Application of Stem Cell Technology in Dental Regenerative Medicine

Kappa-Carrageenan/Chitosan/Gelatin Scaffolds Provide a Biomimetic Microenvironment for Dentin-Pulp Regeneration

This study aims to investigate the impact of kappa-carrageenan on dental pulp stem cells (DPSCs) behavior in terms of biocompatibility and odontogenic differentiation potential when it is utilized as a component for the production of 3D sponge-like scaffolds. For this purpose, we prepared three types of scaffolds by freeze-drying (i) kappa-carrageenan/chitosan/gelatin enriched with KCl (KCG-KCl) as a physical crosslinker for the sulfate groups of kappa-carrageenan, (ii) kappa-carrageenan/chitosan/gelatin (KCG) and (iii) chitosan/gelatin (CG) scaffolds as a control. The mechanical analysis illustrated a significantly higher elastic modulus of the cell-laden scaffolds compared to the cell-free ones after 14 and 28 days with values ranging from 25 to 40 kPa, showing an increase of 27-36%, with the KCG-KCl scaffolds indicating the highest and CG the lowest values. Cell viability data showed a significant increase from days 3 to 7 and up to day 14 for all scaffold compositions. Significantly increasing alkaline phosphatase (ALP) activity has been observed over time in all three scaffold compositions, while the KCG-KCl scaffolds indicated significantly higher calcium production after 21 and 28 days compared to the CG control. The gene expression analysis of the odontogenic markers DSPP, ALP and RunX2 revealed a two-fold higher upregulation of DSPP in KCG-KCl scaffolds at day 14 compared to the other two compositions. A significant increase of the RunX2 expression between days 7 and 14 was observed for all scaffolds, with a significantly higher increase of at least twelve-fold for the kappa-carrageenan containing scaffolds, which exhibited an earlier ALP gene expression compared to the CG. Our results demonstrate that the integration of kappa-carrageenan in scaffolds significantly enhanced the odontogenic potential of DPSCs and supports dentin-pulp regeneration.

Easily attainable and low immunogenic stem cells from exfoliated deciduous teeth enhanced the in vivo bone regeneration ability of gelatin/bioactive glass microsphere composite scaffolds

Repair of critical-size bone defects remains a considerable challenge in the clinic. The most critical cause for incomplete healing is that osteoprogenitors cannot migrate to the central portion of the defects. Herein, stem cells from exfoliated deciduous teeth (SHED) with the properties of easy attainability and low immunogenicity were loaded into gelatin/bioactive glass (GEL/BGM) scaffolds to construct GEL/BGM + SHED engineering scaffolds. An in vitro study showed that BGM could augment the osteogenic differentiation of SHED by activating the AMPK signaling cascade, as confirmed by the elevated expression of osteogenic-related genes, and enhanced ALP activity and mineralization formation in SHED. After implantation in the critical bone defect model, GEL/BGM + SHED scaffolds exhibited low immunogenicity and significantly enhanced new bone formation in the center of the defect. These results indicated that GEL/BGM + SHED scaffolds present a new promising strategy for critical-size bone healing.

Characteristics, Classification, and Application of Stem Cells Derived from Human Teeth

Since mesenchymal stem cells derived from human teeth are characterized as having the properties of excellent proliferation, multilineage differentiation, and immune regulation. Dental stem cells exhibit fibroblast-like microscopic appearance and express mesenchymal markers, embryonic markers, and vascular markers but do not express hematopoietic markers. Dental stem cells are a mixed population with different sensitive markers, characteristics, and therapeutic effects. Single or combined surface markers are not only helpful for understanding the subpopulation of mixed stem cell populations according to cell function but also for improving the stable treatment effect of dental stem cells. Focusing on the discovery and characterization of stem cells isolated from human teeth over the past 20 years, this review outlines the effect of marker sorting on cell proliferation and differentiation ability and the assessment of the clinical application potential. Classified dental stem cells from markers and functional molecules can solve the problem of heterogeneity and ensure the efficacy of cell therapy strategies including dentistry, neurologic diseases, bone repair, and tissue engineering.

Evaluation of cell viability of Human Dental Pulp Stem Cells in Two dimensional and Three dimensional Fibrin Glue Scaffold

Context:

Regenerative endodontics uses the concept of tissue engineering to restore the diseased immature tooth, allowing for continued development of the root to a healthy state. For regenerative endodontics, the use of human dental pulp stem cells (HDPSCs) with appropriate scaffolds and growth factors is imperative.

Aims:

The aim of the study was to evaluate the human dental pulp cell viability in two-dimensional (2D) and 3D fibrin glue scaffold to be used in regenerative endodontics.

Subjects and Methods:

Regenerative potential of HDPSCs was comparatively assessed usings 2D and 3D fibrin glue scaffold. 3D scaffold was made with different concentrations of fibrinogen. Cell morphology was studied under inverted phase-contrast microscopy, and cell proliferation was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay at various time intervals.

Statistical Analysis Used:

Collected data underwent a two-way ANOVA test. The P value of the study was kept 0.05 according to the sample size.

Results:

Study revealed a significant increase in the proliferation of HDPSCs in fibrin glue precoated wells of 2D fibrin glue compared to preseeded cells on day 1 and day 3. The concentration of fibrinogen has a major role in cell viability in 3D fibrin glue scaffold. Homing of HDPSCs in the 3D scaffold improves with time.

Conclusions:

This study concludes that the concentration of fibrin glue has a significant role in HDPSC Viability in 3D scaffold.

Dental pulp stem cells senescence and regenerative potential relationship

Uncomplicated treatments for pulpitis and periodontitis continues to be challenging and regenerative approaches could meet this contingency. Dental pulp stem cells (DPSCs) represent a good candidate for oral recovering therapies. Here, we investigated changes in morphology, proliferation, and in vitro differentiation toward mesenchymal and neuronal phenotypes of human DPSCs harvested from differently aged donors. Aging is a physiologic phenomenon occurring with time that hamper body's capability to maintain homeostasis also affecting the functional reserve. Cytofluorimetric, immunohistochemical, quantitative reverse-transcription polymerase chain reaction (qRT-PCR), and western blot analyses were performed to gain insight for successful regenerative strategies in elderly. We observed a decline in DPSCs proliferation and differentiation potential with age. Interestingly, these cells behaved differently under osteogenic or odontogenic stimuli, showing different age-related mineralization capabilities. Similarly, neurogenic differentiation decreased with age. In conclusion, our observations represent a valid tool for the development of tailored regenerative strategies in an aging society.

Evaluation of the periodontal regenerative properties of patterned human periodontal ligament stem cell sheets

Purpose

The aim of this study was to determine the effects of patterned human periodontal ligament stem cell (hPDLSC) sheets fabricated using a thermoresponsive substratum.

Methods

In this study, we fabricated patterned hPDLSC sheets using nanotopographical cues to modulate the alignment of the cell sheet.

Results

The hPDLSCs showed rapid monolayer formation on various surface pattern widths. Compared to cell sheets grown on flat surfaces, there were no significant differences in cell attachment and growth on the nanopatterned substratum. However, the patterned hPDLSC sheets showed higher periodontal ligamentogenesis-related gene expression in early stages than the unpatterned cell sheets.

Conclusions

This experiment confirmed that patterned cell sheets provide flexibility in designing hPDLSC sheets, and that these stem cell sheets may be candidates for application in periodontal regenerative therapy.

The Effects of Photobiomodulation Delivered by Light-Emitting Diode on Stem Cells from Human Exfoliated Deciduous Teeth: A Study on the Relevance to Pluripotent Stem Cell Viability and Proliferation

OBJECTIVE

Photobiomodulation (PBM) can modulate the proliferation of some types of stem cells. However, few reports have addressed the effects of PBM delivered by light-emitting diode (LED) on stem cells obtained from the pulp tissue of deciduous teeth. The aim of the present study was to investigate the effect of PBM delivered by red LED (630 nm, 75 mW, 37 mW/cm²) with different radiant exposures on the cell cycle, mitochondrial membrane potential, and senescence of stem cells from human exfoliated deciduous teeth (SHED).

MATERIALS AND METHODS

Cultures were irradiated with LED (2, 4, 8, 16, and 32 J/cm²). After 24 h, the cell cycle and mitochondrial membrane potential of the cultures were evaluated using flow cytometry. Nonirradiated cultures served as control.

RESULTS

Cultures irradiated with 16 J/cm² had higher percentages of cells in the synthesis phase than control cultures (p < 0.05), and no significant differences were found regarding the percentage of cells with viable mitochondria between irradiated and control cultures. No significant difference in cell senescence was found between control cultures and cultures irradiated with 2 or 16 J/cm².

CONCLUSIONS

LED irradiation at 630 nm (37 mW/cm², 75 mW) with radiant exposure of 16 J/cm² was capable of inducing a proliferative response in stem cells from the pulp tissue of deciduous teeth without affecting mitochondrial function or inducing senescence.

Biomimetic extracellular matrix mediated somatic stem cell differentiation: applications in dental pulp tissue regeneration

Dental caries is one of the most widely prevalent infectious diseases in the world. It affects more than half of the world's population. The current treatment for necrotic dental pulp tissue arising from dental caries is root canal therapy. This treatment results in loss of tooth sensitivity and vitality making it prone for secondary infections. Over the past decade, several tissue-engineering approaches have attempted regeneration of the dental pulp tissue. Although several studies have highlighted the potential of dental stem cells, none have transitioned into a clinical setting owing to limited availability of dental stem cells and the need for growth factor delivery systems. Our strategy is to utilize the intact ECM of pulp cells to drive lineage specific differentiation of bone marrow derived mesenchymal stem cells. From a clinical perspective, pulp ECM scaffolds can be generated using cell lines and patient specific somatic stem cells can be used for regeneration. Our published results have shown the feasibility of using pulp ECM scaffolds for odontogenic differentiation of non-dental mesenchymal cells. This focused review discusses the issues surrounding dental pulp tissue regeneration and the potential of our strategy to overcome these issues.

Tooth-derived stem cells: Update and perspectives

Tissue engineering is an emerging field of science that focuses on creating suitable conditions for the regeneration of tissues. The basic components for tissue engineering involve an interactive triad of scaffolds, signaling molecules, and cells. In this context, stem cells (SCs) present the characteristics of self-renewal and differentiation capacity, which make them promising candidates for tissue engineering. Although they present some common markers, such as cluster of differentiation (CD)105, CD146 and STRO-1, SCs derived from various tissues have different patterns in relation to proliferation, clonogenicity, and differentiation abilities in vitro and in vivo. Tooth-derived tissues have been proposed as an accessible source to obtain SCs with limited morbidity, and various tooth-derived SCs (TDSCs) have been isolated and characterized, such as dental pulp SCs, SCs from human exfoliated deciduous teeth, periodontal ligament SCs, dental follicle progenitor cells, SCs from apical papilla, and periodontal ligament of deciduous teeth SCs. However, heterogeneity among these populations has been observed, and the best method to select the most appropriate TDSCs for regeneration approaches has not yet been established. The objective of this review is to outline the current knowledge concerning the various types of TDSCs, and discuss the perspectives for their use in regenerative approaches.

Comparison of reprogramming genes in induced pluripotent stem cells and nuclear transfer cloned embryos

The most effective reprogramming methods, somatic cell nuclear transfer (SCNT) and induced pluripotent stem cells (iPSCs), are widely used in biological research and regenerative medicine, yet the mechanism that reprograms somatic cells to totipotency remains unclear and thus reprogramming efficiency is still low. Microarray technology has been employed in analyzing the transcriptomes changes during iPS reprogramming. Unfortunately, it is difficult to obtain enough DNA from SCNT reconstructed embryos to take advantage of this technology. In this study, we aimed to identify critical genes from the transcriptional profile for iPS reprogramming and compared expression levels of these genes in SCNT reprogramming. By integrating gene expression information from microarray databases and published studies comparing somatic cells with either miPSCs or mouse embryonic stem cells (ESCs), we obtained two lists of co-upregulated genes. The gene ontology (GO) enriched analysis of these two lists demonstrated that the reprogramming process is associated with numerous biological processes. Specifically, we selected 32 genes related to heterochromatin, embryonic development, and cell cycle from our co-upregulated gene datasets and examined the gene expression level in iPSCs and SCNT embryos by qPCR. The results revealed that some reprogramming related genes in iPSCs were also expressed in SCNT reprogramming. We established the network of gene interactions that occur with genes differentially expressed in iPS and SCNT reprogramming and then performed GO analysis on the genes in the network. The network genes function in chromatin organization, heterochromatin, transcriptional regulation, and cell cycle. Further researches to improve reprogramming efficiency, especially in SCNT, will focus on functional studies of these selected genes.