The Effect of Low-Frequency Pulsed Electromagnetic Fields on the Differentiation of Permanent Dental Pulp Stem Cells into Odontoblasts.

Introduction: Exposure to pulsed electromagnetic field (PEMF) has been revealed to affect the differentiation and proliferation of human mesenchymal stem cells derived from dental pulp multipotent stromal stem cells (DP-MSCs). This study aimed to investigate the differentiation effect of electromagnetic fields (EMFs) on the DP-MSC. Materials and Methods: PEMF was produced by a system comprising a multi-meter autotransformer, solenoid coils, and teslameter. This study included 10 groups of DP-MSCs which underwent different electromagnetic radiation time and beam intensity. Three samples tested for each group. The effect of PEMF with the intensity of 0.5 and 1 mT (mili Tesla) and 50 Hz on the proliferation rate of DP-MSC was evaluated at 20 and 40 minutes per day for seven days. MTT assay was applied to determine the growth and proliferation of DP-MSC. Gene expression of DMP1 for differentiation of DPSCs to odontoblasts was confirmed by Real Time PCR., ANOVA statistical analysis and Kruskal-Wallis test were used to analyze the data. Results: The survival in all exposure groups was significantly higher than that in control except in the group of 40 minutes, 1 mT (P<0.05). In 20 minutes, 0.5 mT exposure, the survival intensity is significantly more than others (P<0.05). In general, the intensity of survival was recorded, 20, 0.5 mT≥20, 1 mT≥40, 0.5 mT≥40, 1 mT respectively. Therefore, according to the obtained results, ELF-EMF increases the survival of cells except for one case (40 minutes, 1 mT), even though the effective underlying mechanisms in this process are still unclear. Conclusions: The results obtained promise that in the future, by placing an important part of the pulp next to the electromagnetic field, the lost part of the pulp can be reconstructed and the dentin barrier can be created.

Synthesis, characterization, and evaluation of Hesperetin nanocrystals for regenerative dentistry.

Hesperetin (HS), a metabolite of hesperidin, is a polyphenolic component of citrus fruits. This ingredient has a potential role in bone strength and the osteogenic differentiation. The bone loss in the orofacial region may occur due to the inflammation response of host tissues. Nanotechnology applications have been harshly entered the field of regenerative medicine to improve the efficacy of the materials and substances. In the current study, the hesperetin nanocrystals were synthesized and characterized. Then, the anti-inflammatory and antioxidative effects of these nanocrystals were evaluated on inflamed human Dental Pulp Stem Cells (hDPSCs) and monocytes (U937). Moreover, the osteoinduction capacity of these nanocrystals was assessed by gene and protein expression levels of osteogenic specific markers including RUNX2, ALP, OCN, Col1a1, and BSP in hDPSCs. The deposition of calcium nodules in the presence of hesperetin and hesperetin nanocrystals was also assessed. The results revealed the successful fabrication of hesperetin nanocrystals with an average size of 100 nm. The levels of TNF, IL6, and reactive oxygen species (ROS) in inflamed hDPSCs and U937 significantly decreased in the presence of hesperetin nanocrystals. Furthermore, these nanocrystals induced osteogenic differentiation in hDPSCs. These results demonstrated the positive and effective role of fabricated nanocrystal forms of this natural ingredient for regenerative medicine purposes.

Salivary biomarkers in cancer.

In recent years, the comprehensive analysis of saliva, i.e., salivaomics, has played an increasing role in biomarker discovery for disease detection in general and cancer specifically. Saliva is a readily accessible, non-invasive and low-cost specimen that can be used to detect biomarkers of clinical relevance. Saliva-based "omics" technologies, which include proteomics, transcriptomics, metabolomics and microbiomics, have rapidly evolved and may be applicable in point-of-care detection, liquid biopsy and nanoscience. Advances in analytical methods has increased the scope and application of salivaomics from solely the oral cavity to the entire physiologic system, and accordingly to personalized medicine. In this chapter, we highlight recent advances in analytical approaches to identify and detect biomarkers in saliva and their potential use as diagnostic, prognostic and therapeutic markers with a focus on cancer.

Application of Collagen and Mesenchymal Stem Cells in Regenerative Dentistry.

Collagen is an important macromolecule of Extracellular Matrix (ECM) in bones, teeth, and temporomandibular joints. Mesenchymal Stem Cells (MSCs) interact with the components of the ECM such as collagen, proteoglycans, Glycosaminoglycans (GAGs), and several proteins on behalf of variable matrix elasticity and bioactive cues. Synthetic collagen-based biomaterials could be effective scaffolds for regenerative dentistry applications due to mimicking of host tissues' ECM. These biomaterials are biocompatible, biodegradable, readily available, and non-toxic to cells whose capability promotes cellular response and wound healing in the craniofacial region. Collagen could incorporate other biomolecules to induce mineralization in calcified tissues like bone and tooth. Moreover, the addition of these molecules or other polymers to collagen-based biomaterials could enhance mechanical properties, which is important in load-bearing areas such as the mandible. A literature review was performed via a reliable internet database (mainly PubMed) based on MeSH keywords. This review first describes the properties of collagen as a key protein in the structure of hard tissues. Then, it introduces different types of collagens, the correlation between collagen and MSCs, and the methods used to modify collagen in regenerative dentistry, including recent progression on the regeneration of periodontium, dentin-pulp complex, and temporomandibular joint by applying collagen. The prospects and challenges of collagen-based biomaterials in the craniofacial region are pointd out.

Bioactive chitosan biguanidine-based injectable hydrogels as a novel BMP-2 and VEGF carrier for osteogenesis of dental pulp stem cells.

Nowadays, vascularization and mineralization of bone defects is the main bottleneck in the bone regeneration field that is needed to be overcome and developed. Here, we prepared novel in-situ formed injectable hydrogels based on chitosan biguanidine and carboxymethylcellulose loaded with vascular endothelial growth factor (VEGF) and recombinant Bone morphogenetic protein 2 (BMP-2) and studied its influence on osteoblastic differentiation of dental pulp stem cells (DPSCs). The sequential release behavior of the VEGF and BMP-2 from hydrogels adjusted with the pattern of normal human bone growth. MTT assay exhibited that these hydrogels were non-toxic and significantly increased DPSCs proliferation. The Real-time PCR and Western blot analysis on CG11/BMP2-VEGF showed significantly higher gene and protein expression of ALP, COL1α1, and OCN. These results were confirmed by mineralization assay by Alizarin Red staining and Alkaline phosphatase enzyme activity. Based on these evaluations, these hydrogel holds potential as an injectable bone tissue engineering platform.

Electrochemical immunoplatform to assist in the diagnosis of oral cancer through the determination of CYFRA 21.1 biomarker in human saliva samples: Preparation of a novel portable biosensor toward non-invasive diagnosis of oral cancer.

In this study, a novel, low-cost, and flexible paper-based electrochemical immunosensor was developed for the bioanalysis of Cyfra 21.1 biomarker in human saliva samples by using stabilization of synthesis Ag nano-ink on the surface of paper using pen-on-paper technology. The employed electrochemical techniques for the evaluation of immunoplatform performance were differential pulse voltammetry and chronoamperometry. Also, the prepared immunosensor showed great ability in the determination of Cyfra21.1 in human saliva specimens. Under the optimized conditions, the obtained linear range was from 0.0025 to 10 ng/mL, and the obtained LLOQ was 0.0025 ng/mL. The developed immunosensor is easy to prepare, sensitive, cost-effective, portable, and simple. So proposed immunoplatform can be an accomplished biodevice in clinical laboratories. The proposed paper-based immunosensor could be a hopefully new and cheap tool for the diagnosis of other biomarkers. Also, the prepared immunosensor showed great ability in the determination of Cyfra21.1 biomarker in human saliva specimens.

Chemical binding of pyrrolidinyl peptide nucleic acid (acpcPNA-T9) probe with AuNPs toward label-free monitoring of miRNA-21: A novel biosensing platform for biomedical analysis and POC diagnostics.

miRNAs are attractive factors in cancer research studies due to their important roles for regulating of gene expression. Because of miRNA-21 expression surplus in many types of cancers, so accurate identification is important. Increasing efforts have caused different methods to improve the sensitivity and specificity of detection. Present study is an attempt to report a new electrochemical label-free PNA-based bioassay for detection of miRNA-21. In this study, gold electrode was modified by gold nanoparticles to improve a functional PNA-based biosensor. The EDS and field emission scanning electron microscope (FE-SEM) were used to detect fabrication of biosensor. The electrochemical behavior of sensor was evaluated after inserting of acpcPNA probes and miRNA-21 on the stucture of electrode and analyzed essential parameters such as various concentration of target miRNA, hybridization time, reproducibility, stability, and applicability. The results of study demonstrated that engineered biosensor was successfully fabricated. The findings showed the highest amount of current in 5 minutes hybridization time, with suitable reproducibility and stability. This innovative miRNA-based biosensor presents a sensitive and specific method in fast and may be lab-on chip assay in future.

Flexible paper-based label-free electrochemical biosensor for the monitoring of miRNA-21 using core-shell Ag@Au/GQD nano-ink: a new platform for the accurate and rapid analysis by low cost lab-on-paper technology.

miRNA-21 is one of the most famous and prominent microRNAs that is important in the development and emergence of cancers. So, the sensitive and selective monitoring of miRNA-21 as a very common biomarker in cancer treatment is necessary. In this work, a novel paper-based electrochemical peptide nucleic acid (PNA) sensor was developed for the detection of miRNA-21 in human plasma samples by using Ag@Au core-shell nanoparticles electrodeposited on graphene quantum dots (GQD) conductive nano-ink (Ag@Au core-shell/GQD nano-ink), which was designed directly by writing pen-on paper technology on the surface of photographic paper. This nano-ink has a great surface area for biomarker immobilization. The prepared paper-based biosensor is very small and cheap, and also has high stability and sensitivity. Hybridization of PNA was measured using various electrochemical techniques, such as cyclic voltammetry (CV), square wave voltammetry (SWV) and chronoamperometry (ChA). FE-SEM (Field Scanning Electron Microscope), TEM (Transmission Electron Microscope), EDS and DLS (Dynamic Light Scattering) tests were performed to identify the engineering safety sensor. Under optimal conditions, the linear range for the calibration curve was from 5 pM to 5 µM, and the achieved LLOQ was 5 pM. The obtained results recommended that the proposed bioassay might be suitable for an early diagnosis of cancer based on the inhibition of the expression of miRNA-21, which activates the enzyme caspase and accelerates apoptotic proteins and death in tumor cells.

Phytochemicals impact on osteogenic differentiation of mesenchymal stem cells.

Medicinal plants have always been utilized for the prevention and treatment of the spread of different diseases all around the world. To name some traditional medicine that has been used over centuries, we can refer to phytochemicals such as naringin, icariin, genistein, and resveratrol gained from plants. Osteogenic differentiation and mineralization of stem cells can be the result of specific bioactive compounds from plants. One of the most appealing choices for therapy can be mesenchymal stem cells (MSCs) because it has a great capability of self-renewal and differentiation into three descendants, namely, endoderm, mesoderm, and ectoderm. Stem cell gives us the glad tidings of great advances in tissue regeneration and transplantation field for treatment of diseases. Using plant bioactive phytochemicals also holds tremendous promises in treating diseases such as osteoporosis. The purpose of the present review article thus is to investigate what are the roles and consequences of phytochemicals on osteogenic differentiation of MSCs.

Bioactive polymeric scaffolds for osteogenic repair and bone regenerative medicine.

The loss of bone tissue is a striking challenge in orthopedic surgery. Tissue engineering using various advanced biofunctional materials is considered a promising approach for the regeneration and substitution of impaired bone tissues. Recently, polymeric supportive scaffolds and biomaterials have been used to rationally promote the generation of new bone tissues. To restore the bone tissue in this context, biofunctional polymeric materials with significant mechanical robustness together with embedded materials can act as a supportive matrix for cellular proliferation, adhesion, and osteogenic differentiation. The osteogenic regeneration to replace defective tissues demands greater calcium deposits, high alkaline phosphatase activity, and profound upregulation of osteocalcin as a late osteogenic marker. Ideally, the bioactive polymeric scaffolds (BPSs) utilized for bone tissue engineering should impose no detrimental impacts and function as a carrier for the controlled delivery and release of the loaded molecules necessary for the bone tissue regeneration. In this review, we provide comprehensive insights into different synthetic and natural polymers used for the regeneration of bone tissue and discuss various technologies applied for the engineering of BPSs and their physicomechanical properties and biological effects.

The effect of electromagnetic fields on survival and proliferation rate of dental pulp stem cells.

Aims: Extremely low-frequency electromagnetic fields (ELF-EMF) can affect biological systems and alter some cell functions like proliferation rate. Dental pulp tissue is known as a source of multipotent stromal stem cells (MSCs), which can be obtained by a less invasive and more available process compared to bone marrow-derived stem cells (BMSCs). This study aimed to consider the effect of ELF-EMF on proliferation rates of human dental pulp stem cells (hDPSCs).Material and methods: ELF-EMF was generated by a system including autotransformer, multi-meter, solenoid coils, teslameter and its probe. The effect of ELF-EMF with the intensity of 0.5 and 1 mT and 50 Hz on the proliferation rate of hDPSCs was assessed in 20 and 40 min per day for 7 days. MTT assay and DAPI test were used to determine the growth and proliferation of DPSCs.Results: Based on MTT, ELF-EMF has maximum effect with the intensity of 1 mT for 20 min/day on the proliferation of hDPSCs. The survival and proliferation rate in all exposure groups were significantly higher than the control group. Based on the data obtained from MTT and DAPI assay, the number of viable cells in the group exposed to 1 mT for 20 min/day was higher than other groups (p < .05).Conclusions: Regarding to the results of this study, 0.5 and 1 mT ELF-EMF can enhance survival and proliferation rates of hDPSCs.

Stem Cell Therapy: Curcumin Does the Trick.

Curcumin is a dietary polyphenol and a bioactive phytochemical agent that possesses anti-inflammatory, antioxidant, anticancer, and chemopreventive properties. Some of the predominant activities of stem cells include regeneration of identical cells and the ability to maintain the proliferation and multipotentiality. However, these cells could be stimulated to differentiate into specific cell types. Curcumin protects some stem cells from toxicity and can stimulate proliferation and differentiation of stem cells. In the present review, we summarize the antioxidant, stemness activity, antiaging, and neuroprotective as well as wound healing and regenerative effects of curcumin.

The effect of hyaluronic acid hydrogels on dental pulp stem cells behavior.

Dental caries and trauma, particularly in childhood, are among the most prevalent teeth problems, which result in the creation of cavities and probably tooth loss. Thus, novel regenerative approaches with high efficiency and less toxicity are required. Stem cell therapy along with the implementation of scaffolds has provided excellent opportunities in the regeneration of teeth structure. Hyaluronic acid (HA) hydrogels have enticed great attention in the field of regenerative medicine. The unique chemical and structural properties of HA and its derivatives have enabled their application in tissue engineering. Several factors such as the location and type of the lesion, teeth age, the type of capping materials determine the success rate of pulp therapy. HA hydrogels have been considered as biocompatible and safe scaffold supports in human dental cell therapies.

Cell junctions and oral health.

The oral cavity and its appendices are exposed to considerable environmental and mechanical stress. Cell junctions play a pivotal role in this context. Among those, gap junctions permit the exchange of compounds between cells, thereby controlling processes such as cell growth and differentiation. Tight junctions restrict paracellular transportation and inhibit movement of integral membrane proteins between the different plasma membrane poles. Adherens junctions attach cells one to another and provide a solid backbone for resisting to mechanistical stress. The integrity of oral mucosa, normal tooth development and saliva secretion depend on the proper function of all these types of cell junctions. Furthermore, deregulation of junctional proteins and/or mutations in their genes can alter tissue functioning and may result in various human disorders, including dental and periodontal problems, salivary gland malfunction, hereditary and infectious diseases as well as tumorigenesis. The present manuscript reviews the role of cell junctions in the (patho)physiology of the oral cavity and its appendices, including salivary glands.

The role of sclerostin and dickkopf-1 in oral tissues - A review from the perspective of the dental disciplines.

Wnt signaling is of high relevance in the development, homeostasis, and regeneration of oral tissues. Therefore, Wnt signaling is considered to be a potential target for therapeutic strategies. The action of Wnt is tightly controlled by the inhibitors sclerostin (SOST) and Dickkopf (DKK)-1. Given the impact of SOST and DKK-1 in hard tissue formation, related diseases and healing, it is of high relevance to understand their role in oral tissues. The clinical relevance of this knowledge is further underlined by systemic and local approaches which are currently in development for treating a variety of diseases such as osteoporosis and inflammatory hard tissue resorption. In this narrative review, we summarize the current knowledge and understanding on the Wnt signaling inhibitors SOST and DKK-1, and their role in physiology, pathology, and regeneration in oral tissues. We present this role from the perspective of the different specialties in dentistry, including endodontics, orthodontics, periodontics, and oral surgery.

The potentials of umbilical cord-derived mesenchymal stem cells in the treatment of multiple sclerosis.

Stem cell therapy has indicated a promising treatment capacity for tissue regeneration. Multiple sclerosis is an autoimmune-based chronic disease, in which the myelin sheath of the central nervous system is destructed. Scientists have not discovered any cure for multiple sclerosis, and most of the treatments are rather palliative. The pursuit of a versatile treatment option, therefore, seems essential. The immunoregulatory and non-chronic rejection characteristics of mesenchymal stem cells, as well as their homing properties, recommend them as a prospective treatment option for multiple sclerosis. Different sources of mesenchymal stem cells have distinct characteristics and functional properties; in this regard, choosing the most suitable cell therapy approach seems to be challenging. In this review, we will discuss umbilical cord/blood-derived mesenchymal stem cells, their identified exclusive properties compared to another adult mesenchymal stem cells, and the expectations of their potential roles in the treatment of multiple sclerosis.

Retraction Note to: Synthesis, characterization and in vitro studies of doxorubicin-loaded magnetic nanoparticles grafted to smart copolymers on A549 lung cancer cell line.

The Editors have retracted this article [1] because Figs. 6a and 6c have been used in three other publications to represent scanning electron micrographs of different nanoparticles [2-4]. The data reported in this article are therefore unreliable. In addition, Fig. 3 was reproduced from [5] with retrospective permission and the credit line should read as follows: "Reprinted from Acta Biomaterialia, Volume 3, Zhang, J. and Misra, R.D.K., Magnetic drug-targeting carrier encapsulated with thermosensitive smart polymer: core-shell nanoparticle carrier and drug release response, pp. 838-850, copyright (2007) with permission from Acta Materialia Inc. Authors Abolfazl Akbarzadeh, Maryam Anzaby, Soodabeh Davaran, Sang Woo Joo and Mohammad Samiei agree to this retraction. Authors Younes Hanifehpour and Hamid Tayefi Nasrabadi have not responded to any correspondence about this retraction.

Targeted cancer drug delivery with aptamer-functionalized polymeric nanoparticles.

Based on exceptional advantages of aptamers, increasing attention has been presented in the utilise of them as targeted ligands for cancer drug delivery. Recently, the progress of aptamer-targeted nanoparticles has presented new therapeutic systems for several types of cancer with decreased toxicity and improved efficacy. We highlight some of the promising formulations of aptamer-conjugated polymeric nanoparticles for specific targeted drug delivery to cancer cells. This review paper focuses on the current progresses in the use of the novel strategies to aptamer-targeted drug delivery for chemotherapy. An extensive literature review was performed using internet database, mainly PubMed based on MeSH keywords. The searches included full-text publications written in English without any limitation in date. The abstracts, reviews, books as well as studies without obvious relating of aptamers as targeted ligands for cancer drug delivery were excluded from the study. The reviewed literature revealed that aptamers with ability to modify and conjugate to various molecules can be used as targeted cancer therapy agents. However, development of aptamers unique to each individual's tumour to the development of personalised medicine seems to be needed.

The Influence of Pro-Inflammatory Factors on Sclerostin and Dickkopf-1 Production in Human Dental Pulp Cells Under Hypoxic Conditions.

Sclerostin (Sost) and dickkopf (Dkk)-1 are inhibitors of the Wnt signaling pathway that plays a role in regenerative processes. Hypoxia-based strategies are used for regenerative approaches, but the influence of hypoxia on Sost and Dkk-1 production in a pro-inflammatory environment is unclear. The aim of this study was to assess if pro-inflammatory molecules have an influence on Sost and Dkk-1 production in dental pulp cells (DPC) under normoxia and hypoxia. Human DPC were treated with interleukin (IL)-1ß, tumor necrosis factor (TNF)α or transforming growth factor (TGF)ß, with L-mimosine (L-MIM) or hypoxia or a combination. Sost and Dkk-1 mRNA and protein levels were measured with qPCR and western blot, respectively. TNFα, TGFß, L-MIM, or combined treatment did not modulate Sost and Dkk-1. IL-1ß downregulated Sost at the mRNA level. Hypoxia alone and together with inflammatory markers downregulated Dkk-1 at the mRNA level. Sost and Dkk-1 protein production was below the detection limit. In conclusion, there is a differential effect of hypoxia and IL-1ß on the mRNA production of Sost and Dkk-1. Pro-inflammatory molecules do not further modulate the effects of L-MIM or hypoxia on Sost and Dkk-1 production in DPC.

Zeolite-silver-zinc nanoparticles: Biocompatibility and their effect on the compressive strength of mineral trioxide aggregate.

BACKGROUND: This study was carried out to evaluate the biocompatibility of zeolite-silver-zinc (Ze-Ag-Zn) nanoparticles and their effect on the compressive strength of Mineral Trioxide Aggregate (MTA). MATERIAL AND METHODS: Biocompatibility was evaluated by an MTT assay on the pulmonary adenocarcinoma cells with 0.05, 0.1, 0.25, 0.5, 1 and 5 mg/mL concentrations of Ze-Ag-Zn. For compressive strength test, four groups containing 15 stainless-steel cylinders with an internal diameter of 4 and a height of 6 mm were prepared and MTA (groups 1 and 2) or MTA + 2% Ze-Ag-Zn (groups 3 and 4) were placed in the cylinders. The compressive strength was evaluated using a universal testing machine 4 days after mixing in groups 1 and 3, and 21 days after mixing in groups 2 and 4. RESULTS: There was no significant difference between cytotoxicity of different concentrations. The highest (52.22±18.92 MPa) and lowest (19.57±5.76 MPa) compressive strength were observed in MTA group after 21 days and in MTA + 2% Ze-Ag-Zn group after four days, respectively. The effect of time and 2% Ze-Ag-Zn on the compressive strength were significant (P<0.05). Mixing MTA with Ze-Ag-Zn significantly reduced and passage of time from day four to 21 significantly increased the compressive strength. CONCLUSIONS: Mixing MTA with 2% Ze-Ag-Zn had an adverse effect on the compressive strength of MTA, but this combination had no cytotoxic effects. Key words:Compressive strength, Cytotoxicity, Mineral Trioxide Aggregate, Nanoparticle, Zeolite-Silver-Zinc.