Characterization of stem cells from the pulp of unerupted third molar tooth

Molecular Biological Comparison of Dental Pulp- and Apical Papilla-Derived Stem Cells

Both the dental pulp and the apical papilla represent a promising source of mesenchymal stem cells for regenerative endodontic protocols. The aim of this study was to outline molecular biological conformities and differences between dental pulp stem cells (DPSC) and stem cells from the apical papilla (SCAP). Thus, cells were isolated from the pulp and the apical papilla of an extracted molar and analyzed for mesenchymal stem cell markers as well as multi-lineage differentiation. During induced osteogenic differentiation, viability, proliferation, and wound healing assays were performed, and secreted signaling molecules were quantified by enzyme-linked immunosorbent assays (ELISA). Transcriptome-wide gene expression was profiled by microarrays and validated by quantitative reverse transcription PCR (qRT-PCR). Gene regulation was evaluated in the context of culture parameters and functionality. Both cell types expressed mesenchymal stem cell markers and were able to enter various lineages. DPSC and SCAP showed no significant differences in cell viability, proliferation, or migration; however, variations were observed in the profile of secreted molecules. Transcriptome analysis revealed the most significant gene regulation during the differentiation period, and 13 biomarkers were identified whose regulation was essential for both cell types. DPSC and SCAP share many features and their differentiation follows similar patterns. From a molecular biological perspective, both seem to be equally suitable for dental pulp tissue engineering.

Is There Such a Thing as a Genuine Cancer Stem Cell Marker? Perspectives from the Gut, the Brain and the Dental Pulp

The conversion of healthy stem cells into cancer stem cells (CSCs) is believed to underlie tumor relapse after surgical removal and fuel tumor growth and invasiveness. CSCs often arise from the malignant transformation of resident multipotent stem cells, which are present in most human tissues. Some organs, such as the gut and the brain, can give rise to very aggressive types of cancers, contrary to the dental pulp, which is a tissue with a very remarkable resistance to oncogenesis. In this review, we focus on the similarities and differences between gut, brain and dental pulp stem cells and their related CSCs, placing a particular emphasis on both their shared and distinctive cell markers, including the expression of pluripotency core factors. We discuss some of their similarities and differences with regard to oncogenic signaling, telomerase activity and their intrinsic propensity to degenerate to CSCs. We also explore the characteristics of the events and mutations leading to malignant transformation in each case. Importantly, healthy dental pulp stem cells (DPSCs) share a great deal of features with many of the so far reported CSC phenotypes found in malignant neoplasms. However, there exist literally no reports about the contribution of DPSCs to malignant tumors. This raises the question about the particularities of the dental pulp and what specific barriers to malignancy might be present in the case of this tissue. These notable differences warrant further research to decipher the singular properties of DPSCs that make them resistant to transformation, and to unravel new therapeutic targets to treat deadly tumors.

Mesenchymal stem cells from orthodontic premolar teeth

Background

Considering the limitations in isolating Bone Marrow Mesenchymal Stem Cells (BMSCs), alternate sources of Mesenchymal Stem Cells (MSCs) are being intensely investigated. This study evaluated dental pulp MSCs (DP-MSCs) isolated from orthodontically extracted premolar teeth from a bone tissue engineering perspective.

Methods

MSCs isolated from premolar teeth pulp were cultured and studied using BMSCs as the control. Flow cytometry analysis was performed for the positive and negative MSC markers. Multilineage differentiation focusing on bone regeneration was evaluated by specific growth induction culturing media and by alkaline phosphatase (ALP) activity. Data were compared by repeated measurement analysis of variance and Student's t-test at a p value <0.05.

Results

Proliferation rate, population doubling time, and colony formation of DP-MSCs were significantly higher (p < 0.001) than BMSCs. More than 85% of DP-MSCs expressed CD44, CD73, CD90, CD105, and CD166. Negative reaction was found for CD11b CD33, CD34, and CD45. Positive reaction was displayed by 7.2% of cells for early MSC marker, Stro-1. Both the cell populations differentiated into adipogenic, osteogenic, and chondrogenic lineages, with adequate ALP expression.

Conclusion

Because DP-MSCs from orthodontic premolars hold a neural crest/ectomesenchymal ancestry, its prudent growth characteristics and multilineage differentiation open up exciting options in craniofacial tissue engineering.

Differential expression of drug resistance genes in CD146 positive dental pulp derived stem cells and CD146 negative fibroblasts

Introduction

The stem cell portion of the dental pulp derived cultures (DPSCs) showed a higher resistance to cytotoxic effect of restorative dental materials compared to pulpal fibroblasts (DPFs). Here, we aimed to compare the expression of some drug resistant genes between these cells.

Methods and materials

To separate DPSCs from DPFs, we used magnetic cell sorting technique based on CD146 expression. To assess the stem cell properties, the positive and negative portions underwent colony forming assays and were induced to be differentiated into the adipocytes, osteoblasts, hepatocytes, and neural cells. Cell surface antigen panels were checked using immune fluorescence and flow‐cytometry techniques. The mRNA expression of 14 ABC transporters including ABCA2, ABCB1, ABCB11, ABCC1, ABCC2, ABCC3, ABCC4, ABCC5‐2, ABCC5‐4,ABCC5‐13, ABCC6, ABCC10, ABCC11, and ABCG2 genes was assessed, using quantitative RT‐PCR technique.

Results

Only the CD146 positive portion could be differentiated into the desired fates, and they formed higher colonies (16.7 ± 3.32 vs. 1.7 ± 1.67, p < .001). The cell surface antigen panels were the same, except for CD146 and STRO‐1 markers which were expressed only in the positive portion. Among the ABC transporter genes studied, the positive portion showed a higher expression (approximately two‐fold) of ABCA2, ABCC5‐13, and ABCC5‐2 genes.

Conclusion

Dental pulp stem cells which can be separated from dental pulp fibroblasts based on CD146 expression, express higher levels of some drug resistance genes which probably accounts for their features of more resistance to cytotoxic effects of some dental materials. This needs to be more validated in future.

Purification of Stem Cells from Oral Pyogenic Granuloma Tissue

Introduction:

The isolation of stem cells from pathologically damaged dental tissues has been examined only by a few studies. The purpose of this study was to evaluate the possibility of isolation of stem cells from pyogenic granuloma.

Methods:

Pyogenic granuloma tissues were enzymatically digested and the resulting single cells were cultured. Then, the cultured cells differentiated into adipocytes and osteoblasts cells. Flow cytometry analyses were performed on markers such as CD 90, CD 73, CD105, CD 45 and CD14. Other features were also analyzed including the effect of colony formation and potentials of differentiation into adipocytes and osteoblasts.

Results:

The cells derived from pyogenic granuloma tissue formed higher colonies similar to typical spindle-shaped fibroblasts. The cells were positive for mesenchymal markers such as CD 44, CD 271, CD 90, and CD 73, and negative for surface molecules such as CD 14, CD 34 and CD 45. Moreover, they successfully differentiated into adipocytes and osteoblasts.

Conclusion:

The cells isolated from pyogenic granuloma could form CFU fibroblastic units expressing an appropriate marker panel of the cell surface antigen and adequate differentiation potential, all of which met the Cell Therapy International Association criteria for the definition of mesenchymal stromal cells. Pyogenic granuloma contains cells with stem cell properties.

Dental pulp polyps contain stem cells comparable to the normal dental pulps

Objectives: Few studies investigated the isolation of stem cells from pathologically injured dental tissues. The aim of this study was to assess the possibility of isolation of stem cells from pulp polyps (chronic hyperplastic pulpitis), a pathological tissue produced in an inflammatory proliferative response within a tooth. Study design: Pulp polyp tissues were enzymatically digested and the harvested single cells were cultured. Cultured cells underwent differentiation to adipocytes and osteoblasts as well as flowcytometric analysis for markers such as: CD90, CD73, CD105, CD45, and CD14. In addition we tried to compare other characteristics (including colonigenic efficacy, population doubling time and the cell surface antigen panels) of these cells to that of healthy dental pulp stem cells (DPSCs). Results: Cells isolated from pulp polyps displayed spindle shape morphology and differentiated into adipocytes and osteoblasts successfully. These cells expressed CD90, CD73, and CD105 while were negative for CD45, CD14. Number of colonies among 104 tissue cells was higher in the normal pulp tissue derived cells than the pulp polyps (P=0.016); but as polyp tissues are larger and contain more cells (P=0.004), the total number of the stem cell in a sample tissue was higher in polyps but not significantly (P=0.073). Conclusions: The cells isolated from pulp polyps fulfill minimal criteria needed for MSC definition; hence, it can be concluded that pulp polyps contain stem cells. Although pulp polyps are rare tissues in daily practice but when they are present, may serve as a possible new non-invasively acquired tissue resource of stem cells for affected patients. List of abbreviations: APC = allophycocyanin, BM = Bone Marrow, CFU-F = Colony Forming Unit Fibroblast, DPSC = Dental Pulp Stem Cell, FITC = fluorescein isothiocyanate, MNC = mononuclear cells, MSC = Multipotent Mesenchymal Stromal Cell, PE = Phycoerythrin, PerCP = Peridinin chlorophyll protein, PPSC = Pulp Polyp Stem Cell.

Key words:Adult stem cell, chronic hyperplastic pulpitis, dental pulp stem cell, pulp polyp.