Feasibility of Molecularly Targeted Therapy for Tooth Regeneration

[Extract] The tooth is a complex organ that consists of enamel, dentin, cementum, and pulp. Missing teeth is frequently occurring problem in aging populations. To treat these defects, the current approach involves prostheses, autotransplantation, and dental implants. The exploration of new strategies for tooth replacement has become a hot topic. Using the foundations of experimental embryology, developmental and molecular biology, tooth regeneration is becoming realistic possibility. Several different methods have been proposed to achieve biological tooth replacement. These include scaffold-based tooth regeneration, cell pellet engineering, stimulation of the formation of a third dentition, and gene-manipulated tooth regeneration. The idea that a third dentition might be locally induced to replace missing teeth is an attractive concept (Young et al., 2005; Edward & Mason, 2006; Takahashi et al., 2008, 2013). This approach is generally presented in terms of adding molecules to induce de novo tooth initiation in the mouth. Tooth development is the result of reciprocal and reiterative signaling between oral ectoderm-derived dental epithelium and cranial neural crest cell-derived dental mesenchyme under genetic control (Thesleff, 2006). More than 200 genes are known to be expressed during tooth development (http://bite-it.helsinki.fi/). A number of mouse mutants are now starting to provide some insights into the mechanisms of supernumerary tooth formation. Multiple supernumerary teeth may have genetic components in their etiology and partially represent the third dentition in humans. Such candidate molecules might be those that are involved in embryonic tooth induction, in successional tooth formation, or in the control of the number of teeth. This means that it may be possible to induce de novo tooth formation by the in situ repression or activation of a single candidate molecule. In this review, we provide an overview of the collective knowledge of tooth regeneration, especially regarding the control of the number of teeth for molecularly targeted therapy by the stimulation of a third dentition

Pressurization facilitates adenovirus-mediated gene transfer into vein graft

AbstractWe investigated whether application of non-distending hydrostatic pressure facilitates gene transfer into vein grafts. An external jugular vein was placed in a chamber with 100 μl adenovirus solution at a titer of 1010 pfu/ml and was pressurized to up to 8 atm above ambient pressure for 10 min. Histochemical analysis demonstrated a positive transgene expression in all layers of the vessel wall. Gene transfer with 8 atm pressurization resulted in an approximately 50 times higher transgene expression than that without pressurization. Under 8 atm pressurization, the efficiency of gene transfer reached a plateau at 7.5 min. The application of hydrostatic pressure may improve the effectiveness of intraoperative genetic engineering of vein grafts

LXR agonist increases apoE secretion from HepG2 spheroid, together with an increased production of VLDL and apoE-rich large HDL

<p>Abstract</p> <p>Background</p> <p>The physiological regulation of hepatic apoE gene has not been clarified, although the expression of apoE in adipocytes and macrophages has been known to be regulated by LXR.</p> <p>Methods and Results</p> <p>We investigated the effect of TO901317, a LXR agonist, on hepatic apoE production utilizing HepG2 cells cultured in spheroid form, known to be more differentiated than HepG2 cells in monolayer culture. Spheroid HepG2 cells were prepared in alginate-beads. The secretions of albumin, apoE and apoA-I from spheroid HepG2 cells were significantly increased compared to those from monolayer HepG2 cells, and these increases were accompanied by increased mRNA levels of apoE and apoA-I. Several nuclear receptors including LXRα also became abundant in nuclear fractions in spheroid HepG2 cells. Treatment with TO901317 significantly increased apoE protein secretion from spheroid HepG2 cells, which was also associated with the increased expression of apoE mRNA. Separation of the media with FPLC revealed that the production of apoE-rich large HDL particles were enhanced even at low concentration of TO901317, and at higher concentration of TO901317, production of VLDL particles increased as well.</p> <p>Conclusions</p> <p>LXR activation enhanced the expression of hepatic apoE, together with the alteration of lipoprotein particles produced from the differentiated hepatocyte-derived cells. HepG2 spheroids might serve as a good model of well-differentiated human hepatocytes for future investigations of hepatic lipid metabolism.</p

Effects of Usag-1 and Bmp7 deficiencies on murine tooth morphogenesis

[ackground]Wnt5a and Mrfzb1 genes are involved in the regulation of tooth size, and their expression levels are similar to that of Bmp7 during morphogenesis, including during the cap and early bell stages of tooth formation. We previously reported that Usag-1-deficient mice form supernumerary maxillary incisors. Thus, we hypothesized that BMP7 and USAG-1 signaling molecules may play important roles in tooth morphogenesis. In this study, we established double genetically modified mice to examine the in vivo inter-relationships between Bmp7 and Usag-1. [Results]We measured the volume and cross-sectional areas of the mandibular incisors using micro-computed tomography (micro-CT) in adult Bmp7- and Usag-1-LacZ knock-in mice and their F2 generation upon interbreeding. The mandibular incisors of adult Bmp7+/− mice were significantly larger than those of wild-type (WT) mice. The mandibular incisors of adult Usag-1−/− mice were the largest of all genotypes examined. In the F2 generation, the effects of these genes were additive; Bmp7+/− was most strongly associated with the increase in tooth size using generalized linear models, and the total area of mandibular supernumerary incisors of Usag-1−/−Bmp7+/− mice was significantly larger than that ofUsag-1−/−Bmp7 +/+ mice. At embryonic day 15 (E15), BrdU assays demonstrated that the labeling index of Bmp7+/− embryos was significantly higher than that of WT embryos in the cervical loop. Additionally, the labeling index of Usag-1−/− embryos was significantly the highest of all genotypes examined in dental papilla. [Conclusions]Bmp7 heterozygous mice exhibited significantly increased tooth sizes, suggesting that tooth size was controlled by specific gene expression. Our findings may be useful in applications of regenerative medicine and dentistry

Non-destructive measurements of cosmogenic 26Al, natural 40K and fallout 137Cs in Antarctic meteorites

Non-destructive γ-ray measurements have been made to determine cosmogenic ^(Al), natural ^K and fallout ^(Cs) activities in 15 Antarctic meteorites (14 from Yamato Mountains and 1 from Allan Hills). The ^(Al) activities range from 72 to 29 dpm/kg. If we assume that the saturation activity of ^(Al) in chondrites is 60,about 1/3 of the measured meteorites show the contents close to this value; however, the rest show lower values. A simple graphical method was applied to estimate the exposure and terrestrial ages based on ^(Al) and ^(Mn) data, and these ages are compared with exposure ages obtained by ^(Ne) measurements. The results are generally consistent with the ^(Ne) data. It must be noted that the Antarctic meteorites are highly contaminated with fallout ^(Cs) derived from nuclear test explosions