 months, with assessment of clinical response and change in lesion area as primary end point and an intent-to-treat analysis. One hundred and thirty two subjects were randomized; and 89 subjects completed six months on study drug or placebo. Both placebo and BBIC showed a statistically significant decrease in mean lesion area of 17.1% and 20.6%, respectively, and partial or greater clinical responses of 30% and 28% respectively. No significant difference between placebo and study drug arms was observed. Histologic review, review of photographs of lesions, and comparison of serum neu protein and oral mucosal cell protease activity also did not show significant differences between study arms. Probable reasons for these negative results were considered, are discussed, and include a placebo with non-BBIC clinical activity and reduced pharmacokinetic availability of the second batch of BBIC. This experience should be a strong cautionary note to those considering "Green" chemoprevention.

Proceedings from the 2013 American Association of Oral and Maxillofacial Surgeons Research Summit

The American Association of Oral and Maxillofacial Surgeons, the Oral and Maxillofacial Surgery Foundation, and the International Association of Oral and Maxillofacial Surgeons sponsored the fifth research summit, which convened on May 2 and 3 in Rosemont, Illinois. The Research Summits are convened biennially to facilitate the discussion and collaboration of oral and maxillofacial surgeons with clinical and basic science researchers in fields affecting the specialty. The goal is to advance the field of oral and maxillofacial surgery through exposure and education in topics that ultimately benefit the oral and maxillofacial surgical patient. This edition of the research summit included the topics of robotic surgery and antiresorptive-related osteonecrosis of the jaws (ARONJ). Most importantly, this research summit saw the development of research interest groups (RIGs) in the fields of anesthesia, maxillofacial oncology and reconstructive surgery, obstructive sleep apnea and orthognathic surgery, temporomandibular joint surgery, and trauma. These RIGs developed specific research goals with a plan to continue working on potential projects at the AAOMS Clinical Trials Course on May 7 to 9, 2013 at the University of Michigan in Ann Arbor. The summit program was developed by the AAOMS Committee on Research Planning and Technology Assessment. The charge of the committee is to encourage and promote research within the specialty and to encourage interdisciplinary collaboration. The research summit serves as a platform for oral and maxillofacial surgeons to lead the goal of advancement of research relevant to the specialty. This article provides an overview of the presentations that were made in the sessions on robotic surgery and ARONJ. The research summit keynote address and two additional presentations on patient registries are summarized and updates from the RIGs that were formed at the 2013 research summit are highlighted.

Gingivae contain neural-crest- and mesoderm-derived mesenchymal stem cells

Gingivae represent a unique soft tissue that serves as a biological barrier to cover the oral cavity side of the maxilla and mandible. Recently, the gingivae were identified as containing mesenchymal stem cells (GMSCs). However, it is unknown whether the GMSCs are derived from cranial neural crest cells (CNCC) or the mesoderm. In this study, we show that around 90% of GMSCs are derived from CNCC and 10% from the mesoderm. In comparison with mesoderm MSCs (M-GMSCs), CNCC-derived GMSCs (N-GMSCs) show an elevated capacity to differentiate into neural cells and chondrocytes and induce activated T-cell apoptosis in vitro. When transplanted into mice with dextran sulfate sodium (DSS)-induced colitis, N-GMSCs showed superior effects in ameliorating inflammatory-related disease phenotype in comparison with the M-GMSC treatment group. Mechanistically, the increased immunomodulatory effect of N-GMSCs is associated with up-regulated expression of FAS ligand (FASL), a transmembrane protein that plays an important role in MSC-based immunomodulation. In summary, our study indicates that the gingivae contain both neural-crest- and mesoderm-derived MSCs with distinctive stem cell properties.

Quantification by energy dispersive x-ray spectroscopy of alendronate in the diseased jaw bone of patients with bisphosphonate-related jaw osteonecrosis

OBJECTIVE

Recently, specific in vitro bisphosphonate concentrations have been established for reaching a toxic threshold that could result in the induction of bisphosphonate-related osteonecrosis of the jaw (BRONJ), but these data have not been validated in vivo. The purpose of this study was to quantify the concentration of bisphosphonates (BPs) in the diseased jaw bone of patients experiencing BRONJ.

STUDY DESIGN

We hypothesized that if the average natural nitrogen content of mammalian bone is known, the excess of nitrogen in the jaw bone of BRONJ patients is likely to reflect the concentration of amino-BP. To test our hypothesis, jaw bone specimens from patients with BRONJ were acquired after sequestrectomy and analyzed by energy-dispersive X-ray spectroscopy (EDS).

RESULTS

The EDS analysis of the bone demonstrated a highly linear correlation between increasing concentrations of BP and the increasing percentage of nitrogen measured at the bone surfaces (R(2) = .9851, P = .0149).

CONCLUSIONS

SEM/EDS can be a valuable tool for assessing BP concentration in jaw bone and provides important insight into BP pharmacokinetics and BRONJ.

Adoptive transfer of human gingiva-derived mesenchymal stem cells ameliorates collagen-induced arthritis via suppression of Th1 and Th17 cells and enhancement of regulatory T cell differentiation

OBJECTIVE

Current approaches offer no cures for rheumatoid arthritis (RA). Accumulating evidence has revealed that manipulation of bone marrow-derived mesenchymal stem cells (BM-MSCs) may have the potential to control or even prevent RA, but BM-MSC-based therapy faces many challenges, such as limited cell availability and reduced clinical feasibility. This study in mice with established collagen-induced arthritis (CIA) was undertaken to determine whether substitution of human gingiva-derived mesenchymal stem cells (G-MSCs) would significantly improve the therapeutic effects.

METHODS

CIA was induced in DBA/1J mice by immunization with type II collagen and Freund's complete adjuvant. G-MSCs were injected intravenously into the mice on day 14 after immunization. In some experiments, intraperitoneal injection of PC61 (anti-CD25 antibody) was used to deplete Treg cells in arthritic mice.

RESULTS

Infusion of G-MSCs in DBA/1J mice with CIA significantly reduced the severity of arthritis, decreased the histopathology scores, and down-regulated the production of inflammatory cytokines (interferon-γ and interleukin-17A). Infusion of G-MSCs also resulted in increased levels of CD4+CD39+FoxP3+ cells in arthritic mice. These increases were noted early after infusion in the spleens and lymph nodes, and later after infusion in the synovial fluid. The FoxP3+ Treg cells that were increased in frequency mainly consisted of Helios-negative cells. When Treg cells were depleted, infusion of G-MSCs partially interfered with the progression of CIA. Pretreatment of G-MSCs with a CD39 or CD73 inhibitor significantly reversed the protective effect of G-MSCs on CIA.

CONCLUSION

The role of G-MSCs in controlling the development and severity of CIA mostly depends on CD39/CD73 signals and partially depends on the induction of CD4+CD39+FoxP3+ Treg cells. G-MSCs provide a promising approach for the treatment of autoimmune diseases.

IL-17-mediated M1/M2 macrophage alteration contributes to pathogenesis of bisphosphonate-related osteonecrosis of the jaws

PURPOSE

Osteonecrosis of the jaw (ONJ) is emerging as one of the important complications in cancer patients treated with antiresorptive agents. This study explored the potential role of interleukin (IL)-17-mediated M1/M2 macrophage alterations in the pathogenesis of bisphosphonate-related osteonecrosis of the jaw (BRONJ).

EXPERIMENTAL DESIGN

The expression of IL-17 and M1 and M2 macrophage markers at the local mucosal site of human BRONJ lesions was examined by immunofluorescence studies. BRONJ-like disease was induced in C57BL/6 mice and multiple myeloma-burdened mice by intravenous injection of zoledronate to evaluate the correlation of elevated IL-17 levels with changes in M1 and M2 macrophage phenotypes and the therapeutic effects of blocking IL-17 on pathogenesis of BRONJ-like disease.

RESULTS

Increased T-helper (TH)17 cells and IL-17 cytokine correlate with an increase in M1/M2 macrophages ratio at the local mucosal site of both murine and human BRONJ lesion. Convincingly, in mice burdened with multiple myeloma, a combination of elevated suprabasal level and drug-induced IL-17 activity augmented the incidence of BRONJ; both systemic increase of IL-17 and disease severity could be reversed by adoptive transfer of ex vivo expanded M2 macrophages. Targeting IL-17 via specific neutralizing antibodies or a small inhibitory molecule, laquinimod, significantly decreased M1/M2 ratio and concomitantly suppressed BRONJ-like condition in mice. Mechanistically, IL-17 enhanced IFN-γ-induced M1 polarization through augmenting STAT-1 phosphorylation while suppressing IL-4-mediated M2 conversion via inhibiting STAT-6 activation.

CONCLUSIONS

These findings have established a compelling linkage between activated IL-17-mediated polarization of M1 macrophages and the development of BRONJ-like conditions in both human disease and murine models.

Evaluation of chemically diverse 5-HT₂c receptor agonists on behaviours motivated by food and nicotine and on side effect profiles

RATIONALE

Selective 5-HT2C receptor agonists, such as lorcaserin, are being developed for the treatment of obesity. Studies suggest that they may also have therapeutic potential for addictive behaviours including nicotine dependence, although few drugs of this class have been evaluated.

OBJECTIVES

The primary aim was to evaluate the highly selective 5-HT2C agonist, CP-809101, against food-motivated (operant FR5 and progressive ratio schedules, palatability-induced feeding) and nicotine-motivated (intravenous self-administration, drug discrimination) behaviours in rats and to compare with equivalent findings for the structurally distinct 5-HT2C receptor agonists lorcaserin and Ro 60-0175. The secondary aims were to evaluate the side effect profiles of lorcaserin and CP-809101 and to determine the plasma levels of lorcaserin at a dose (1 mg/kg) that reduces both food and nicotine reinforcement for comparison to plasma concentrations reported in human trials.

RESULTS

CP-809101 (0.3-3 mg/kg SC) reduced responding for both nicotine and food and blocked the discriminative stimulus properties of nicotine in a similar manner to lorcaserin and Ro 60-0175. Behaviours such as hypolocomotion, chewing and ptosis became evident following both CP-809101 and lorcaserin administration at higher doses. Plasma levels of lorcaserin were of similar range to those reported in obesity trials.

CONCLUSIONS

These studies support the utility of 5-HT2C agonists as a therapeutic approach to treat nicotine dependence. Plasma exposure levels after acute lorcaserin treatment suggest that equivalent dosages could be used to evaluate these drugs in obesity and smoking cessation trials. Finally, there may be differences in the side effect profiles between lorcaserin and CP-809101, raising the possibility for tolerability differences amongst 5-HT2C agonists.

(-)-Epigallocatechin-3-gallate inhibits human papillomavirus (HPV)-16 oncoprotein-induced angiogenesis in non-small cell lung cancer cells by targeting HIF-1α

PURPOSE

To investigate the effects of (-)-epigallocatechin-3-gallate (EGCG) on human papillomavirus (HPV)-16 oncoprotein-induced angiogenesis in non-small cell lung cancer (NSCLC) cells and the underlying mechanisms.

METHODS

NSCLC cells (A549 and NCI-H460) transfected with EGFP plasmids containing HPV-16 E6 or E7 oncogene were treated with different concentrations of EGCG for 16 h. The effects of EGCG on angiogenesis in vitro and in vivo were observed. The expression of HIF-1α, p-Akt, and p-ERK1/2 proteins in NSCLC cells was analyzed by Western blot. The levels of HIF-1α mRNA in NSCLC cells were detected by real-time RT-PCR. The concentration of VEGF and IL-8 in the conditioned media was determined by ELISA. HIF-1α, VEGF, and CD31 expression in A549 xenografted tumors of nude mice was analyzed by immunohistochemistry.

RESULTS

HPV-16 E6 and E7 oncoproteins HIF-1α-dependently promoted angiogenesis in vitro and in vivo, which was inhibited by EGCG. Mechanistically, EGCG inhibited HPV-16 oncoprotein-induced HIF-1α protein expression but had no effect on HIF-1α mRNA expression in NSCLC cells. Additionally, 50 and 100 μmol/L of EGCG significantly reduced the secretion of VEGF and IL-8 proteins induced by HPV-16 E7 oncoprotein in NSCLC A549 cells. Meanwhile, HPV-16 E6 and E7 oncoproteins HIF-1α-dependently enhanced Akt activation in A549 cells, which was suppressed by EGCG. Furthermore, EGCG inhibited HPV-16 oncoprotein-induced HIF-1α and HIF-1α-dependent VEGF and CD31 expression in A549 xenografted tumors.

CONCLUSIONS

EGCG inhibited HPV-16 oncoprotein-induced angiogenesis conferred by NSCLC through the inhibition of HIF-1α protein expression and HIF-1α-dependent expression of VEGF, IL-8, and CD31 as well as activation of Akt, suggesting that HIF-1α may be a potential target of EGCG against HPV-related NSCLC angiogenesis.

The α7nACh-NMDA receptor complex is involved in cue-induced reinstatement of nicotine seeking

Smoking is the leading preventable cause of disease, disability, and premature death. Nicotine, the main psychoactive drug in tobacco, is one of the most heavily used addictive substances, and its continued use is driven through activation of nicotinic acetylcholine receptors (nAChRs). Despite harmful consequences, it is difficult to quit smoking because of its positive effects on mood and cognition that are strong reinforcers contributing to addiction. Furthermore, a formidable challenge for the treatment of nicotine addiction is the high vulnerability to relapse after abstinence. There is no currently available smoking cessation product able to achieve a >20% smoking cessation rate after 52 wk, and there are no medications that directly target the relapse process. We report here that the α7nAChR forms a protein complex with the NMDA glutamate receptor (NMDAR) through a direct protein-protein interaction. Chronic nicotine exposure promotes α7nAChR-NMDAR complex formation. Interestingly, administration of an interfering peptide that disrupts the α7nAChR-NMDAR complex decreased extracellular signal-regulated kinase (ERK) activity and blocked cue-induced reinstatement of nicotine seeking in rat models of relapse, without affecting nicotine self-administration or locomotor activity. Our results may provide a novel therapeutic target for the development of medications for preventing nicotine relapse.

Human oral mucosa and gingiva: a unique reservoir for mesenchymal stem cells

Mesenchymal stem cells (MSCs) represent a heterogeneous population of progenitor cells with self-renewal and multipotent differentiation potential. Aside from their regenerative role, extensive in vitro and in vivo studies have demonstrated that MSCs are capable of potent immunomodulatory effects on a variety of innate and adaptive immune cells. In this article, we will review recent experimental studies on the characterization of a unique population of MSCs derived from human oral mucosa and gingiva, especially their immunomodulatory and anti-inflammatory functions and their application in the treatment of several in vivo models of inflammatory diseases. The ease of isolation, accessible tissue source, and rapid ex vivo expansion, with maintenance of stable stem-cell-like phenotypes, render oral mucosa- and gingiva-derived MSCs a promising alternative cell source for MSC-based therapies.