Titanium phosphate glass microcarriers induce enhanced osteogenic cell proliferation and human mesenchymal stem cell protein expression.

In this study, we have developed 50- to 100-µm-sized titanium phosphate glass microcarriers (denoted as Ti5) that show enhanced proliferation of human mesenchymal stem cells and MG63 osteosarcoma cells, as well as enhanced human mesenchymal stem cell expression of bone differentiation markers, in comparison with commercially available glass microspheres at all time points. We also demonstrate that these microcarriers provide superior human mesenchymal stem cell proliferation with conventional Dulbecco's Modified Eagle medium than with a specially developed commercial stem cell medium. The microcarrier proliferative capacity is revealed by a 24-fold increase in MG63 cell numbers in spinner flask bioreactor studies performed over a 7-day period, versus only a 6-fold increase in control microspheres under the same conditions; the corresponding values of Ti5 and control microspheres under static culture are 8-fold and 7-fold, respectively. The capability of guided osteogenic differentiation is confirmed by ELISAs for bone morphogenetic protein-2 and osteopontin, which reveal significantly greater expression of these markers, especially osteopontin, by human mesenchymal stem cells on the Ti5 microspheres than on the control. Scanning electron microscopy and confocal laser scanning microscopy images reveal favorable MG63 and human mesenchymal stem cell adhesion on the Ti5 microsphere surfaces. Thus, the results demonstrate the suitability of the developed microspheres for use as microcarriers in bone tissue engineering applications

Quantitative Assessment of Desensitizing Agents in Occluding Dentine Tubules using Image Analysis

Previous in vitro studies assessing the tubule occluding properties of various desensitizing agents in the dentine disc model appear to provide only qualitative data. The aim of this study was to establish a reliable and reproducible system to evaluate the in vitro effectiveness of three desensitizing agents. Six selected fields from SEM negatives (magnification x1000; working distance 10mm) of test and control dentine disc specimens treated with the desensitizing agents (Butler Protect, Colgate FluoriGard (GelKam), Macleans Sensitive) were evaluated. Fields were assessed using a Quantimet 520 Image analysis system (Leica UK) and the data recorded included patent tubule area, mean tubule diameter, mean patent/field area and number of tubules per unit area. Comparison of test and control specimens indicated that differences in the number of tubules, patent area, width of tubules and percentage of patent areas can be assessed quantitatively Furthermore, this methodology also demonstrated differences between the tubule occluding properties of the selected desensitizing agents