Engineering models of head and neck and oral cancers on-a-chip.

Head and neck cancers (HNCs) rank as the sixth most common cancer globally and result in over 450 000 deaths annually. Despite considerable advancements in diagnostics and treatment, the 5-year survival rate for most types of HNCs remains below 50%. Poor prognoses are often attributed to tumor heterogeneity, drug resistance, and immunosuppression. These characteristics are difficult to replicate using in vitro or in vivo models, culminating in few effective approaches for early detection and therapeutic drug development. Organs-on-a-chip offer a promising avenue for studying HNCs, serving as microphysiological models that closely recapitulate the complexities of biological tissues within highly controllable microfluidic platforms. Such systems have gained interest as advanced experimental tools to investigate human pathophysiology and assess therapeutic efficacy, providing a deeper understanding of cancer pathophysiology. This review outlines current challenges and opportunities in replicating HNCs within microphysiological systems, focusing on mimicking the soft, glandular, and hard tissues of the head and neck. We further delve into the major applications of organ-on-a-chip models for HNCs, including fundamental research, drug discovery, translational approaches, and personalized medicine. This review emphasizes the integration of organs-on-a-chip into the repertoire of biological model systems available to researchers. This integration enables the exploration of unique aspects of HNCs, thereby accelerating discoveries with the potential to improve outcomes for HNC patients.

High-Throughput Bioprinting of Geometrically-Controlled Pre-Vascularized Injectable Microgels for Accelerated Tissue Regeneration.

Successful integration of cell-laden tissue constructs with host vasculature depends on the presence of functional capillaries to provide oxygen and nutrients to the embedded cells. However, diffusion limitations of cell-laden biomaterials challenge regeneration of large tissue defects that require bulk-delivery of hydrogels and cells. Herein, a strategy to bioprint geometrically controlled, endothelial and stem-cell laden microgels in high-throughput is introduced, allowing these cells to form mature and functional pericyte-supported vascular capillaries in vitro, and then injecting these pre-vascularized constructs minimally invasively in-vivo. It is demonstrated that this approach offers both desired scalability for translational applications as well as unprecedented levels of control over multiple microgel parameters to design spatially-tailored microenvironments for better scaffold functionality and vasculature formation. As a proof-of-concept, the regenerative capacity of the bioprinted pre-vascularized microgels is compared with that of cell-laden monolithic hydrogels of the same cellular and matrix composition in hard-to-heal defects in vivo. The results demonstrate that the bioprinted microgels have faster and higher connective tissue formation, more vessels per area, and widespread presence of functional chimeric (human and murine) vascular capillaries across regenerated sites. The proposed strategy, therefore, addresses a significant issue in regenerative medicine, demonstrating a superior potential to facilitate translational regenerative efforts.

3D-printed microgels supplemented with dentin matrix molecules as a novel biomaterial for direct pulp capping.

OBJECTIVES: To develop a 3D-printed, microparticulate hydrogel supplemented with dentin matrix molecules (DMM) as a novel regenerative strategy for dental pulp capping. MATERIALS AND METHODS: Gelatin methacryloyl microgels (7% w/v) mixed with varying concentrations of DMM were printed using a digital light projection 3D printer and lyophilized for 2 days. The release profile of the DMM-loaded microgels was measured using a bicinchoninic acid assay. Next, dental pulp exposure defects were created in maxillary first molars of Wistar rats. The exposures were randomly capped with (1) inert material - negative control, (2) microgels, (3) microgels + DMM 500 µg/ml, (4) microgels + DMM 1000 µg/ml, (5) microgels + platelet-derived growth factor (PDGF 10 ng/ml), or (6) MTA (n = 15/group). After 4 weeks, animals were euthanized, and treated molars were harvested and then processed to evaluate hard tissue deposition, pulp tissue organization, and blood vessel density. RESULTS: All the specimens from groups treated with microgel + 500 µg/ml, microgel + 1000 µg/ml, microgel + PDGF, and MTA showed the formation of organized pulp tissue, tertiary dentin, newly formed tubular and atubular dentin, and new blood vessel formation. Dentin bridge formation was greater and pulp necrosis was less in the microgel + DMM groups compared to MTA. CONCLUSIONS: The 3D-printed photocurable microgels doped with DMM exhibited favorable cellular and inflammatory pulp responses, and significantly more tertiary dentin deposition. CLINICAL RELEVANCE: 3D-printed microgel with DMM is a promising biomaterial for dentin and dental pulp regeneration in pulp capping procedures.

In-vitro models of biocompatibility testing for restorative dental materials: From 2D cultures to organs on-a-chip.

Dental caries is a biofilm-mediated, diet-modulated, multifactorial and dynamic disease that affects more than 90% of adults in Western countries. The current treatment for decayed tissue is based on using materials to replace the lost enamel or dentin. More than 500 million dental restorations are placed annually worldwide, and materials used for these purposes either directly or indirectly interact with dentin and pulp tissues. The development and understanding of the effects of restorative dental materials are based on different in-vitro and in-vivo tests, which have been evolving with time. In this review, we first discuss the characteristics of the tooth and the dentin-pulp interface that are unique for materials testing. Subsequently, we discuss frequently used in-vitro tests to evaluate the biocompatibility of dental materials commonly used for restorative procedures. Finally, we present our perspective on the future directions for biological research on dental materials using tissue engineering and organs on-a-chip approaches. STATEMENT OF SIGNIFICANCE: Dental caries is still the most prevalent infectious disease globally, requiring more than 500 million restorations to be placed every year. Regrettably, the failure rates of such restorations are still high. Those rates are partially based on the fact that current platforms to test dental materials are somewhat inaccurate in reproducing critical components of the complex oral microenvironment. Thus, there is a collective effort to develop new materials while evolving the platforms to test them. In this context, the present review critically discusses in-vitro models used to evaluate the biocompatibility of restorative dental materials and brings a perspective on future directions for tissue-engineered and organs-on-a-chip platforms for testing new dental materials.

Vascular inflammation exposes perivascular cells to SARS-CoV-2 infection.

Pericytes stabilize blood vessels and promote vascular barrier function. However, vessels subjected to pro-inflammatory conditions have impaired barrier function, which has been suggested to potentially expose perivascular cells to SARS-CoV-2. To test this hypothesis, we engineered pericyte-supported vascular capillaries on-a-chip, and determined that the extravasation and binding of spike protein (S1) on perivascular cells of inflamed vessels to be significantly higher that in healthy controls, indicating a potential target to understand COVID-19 vascular complications.

Histological and biochemical effects of preventive and therapeutic vascular photobiomodulation on rat muscle injury.

The intravascular or transcutaneous application of photobiomodulation (PBM) over blood vessels (vascular photobiomodulation, VPBM) has been used for the treatment of inflammatory and chronic conditions with promising systemic results. This study evaluated the VPBM effects on a model of muscle regeneration after acute injury and compared the outcomes of preventive and therapeutic VPBM. Transcutaneous VPBM was administered over the rat's main tail vein. Serum levels of creatine kinase (CK), aspartate aminotransferase (AST), and lactate were evaluated and muscles were processed for macroscopic and microscopic analysis. Preventive and therapeutic VPBM led to decreased inflammatory infiltrate, edema, and myonecrosis but with an increase in immature muscle fibers. CK, AST, and lactate levels were lower in the groups treated with VPBM (lowest concentrations in preventive VPBM application). Preventive and therapeutic VPBM were capable of exerting a positive effect on acute muscle injury repair, with more accentuated results when preventive VPBM was administered.

A dual-ink 3D printing strategy to engineer pre-vascularized bone scaffolds in-vitro.

A functional vascular supply is a key component of any large-scale tissue, providing support for the metabolic needs of tissue-remodeling cells. Although well-studied strategies exist to fabricate biomimetic scaffolds for bone regeneration, success rates for regeneration in larger defects can be improved by engineering microvascular capillaries within the scaffolds to enhance oxygen and nutrient supply to the core of the engineered tissue as it grows. Even though the role of calcium and phosphate has been well understood to enhance osteogenesis, it remains unclear whether calcium and phosphate may have a detrimental effect on the vasculogenic and angiogenic potential of endothelial cells cultured on 3D printed bone scaffolds. In this study, we presented a novel dual-ink bioprinting method to create vasculature interwoven inside CaP bone constructs. In this method, strands of a CaP ink and a sacrificial template material was used to form scaffolds containing CaP fibers and microchannels seeded with vascular endothelial and mesenchymal stem cells (MSCs) within a photo-crosslinkable gelatin methacryloyl (GelMA) hydrogel material. Our results show similar morphology of growing vessels in the presence of CaP bioink, and no significant difference in endothelial cell sprouting was found. Furthermore, our initial results showed the differentiation of hMSCs into pericytes in the presence of CaP ink. These results indicate the feasibility of creating vascularized bone scaffolds, which can be used for enhancing vascular formation in the core of bone scaffolds.

Engineering pericyte-supported microvascular capillaries in cell-laden hydrogels using stem cells from the bone marrow, dental pulp and dental apical papilla.

Engineered tissue constructs require the fabrication of highly perfusable and mature vascular networks for effective repair and regeneration. In tissue engineering, stem cells are widely employed to create mature vascularized tissues in vitro. Pericytes are key to the maturity of these vascular networks, and therefore the ability of stem cells to differentiate into pericyte-like lineages should be understood. To date, there is limited information regarding the ability of stem cells from the different tissue sources to differentiate into pericytes and form microvascular capillaries in vitro. Therefore, here we tested the ability of the stem cells derived from bone marrow (BMSC), dental pulp (DPSC) and dental apical papilla (SCAP) to engineer pericyte-supported vascular capillaries when encapsulated along with human umbilical vein endothelial cells (HUVECs) in gelatin methacrylate (GelMA) hydrogel. Our results show that the pericyte differentiation capacity of BMSC was greater with high expression of α-SMA and NG2 positive cells. DPSC had α-SMA positive cells but showed very few NG2 positive cells. Further, SCAP cells were positive for α-SMA while they completely lacked NG2 positive cells. We found the pericyte differentiation ability of these stem cells to be different, and this significantly affected the vasculogenic ability and quality of the vessel networks. In summary, we conclude that, among stem cells from different craniofacial regions, BMSCs appear more suitable for engineering of mature vascularized networks than DPSCs or SCAPs.

Equivalence of human and bovine dentin matrix molecules for dental pulp regeneration: proteomic analysis and biological function.

OBJECTIVE: To compare proteomics and biological function of human dentin matrix molecules (hDMMs) and bovine dentin matrix molecules (bDMMs). DESIGN: Dentin powder from human or bovine teeth (n = 4) was demineralized in 10% (v/v) ethylenediaminetetraacetic acid for 7 days. The extracts were dialyzed, lyophilized and proteins were characterized using liquid chromatography-tandem mass spectrometry and shotgun proteomic analysis. To study biological function, mouse-derived undifferentiated dental pulp cells (OD21) were treated with 0.01, 0.1 or 1 µg/mL of hDMMs or bDMMs and proliferation was measured after 24 hours and 48 hours using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell migration was assessed after 24 hours using a Boyden chamber. Alizarin Red S staining was used to evaluate mineral formation. RESULTS: There were 307 proteins identified, of which 93 proteins were common to both species. Gene Ontology functional analysis demonstrated similar pattern of biological process in both species which consisted mainly of tissue development and biomineralization. hDMMs and bDMMs both enhanced cell proliferation. After 24 hours, all concentrations of bDMMs promoted cell proliferation (p ≤ 0.05), while hDMMs did not affect proliferation. After 48 hours, groups with 1µg/mL of bDMMs and 0.01µg/mL of hDMMs had increased cell proliferation compared to control (p ≤ 0.0001). All concentrations of hDMMs and bDMMs enhanced cell migration and mineralization (p ≤ 0.0001). CONCLUSION: bDMMs has similar biological functions as hDMMs. Moreover, bDMMs stimulated cell proliferation, migration and differentiation similar to hDMMs.

Synthesis of di- and triacrylamides with tertiary amine cores and their evaluation as monomers in dental adhesive interfaces.

PURPOSE/AIM: In an attempt to increase the service life of dental adhesive interfaces, more hydrolytically and enzymatically-stable methacrylate alternatives, such as methacrylamides, have been proposed. The aim of this study was to investigate polymerization behavior, as well as mechanical and biological properties of experimental adhesives containing multi-functional acrylamides. MATERIALS AND METHODS: Multi-functional acrylamides (N,N-Bis[(3-methylaminoacryl)propyl]methylamine - BMAAPMA, Tris[(2-methylaminoacryl)ethyl]amine - TMAAEA, N,N'-bis(acrylamido) 1,4-diazepane - BAADA, N,N-Diethyl-1,3-bis(acrylamido)propane - DEBAAP) or HEMA (2-Hydroxyethyl methacrylate - control) were added at 40 wt% to UDMA. 0.2 wt% DMPA and 0.4 wt% DPI-PF6 were used as initiators. Polymerization kinetics was followed in real-time in near-IR during photoactivation (320-500 nm, at 630 mW/cm2). Water sorption/solubility and flexural strength/modulus were measured according to ISO 4049. 1H NMR was used to assess monomer degradation kinetics. MTT assay was used to assess cytotoxicity against OD-21 and DPSC cells. Biofilm formation and adhesion were assessed by Luciferase Assay and Impingement technique, respectively. Solvated adhesives (40 vol% ethanol) were used to test interfacial adhesion strength. The results were analyzed by ANOVA/Tukey's test (α = 0.05). RESULTS: In general, the pure methacrylate mixture had higher rate of polymerization (Rpmax), degree of conversion (DC) at Rpmax, and final DC than the acrylamides. Flexural properties after water storage decreased between 11 and 65%, more markedly for acrylamides. Interfacial bond strength was greater and more stable long-term for the newly synthesized acrylamide formulations (less than 4% reduction at 6 months) compared to the methacrylate experimental control (42% reduction at 6 months). HEMA degraded by almost 90%, while the acrylamides showed no degradation in acidic conditions. Cytotoxicity and biofilm formation, in general, were similar for all groups. CONCLUSIONS: Despite demonstrating high water sorption, the acrylamide-containing materials had similar mechanical and biological properties and enhanced interfacial bond strength stability compared to the methacrylate control.

3D Printing of Microgel-Loaded Modular Microcages as Instructive Scaffolds for Tissue Engineering.

Biomaterial scaffolds have served as the foundation of tissue engineering and regenerative medicine. However, scaffold systems are often difficult to scale in size or shape in order to fit defect-specific dimensions, and thus provide only limited spatiotemporal control of therapeutic delivery and host tissue responses. Here, a lithography-based 3D printing strategy is used to fabricate a novel miniaturized modular microcage scaffold system, which can be assembled and scaled manually with ease. Scalability is based on an intuitive concept of stacking modules, like conventional toy interlocking plastic blocks, allowing for literally thousands of potential geometric configurations, and without the need for specialized equipment. Moreover, the modular hollow-microcage design allows each unit to be loaded with biologic cargo of different compositions, thus enabling controllable and easy patterning of therapeutics within the material in 3D. In summary, the concept of miniaturized microcage designs with such straight-forward assembly and scalability, as well as controllable loading properties, is a flexible platform that can be extended to a wide range of materials for improved biological performance.

The effects of photodynamic therapy with blue light and papain-based gel associated with Urucum, on collagen and fibroblasts: a spectroscopic and cytotoxicity analysis.

Papacarie Duo™ is clinically used and has proven effectiveness; however, it is necessary to improve its antimicrobial action. The combined treatment of Papacarie Duo™ with Urucum (Bixa Orellana) could create a potential tool for dental caries treatment; its extract obtained from the seeds' pericarp contains a water-soluble primary pigment (cis-bixin) with smaller amounts of other carotenoids. The dicarboxylic acid salts of cis-norbixin and trans-norbixin occur in heated alkaline solutions. To analyze the absorption spectra and cytotoxicity (with human dermal fibroblasts) in different concentrations of Urucum, associated or not with Papacarie Duo™, we performed this in vitro study. The effects of pure Urucum, Papacarie Duo™, and PapaUrucum™ on the microstructure of collagen were also analyzed. The application of papain-based gel with Urucum did not present cytotoxicity, its exhibit UV absorption spectrum peak around 460 ± 20 nm. Also, it showed that the compound used did not alter the chemical structure of collagen. Consequently, this product could be used as a chemomechanical method to remove dentin caries as well as being a potential product for antimicrobial photodynamic therapy (aPDT) application.

The tooth on-a-chip: a microphysiologic model system mimicking the biologic interface of the tooth with biomaterials.

The tooth has a unique configuration with respect to biomaterials that are used for its treatment. Cells inside of the dental pulp interface indirectly with biomaterials via a calcified permeable membrane, formed by the dentin matrix and several thousands of dentinal tubules (∼2 µm in diameter). Although the cytotoxic response of the dental pulp to biomaterials has been extensively studied, there is a shortage of in vitro model systems that mimic the dentin-pulp interface and enable an improved understanding of the morphologic, metabolic and functional influence of biomaterials on live dental pulp cells. To address this shortage, here we developed an organ-on-a-chip model system which integrates cells cultured directly on a dentin wall within a microfluidic device that replicates some of the architecture and dynamics of the dentin-pulp interface. The tooth-on-a-chip is made out of molded polydimethylsiloxane (PDMS) with a design consisting of two chambers separated by a dentin fragment. To characterize pulp cell responses to dental materials on-chip, stem cells from the apical papilla (SCAPs) were cultured in odontogenic medium and seeded onto the dentin surface, and observed using live-cell microscopy. Next, to evaluate the tooth-on-a-chip as a platform for materials testing, standard dental materials used clinically (2-hydroxyethylmethacrylate - HEMA, phosphoric acid - PA, and Adper-Scotchbond - SB) were tested for cytotoxicity, cell morphology, and metabolic activity on-chip, and compared against standardized off-chip controls. All dental materials had cytotoxic effects in both on-chip and off-chip systems in the following order: HEMA > SB > PA (p < 0.05), and cells presented consistently higher metabolic activity on-chip than off-chip (p < 0.05). Furthermore, the tooth-on-a-chip enabled real-time tracking of gelatinolytic activity in a model hybrid layer (HL) formed in the microdevice, which suggests that dental pulp cells may contribute to the proteolytic activity in the HL more than endogenous proteases. In conclusion, the tooth-on-a-chip is a novel platform that replicates near-physiologic conditions of the pulp-dentin interface and enables live-cell imaging to study dental pulp cell response to biomaterials.

Antibacterial, ester-free monomers: Polymerization kinetics, mechanical properties, biocompatibility and anti-biofilm activity.

OBJECTIVES: Quaternary ammonium (QA) methacrylate monomers have been extensively investigated and demonstrate excellent antibacterial properties. However, the presence of ester bonds makes them prone to degradation in the oral cavity. In this study, ester-free QA monomers based on meth-acrylamides were synthesized and screened for polymerization kinetics, mechanical properties and antibacterial effects. MATERIALS AND METHODS: Tertiary quaternary ammonium acrylamides (AM) and methacrylamides (MAM) with alkyl side chain lengths of 9 and 14 carbons (C9 and C14) were synthesized and incorporated at 10 wt% into experimental composites based on BisGMA:TEGDMA (1:1), camphorquinone/ethyl-4-dimethylaminobenzoate (0.2/0.8 wt%) and 70 wt% barium glass fillers. Analogous methacrylate versions (MA) were used as controls. Degree of conversion (DC) and rate of polymerization (RP) during photoactivation (800 mW/cm2) were followed in real-time with near-IR. Flexural Strength (FS) and Modulus (E) were measured on 2 × 2 × 25 mm bars in 3-point bending after 24 h dry storage and 7-day storage in water at 37 °C. Antimicrobial properties and biofilm adhesion (fouling) were evaluated by bioluminescence (Luciferase Assay) and biofilm removal by water spray microjet impingement test, respectively. Cytotoxicity was assessed by MTT assay on dental pulp stem cells (DPSC). Data were analyzed with one-way ANOVA/Tukey's test (α = 0.05). RESULTS: DC was similar for all groups tested (∼70%). Both MAMs and C14-AM presented significantly lower RP. Under dry conditions, FS (110-120 MPa) and E (8-9 GPa) were similar for all groups. After water storage, all materials presented FS/E similar to the control, except for C14-AM (for FS) and C14-MAM (for E), which were lower. All C14 versions were strongly antibacterial, decreasing the titer counts of biofilm by more than two orders of magnitude in comparison to the control. C9 monomers did not present significant antibacterial nor antifouling properties. And biofilms had approximately equivalent adhesion on the C9 composites as on the control. Cytotoxicity did not show significant differences between the MA and AM versions and the control group. CONCLUSIONS: C14-QA monomers based on methacrylates and meth-acrylamides present strong antibacterial properties, and in general, similar conversion/mechanical properties compared to the methacrylate control. STATEMENT OF SIGNIFICANCE: This work demonstrates the viability of methacrylamides and acrylamides as potential components in dental restorative materials with antimicrobial properties. The use of ester-free polymerizable functionalities has the potential of improving the degradation resistance of these materials long-term. The use of (meth)acrylamides did not interfere with the antimicrobial potential of quaternary ammonium-based materials.

3D-Imaging of Whole Neuronal and Vascular Networks of the Human Dental Pulp via CLARITY and Light Sheet Microscopy.

Direct visualization of the spatial relationships of the dental pulp tissue at the whole-organ has remained challenging. CLARITY (Clear Lipid-exchanged Acrylamide Tissue hYdrogel) is a tissue clearing method that has enabled successful 3-dimensional (3D) imaging of intact tissues with high-resolution and preserved anatomic structures. We used CLARITY to study the whole human dental pulp with emphasis on the neurovascular components. Dental pulps from sound teeth were CLARITY-cleared, immunostained for PGP9.5 and CD31, as markers for peripheral neurons and blood vessels, respectively, and imaged with light sheet microscopy. Visualization of the whole dental pulp innervation and vasculature was achieved. Innervation comprised 40% of the dental pulp volume and the vasculature another 40%. Marked innervation morphological differences between uni- and multiradicular teeth were found, also distinct neurovascular interplays. Quantification of the neural and vascular structures distribution, diameter and area showed that blood vessels in the capillary size range was twice as high as that of nerve fibers. In conclusion whole CLARITY-cleared dental pulp samples revealed 3D-morphological neurovascular interactions that could not be visualized with standard microscopy. This represents an outstanding tool to study the molecular and structural intricacies of whole dental tissues in the context of disease and treatment methods.

Carvacrol/ß-cyclodextrin inclusion complex inhibits cell proliferation and migration of prostate cancer cells.

Carvacrol, a phenolic monoterpene derived from thyme oil has gained wide interest recently because of its anticancer activities. To improve the solubility of carvacrol, the formation of inclusion complexes with ß-cyclodextrin was performed by ultrasound and freeze-drying methods and characterized using thermal analysis, FTIR, XRD, SEM, NMR and HPLC analysis. From these results, carvacrol was successfully complexed within ß-cyclodextrin cavity. Moreover, HPLC analysis demonstrated a higher entrapment efficiency for freeze-drying method (81.20 ±â€¯0.52%) in contrast to ultrasound method (34.02 ±â€¯0.67%). Hence, freeze-drying inclusion complex was evaluated for its antiproliferative effect and cytotoxicity against prostate cancer cell line (PC3) in vitro. Further, freeze-drying complex led to a dose-dependent inhibition in tumor cell growth in 2D and 3D cell culture systems. Altogether, the inclusion of carvacrol in ß-cyclodextrin led to the formation of stable complexes with potent antiproliferative effects against PC3 cells, in vitro. Such an improved cytotoxic effect can be attributed to the enhanced the aqueous solubility and bioavailability of carvacrol by effective complexation in ß-cyclodextrin.

The influence of osteopontin-guided collagen intrafibrillar mineralization on pericyte differentiation and vascularization of engineered bone scaffolds.

Biomimetically mineralized collagen scaffolds are promising for bone regeneration, but vascularization of these materials remains to be addressed. Here, we engineered mineralized scaffolds using an osteopontin-guided polymer-induced liquid-precursor mineralization method to recapitulate bone's mineralized nanostructure. SEM images of mineralized samples confirmed the presence of collagen with intrafibrillar mineral, also EDS spectra and FTIR showed high peaks of calcium and phosphate, with a similar mineral/matrix ratio to native bone. Mineralization increased collagen compressive modulus up to 15-fold. To evaluate vasculature formation and pericyte-like differentiation, HUVECs and hMSCs were seeded in a 4:1 ratio in the scaffolds for 7 days. Moreover, we used RT-PCR to investigate the gene expression of pericyte markers ACTA2, desmin, CD13, NG2, and PDGFRß. Confocal images showed that both nonmineralized and mineralized scaffolds enabled endothelial capillary network formation. However, vessels in the nonmineralized samples had longer vessel length, a larger number of junctions, and a higher presence of αSMA+ mural cells. RT-PCR analysis confirmed the downregulation of pericytic markers in mineralized samples. In conclusion, although both scaffolds enabled endothelial capillary network formation, mineralized scaffolds presented less pericyte-supported vessels. These observations suggest that specific scaffold characteristics may be required for efficient scaffold vascularization in future bone tissue engineering strategies. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1522-1532, 2019.

Photodynamic therapy with Bixa orellana extract and LED for the reduction of halitosis: study protocol for a randomized, microbiological and clinical trial.

BACKGROUND: Halitosis is an unpleasant breath odour that can interfere with the professional life, social life and quality of life of people who suffer from it. A modality of treatment that has been increasing in dentistry is antimicrobial photodynamic therapy (aPDT). Bixa orellana, popularly known as "urucum" is a plant native to Brazil. The seeds are used to produce a dye that is largely used in the food, textile, paint and cosmetic industries. The aim of this study is to verify whether aPDT with Bixa orellana extract and blue light-emitting diodes (LEDs) is effective in reducing halitosis. This method will also be compared with tongue scraping, the most commonly used conventional method for tongue coating removal, and the association of both methods will be evaluated. METHODS/DESIGN: A randomized clinical trial will be conducted at the dental clinic of the Universidade Nove de Julho. Thirty-nine patients will be divided by block randomization into three groups (n = 13) according to the treatment to be performed. In Group 1, tongue scraping will be performed by the same operator in all patients for analysis of the immediate results. Patients will also be instructed on how to use the scraper at home. Group 2 will be treated with aPDT with Bixa orellana extract and the LED light curing device: Valo Cordless Ultradent®. Six points in the tongue dorsum with a distance of 1 cm between them will be irradiated. The apparatus will be pre-calibrated at wavelength 395-480 nm for 20 s and 9.6 J per point. In Group 3, patients will be submitted to the tongue scraping procedure, as well as to the previously explained aPDT. Oral air collection with the Oral Chroma™ and microbiological collections of the tongue coating shall be done before, immediately after and 7 days after treatment for comparison. DISCUSSION: Halitosis treatment is a topic that still needs attention. The results of this trial could support decision-making by clinicians regarding aPDT using blue LEDs for treating halitosis on a daily basis, as most dentists already have this light source in their offices. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03346460 . Registered on 17 November 2017.