In vitro characterization of human dental pulp stem cells isolated by three different methods

Effects of simulated microgravity on dental pulp stem cell stemness

Dental pulp stem cells (DPSCs), a subset of tooth-derived mesenchymal stem cells (MSCs), demonstrate significant promise in clinical stem cell therapy. However, prolonged in vitro expansion commonly results in compromised stemness, limiting therapeutic efficacy. Thus, maintaining the stemness of DPSCs during expansion and culture is a key challenge for regenerative medicine. In the current study, the impact of simulated microgravity (SMG) on DPSC stemness was investigated using the three-dimensional clinostat Cellspace-3D. After SMG treatment for 3 days, DPSCs demonstrated markedly enhanced replicative activity, proliferation efficiency, self-renewal capacity, and effective inhibition of the senescence process. Under specific differentiation induction conditions, DPSCs in the SMG group exhibited superior osteogenic, adipogenic, chondrogenic, and neural differentiation potentials. Additionally, DPSCs exhibited higher expression levels of the MSC surface markers Stro-1 and CD146 and stemness maintenance-related genes Oct4, Nanog, and Sox2 in the SMG group compared to those from the normal gravity (NG) group. To elucidate the potential molecular mechanisms by which SMG influences the stemness of DPSCs, transcriptome sequencing of total RNA was performed, and identified that differentially expressed genes (DEGs) are closely associated with the MAPK signaling pathway. Further verification experiments demonstrated that the MAPK/ERK signaling pathway was activated in the SMG group. In conclusion, SMG effectively maintains the stemness of DPSCs cultivated in vitro, and its mechanism of action may be associated with the activation of the MAPK/ERK signaling pathway.

Intra-Individual Variability of Human Dental Pulp Stem Cell Features Isolated from the Same Donor

It is primarily important to define the standard features and factors that affect dental pulp stem cells (DPSCs) for their broader use in tissue engineering. This study aimed to verify whether DPSCs isolated from various teeth extracted from the same donor exhibit intra-individual variability and what the consequences are for their differentiation potential. The heterogeneity determination was based on studying the proliferative capacity, viability, expression of phenotypic markers, and relative length of telomere chromosomes. The study included 14 teeth (6 molars and 8 premolars) from six different individuals ages 12 to 16. We did not observe any significant intra-individual variability in DPSC size, proliferation rate, viability, or relative telomere length change within lineages isolated from different teeth but the same donor. The minor non-significant variances in phenotype were probably mainly because DPSC cell lines comprised heterogeneous groups of undifferentiated cells independent of the donor. The other variances were seen in DPSC lineages isolated from the same donor, but the teeth were in different stages of root development. We also did not observe any changes in the ability of cells to differentiate into mature cell lines—chondrocytes, osteocytes, and adipocytes. This study is the first to analyze the heterogeneity of DPSC dependent on a donor.

Comparison of Osteogenic Potentials of Dental Pulp and Bone Marrow Mesenchymal Stem Cells Using the New Cell Transplantation Platform, CellSaic, in a Rat Congenital Cleft-Jaw Model

Scaffolds stimulate cell proliferation and differentiation and play major roles in providing growth and nutrition factors in the repair of bone defects. We used the recombinant peptide Cellnest™ to prepare the three-dimensional stem cell complex, CellSaic, and evaluated whether CellSaic containing rat dental pulp stem cells (rDPSCs) was better than that containing rat bone marrow stem cells (rBMSCs). rDPSC-CellSaic or rBMSC-CellSaic, cultured with or without osteogenic induction medium, formed the experimental and control groups, respectively. Osteoblast differentiation was evaluated in vitro and transplanted into a rat model with a congenital jaw fracture. Specimens were collected and evaluated by microradiology and histological analysis. In the experimental group, the amount of calcium deposits, expression levels of bone-related genes (RUNX2, ALP, BSP, and COL1), and volume of mineralized tissue, were significantly higher than those in the control group (p < 0.05). Both differentiated and undifferentiated rDPSC-CellSaic and only the differentiated rBMSC-CellSaic could induce the formation of new bone tissue. Overall, rBMSC-CellSaic and rDPSC-CellSaic made with Cellnest™ as a scaffold, provide excellent support for promoting bone regeneration in rat mandibular congenital defects. Additionally, rDPSC-CellSaic seems a better source for craniofacial bone defect repair than rBMSC-CellSaic, suggesting the possibility of using DPSCs in bone tissue regenerative therapy.

Sinking Our Teeth in Getting Dental Stem Cells to Clinics for Bone Regeneration

Dental stem cells have been isolated from the medical waste of various dental tissues. They have been characterized by numerous markers, which are evaluated herein and differentiated into multiple cell types. They can also be used to generate cell lines and iPSCs for long-term in vitro research. Methods for utilizing these stem cells including cellular systems such as organoids or cell sheets, cell-free systems such as exosomes, and scaffold-based approaches with and without drug release concepts are reported in this review and presented with new pictures for clarification. These in vitro applications can be deployed in disease modeling and subsequent pharmaceutical research and also pave the way for tissue regeneration. The main focus herein is on the potential of dental stem cells for hard tissue regeneration, especially bone, by evaluating their potential for osteogenesis and angiogenesis, and the regulation of these two processes by growth factors and environmental stimulators. Current in vitro and in vivo publications show numerous benefits of using dental stem cells for research purposes and hard tissue regeneration. However, only a few clinical trials currently exist. The goal of this review is to pinpoint this imbalance and encourage scientists to pick up this research and proceed one step further to translation.

Isolation, Characterization, and Differentiation of Stem Cells From Various Dental Sources: An In Vitro Study

Aim:

The aim of the current study was to isolate stem cells from various dental sources such as dental pulp, periodontal ligament (PDL), and apical papilla, and to characterize stem cells by staining for the presence/absence of specific surface markers and also to differentiate stem cells into osteogenic, chondrogenic, and adipogenic cell lineages by exposing them to specific growth factors under the ideal conditions.

Materials and Methods:

A total of 117 samples were included in the study, consisting of 30 pulp, 50 gingival, 35 PDL, and 2 apical papilla samples. The pulp was extirpated and transported to the Central Research Laboratory. Gingival connective tissue was collected from the participants undergoing any crown lengthening procedure or any gingivectomy procedure from the Department of Periodontology. A similar procedure was also followed for apical papilla and PDL. Isolation was done followed by the identification of the cells by immunocytochemistry using different markers. Once the identity of cells was confirmed, these cells were treated with different culture media to attain 70% to 100% confluency. Then the medium was replaced with a conditioning medium containing specific growth factors for differentiation into osteogenic, chondrogenic, and adipogenic cell lineages.

Result:

In our study, the number of samples collected and processed was 117. The isolation rate of stem cells from the above-collected samples was 70%. Statistical analysis—no statistical analysis was done as there was no variability expected.

Conclusion:

Our study showed that stem cells could be isolated, differentiated, and characterized from different dental sources.

Micro-computed tomographic evaluation of the flow and filling ability of endodontic materials using different test models

Objectives

This study compared the flow and filling of several retrograde filling materials using new different test models.

Materials and Methods

Glass plates were manufactured with a central cavity and 4 grooves in the horizontal and vertical directions. Grooves with the dimensions used in the previous study (1 × 1 × 2 mm; length, width, and height respectively) were compared with grooves measuring 1 × 1 × 1 and 1 × 2 × 1 mm. Biodentine, intermediate restorative material (IRM), and mineral trioxide aggregate (MTA) were evaluated. Each material was placed in the central cavity, and then another glass plate and a metal weight were placed over the cement. The glass plate/material set was scanned using micro-computed tomography. Flow was calculated by linear measurements in the grooves. Central filling was calculated in the central cavity (mm³) and lateral filling was measured up to 2 mm from the central cavity.

Results

Biodentine presented the least flow and better filling than IRM when evaluated in the 1 × 1 × 2 model. In a comparison of the test models, MTA had the most flow in the 1 × 1 × 2 model. All materials had lower lateral filling when the 1 × 1 × 2 model was used.

Conclusions

Flow and filling were affected by the size of the test models. Higher grooves and materials with greater flow resulted in lower filling capacity. The test model measuring 1 × 1 × 2 mm showed a better ability to differentiate among the materials.

In Vitro Characterization of Dental Pulp Stem Cells Cultured in Two Microsphere-Forming Culture Plates

Various three-dimensional (3D) culture methods have been introduced to overcome the limitations of in vitro culture and mimic in vivo conditions. This study aimed to evaluate two microsphere-forming culture methods and a monolayer culture method. We evaluated cell morphology, viability, osteo-, adipo-, and chondrogenic differentiation potential of dental pulp stem cells (DPSCs) cultured in 3D culture plates: ultra-low attachment (ULA) and U-bottomed StemFit 3D (SF) plates, and a two-dimensional (2D) monolayer plate. RNA sequencing (RNA-seq) revealed differentially expressed gene (DEG) profiles of the DPSCs. In contrast to an increasing pattern in the 2D group, cell viability in 3D groups (ULA and SF) showed a decreasing pattern; however, high multilineage differentiation was observed in both the 3D groups. RNA-seq showed significantly overexpressed gene ontology categories including angiogenesis, cell migration, differentiation, and proliferation in the 3D groups. Hierarchical clustering analysis revealed a similar DEG regulation pattern between the 3D groups; however, a comparatively different DEG was observed between the 2D and 3D groups. Taken together, this study shows that DPSCs cultured in microsphere-forming plates present superior multilineage differentiation capacities and demonstrate higher DEG expression in regeneration-related gene categories compared to that in DPSCs cultured in a conventional monolayer plate.

The effect of platelet lysate in culture of PDLSCs: an in vitro comparative study

Background

Cellular therapy clinical applications require large-scale production of stem cells. Therefore, abundance, ease of isolation, and proliferative potential are the most important factors in choosing the appropriate source of cells for transplantation studies. Multipotent stem cells obtained from periodontal ligament (PDL) can be used in periodontal tissue regeneration. In this study, we aimed to evaluate and compare the characteristics of periodontal ligament stem cells (PDLSCs), extracted by either enzymatic digestion or explant methods, and expanded using two different serum types: fetal bovine serum (FBS) and xeno-free platelet lysate (PL).

Methods

Expanded PDLSCs were assessed for their proliferation capacity, surface markers expression, colony formation, differentiation potential and ability to self-renewal. Most importantly, PDLSCs were evaluated for their ability to produce osteoblasts in vitro.

Results

PDLSCs isolated by explant method and expanded in PL serve as a promising source of stem cells for osteoblasts regeneration. These cells showed higher proliferation capacity, they retained their stemness characteristics throughout the passages and they revealed an increase in the expression level of osteogenic markers, without showing any karyotypic abnormalities after cell expansion.

Conclusions

PDLSCs produced using explant extraction method and expanded in cell culture media supplemented with PL provide an excellent source of xeno-free cells for the generation of functional osteoblasts.

Isolation and culture of dental pulp stem cells from permanent and deciduous teeth

Objective:

To isolate dental pulp mesenchymal stem cells (MSCs) from non-infected human permanent and deciduous teeth.

Methods:

It was an in-vitro experimental study. Human teeth were collected from 13 apparently healthy subjects including nine adults and four children. After decoronation dental pulps were extirpated from teeth and cultured via explant method in a stem cell defined media. Data was analyzed by descriptive statistics.

Results:

As above MSCs emerged exhibiting fibroblast-like morphology. In vitro culture was positive for 100% (9/9) and 75% (3/4) of the permanent and deciduous teeth respectively. First cell appeared from deciduous teeth pulp in 10±6.2 days while permanent teeth pulp took 12.4±3.7 days. Together, 26.6±3.6 and 24.5±3.5 days were required for permanent and deciduous tooth pulp stem cells to be ready for further assays.

Conclusions:

The protocol we developed is easy and consistent and can be used to generate reliable source of MScs for engineering of calcified and non-calcified tissue for regenerative medicine approaches.

Metabolism as an early predictor of DPSCs aging

Tissue resident adult stem cells are known to participate in tissue regeneration and repair that follows cell turnover, or injury. It has been well established that aging impedes the regeneration capabilities at the cellular level, but it is not clear if the different onset of stem cell aging between individuals can be predicted or prevented at an earlier stage. Here we studied the dental pulp stem cells (DPSCs), a population of adult stem cells that is known to participate in the repair of an injured tooth, and its properties can be affected by aging. The dental pulp from third molars of a diverse patient group were surgically extracted, generating cells that had a high percentage of mesenchymal stem cell markers CD29, CD44, CD146 and Stro1 and had the ability to differentiate into osteo/odontogenic and adipogenic lineages. Through RNA seq and qPCR analysis we identified homeobox protein, Barx1, as a marker for DPSCs. Furthermore, using high throughput transcriptomic and proteomic analysis we identified markers for DPSC populations with accelerated replicative senescence. In particular, we show that the transforming growth factor-beta (TGF-β) pathway and the cytoskeletal proteins are upregulated in rapid aging DPSCs, indicating a loss of stem cell characteristics and spontaneous initiation of terminal differentiation. Importantly, using metabolic flux analysis, we identified a metabolic signature for the rapid aging DPSCs, prior to manifestation of senescence phenotypes. This metabolic signature therefore can be used to predict the onset of replicative senescence. Hence, the present study identifies Barx1 as a DPSCs marker and dissects the first predictive metabolic signature for DPSCs aging.

Stem Cells for the Oromaxillofacial Area: Could they be a promising source for regeneration in dentistry?

Oromaxillofacial tissues (OMT) are composed of tooth and bone, together with nerves and blood vessels. Such a composite material is a huge source for mesenchymal stem cells (MSCs) that can be obtained with ease from extracted teeth, teeth structures and socket blood, flapped gingiva tissue, and mandibular/maxillar bone marrow. They offer a biological answer for restoring damaged dental tissues such as the regeneration of alveolar bone, prevention of pulp tissue defects, and dental structures. Dental tissue-derived mesenchymal stem cells share properties with bone marrow-derived mesenchymal stem cells and there is a considerable potential for these cells to be used in different stem cell-based therapies, such as bone and nerve regeneration. Dental pulp tissue might be a very good source for neurological disorders whereas gingiva-derived mesenchymal stem cells could be a good immune modulatory/suppressive mediators. OMT-MSCs is also promising candidates for regeneration of orofacial tissues from the perspective of developmental fate. Here, we review the fundamental biology and potential for future regeneration strategies of MSCs in oromaxillofacial research.

Enzymatic Isolation, Amplification and Characterization of Dental Pulp Stem Cells

The dental pulp represents an easily accessible source of adult dental pulp stem cells (DPSCs). The preferred approach to DPSC isolation is enzymatic digestion. However, the duration of the enzymatic activity is crucial. The purpose of this study was to isolate the DPSC populations using this method, characterize their biological properties and proliferation capacity, and to determine their ability to differentiate into mature cells. Before enzymatic digestion using 0.05% trypsin, we used the homogenization method in order to obtain a fine homogenate from the solid pulp tissue. The stem cells were cultivated in modified cultivation medium for mesenchymal adult progenitor cells containing 2% foetal bovine serum, growth factors and insulin-transferrin-selenium supplement. We were successfully able to isolate 10 populations of DPSCs. The vitality of DPSCs did not drop below 90 %. However, the DPSCs showed a significant decrease in the relative telomere length number with increasing passaging (P < 0.05). Isolated DPSCs highly expressed the CD markers: CD29, CD44, CD90, CD13, CD73 and CD166. In contrast, CD markers CD31, CD106, CD34 and CD45 were negative or low positive. We confirmed the high osteogenic and chondrogenic potential of the isolated stem cells. Isolated DPSCs did not show signs of cell degeneration or spontaneous differentiation during the entire cultivation. In addition, we were able to shorten the enzyme activity duration, and we were the first to demonstrate trypsin as the enzyme used for the enzymatic digestion method with the viability over 90 % of isolated DPSCs using this method.

Progress in the use of dental pulp stem cells in regenerative medicine

The field of tissue engineering is emerging as a multidisciplinary area with promising potential for regenerating new tissues and organs. This approach requires the involvement of three essential components: stem cells, scaffolds and growth factors. To date, dental pulp stem cells have received special attention because they represent a readily accessible source of stem cells. Their high plasticity and multipotential capacity to differentiate into a large array of tissues can be explained by its neural crest origin, which supports applications beyond the scope of oral tissues. Many isolation, culture and cryopreservation protocols have been proposed that are known to affect cell phenotype, proliferation rate and differentiation capacity. The clinical applications of therapies based on dental pulp stem cells demand the development of new biomaterials suitable for regenerative purposes that can act as scaffolds to handle, carry and implant stem cells into patients. Currently, the development of xeno-free culture media is emerging as a means of standardization to improve safe and reproducibility. The present review aims to describe the current knowledge of dental pulp stem cells, considering in depth the key aspects related to the characterization, establishment, maintenance and cryopreservation of primary cultures and their involvement in the multilineage differentiation potential. The main clinical applications for these stem cells and their combination with several biomaterials is also covered.

Conditioned medium from relapsing-remitting multiple sclerosis patients reduces the expression and release of inflammatory cytokines induced by LPS-gingivalis in THP-1 and MO3.13 cell lines

The present research was aimed at evaluating the effect of the conditioned medium (CM) from human periodontal ligament stem cells (hPDLSCs) obtained from healthy donors (hPDLSCs-CM) and from Relapsing-Remitting Multiple Sclerosis patients (RR-MS-CM) on inflammatory response induced by Porphyromonas gingivalis lipopolysaccharide (LPS-G) in a monocytoid human cell line (THP-1) and human oligodendrocyte cell line (MO3.13). Human periodontal ligament biopsies were carried out from control donor patients and selected RR-MS donors. Sample tissues were obtained from premolar teeth during root scaling and subsequently cultured. The effect of hPDLSCs-CM and RR-MS-CM on cell viability in PMA differentiated THP-1 (as a model of microglia) was measured using a 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide (MTT) assay. The same experiments were performed in undifferentiated and differentiated MO3.13 cells used as models of progenitor cells and oligodendrocytes, respectively. The expression of tumor necrosis factor alpha (TNF)-α, interleukin (IL)-1β and IL-6 was evaluated by Real-Time Polymerase Chain Reaction (RT-PCR), and enzyme-linked immunosorbent assay (ELISA). The expression level of the Toll-like receptor 4 (TLR-4), for which LPS-G is a ligand, was evaluated by Western blot analysis. The results were analyzed by ANOVA using Graph Pad Prism software. LPS-G significantly increased TNFα, IL-1β and IL-6 mRNA expression and protein levels in the differentiated THP-1 cells and oligodendrocyte MO3.13 progenitor cells. Treatment with hPDLSCs-CM or with RR-MS-CM significantly attenuated the LPS-induced expression and production of these pro-inflammatory cytokines. The CM from both healthy donors and RR-MS patients also reduced the LPS-G stimulated protein levels of TLR-4 in differentiated THP-1 cells. On the whole our data add new evidence on the anti-inflammatory effects of these peculiar stem cells even when derived from RR-MS patients and open novel perspectives in the therapeutic use of autologous periodontal stem cells in neuroinflammatory/neurodegenerative diseases including MS.