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.