Dexamethasone stimulates differentiation of odontoblast-like cells in human dental pulp cultures

Implications of Gene Therapy in Dentistry and Periodontics: A Narrative Review

The relentless march of technological progress entails constant evolution and adaptation. A concerted effort is underway in medical research to unravel various diseases' cellular and molecular underpinnings. The traditional approaches to disease treatment often fall short of delivering entirely satisfactory outcomes, which has prompted a shifting spotlight on gene therapy as a versatile solution for many inherited and acquired disorders. Genes, intricate sequences of genetic code, are the complicated blueprints dictating the production of essential proteins within the human body. Remarkably, each individual's genetic makeup is uniquely distinct, with variations in these genetic sequences serving as the bedrock of our diversity. Gene therapy represents an innovative medical strategy that harnesses the power of genes themselves to function as therapeutic agents. It serves as a conduit through which defective genes are either substituted or mended with the introduction of remedial genetic material. This groundbreaking method can tackle various illnesses, from conditions originating from single-gene abnormalities to intricate disorders influenced by multiple genes. In dentistry and periodontics, gene therapy finds a promising array of applications. It contributes significantly to managing salivary gland disorders, autoimmune diseases, and the regeneration of damaged bone tissue, as well as addressing cancerous and precancerous conditions. Moreover, the possibilities extend into DNA vaccination and broader areas of oral health. The advent of gene therapy in dentistry represents a new era of significant progress, offering substantial advancements in the management of periodontal disease and the reconstruction of the dental alveolar apparatus. The aim of this narrative review is to provide a comprehensive overview of the landscape of gene therapy investigations in these disciplines, shedding light on its potential implications for oral health and treatment. With its potential to rectify the genetic underpinnings of various conditions, gene therapy offers a novel frontier in healthcare that continually shapes the landscape of medicine and holds the promise of more effective and personalised treatments.

Markers of dental pulp stem cells in in vivo developmental context

Teeth and their associated tissues contain several populations of mesenchymal stem cells, one of which is represented by dental pulp stem cells (DPSCs). These cells have mainly been characterised in vitro and numerous positive and negati ve markers for these cells have been suggested. To investigate the presence and localization of these molecules during development, forming dental pulp was examined using the mouse first mandibular molar as a model. The stages corresponding to postnatal (P) days 0, 7, 14, and 21 were investigated. The expression was monitored using customised PCR Arrays. Additionally, in situ localization of the key trio of markers (Cd73, Cd90, Cd105 coded by genes Nt5e, Thy1, Eng) was performed at prenatal and postnatal stages using immunohistochemistry. The expression panel of 24 genes assigned as in vitro markers of DPSCs or mesenchymal stem cells (MSCs) revealed their developmental dynamics during formation of dental pulp mesenchyme. Among the positive markers, Vcam1, Fgf2, Nes were identified as increasing and Cd44, Cd59b, Mcam, Alcam as decreasing between perinatal vs. postnatal stages towards adulthood. Within the panel of negative DPSC markers, Cd14, Itgb2, Ptprc displayed increased and Cd24a decreased levels at later stages of pulp formation. Within the key trio of markers, Nt5e did not show any significant expression difference within the investigated period. Thy1 displayed a strong decrease between P0 and P7 while Eng increased between these stages. In situ localization of Cd73, Cd90 and Cd105 showed them overlap in differentiated odontoblasts and in the sub-odontoblastic layer that is speculated to host odontoblast progenitors. The highly prevalent expression of particularly Cd73 and Cd90 opens the question of potential multiple functions of these molecules. The results from this study add to the in vitro based knowledge by showing dynamics in the expression of DPSC/MSC markers during dental pulp formation in an in vivo context and thus with respect to the natural environment important for commitment of stem cells.

Impact of corticosteroid administration on the response of exposed dental pulp to capping with bioactive cements-experimental study on mongrel dogs

BACKGROUND

Corticosteroids are commonly used as a treatment for a variety of pathological conditions, however, systemic corticosteroid administration has adverse effects including impaired immune response and wound healing. Such complications may affect pulp healing after direct pulp capping. The current study evaluated the influence of corticosteroids on the healing ability of exposed dogs' dental pulps after direct pulp capping (DPC) with bioactive materials.

METHODS

Ten healthy male dogs were assigned randomly into two groups, 5 dogs each: group I represent the control group which did not receive any medication, and group II was given corticosteroid for 45 days before DPC and till the dogs were euthanized (n = 75 teeth for each group). Following mechanical exposure, the pulps were randomly capped with either Ca(OH)_2, MTA, or Biodentine. The pulpal tissues' reaction to the capping materials was evaluated 65 days postoperatively according to the following parameters: calcific bridge formation, pulpal inflammation, pulp necrosis, and bacterial infiltration.

RESULTS

The corticosteroid-treated group revealed no significant difference compared to the control group concerning the pulp healing response (P > 0.05). Both Biodentine and MTA-treated specimens revealed significant differences with Ca(OH)₂-treated specimens (P < 0.05) which displayed a superior positive effect of both MTA and Biodentine to Ca(OH)₂ regarding all the parameters.

CONCLUSIONS

Direct pulp capping technique whenever indicated in subjects treated with corticosteroid immunosuppressive drugs like prednisone performed well in aseptic conditions especially when capped with bioactive materials.

Applications of Gene Therapy in Dentistry: A Review Article

Gene therapy promises to possess a good prospect in bridging the gap between dental applications and medicine. The dynamic therapeutic modalities of gene therapy have been advancing rapidly. Conventional approaches are being revamped to be more comprehensive and pre-emptive, which could do away with the need for surgery and medicine altogether. The complementary base sequences known as genes convey the instructions required to manufacture proteins. The oral cavity is one of the most accessible locations for the therapeutic intervention of gene therapy for several oral tissues. In 1990, the first significant trial of gene therapy was overseen to alleviate adenosine deaminase deficiency. The notion of genetic engineering has become increasingly appealing as a reflection of its benefits over conventional treatment modalities. An example of how this technology may alter dentistry is the implementation of gene therapy for dental and oral ailments. The objective of this article is to examine the effects of gene therapy on the field of dentistry, periodontology and implantology. Furthermore, the therapeutic factors of disease therapy, minimal invasion, and appropriate outcome have indeed been taken into consideration.

Phenytoin Is Promoting the Differentiation of Dental Pulp Stem Cells into the Direction of Odontogenesis/Osteogenesis by Activating BMP4/Smad Pathway

Background

The purpose of this study was the evaluation of the potential and mechanism of phenytoin to promote differentiation of human dental pulp stem cells (hDPSC) into odontoblasts/osteoblasts.

Methods

Fourth-generation human hDPSC originating from healthy pulp of third molars was cultured in control as well as phenytoin-containing media (PHT) for 14 days. qPCR was applied to detect the expression of DSPP, DMP1, and ALP genes. Western blot analysis was used to confirm the findings. One-way analysis of variance (ANOVA) was used for statistical analysis (p < 0.05). Information about phenytoin was assessed from PubChem database, while targets of phenytoin were assessed from six databases. Drug targets were extracted based on the differentially expressed genes (‖logFC‖ ≥ 1, p < 0.05) in the experimental group (50 mg/L PHT, 14 days). GO BP and KEGG pathway enrichment analysis on the obtained drug targets was performed and the target protein functional network diagram was constructed.

Results

A concentration below 200 mg/L PHT had no obvious toxicity to hDPSC. The expression of DSPP, DMP1, and ALP genes in the 50 mg/L PHT concentration group increased significantly. The WB experiment showed that the protein content of BMP4, Smad1/5/9, and p-Smad1/5 was significantly increased in 50 mg/L PHT in comparison with the NC group (the group without treatment of PHT) at 14 days.

Conclusion

Phenytoin has the ability of promoting the differentiation of hDPSC into odontoblasts and osteoblasts. BMP4/Smad pathway, inducing odontogenic/osteogenic differentiation of hDPSC, appears a main process in this context.

In Vitro Toxicity of Bone Graft Materials to Human Mineralizing Cells

Bone graft materials from synthetic, bovine, and human sources were analyzed and tested for in vitro cytotoxicity on dental pulp stem cells (DPSCs) and osteosarcoma cells (Saos-2). Raman spectroscopy indicated significant amounts of collagen only in human bone-derived materials, where the mineral to protein ratio was 3.55 ± 0.45, consistent with bone. X-ray fluorescence revealed tungsten (W) concentrations of 463 ± 73, 400 ± 77, and 92 ± 42 ppm in synthetic, bovine, and human bone chips, respectively. When these chips were added to DPSCs on tissue culture plastic, the doubling times after two days were the same as the controls, 16.5 ± 0.5 h. Those cultured with synthetic or bovine chips were 96.5 ± 8.1 and 25.2 ± 1.4 h, respectively. Saos-2 was more sensitive. During the first two days with allogeneic or bovine graft materials, cell numbers declined. When DPSC were cultured on collagen, allogeneic and bovine bone chips did not increase doubling times. We propose cytotoxicity was associated with tungsten, where only the concentration in human bone chips was below 184 ppm, the value reported as cytotoxic in vitro. Cells on collagen were resistant to bone chips, possibly due to tungsten adsorption by collagen.

Different concentrations of C5a affect human dental pulp mesenchymal stem cells differentiation

Background

During the process of deep decay, when decay approaches the pulp, an immune response is triggered inside the pulp, which activates the complement cascade. The effect of complement component 5a (C5a) on the differentiation of dental pulp mesenchymal stem cells (DPSCs) is related to dentin reparation. The aim of the present study was to stimulate DPSCs with different concentrations of C5a and evaluate the differentiation of odontoblasts using dentin sialoprotein (DSP).

Methods

DPSCs were divided into the following six groups: (i) Control; (ii) DPSCs treated with 50 ng/ml C5a; (iii) DPSCs treated with 100 ng/ml C5a; (iv) DPSCs treated with 200 ng/ml C5a; (v) DPSCs treated with 300 ng/ml C5a; and (vi) DPSCs treated with 400 ng/ml C5a. Flow cytometry and multilineage differentiation potential were used to identify DPSCs. Mineralization induction, Real-time PCR and Western blot were conducted to evaluate the differentiation of odontoblast in the 6 groups.

Result

DPSCs can express mesenchymal stem cell markers, including CD105, CD90, CD73 and, a less common marker, mesenchymal stromal cell antigen-1. In addition, DPSCs can differentiate into adipocytes, neurocytes, chondrocytes and odontoblasts. All six groups formed mineralized nodules after 28 days of culture. Reverse transcription-quantitative PCR and western blotting indicated that the high concentration C5a groups expressed higher DSP levels and promoted DPSC differentiation, whereas the low concentration C5a groups displayed an inhibitory effect.

Conclusion

In this study, the increasing concentration of C5a, which accompanies the immune process in the dental pulp, has demonstrated an enhancing effect on odontoblast differentiation at higher C5a concentrations in vitro.

Effect of treatment with resiniferatoxin in an experimental model of pulpal inflammatory in mice

AIM

To evaluate whether treatment with resiniferatoxin (RTX) is capable of lowering the plasma levels of PGE₂ and TNF-α, as well as histopathological parameters in inflammation of pulp tissue in a mouse experimental model.

METHODOLOGY

Ten groups of six BALB/c mice were formed as follows: healthy group (H_C ), healthy group treated with RTX (H_RTX ), two groups with pulp inflammation at 14 and 18 hours (PI₁₄ /PI₁₈ ), six groups with pulpal inflammation plus treatment with Ibuprofen (IBU₁₄ /IBU₁₈ ), dexamethasone (DEX₁₄ /DEX₁₈ ) and resiniferatoxin (RTX₁₄ /RTX₁₈ ) at 14 and 18 hours, respectively. Pulpal inflammation was induced through occlusal exposure of the pulp of the maxillary first molar. The plasma levels of PGE₂ and TNF-α and the histological parameters of the pulp tissue of the H_C and H_RTX groups were evaluated at the time of acquiring the animals. In the other groups, the plasma levels of PGE₂ and TNF-α and the histopathological parameters were evaluated at 14 and 18 hours after pulp damage. Plasma levels of PGE₂ and TNF-α were quantified by ELISA, and the histopathological parameters were evaluated by H/E staining. Statistical significance was determined by one-way analysis of variance (ANOVA) to test for overall differences between group means.

RESULTS

A significant increase (*p < .05) in plasma levels of PGE₂ and TNF-α occurred 14 and 18 hours after pulp damage. In addition, treatment with RTX significantly decreased (*p < .05) the plasma levels of PGE₂ and TNF-α at 14 and 18 hours after pulp damage, as well as the infiltrate of inflammatory cells at 18 hours after pulp damage, similarly to treatment with ibuprofen and dexamethasone.

CONCLUSION

It was possible to detect systemic levels of PGE₂ and TNF-α at 14 and 18 hours after pulp damage. Likewise, treatment with RTX was associated with an anti-inflammatory effect similar to treatment with ibuprofen and dexamethasone. These findings place resiniferatoxin as a therapeutic alternative in the treatment of inflammatory diseases in Dentistry.

LncRNA MALAT1 Functions as a Competing Endogenous RNA to Regulate BMI1 Expression by Sponging miR-200c/miR-203 in the Control of the Differentiation of Pulp Cells

BACKGROUND

Long non-coding RNAs (lncRNAs) and miRNAs (microRNAs) are considered as key regulators of several biological processes, including dental development. In this study, we explored the lncRNAs and miRNAs which are involved in dental development.

METHOD

Real-time PCR was performed to identify the candidate lncRNAs and miRNAs involved in dental development. Bioinformatics analysis and luciferase assay were carried out to establish the regulatory relationships between MALAT1, miR-203 and miR-200c in dental development.

RESULTS

Among all candidate lncRNAs, only MALAT1 was highly expressed in differentiated human dental pulp cells (hDPCs), and among all candidate miRNAs which are down-regulated in differentiated hDPCs, miR-203, and miR-200c are most decreased. Furthermore, MALAT1 was up-regulated while miR-203 and miR-200c were down-regulated in differentiated hDPCs in a time-dependent manner. MiR-203 and miR-200c were proved to bind to MALAT1. Moreover, BMI1 was identified as a target gene of miR-203 or miR-200c, and BMI1 was time-dependently decreased in hDPCs cultured with odontogenic medium. On the contrary, dentin sialophosphoprotein (DSPP), dentin matrix protein-1 (DMP-1), osteocalcin (OCN), and alkaline phosphatase (ALP), were time-dependently increased in hDPCs cultured with odontogenic medium. Finally, the overexpression of MALAT1 and the knockdown of miR-203/miR-200c both significantly increased the levels of BMI1, DSPP, DMP-1, OCN, and ALP, while the effect of knockdown of miR-203/miR-200c was much stronger than that of the overexpression of MALAT1.

CONCLUSION

Our results demonstrated that MALAT1 functions as a competing endogenous RNA of miR-203 and miR-200c and accordingly promotes BMI1 expression. Therefore, MALAT1 may serve as a biomarker for dental development.

FNDC5/irisin is expressed and regulated differently in human periodontal ligament cells, dental pulp stem cells and osteoblasts

OBJECTIVE

To examine the expression and regulation of fibronectin type III domain-containing protein 5/irisin (FNDC5/irisin) in primary human periodontal ligament (hPDL) cells, dental pulp stem cells (hDPCs) and osteoblasts (hOBs).

METHODS

FNDC5/irisin was identified in sections of paraffin embedded rat maxillae, cryo-sections of 3D cultured spheroids hPDL cells, hDPCs and hOBs, 2D cultured hPDL cells, hDPCs and hOBs by immunohistochemistry. The expression of FNDC5/irisin was identified by qPCR, followed by sequencing of the qPCR product. Regulation of FNDC5/irisin expression in hPDL cells, hDPCs and hOBs were evaluated after administration of different concentrations of irisin and all-trans retinoic acid (ATRA). qPCR and ELISA were used to identify expression and secretion of FNDC5/irisin in odontoblast-like differentiation of hDPCs.

RESULTS

FNDC5/irisin was confirmed to be present in rat periodontium and dental pulp regions, as well as in 2D and 3D cultured hPDL cells, hDPCs and hOBs. BLAST analyses verified the generated nucleotide alignments matched human FNDC5/irisin. FNDC5/irisin gene expression was enhanced during odontoblast-like differentiation of hDPCs whereas the secretion of the protein was decreased compared to control. The protein signals in rat periodontal and pulpal tissues were higher than that of alveolar bone, and the expression of FNDC5/irisin was differently regulated by recombinant irisin and ATRA in hPDL cells and hDPCs compared to hOBs.

CONCLUSIONS

FNDC5/irisin expression was verified in rodent periodontium and dental pulp, and in hPDL cells, hDPCs and hOBs. The FNDC5/irisin expression was regulated by recombinant irisin and ATRA. Finally, expression and secretion of FNDC5/irisin were affected during odontoblast-like differentiation of hDPCs.

Cytotoxicity of NeoMTA Plus, ProRoot MTA and Biodentine on human dental pulp stem cells

Background/purpose

Dental pulp stem cells (DPSCs) play a crucial role in the tissue healing process through odontoblast like cell differentiation. The aim of this study was to evaluate the biocompatibility and compare the potential invitro cytotoxic effects of NeoMTA Plus, ProRootMTA and Biodentine on human dental pulp stem cells (hDPSCs).

Materials and methods

To assess the effects of NeoMTA Plus, ProRoot MTA and Biodentine extracts at 1st, 3rd and 7th d on hDPCs, cell populations was determined by flow cytometry using an Annexin V detection kit. The data were analyzed statistically using the Kruskal–Wallis test. A p < 0.05 was considered as statistically significant.

Results

All groups showed cell viability similar to that of the control group on 1st, 3rd and 7th d. Although Biodentine exhibited higher cell viability rates than the other material groups, no statistically significant differences were noted between the sampled days (p > 0.05).

Conclusion

All materials extracts are not cytotoxic and do not induce apoptosis in the hDPSCs. These results suggest that all the tested materials can lead to positive outcomes when used as reparative biomaterials.

TiO2 nanoparticles synergize with substrate mechanics to improve dental pulp stem cells proliferation and differentiation

Multiple studies exist on the influence of TiO₂ nanoparticle uptake on cell behavior. Yet little is known about the lingering influence of nanoparticles accumulation within the external environment which is particularly important to stem cell differentiation. Herein, dental pulp stem cells were cultured on hard and soft polybutadiene substrates, where 0.1 mg/mL rutile TiO₂ nanoparticles were introduced once, 24 h after plating. In the absence of TiO₂, the doubling time on soft substrate is significantly longer, while addition of TiO₂ decreases it to the same level as on the hard substrate. FACS analysis indicates particle uptake initially at 25% is reduced to 2.5% after 14 days. In the absence of TiO₂, no biomineralization on the soft and snowflake-like hydroxyapatite deposits on the hard substrate are shown at week 4. With the addition of TiO₂, SEM/EDAX reveals copious mineral deposition templated on large banded collagen fibers on both substrates. The mineral-to-matrix ratios analyzed by Raman spectroscopy are unremarkable in the absence of TiO₂. However, with addition of TiO₂, the ratios are consistent with native bone on the hard and dentin on the soft substrates. This is further confirmed by RT-PCR, which showed upregulation of markers consistent with osteogenesis and odontogenesis, respectively.

Follicle-stimulating hormone impairs dental pulp stem cells odontogenic differentiation

In addition to bone, the dentin‐pulp complex is also influenced by menopause, showing a decreased regenerative capacity. High levels of follicle‐stimulating hormone (FSH) during menopause could directly regulate bone metabolism. Here, the role of FSH in the odontogenic differentiation of the dentin‐pulp complex was investigated. Dental pulp stem cells (DPSCs) were isolated. CCK‐8 assays, cell apoptosis assays, Western blotting (WB), real‐time RT‐PCR, alkaline phosphatase activity assays, and Alizarin Red S staining were used to clarify the effects of FSH on the proliferation, apoptosis and odontogenic differentiation of the DPSCs. MAPK pathway‐related factors were explored by WB assays. FSH and its inhibitor were used in OVX rats combined with a direct pulp‐capping model. HE and immunohistochemistry were used to detect reparative dentin formation and related features. The results indicated that FSH significantly decreased the odontogenic differentiation of the DPSCs without affecting cell proliferation and apoptosis. Moreover, FSH significantly activated the JNK signalling pathway, and JNK inhibitor partly rescued the inhibitory effect of FSH on DPSC differentiation. In vivo, FSH treatment attenuated the dentin bridge formation and mineralization‐related protein expression in the OVX rats. Our findings indicated that FSH reduced the odontogenic capacity of the DPSCs and was involved in reparative dentinogenesis during menopause.

Transplantation of human endometrial perivascular cells with elevated CYR61 expression induces angiogenesis and promotes repair of a full-thickness uterine injury in rat

Background

Disruptions of angiogenesis can have a significant effect on the healing of uterine scars. Human endometrial perivascular cells (CD146+PDGFRβ+) function as stem cells in the endometrium. Cysteine-rich angiogenic inducer 61 (CYR61) plays an important role in vascular development. The purpose of this study was to observe the effects of the transplantation of human endometrial perivascular cells (En-PSCs) overexpressing CYR61 on structural and functional regeneration in rat models of partial full-thickness uterine excision.

Methods

We first sorted human En-PSCs from endometrial single-cell suspensions by flow cytometry. Human En-PSCs expressing low or high levels of CYR61 were then generated via transfection with a CYR61-specific small interfering ribonucleic acid (si-CYR61) construct or overexpression plasmid. To establish a rat model of uterine injury, a subset of uterine wall was then resected from each uterine horn in experimental animals. Female rats were randomly assigned to five groups, including a sham-operated group and four repair groups that received either PBS loaded on a collagen scaffold (collagen/PBS), En-PSCs loaded on a collagen scaffold (collagen/En-PSCs), En-PSCs with low CYR61 expression loaded on a collagen scaffold (collagen/si-CYR61 En-PSCs), and En-PSCs overexpressing CYR61 loaded on a collagen scaffold (collagen/ov-CYR61 En-PSCs). These indicated constructs were sutured in the injured uterine area to replace the excised segment. On days 30 and 90 after transplantation, a subset of rats in each group was sacrificed, and uterine tissue was recovered and serially sectioned. Hematoxylin and eosin staining and immunohistochemical staining were then performed. Finally, the remaining rats of each group were mated with fertile male rats on day 90 for a 2-week period.

Results

Sorted En-PSCs expressed all recognized markers of mesenchymal stem cells (MSCs), including CD10, CD13, CD44, CD73, CD90, and CD105, and exhibited differentiation potential toward adipocytes, osteoblasts, and neuron-like cells. Compared with En-PSCs and En-PSCs with low CYR61 expression, En-PSCs with elevated CYR61 expression enhanced angiogenesis by in vitro co-culture assays. At day 90 after transplantation, blood vessel density in the collagen/ov-CYR61 En-PSCs group (11.667 ± 1.287) was greater than that in the collagen/En-PSCs group (7.167 ± 0.672) (P < 0.05) and the collagen/si-CYR61 En-PSCs group (3.750 ± 0.906) (P < 0.0001). Pregnancy rates differed among groups, from 40% in the collagen/PBS group to 80% in the collagen/En-PSCs group, 12.5% in the collagen/si-CYR61 En-PSCs group, and 80% in the collagen/ov-CYR61 En-PSCs group. In addition, four embryos were evident in the injured uterine horns of the collagen/ov-CYR61 En-PSCs group, while no embryos were identified in the injured uterine horns of the collagen/PBS group.

Conclusions

The results showed that CYR61 plays an important role in angiogenesis. Collagen/ov-CYR61 En-PSCs promoted endometrial and myometrial regeneration and induced neovascular regeneration in injured rat uteri. The pregnancy rate of rats treated with transplantation of collagen/En-PSCs or collagen/ov-CYR61 En-PSCs was improved. Moreover, the number of embryos implantation on the injured area in uterus was increased after transplantation of collagen/ov-CYR61 En-PSCs.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1272-3) contains supplementary material, which is available to authorized users.

Regulating substrate mechanics to achieve odontogenic differentiation for dental pulp stem cells on TiO2 filled and unfilled polyisoprene

We have shown that materials other than hydrogels commonly used in tissue engineering can be effective in enabling differentiation of dental pulp stem cells (DPSC). Here we demonstrate that a hydrophobic elastomer, polyisoprene (PI), a component of Gutta-percha, normally used to obturate the tooth canal, can also be used to initiate differentiation of the pulp. We showed that PI substrates without additional coating promote cell adhesion and differentiation, while their moduli can be easily adjusted either by varying the coating thickness or incorporation of inorganic particles. DPSC plated on those PI substrates were shown, using SPM and hysitron indentation, to adjust their moduli to conform to differentially small changes in the substrate modulus. In addition, optical tweezers were used to separately measure the membrane and cytoplasm moduli of DPSC, with and without Rho kinase inhibitor. The results indicated that the changes in modulus were attributed predominantly to changes within the cytoplasm, rather than the cell membrane. CLSM was used to identify cell morphology. Differentiation, as determined by qRT-PCR, of the upregulation of OCN, and COL1α1 as well as biomineralization, characterized by SEM/EDAX, was observed on hard PI substrates in the absence of induction factors, i.e. dexamethasone, with moduli 3-4 MPa, regardless of preparation. SEM showed that even though biomineralization was deposited on both spun cast thin PI and filled thick PI substrates, the minerals were aggregated into large clusters on thin PI, and uniformly distributed on filled thick PI, where it was templated within banded collagen fibers. STATEMENT OF SIGNIFICANCE: This manuscript demonstrates the potential of polyisoprene (PI), an elastomeric polymer, for use in tissue engineering. We show how dental pulp stem cells adjust their moduli continuously to match infinitesimally small changes in substrate mechanics, till a critical threshold is reached when they will differentiate. The lineage of differentiation then becomes a sensitive function of both mechanics and morphology for a given chemical composition. Since PI is a major component of Gutta-percha, the FDA approved material commonly used for obturating the root canal, this work suggests that it can easily be adapted for in vivo use in dental regeneration.

Nano Hydroxyapatite & Mineral Trioxide Aggregate Efficiently Promote Odontogenic Differentiation of Dental Pulp Stem Cells

BACKGROUND:

There has been an urge to shift from conventional therapies to the more promising regenerative strategy since conventional treatment relies on synthetic materials to fill defects and replace missing tissues, lacking the ability to restore the tissues’ physiological architecture and function.

AIM:

The present study focused on the assessment of the role of two commonly used biomaterials namely; mineral trioxide aggregate (MTA) and nano hydroxy-apatite as promoters of odontogenic differentiation of dental pulp stem cells (DPSCs).

METHODS:

DPSCs were isolated, cultured in odontogenic media and divided into three groups; control group, MTA group and nanohydroxyapatite group. Odontogenic differentiation was assessed by tracing genes characteristic of different stages of odontoblasts via qRT-PCR. Calcific nodules formation was evaluated by Alizarin red staining.

RESULTS:

Results demonstrated that both MTA and nanohydroxyapatite were capable of enhancing odontogenic differentiation of DPSCs.

CONCLUSION:

Nano hydroxyapatite was found to have a higher promoting effect. However, in the absence of an odontogenic medium, MTA and nanohydroxyapatite could not enhance the odontogenic differentiation of DPSCs.

High-temperature Requirement Protein A1 Regulates Odontoblastic Differentiation of Dental Pulp Cells via the Transforming Growth Factor Beta 1/Smad Signaling Pathway

INTRODUCTION

Dentinogenesis includes odontoblast differentiation and extracellular matrix maturation as well as dentin mineralization. It is regulated by numerous molecules. High-temperature requirement protein A1 (HtrA1) plays crucial roles in bone mineralization and development and is closely associated with the transforming growth factor beta (TGF-β) signal in osteogenesis differentiation. Simultaneously, the TGF-β1/small mother against decapentaplegic (Smad) signaling pathway is an important signaling pathway in various physiological processes and as a downstream regulation factor of HtrA1. However, the role of HtrA1 and its relationship with the TGF-β1/Smad signaling pathway in dentin mineralization is unknown.

METHODS

We detected the role of HtrA1 and its relationship with the TGF-β1/Smad signaling pathway in odontoblastic differentiation of human dental pulp cells (hDPCs) in this study. First, hDPCs were cultured in mineralized medium, and odontoblastic differentiation was confirmed by investigating mineralized nodule formation, alkaline phosphatase (ALP) activity, and the expression of mineral-associated genes, including ALP, collagen I, and dentin sialophosphoprotein. Then, the expression of HtrA1 and TGF-β1/Smad in hDPCs was investigated in hDPCs during mineralized induction. After HtrA1 knockdown by lentivirus, the mineralized nodule formation, ALP activity, and expression of mineral-associated genes and TGF-β1/Smad genes were investigated to confirm the effect of HtrA1 on odontoblastic differentiation and its relationship with the TGF-β1/Smad signaling pathway.

RESULTS

The expression of HtrA1 and TGF-β1 was increased during odontoblastic differentiation of hDPCs along with the messenger RNA expression of downstream factors of the TGF-β1/Smad signaling pathway. In addition, lentivirus-mediated HtrA1 knockdown inhibited the process of mineralization and the expression of HtrA1 and TGF-β1/Smad genes.

CONCLUSIONS

These findings suggest that HtrA1 might positively regulate odontoblastic differentiation of hDPCs through activation of the TGF-β1/Smad signaling pathway.

In vitro effects of two silicate-based materials, Biodentine and BioRoot RCS, on dental pulp stem cells in models of reactionary and reparative dentinogenesis

Background

Calcium silicate-based cements are biomaterials with calcium oxide and carbonate filler additives. Their properties are close to those of dentin, making them useful in restorative dentistry and endodontics. The aim of this study was to evaluate the in vitro biological effects of two such calcium silicate cements, Biodentine (BD) and Bioroot (BR), on dental stem cells in both direct and indirect contact models. The two models used aimed to mimic reparative dentin formation (direct contact) and reactionary dentin formation (indirect contact). An original aspect of this study is the use of an interposed thin agarose gel layer to assess the effects of diffusible components from the materials.

Results

The two biomaterials were compared and did not modify dental pulp stem cell (DPSC) proliferation. BD and BR showed no significant cytotoxicity, although some cell death occurred in direct contact. No apoptosis or inflammation induction was detected. A striking increase of mineralization induction was observed in the presence of BD and BR, and this effect was greater in direct contact. Surprisingly, biomineralization occurred even in the absence of mineralization medium. This differentiation was accompanied by expression of odontoblast-associated genes. Exposure by indirect contact did not stimulate the induction to such a level.

Conclusion

These two biomaterials both seem to be bioactive and biocompatible, preserving DPSC proliferation, migration and adhesion. The observed strong mineralization induction through direct contact highlights the potential of these biomaterials for clinical application in dentin-pulp complex regeneration.

Effect of Boron on Thymic Cytokine Expression, Hormone Secretion, Antioxidant Functions, Cell Proliferation, and Apoptosis Potential via the Extracellular Signal-Regulated Kinases 1 and 2 Signaling Pathway

Boron is an essential trace element in animals. Appropriate boron supplementation can promote thymus development; however, a high dose of boron can lead to adverse effects and cause toxicity. The influencing mechanism of boron on the animal body remains unclear. In this study, we examined the effect of boron on cytokine expression, thymosin and thymopoietin secretion, antioxidant function, cell proliferation and apoptosis, and extracellular signal-regulated kinases 1 and 2 (ERK1/2) pathway in the thymus of rats. We found that supplementation with 10 and 20 mg/L boron to the drinking water significantly elevated levels of interleukin 2 (IL-2), interferon γ (IFN-γ), interleukin 4 (IL-4), and thymosin α1 in the thymus of rats (p < 0.05), increased the number of positive proliferating cell nuclear antigen (PCNA⁺) cells and concentrations of glutathione peroxidase (GSH-Px) and phosphorylated extracellular signal-regulated kinase (p-ERK) (p < 0.05), and promoted mRNA expression of PCNA and ERK1/2 in thymocytes (p < 0.05). However, the number of caspase-3⁺ cells and the expression level of caspase-3 mRNA were reduced (p < 0.05). Supplementation with 40, 80, and 160 mg/L boron had no apparent effect on many of the above indicators. In contrast, supplementation with 480 and 640 mg/L boron had the opposite effect on the above indicators in rats and elevated levels of pro-inflammatory cytokines, such as interleukin 6 (IL-6), interleukin 1β (IL-1β), and tumor necrosis factor α (TNF-α) (p < 0.05). Our study showed that supplementation of various doses of boron to the drinking water had a U-shaped dose-effect relationship with thymic cytokine expression, hormone secretion, antioxidant function, cell proliferation, and apoptosis. Specifically, supplementation with 10 and 20 mg/L boron promoted thymocyte proliferation and enhanced thymic functions. However, supplementation with 480 and 640 mg/L boron inhibited thymic functions and increased the number of apoptotic thymocytes, suggesting that the effects of boron on thymic functions may be caused via the ERK1/2 signaling pathway.

A New Method to Develop Human Dental Pulp Cells and Platelet-rich Fibrin Complex

INTRODUCTION

Platelet-rich fibrin (PRF) has been used as a scaffold material in various tissue regeneration studies. In the previous methods to combine seed cells with PRF, the structure of PRF was damaged, and the manipulation time in vitro was also increased. The objective of this in vitro study was to explore an appropriate method to develop a PRF-human dental pulp cell (hDPC) complex to maintain PRF structure integrity and to find out the most efficient part of PRF.

METHODS

The PRF-hDPC complex was developed at 3 different time points during PRF preparation: (1) the before centrifugation (BC) group, the hDPC suspension was added to the venous blood before blood centrifugation; (2) the immediately after centrifugation (IAC) group, the hDPC suspension was added immediately after blood centrifugation; (3) the after centrifugation (AC) group, the hDPC suspension was added 10 minutes after blood centrifugation; and (4) the control group, PRF without hDPC suspension. The prepared PRF-hDPC complexes were cultured for 7 days. The samples were fixed for histologic, immunohistochemistry, and scanning electron microscopic evaluation. Real-time polymerase chain reaction was performed to evaluate messenger RNA expression of alkaline phosphatase and dentin sialophosphoprotein. Enzyme-linked immunosorbent assay quantification for growth factors was performed within the different parts of the PRF.

RESULTS

Histologic, immunohistochemistry, and scanning electron microscopic results revealed that hDPCs were only found in the BC group and exhibited favorable proliferation. Real-time polymerase chain reaction revealed that alkaline phosphatase and dentin sialophosphoprotein expression increased in the cultured PRF-hDPC complex. The lower part of the PRF released the maximum quantity of growth factors.

CONCLUSIONS

Our new method to develop a PRF-hDPCs complex maintained PRF structure integrity. The hDPCs were distributed in the buffy coat, which might be the most efficient part of PRF.

Osteoinductive effects of preoperative dexamethasone in human dental pulp stem cells primary culture

AIM

The use of dexamethasone (DEX) in mesenchymal cell culture induces osteoblastic differentiation and, consequently, formation of mineralized tissues. Tissue engineering proposes the development of therapeutic strategies aimed at structural and functional regeneration of biological tissues. In this sense, cell characterization in vitro is critical to ensure the development of such techniques. Our objective was to evaluate the osteoinductive effect of DEX administered as a preoperative medication in primary cell culture of human dental pulp stem cell.

METHODOLOGY

Cells from the third molar pulp were divided into two experimental groups, each with two preoperative medication protocols used in dental practice and differentiated by the intake of DEX in one of them. The assessment of proliferation, differentiation and viability through trypan blue, methylthiazol tetrazolium, and von Kossa and alizarin red assays, respectively, were held within fixed intervals: 7, 14, 21 and 28 days.

CONCLUSION

This study has shown that DEX may influence in vitro human dental pulp stem cell behavior.

Dental Pulp Stem Cells: Current Advances in Isolation, Expansion and Preservation

Dental pulp stem cells (DPSCs) are mesenchymal stem cells with high self-renewal potential that have the ability to differentiate into several cell types. Thus, DPSCs have become a promising source of cells for several applications in regenerative medicine, tissue engineering, and stem cell therapy. Numerous methods have been reported for the isolation, expansion, and preservation of DPSCs. However, methods are diverse and do not follow specific rules or parameters, which can affect stem cell properties, adding more variation to experimental results. In this review, we compare and analyze current experimental evidence to propose some factors that can be useful to establish better methods or improved protocols to prolong the quality of DPSCs. In addition, we highlight other factors related to biological aspects of dental tissue source (e.g., age, genetic background) that should be considered before tooth selection. Although current methods have reached significant advances, optimization is still required to improve culture stability and its maintenance for an extended period without losing stem cell properties. In addition, there is still much that needs to be done toward clinical application due to the fact that most of DPSCs procedures are not currently following good manufacturing practices. The establishment of optimized general or tailored protocols will allow obtaining well-defined DPSCs cultures with specific properties, which enable more reproducible results that will be the basis to develop effective and safe therapies.

The Role of Transient Receptor Potential Cation Channel, Subfamily C, Member 1 in the Odontoblast-like Differentiation of Human Dental Pulp Cells

INTRODUCTION

Calcium ions (Ca²⁺) actively participate in reparative dentin formation by promoting cellular proliferation and differentiation of human dental pulp cells (hDPCs). Transient receptor potential cation channel, subfamily C, member 1 (TRPC1) activates Ca²⁺ entry upon store depletion in a variety of cell types. However, the function of TRPC1 in hDPCs has not been reported. Therefore, we aimed to analyze the role of TRPC1 in hDPCs undergoing odontoblast-like differentiation.

METHODS

Immunohistochemical staining was used to determine the distribution of TRPC1 in pulp tissues. Western blot analysis was used to detect the protein level of TRPC1 in the odontoblast-like differentiation of hDPCs. Knockdown of TRPC1 was performed with an adenoviral vector to evaluate the role of TRPC1 in hDPCs during odontoblast-like differentiation.

RESULTS

The results showed that TRPC1 was highly expressed in the cytoplasm of dental pulp cells, especially in the odontoblast layer of the healthy pulp. Moreover, the protein level of TRPC1 increased in a time-dependent manner during the odontoblast-like differentiation of hDPCs. Importantly, knockdown of TRPC1 attenuated the process of odontoblast-like differentiation as indicated by the reduction in mineralized nodules and the down-regulation of dentin sialophosphoprotein and dentin matrix protein 1. Moreover, knockdown of TRPC1 decreased Ca²⁺ entry to the cytoplasm of hDPCs.

CONCLUSIONS

Our data indicated a pivotal role of TRPC1 in the odontoblastlike differentiation of hDPCs, which may be a therapeutic target to enhance reparative dentin formation.

Perivascular cells and tissue engineering: Current applications and untapped potential

The recent development of tissue engineering provides exciting new perspectives for the replacement of failing organs and the repair of damaged tissues. Perivascular cells, including vascular smooth muscle cells, pericytes and other tissue specific populations residing around blood vessels, have been isolated from many organs and are known to participate to the in situ repair process and angiogenesis. Their potential has been harnessed for cell therapy of numerous pathologies; however, in this Review we will discuss the potential of perivascular cells in the development of tissue engineering solutions for healthcare. We will examine their application in the engineering of vascular grafts, cardiac patches and bone substitutes as well as other tissue engineering applications and we will focus on their extensive use in the vascularization of engineered constructs. Additionally, we will discuss the emerging potential of human pericytes for the development of efficient, vascularized and non-immunogenic engineered constructs.

Immunophenotyping Reveals the Diversity of Human Dental Pulp Mesenchymal Stromal Cells In vivo and Their Evolution upon In vitro Amplification

Mesenchymal stromal/stem cells (MSCs) from human dental pulp (DP) can be expanded in vitro for cell-based and regenerative dentistry therapeutic purposes. However, their heterogeneity may be a hurdle to the achievement of reproducible and predictable therapeutic outcomes. To get a better knowledge about this heterogeneity, we designed a flow cytometric strategy to analyze the phenotype of DP cells in vivo and upon in vitro expansion with stem cell markers. We focused on the CD31⁻ cell population to exclude endothelial and leukocytic cells. Results showed that the in vivo CD31⁻ DP cell population contained 1.4% of CD56⁺, 1.5% of CD146⁺, 2.4% of CD271⁺ and 6.3% of MSCA-1⁺ cells but very few Stro-1⁺ cells (≤ 1%). CD56⁺, CD146⁺, CD271⁺, and MSCA-1⁺ cell subpopulations expressed various levels of these markers. CD146⁺MSCA-1⁺, CD271⁺MSCA-1⁺, and CD146⁺CD271⁺ cells were the most abundant DP-MSC populations. Analysis of DP-MSCs expanded in vitro with a medicinal manufacturing approach showed that CD146 was expressed by about 50% of CD56⁺, CD271⁺, MSCA-1⁺, and Stro-1⁺ cells, and MSCA-1 by 15–30% of CD56⁺, CD146⁺, CD271⁺, and Stro-1⁺ cells. These ratios remained stable with passages. CD271 and Stro-1 were expressed by <1% of the expanded cell populations. Interestingly, the percentage of CD56⁺ cells strongly increased from P1 (25%) to P4 (80%) both in all sub-populations studied. CD146⁺CD56⁺, MSCA-1⁺CD56⁺, and CD146⁺MSCA-1⁺ cells were the most abundant DP-MSCs at the end of P4. These results established that DP-MSCs constitute a heterogeneous mixture of cells in pulp tissue in vivo and in culture, and that their phenotype is modified upon in vitro expansion. Further studies are needed to determine whether co-expression of specific MSC markers confers DP cells specific properties that could be used for the regeneration of human tissues, including the dental pulp, with standardized cell-based medicinal products.

Differentiation of Dental Pulp Stem Cells on Gutta-Percha Scaffolds

Advances in treatment of tooth injury have shown that tooth regeneration from the pulp was a viable alternative of root canal therapy. In this study, we demonstrated that Gutta-percha, nanocomposites primarily used for obturation of the canal, are not cytotoxic and can induce differentiation of dental pulp stem cells (DPSC) in the absence of soluble mediators. Flat scaffolds were obtained by spin coating Si wafers with three Gutta-percha compounds: GuttaCore™, ProTaper™, and Lexicon™. The images of annealed surfaces showed that the nanoparticles were encapsulated, forming surfaces with root mean square (RMS) roughness of 136⁻211 nm. Then, by culturing DPSC on these substrates we found that after some initial difficulty in adhesion, confluent tissues were formed after 21 days. Imaging of the polyisoprene (PI) surfaces showed that biomineral deposition only occurred when dexamethasone was present in the media. Spectra obtained from the minerals was consistent with that of hydroxyapatite (HA). In contrast, HA deposition was observed on all Gutta-percha scaffolds regardless of the presence or absence of dexamethasone, implying that surface roughness may be an enabling factor in the differentiation process. These results indicate that Gutta-percha nanocomposites may be good candidates for pulp regeneration therapy.

Biomineralization on enzymatically cross-linked gelatin hydrogels in the absence of dexamethasone

A mechanical stimulus and chemical induction by dexamethasone have been important factors in dental pulp stem cell (DPSC) differentiation and biomineralization. We have demonstrated that the enzymatically crosslinked gelatin hydrogels are extremely effective substrates for DPSC differentiation towards odontoblasts. DPSCs were seeded on the crosslinked hard (∼8 kPa) and soft (∼0.15 kPa) gelatin hydrogels for 35 days with and without dexamethasone. Odontogenic differentiation markers such as OCN, ALP and DSPP were upregulated after 35 days of culture on crosslinked hydrogels with and without dexamethasone. SEM and Alizarin red staining of the crosslinked hydrogels showed a biomineralized sheet of hydroxyapatite deposits laid by the DPSCs on the top surface and inside the hydrogel. We found that the DPSC differentiation and biomineralization were independent of the hydrogel stiffness and dexamethasone. We hypothesize that this biomineralization was indeed triggered by the surface chemistry of the crosslinked gelatin hydrogels since we did not observe any biomineralization on the uncrosslinked gelatin or mTG. We also showed that the DPSCs, when removed from hard hydrogel surfaces and re-seeded on a TCPS, retained their odontogenic lineage and showed a permanent mineralization effect. Our results show the potential of enzymatically crosslinked gelatin hydrogels as scaffolds for dentin regeneration.

Temporal-controlled Dexamethasone Releasing Chitosan Nanoparticle System Enhances Odontogenic Differentiation of Stem Cells from Apical Papilla

INTRODUCTION

The spatial and temporal control of stem cell differentiation into odontoblast-like cells remains one of the major challenges in regenerative endodontic procedures. The current study aims to synthesize and compare the effect of dexamethasone (Dex) release from 2 variants of Dex-loaded chitosan nanoparticles (CSnp) on the odontogenic differentiation of stem cells from apical papilla (SCAP).

METHODS

Two variants of Dex-loaded CSnp were synthesized by encapsulation (Dex-CSnpI) and adsorption (Dex-CSnpII) methods. The physicochemical characterization of Dex-CSnpI and Dex-CSnpII was assessed by transmission electron microscopy, Zetasizer, and Fourier transform infrared spectroscopy, whereas the Dex release kinetics was assessed by spectrophotometry. A previously characterized SCAP cell line was cultured onto CSnp, Dex-CSnpI, or Dex-CSnpII. The biomineralization potential was determined by alizarin red staining. Alkaline phosphatase, dentin sialophosphoprotein, and dentin matrix protein-1 gene expressions were analyzed by real-time reverse-transcription polymerase chain reaction.

RESULTS

Dex-CSnpI resulted in slower release of Dex compared with Dex-CSnpII, but both demonstrated sustained release of Dex for 4 weeks. Biomineralization of SCAP was significantly higher (P < .05) in presence of Dex-CSnpII compared with that in Dex-CSnpI at 3 weeks. Alkaline phosphatase gene expression was significantly higher in the presence of Dex-CSnpII compared with Dex-CSnpI, with peak expression seen at 2 weeks (P < .05). The expression of odontogenic specific marker dentin matrix protein-1 was significantly higher in presence of Dex-CSnpII compared with Dex-CSnpI at 3 weeks (P < .05).

CONCLUSIONS

Collectively, these data suggest that sustained release of Dex results in enhanced odontogenic differentiation of SCAP. These findings highlight the potential of temporal-controlled delivery of bioactive molecules to direct the spatial- and temporal-controlled odontogenic differentiation of dental stem cells.

Enamel matrix derivative promote primary human pulp cell differentiation and mineralization

Enamel matrix derivative (EMD) has been found to induce reactive dentin formation; however the molecular mechanisms involved are unclear. The effect of EMD (5–50 μg/mL) on primary human pulp cells were compared to untreated cells and cells incubated with 10⁻⁸ M dexamethasone (DEX) for 1, 2, 3, 7, and 14 days in culture. Expression analysis using Affymetrix microchips demonstrated that 10 μg/mL EMD regulated several hundred genes and stimulated the gene expression of proteins involved in mesenchymal proliferation and differentiation. Both EMD and DEX enhanced the expression of amelogenin (amel), and the dentinogenic markers dentin sialophosphoprotein (DSSP) and dentin matrix acidic phosphoprotein 1 (DMP1), as well as the osteogenic markers osteocalcin (OC, BGLAP) and collagen type 1 (COL1A1). Whereas, only EMD had effect on alkaline phosphatase (ALP) mRNA expression, the stimulatory effect were verified by enhanced secretion of OC and COL1A from EMD treated cells, and increased ALP activity in cell culture medium after EMD treatment. Increased levels of interleukin-6 (IL-6), interleukin-8 (IL-8), and monocyte chemoattractant proteins (MCP-1) in the cell culture medium were also found. Consequently, the suggested effect of EMD is to promote differentiation of pulp cells and increases the potential for pulpal mineralization to favor reactive dentine formation.

Effect of Biodentine™ on the proliferation, migration and adhesion of human dental pulp stem cells

OBJECTIVES

To investigate the proliferative, migratory and adhesion effect of Biodentine™, a new tricalcium silicate cement formulation, on the human dental pulp stem cells (hDPSCs).

METHODS

The cell cultures of hDPSCs obtained from impacted third molars were treated with Biodentine™ extract at four different concentrations: Biodentine™ 0.02mg/ml (BD 0.02), Biodentine™ 0.2mg/ml (BD 0.2), Biodentine™ 2mg/ml (BD 2) and Biodentine™ 20mg/ml (BD 20). Human dental pulp stem cells proliferation was evaluated by MTT (3-(4,5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium bromide) and BrdU (5-bromo-2'-deoxyuridine) viability analysis at different times. Migration was investigated by microphotographs of wound healing and transwell migration assays. Adhesion assay was performed as well in presence of BD 0.2, BD 2 and blank control, while qRT-PCR (quantitative real-time reverse-transcriptase polymerase chain) was used for further analysis of the mRNA expression of chemokine and adhesion molecules in hDPSCs.

RESULTS

Biodentine™ significantly increased proliferation of stem cells at BD 0.2 and BD 2 concentrations while decreased significantly at higher concentration of BD 20. BD 0.2 concentration had a statistically significant increased migration and adhesion abilities. In addition, qRT-PCR results showed that BD 0.2 could have effect on the mRNA expression of chemokines and adhesion molecules in human dental pulp stem cells.

CONCLUSIONS

The data imply that Biodentine™ is a bioactive and biocompatible material capable of enhancing hDPSCs proliferation, migration and adhesion abilities.

CLINICAL SIGNIFICANCE

Biodentine™ when placed in direct contact with the pulp during pulp exposure can positively influence healing by enhancing the proliferation, migration and adhesion of human dental pulp stem cells.

Human dental pulp stem cells cultured in serum-free supplemented medium

Growing evidence show that human dental pulp stem cells (DPSCs) could provide a source of adult stem cells for the treatment of neurodegenerative pathologies. In this study, DPSCs were expanded and cultured with a protocol generally used for the culture of neural stem/progenitor cells.

Methodology: DPSC cultures were established from third molars. The pulp tissue was enzymatically digested and cultured in serum-supplemented basal medium for 12 h. Adherent (ADH) and non-adherent (non-ADH) cell populations were separated according to their differential adhesion to plastic and then cultured in serum-free defined N2 medium with epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF). Both ADH and non-ADH populations were analyzed by FACS and/or PCR.

Results: FACS analysis of ADH-DPSCs revealed the expression of the mesenchymal cell marker CD90, the neuronal marker CD56, the transferrin receptor CD71, and the chemokine receptor CXCR3, whereas hematopoietic stem cells markers CD45, CD133, and CD34 were not expressed. ADH-DPSCs expressed transcripts coding for the Nestin gene, whereas expression levels of genes coding for the neuronal markers β-III tubulin and NF-M, and the oligodendrocyte marker PLP-1 were donor dependent. ADH-DPSCs did not express the transcripts for GFAP, an astrocyte marker. Cells of the non-ADH population that grew as spheroids expressed Nestin, β-III tubulin, NF-M and PLP-1 transcripts. DPSCs that migrated out of the spheroids exhibited an odontoblast-like morphology and expressed a higher level of DSPP and osteocalcin transcripts than ADH-DPSCs.

Conclusion: Collectively, these data indicate that human DPSCs can be expanded and cultured in serum-free supplemented medium with EGF and bFGF. ADH-DPSCs and non-ADH populations contained neuronal and/or oligodendrocyte progenitors at different stages of commitment and, interestingly, cells from spheroid structures seem to be more engaged into the odontoblastic lineage than the ADH-DPSCs.

Preparation of a sustained release drug delivery system for dexamethasone by a thermosensitive, in situ forming hydrogel for use in differentiation of dental pulp

In situ forming delivery systems composed of block copolymers are attracting substantial attention due to their ease of use, biocompatibility, and biodegradability. In this study, the thermoresponsive triblock copolymer PLGA-PEG-PLGA was studied as a dexamethasone delivery system. Dexamethasone, a synthetic glucocorticoid, is used clinically to improve inflammation, pain, and the hyperemesis of chemotherapy, and it is applied experimentally as a differentiation factor in tissue engineering. PLGA-PEG-PLGA was synthesised under microwave irradiation for 5 min. The obtained copolymer was characterised to determine its structure and phase transition temperature. An in vitro release study was conducted for various copolymer structures and drug concentrations. The yield of the reaction and HNMR analysis confirmed the appropriateness of the microwave-assisted method for PLGA-PEG-PLGA synthesis. Phase transition temperature was affected by the drug molecule as well as by the copolymer concentration and structure. An in vitro release study demonstrated that release occurs mainly by diffusion and does not depend on the copolymer structure or dexamethasone concentration.

Induction of dental epithelial cell differentiation marker gene expression in non-odontogenic human keratinocytes by transfection with thymosin beta 4

Previous studies have shown that the recombination of cells liberated from developing tooth germs develop into teeth. However, it is difficult to use human developing tooth germ as a source of cells because of ethical issues. Previous studies have reported that thymosin beta 4 (Tmsb4x) is closely related to the initiation and development of the tooth germ. We herein attempted to establish odontogenic epithelial cells from non-odontogenic HaCaT cells by transfection with TMSB4X. TMSB4X-transfected cells formed nodules that were positive for Alizarin-red S (ALZ) and von Kossa staining (calcium phosphate deposits) when cultured in calcification-inducing medium. Three selected clones showing larger amounts of calcium deposits than the other clones, expressed PITX2, Cytokeratin 14, and Sonic Hedgehog. The upregulation of odontogenesis-related genes, such as runt-related transcription factor 2 (RUNX2), Amelogenin (AMELX), Ameloblastin (AMBN) and Enamelin (ENAM) was also detected. These proteins were immunohistochemically observed in nodules positive for the ALZ and von Kossa staining. RUNX2-positive selected TMSB4X-transfected cells implanted into the dorsal subcutaneous tissue of nude mice formed matrix deposits. Immunohistochemically, AMELX, AMBN and ENAM were observed in the matrix deposits. This study demonstrated the possibility of induction of dental epithelial cell differentiation marker gene expression in non-odontogenic HaCaT cells by TMSB4X.

Wnt11 expression in rat dental pulp and promotional effects of Wnt signaling on odontoblast differentiation

Congenital anomalies of wingless-type mouse mammary tumor virus (MMTV) integration site family (Wnt) are frequently accompanied with tooth and dentin abnormality. The aim of this study was to investigate the effects of Wnt signaling on odontoblast differentiation of mouse dental papilla cells (MDPs). Mouse dental papilla cells were cultured in α-modified minimum essential medium containing 10% fetal bovine serum and antibiotics. Odontoblast differentiation was induced by bone morphogenic protein 2 (BMP2), and the expression of odontoblast-specific markers and Wnt-related signaling molecules was analyzed by real-time reverse transcription-polymerase chain reaction and immunohistochemistry. Odontoblast differentiation was evaluated by dentin sialophosphoprotein (Dspp) and dentin matrix protein (DMP) 1 expression. Localization of β-catenin in MDPs was detected by immunocytochemistry using an anti-β-catenin antibody. Dspp expression in MDPs was upregulated in the presence of BMP2. Wnt5a, Wnt11, Lef1 and Tcf4 expression was upregulated in BMP2-treated MDPs. Wnt11 expression was detected in rat dental pulp in vivo, and particularly strong expression of Wnt11 was detected in odontoblasts. Enhanced Dspp and DMP1 expression and alkaline phosphatase activity induced by BMP2 were completely negated by the Wnt antagonist: IWR-1-endo treatment. Nuclear translocation of β-catenin observed in BMP2-treated MDPs was also negated by IWR-1-endo treatment. These results indicate that Wnt signaling upregulates odontoblast marker expression in MDPs, suggesting a promoting effect of Wnt signaling on odontoblast differentiation.

Epigenetic control of skeletal muscle regeneration: Integrating genetic determinants and environmental changes

During embryonic development, pluripotent cells are genetically committed to specific lineages by the expression of cell-type-specific transcriptional activators that direct the formation of specialized tissues and organs in response to developmental cues. Chromatin-modifying proteins are emerging as essential components of the epigenetic machinery, which establishes the nuclear landscape that ultimately determines the final identity and functional specialization of adult cells. Recent evidence has revealed that discrete populations of adult cells can retain the ability to adopt alternative cell fates in response to environmental cues. These cells include conventional adult stem cells and a still poorly defined collection of cell types endowed with facultative phenotype and functional plasticity. Under physiological conditions or adaptive states, these cells cooperate to support tissue and organ homeostasis, and to promote growth or compensatory regeneration. However, during chronic diseases and aging these cells can adopt a pathological phenotype and mediate maladaptive responses, such as the formation of fibrotic scars and fat deposition that progressively replaces structural and functional units of tissues and organs. The molecular determinants of these phenotypic transitions are only emerging from recent studies that reveal how dynamic chromatin states can generate flexible epigenetic landscapes, which confer on cells the ability to retain partial pluripotency and adapt to environmental changes. This review summarizes our current knowledge on the role of the epigenetic machinery as a 'filter' between genetic commitment and environmental signals in cell types that can alternatively promote skeletal muscle regeneration or fibro-adipogenic degeneration.

Boron enhances odontogenic and osteogenic differentiation of human tooth germ stem cells (hTGSCs) in vitro

Stem cell technology has been a great hope for the treatment of many common problems such as Parkinson's disease, Alzheimer's disease, diabetes, cancer, and tissue regeneration. Therefore, the main challenge in hard tissue engineering is to make a successful combination of stem cells and efficient inductors in the concept of stem cell differentiation into odontogenic and osteogenic cell types. Although some boron derivatives have been reported to promote bone and teeth growth in vivo, the molecular mechanism of bone formation has not been elucidated yet. Different concentrations of sodium pentaborate pentahydrate (NaB) were prepared for the analysis of cell toxicity and differentiation evaluations. The odontogenic, osteogenic differentiation and biomineralization of human tooth germ stem cells (hTGSCs) were evaluated by analyzing the mRNA expression levels, odontogenic and osteogenic protein expressions, alkaline phosphatase (ALP) activity, mineralization, and calcium deposits. The NaB-treated group displayed the highest ALP activity and expression of osteo- and odontogenic-related genes and proteins compared to the other groups and baseline. In the current study, increased in vitro odontogenic and osteogenic differentiation capacity of hTGSCs by NaB application has been shown for the first time. The study offers considerable promise for the development of new scaffold systems combined with NaB in both functional bone and tooth tissue engineering.

Enhanced dentin-like mineralized tissue formation by AdShh-transfected human dental pulp cells and porous calcium phosphate cement

The aim of the present study was to investigate the effect of Sonic hedgehog (Shh) on human dental pulp cells (hDPCs) and the potential of complexes with Shh gene modified hDPCs and porous calcium phosphate cement (CPC) for mineralized tissue formation. hDPCs were cultured and transfected with adenoviral mediated human Shh gene (AdShh). Overexpression of Shh and cell proliferation was tested by real-time PCR analysis, western blotting analysis, and MTT analysis, respectively. The odontoblastic differentiation was assessed by alkaline phosphatase (ALP) activity and real-time PCR analysis on markers of Patched-1 (Ptc-1), Smoothened (Smo), Gli 1, Gli 2, Gli 3, osteocalcin (OCN), dentin matrix protein-1 (DMP-1), and dentin sialophosphoprotein (DSPP). Finally, AdShh-transfected hDPCs were combined with porous CPC and placed subcutaneously in nude mice for 8 and 12 weeks, while AdEGFP-transfected and untransfected hDPCs were treated as control groups. Results indicated that Shh could promote proliferation and odontoblastic differentiation of hDPCs, while Shh/Gli 1 signaling pathway played a key role in this process. Importantly, more mineralized tissue formation was observed in combination with AdShh transfected hDPCs and porous CPC, moreover, the mineralized tissue exhibited dentin-like features such as structures similar to dentin-pulp complex and the positive staining for DSPP protein similar to the tooth tissue. These results suggested that the constructs with AdShh-transfected hDPCs and porous CPC might be a better alternative for dental tissue regeneration.

Proliferation and osteo/odontoblastic differentiation of stem cells from dental apical papilla in mineralization-inducing medium containing additional KH(2)PO(4)

OBJECTIVES

Stem cells from the dental apical papilla (SCAPs) can be induced to differentiate along both osteoblast and odontoblast lineages. However, little knowledge is available concerning their differentiation efficiency in osteogenic media containing additional KH2 PO4 .

MATERIALS AND METHODS

Stem cells from the dental apical papilla were isolated from apical papillae of immature third molars and treated with two kinds of mineralization-inducing media, MM1 and MM2, differing in KH2 PO4 concentration. Proliferation and osteo/odontogenic differentiation capacity of MM1/MM2-treated SCAPs were investigated and compared both in vitro and in vivo.

RESULTS

Cell counting and flow cytometry demonstrated that MM2 containing 1.8 mm additional KH2 PO4 significantly enhanced proliferative potential of SCAPs, compared to MM1. Osteo/odontogenic capacity of SCAPs was much better in MM2 medium than in MM1, as indicated by elevated alkaline phosphatase activity, increased calcium deposition and upregulated expression of osteo/odontoblast-specific genes/proteins (for example, runt-related transcription factor 2, osterix, osteocalcin, dentin sialoprotein, and dentin sialophosphoprotein). In vivo transplantation findings proved that SCAPs in MM2 group generated more mineralized tissues, and presented higher expression of osteo/odontoblast-specific proteins (osteocalcin and dentin sialoprotein) than those in the MM1 group.

CONCLUSION

Mineralization-inducing media supplemented with 1.8 mm additional KH2 PO4 significantly enhanced cell proliferation and improved differentiation capacity of SCAPs along osteo/odontogenic cell lineages, compared to counterparts lacking additional KH2 PO4 .

Effect of dentine matrix proteins on human endometrial adult stem-like cells: in vitro regeneration of odontoblasts cells

OBJECTIVE

Human endometrium has enormous regenerative capacity due to the presence of endometrial stem cells. The present study sought to assess the possibility of differentiation of these cells into odontoblast-like cells by in vitro induction.

METHODS

Endometrial stem-like cells were obtained using enzymatic digestion of the biopsy samples of the endometrium after hysterectomy and cultured in Dulbecco's Modified Eagle's Medium (DMEM) which contained dentine non-collagenous proteins (dNCPs). The results were evaluated using the following assays: analysis of morphology, enzymatic assay for measuring alkaline phosphatase activity, Alizarin Red staining to detect in vitro formation of mineralized nodules, immunofluorescence for detection of dentine sialoprotein (DSP) and dentine-matrix protein (DMP1), and Western blotting for DMP1 expression.

RESULTS

Following induction, endometrial stem-like cells demonstrated high alkaline phosphatase activity, and expression of DSP and DMP1 confirmed the odontoblast phenotype. DMP1 level increased in samples treated with dNCPs.

CONCLUSIONS

Study results indicated that odontoblastic differentiation of endometrial stem cells can be induced by extracellular matrix proteins (e.g. dNCPs). The capacity of endometrial stem-like cells to differentiate into odontoblast-like cells under specific conditions gives new insights into the mechanism of odontogenesis and highlights the potential of such approaches for further research on dental tissue regeneration.

Human Dental Pulp Facilitates Bone Regeneration in a Rat Bone Defect Model

The objective of this work was to investigate the osteogenetic ability of the human dental pulp stem cells (hDPSCs) derived from human third molars. We induced alkaline phosphatase (ALP) activity and bone morphogenetic protein 2 (BMP-2) mRNA expression, the markers for bone formation, in hDPSCs by using osteoinductive factors. The implantation of hDPSCs with collagen sponge promoted osteogenesis and fracture healing in the femur of an immunocompromised rat, which was a bone defect model for pseudoarthrosis. Histological analyses revealed that after implantation of the hDPSCs, the size and number of osteoblasts and the rates of osteoid production and mineralization increased to an appreciable extent, whereas the rate of bone resorption decreased. We believe that hDPSC implantation is a simple and safe procedure that can be beneficial in bone regeneration therapy in clinical practice.

Nanodentistry: combining nanostructured materials and stem cells for dental tissue regeneration

Regenerative dentistry represents an attractive multidisciplinary therapeutic approach that complements traditional restorative/surgery techniques and benefits from recent advances in stem cell biology, molecular biology, genomics and proteomics. Materials science is important in such advances to move regenerative dentistry from the laboratory to the clinic. The design of novel nanostructured materials, such as biomimetic matrices and scaffolds for controlling cell fate and differentiation, and nanoparticles for diagnostics, imaging and targeted treatment, is needed. The combination of nanotechnology, which allows the creation of sophisticated materials with exquisite fine structural detail, and stem cell biology turns out to be increasingly useful in regenerative medicine. The administration to patients of dynamic biological agents comprising stem cells, bioactive scaffolds and/or nanoparticles will certainly increase the regenerative impact of dental pathological tissues. This overview briefly describes some of the actual benefits and future possibilities of nanomaterials in the emerging field of stem cell-based regenerative dentistry.