BONE MORPHOGENETIC PROTEIN-2 AND COLLAGEN TYPE 1 FROM DIFFERENT SOURCES OF DEMINERALIZED DENTINE MATRIX: RELEASE KINETIC AND CHEMOTAXIS POTENTIAL FOR OSTEOPROGENITOR CELLS

Objective: To investigate the release of bone morphogenetic protein-2 (BMP-2) and collagen type I proteins (COL1) from different sources ofdemineralized dentine matrix (DDM) and their chemotaxis to mouse osteoprogenitor cells.Methods: The release kinetic of BMP-2 and COL1 was measured from custom-made DDM (CMDDM) and commercially available DDM (CADDM).Using Urist physicochemical method, CMDDM was collected from the extracted teeth in a certified dental clinic. Levels of BMP-2 and COL1 releasedwere measured at days 1, 2, 3, 5, 7, 9, 11, and 13. Next, mouse osteoprogenitor cells, MC3T3-E1, were cultured with a variety of materials as follows:CMDDM, CADDM, Bio-Oss®, and blank control in transwell system. The number of cell migration was determined by crystal violet staining to explorechemotaxis of different DDMs to mouse osteoprogenitor cells.Results: BMP-2 was detected at 588.32 ± 14.53 pg/ml from 5 g of CMDDM. In the release kinetic assay, the concentration of BMP-2 in the CMDDMgroup increased rapidly and peaked at 113.9 pg/ml on day 5, almost four times higher than that of CADDM. The release of COL1 showed similarpattern in both CMDDM and CADDM; however, the amount was significantly higher in the CMDDM group. In cell culture experiment, the number ofmigrated MC3T3-E1 was ranked as the highest in CMDDM, followed by CADDM and Bio-Oss® (p<0.05).Conclusion: CMDDM released BMP-2 and COL1 greater than CADDM, which can induce more osteoblast-like cell migration. These results demonstrateda release kinetic of proteins and osteoinductivity of CMDDM, which supports a benefit of using autogenous bone graft

3, 3′, 5-triiodo-L-thyronine increases in vitro chondrogenesis of mesenchymal stem cells from human umbilical cord stroma through SRC2

[Abstract] Our group focuses on the study of mesenchymal stem cells (MSCs) from human umbilical cord stroma or Warthońs jelly and their directed differentiation toward chondrocyte-like cells capable of regenerating damaged cartilage when transplanted into an injured joint. This study aimed to determine whether lactogenic hormone prolactin (PRL) or 3, 3′, 5-triiodo-L-thyronine (T3), the active thyroid hormone, modulates chondrogenesis in our in vitro model of directed chondrogenic differentiation, and whether Wnt signalling is involved in this modulation. MSCs from human umbilical cord stroma underwent directed differentiation toward chondrocyte-like cells by spheroid formation. The addition of T3 to the chondrogenic medium increased the expression of genes linked to chondrogenesis like collagen type 2, integrin alpha 10 beta 1, and Sox9 measured by quantitative real time polymerase chain reaction (qRT-PCR) analysis. Levels of collagen type 2 and aggrecane analyzed by immunohistochemistry, and staining by Safranin O were increased after 14 days in spheroid culture with T3 compared to those without T3 or only with PRL. B-catenin, Frizzled, and GSK-3β gene expressions were significantly higher in spheroids cultured with chondrogenic medium (CM) plus T3 compared to CM alone after 14 days in culture. The increase of chondrogenic differentiation was inhibited when the cells were treated with T3 plus ML151, an inhibitor of the T3 steroid receptor. This work demonstrates, for first time, that T3 promotes differentiation towards chondrocytes-like cells in our in vitro model, that this differentiation is mediated by steroid receptor co-activator 2 (SRC2) and does not induce hypertrophy.Instituto de Salud Carlos III; PI11/0279

Correlation between the thickness of the crestal and buccolingual cortical bone at varying depths and implant stability quotients.

Resonance frequency analysis (RFA) is clinically used in dentistry to access the stiffness of dental implants in surrounding bone. However, the clear advantages and disadvantages of this method are still inconclusive. The aim of this study was to investigate and compare implant stability quotient (ISQ) values obtained from RFA with parameters obtained from a cone beam computed tomography (CBCT) scan of the same region.Nineteen implants (Conelog) were inserted in the posterior maxillary and mandibular partially edentulous regions of 16 patients. At the time of implant placement, the ISQ values were obtained using RFA (Osstell). CBCT was used to measure the thickness of the crestal, cortical, buccolingual cortical, and cancellous bone at 3, 6, and 9 mm below the crestal bone level, as indicated by radiographic markers. The ratio of the thickness of the cortical to cancellous bone at varying depths was also calculated and classified into 4 groups (Group 1-4).There was a strong correlation between the crestal cortical bone thickness and ISQ values (P<0.001). The thickness of the buccolingual cortical bone and ratio of the cortical to cancellous bone thickness at 3 mm were significantly related to the ISQ (P = 0.018 and P = 0.034, respectively). Furthermore, the ISQs in Group 1 were the highest compared with those in Group 2 and Group 3, whereas the CBCT parameters at 6 and 9 mm did not have any specific correlation with the ISQ values.This study showed that the ISQ values obtained from RFA highly correlated with the quantity and quality of bone 3 mm below the crestal bone level. The correlation between the ISQ and bone surrounding the implant site was dependent on the depth of measurement. Therefore, RFA can help to predict the marginal bone level, as confirmed in this study

Evidence for Direct Effects of Prolactin on Human Osteoblasts: Inhibition-of Cell Growth and Mineralization

Hyperprolactinemia is one of the risk factor of decrease in bone mass which has been believed to be mediated by hypogonadism. However, the presence of prolactin receptor in human osteosarcoma cell line and primary bone cell culture from mouse calvariae supported the hypothesis of a direct prolactin (PRL) action on bone cells. Therefore, the aim of this study was to investigate the role of PRL and its signal transduction pathway in the regulation of bone metabolism via osteoblast differentiation. Human pre-osteoblasts (SV-HFO) that differentiate in a 3-week period from proliferating pre-osteoblasts (days 2-7) to extracellular matrix producing cells (days 7-14) which is eventually mineralized (days 14-21) were used. Concentration of PRL mimicked a lactating period (100 ng/ml) was used to incubate SV-HFO for 21 days in osteogenic medium. Human prolactin receptor mRNA and protein are expressed in SV-HFO. PRL significantly decreased osteoblast number (DNA content) which was due to a decrease in proliferation. PRL increased osteogenic markers, RUNX2 and ALP in early stage of osteoblast differentiation while decreasing it later suggesting a bi-directional effect. Calcium measurement and Alizarin red staining showed a reduction of mineralization by PRL while having neither an effect on osteoblast activity nor RANKL/OPG mRNA ratio. We also demonstrated that PRL action on mineralization was not via PI-3 kinase pathway. The present study provides evidence of a direct effect of prolactin on osteoblast differentiation and in vitro mineralization. J. Cell. Biochem. 107: 677-685, 2009. (C) 2009 Wiley-Liss, Inc

Schematic measurement of bone thickness at the depths of 3, 6 and 9 mm.

<p>The buccolingual cortical bone thickness (yellow line) and the cancellous bone thickness (cyan line) were measured from a cross-sectional image of the mandible.</p

Mean thickness of crestal cortical, buccolingual cortical, and cancellous bone and ratio of the thickness of cortical to cancellous bone 3, 6 and 9 mm below the crestal bone level in all patients.

<p>Mean thickness of crestal cortical, buccolingual cortical, and cancellous bone and ratio of the thickness of cortical to cancellous bone 3, 6 and 9 mm below the crestal bone level in all patients.</p