Role of CD146 Enrichment in Purification of Stem Cells Derived from Dental Pulp Polyp

Introduction: Hyperplastic pulpitis (pulp polyp)tissues contains cells with stem cell properties similar to that of the dental pulp stem cells (DPSCs). It has also been shown that CD146 enrichment can homogenize the cultures of DPSCs and enhance the colony forming potentials of their cultures. This study determines whether CD146 enrichment can help purifying the stem cells from heterogeneous cultures of the pulp polyp derived stem cells (PPSCs). Methods and Materials: Healthy dental pulps and pulp polyp tissues were enzymatically digested and the harvested single cells were sorted according to the presence of CD146 marker. The sorted cells were seeded directly for colony forming unit (CFU) assays of the negative and positive portions. Flowcytometric antigen panel and differentiation assays were used to see if these cells conform with mesenchymal stems cells (MSCs) definition. Differences between the between groups was assessed using independent t-test. The level of significance was set at 0.05. Results: Normal pulp tissue derived cells formed higher colonies (42.5±16.8 per 104 cells) than the pulp polyp (17.75±8.9 per 104 cells) (P=0.015). The CD146 positive portion of the polyp derived cells formed an average of 91.5±29.7 per 104 cells per CFU. On the other hand, CD146 negative portion did not show any colonies (P<0.001). Both resources showed cells with flowcytometric antigen panel and differentiation potentials conforming to MSC definition. Conclusion: The entire CFU of PPSCs were formed within CD146 enriched portion. It seems that CD146 enrichment may reduce the number of possible fibroblasts of the pulp polyps and may further homogenize the culture of the PPSCs.Keywords: Adult Stem Cell; CD146; Dental Pulp; Dental Pulp Disease; Pulpitis; Pulp Polyp; Stem cell Assa

Cytotoxic effect of silorane and methacrylate based composites on the human dental pulp stem cells and fibroblasts

Objectives: The aim of this study was to compare the cytotoxic effect of a methacrylate-based and a silorane- based composite on the human dental pulp stem cells (DPSCs) versus human dental pulp fibroblasts (DPFs). Study Design: Samples of the Filtek Z250 and P90 were polymerized and immersed in the culture medium to obtain extracts after incubation for one, seven and 14 days. Magnetic cell sorting based on the CD146 expression was performed to purify DPSCs and DPFs. After incubation of both cells with the extracts, cytotoxicity was de - termined using the MTT test. Results: For the extracts of first and seventh day, both composites showed significantly lower cytotoxicity on DPSCs than DPFs ( p =0.003). In addition, there was a significant difference in the time-group interaction of both materials indicating different cytotoxic behaviours ( p =0.014). In contrast to Z250, exposure to the 14th day extract of P90 resulted in higher cell viability compared to that of day seven. Conclusions: DPSCs are less susceptible to the cytotoxic effect of the composites than DPFs. Compared to Z250, the cytotoxic effect of silorane-based composite decreases as the time passes on. This difference should be con - sidered, particularly in deep cavities, in order to preserve the regenerative capacity of the pulp

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

Fracture toughness and color change of Nanohybrid resin composites in dry and wet conditions up to 60 days

Background and Aims: Fracture and color change are among the most common causes of clinical failure of resin composite restorations. Therefore, this study aimed to examine the fracture toughness and color changes of 3 Nano-hybrid resin composites in dry and wet conditions. Materials and Methods: Three resin composites were studied. A total of 36 rectangular specimens were prepared for each material, randomly divided into 2 groups, and stored at 37°C dry or soaked in distilled water. In each group, the specimens were subdivided into three groups (n=6) and stored for 1, 7, and 60 days. After each time interval, the specimens were tested for the fracture toughness and loaded at a cross-head speed of 0.5mm/min using a universal testing machine. The baseline and final color measurement was recorded for each specimen using a spectrophotometer. The collected data was analyzed using ANOVA and Kruskal-Wallis tests. Results: After 60 days, the mean value of fracture toughness was lower in the wet condition compared to that of dry condition. However, it was not significantly different except for aura Bulkfil (P=0.001). Color change was significantly different for Tetric Evoceram and aura with a greater value in the wet condition compared to that of dry (P=0.004). The greatest color stability was found for aura and the least for Tetric Evoceram. Conclusion: In this study, most of the materials stored in a dry condition showed a greater fracture toughness and color change