Abstract Dental trauma in immature permanent teeth can damage pulp vascularization, which leads to necrosis and cessation of apexogenesis. Studies on tissue engineering using stem cells from human exfoliated deciduous teeth (SHEDs) have yielded promising results. Laser phototherapy (LPT) is able to influence the proliferation and differentiation of these cells, which could improve tissue engineering. SHEDs (eighth passage) were seeded into 96-well culture plates (103 cells/well) and were grown in culture medium supplemented with 15% defined fetal bovine serum (FBS) for 12 h. After determining the appropriate nutrition deficiency status (5% FBS), the cells were assigned into four groups: 1) G1 – 15% FBS (positive control); 2) G2 – 5% FBS (negative control); 3) G3 – 5% FBS+LPT 3 J/cm2; and 4) G4 – 5% FBS+LPT 5 J/cm2. For the LPT groups, two laser irradiations at 6 h intervals were performed using a continuous wave InGaAlP diode laser (660 nm, with a spot size of 0.028 cm2, 10 mW) in punctual and contact mode. Cell viability was assessed via an MTT reduction assay immediately after the second laser irradiation (0 h) and 24, 48, and 72 h later. We found that G3 and G4 presented a significantly higher cell growth rate when compared with G2 (p < 0.01). Moreover, G4 exhibited a similar cell growth rate as G1 throughout the entire experiment (p > 0.05). These findings indicate that LPT with 5 J/cm2 can enhance the growth of SHEDs during situations of nutritional deficiency. Therefore, LPT could be a valuable adjunct treatment in tissue engineering when using stem cells derived from the dental pulp of primary teeth.
ABSTRACTMyeloproliferative neoplasms are caused by a clonal proliferation of a hematopoietic progenitor. First described in 1951 as 'Myeloproliferative Diseases' and reevaluated by the World Health Organization classification system in 2011, myeloproliferative neoplasms include polycythemia vera, essential thrombocythemia and primary myelofibrosis in a subgroup called breakpoint cluster region-Abelson fusion oncogene-negative neoplasms. According to World Health Organization regarding diagnosis criteria for myeloproliferative neoplasms, the presence of the JAK2 V617F mutation is considered the most important criterion in the diagnosis of breakpoint cluster region-Abelson fusion oncogene-negative neoplasms and is thus used as a clonal marker. The V617F mutation in the Janus kinase 2(JAK2) gene produces an altered protein that constitutively activates the Janus kinase/signal transducers and activators of transcription pathway and other pathways downstream as a result of signal transducers and activators of transcription which are subsequently phosphorylated. This affects the expression of genes involved in the regulation of apoptosis and regulatory proteins and modifies the proliferation rate of hematopoietic stem cells.
Little is known about the histogenesis of the odontogenic myxoma (OM). Dental pulp stem cells could be candidate precursors of OM because both OM and the dental pulp share the same embryological origin: the dental papilla. For the purpose of comparing OM and stem cells, this study analyzed the expression of two proteins related to OM invasiveness (MMP-2 and hyaluronic acid) in human immature dental pulp stem cells (hIDPSCs). Three lineages of hIDPSCs from deciduous and permanent teeth were used in this study. Immunofluorescence revealed positive reactions for MMP-2 and hyaluronic acid (HA) in all hIDPSCs. MMP-2 appeared as dots throughout the cytoplasm, whereas HA appeared either as diffuse and irregular dots or as short fibrils throughout the cytoplasm and outside the cell bodies. The gene expression profile of each cell lineage was evaluated using RT-PCR analysis, and HA was expressed more intensively than MMP-2. HA expression was similar among the three hIDPSCs lineages, whereas MMP-2 expression was higher in DL-1 than in the other cell lines. The expression of proteins related to OM invasiveness in hIDPSCs could indicate that OM originates from dental pulp stem cells.