Short-term evaluation of photobiomodulation therapy on the proliferation and undifferentiated status of dental pulp stem cells.

The aim of this in vitro study was to analyze the effect of photobiomodulation therapy (PBMT) on the proliferation and undifferentiating status of stem cell from human exfoliated deciduous teeth (SHEDs). PBMT was carried out with an aluminum gallium indium phosphide (InGaAlP) diode laser in contact and punctual mode (continuous wave, 660 nm, 20 mW, 0.028 cm2, and average energy densities of 1 (1 s), 3 (4 s), 5 (7 s), 10 (14 s), 15 (21 s), or 20 (28 s) J/cm2 per point). The immunoprofile of the SHEDs was analyzed using flow cytometry. Cell proliferation was assessed by the MTT reduction assay. Gene expressions of mesenchymal stem cell markers (OCT4, Nestin, CD90, and CD105) were assessed by RT-qPCR 48 h after PBMT. Data were compared by analysis of variance (ANOVA) and Tukey's test (p ≤ 0.05). Cells cultured under nutritional deficit and treated with PBMT at 5 J/cm2 presented similar cell growth than those of positive control group. Cell growth was significantly higher than those of other groups. Mesenchymal stem cell gene markers were still expressed after PBMT at 5 J/cm2. In a short-term analysis, PBMT increases the number of stem cells with no interference in the undifferentiated state of the irradiated cells, which opens wide possibilities for application in tissue regeneration.

The effect of a reconstituted basement membrane (matrigel) on a human salivary gland myoepithelioma cell line.

We have already demonstrated that a reconstituted basement membrane (Matrigel) is a key modulator of morphogenetic changes and cytodifferentiation of pleomorphic adenoma cells in culture. Myoepithelioma is considered to be a neoplasm closely related to pleomorphic adenoma and should experience similar induction processes. Thus, the aim of this study was to investigate whether Matrigel would influence myoepithelioma cells. We used a cell line derived from a human salivary gland plasmacytoid myoepithelioma (M1 cells) grown in a three-dimensional preparation of Matrigel. Phenotype differences were assessed using conventional light microscopy technique (haematoxylin and eosin) and phase and differential interference contrast (Nomarski). Immunofluorescence was carried out to detect smooth-muscle actin, laminin and type-IV collagen. M1 cells exhibited all proteins studied, showing a myoepithelial differentiation. M1 cells grown inside Matrigel presented morphological changes and changes in smooth-muscle actin status. By growing M1 cells inside Matrigel, it was possible to reproduce the tumour architecture with no duct-like structures. Based on our findings, we suggest that myoepithelioma would be derived from a cell with a commitment to myoepithelial differentiation. We also suggest that the mechanical properties of the matrix environment will likely regulate smooth-muscle actin expression in myoepithelioma.