Response of rat bone marrow cells to differently roughened titanium discs

The purpose of the present in vitro study was to examine the effect of surface roughness on the behaviour of osteoblast-like cells. Rat bone marrow (RBM) cells were cultured on commercially pure titanium discs. The discs were used as machined (Ti M) or ground with 4000 (Ti 4000) or 320 (Ti 320) grit paper. Proliferation rate and alkaline phosphatase activity were determined, and morphology of the cells was studied with scanning electron microscopy (SEM). Besides, fluorescent markers, energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) were used to obtain quantitative and compositional information about the produced calcified extracellular matrix (ECM). Results demonstrated after 2 days of incubation no significant difference in the percentage of attached cells to all substrates. At 5 days, Ti 320 surfaces showed significantly lower (P < 0.05) cell attachment percentages compared with Ti M and Ti 4000 surfaces. At 8 days, Ti 320 surfaces showed significantly more (P < 0.05) cell attachment than the other surfaces. The Ti 4000 surfaces showed after 8 days significantly (P < 0.05) higher alkaline phosphatase activity compared to both other surfaces. At 15 days of incubation, the alkaline phosphatase activity on Ti 4000 substrates was significantly lower (P < 0.05) than on the other substrates. No significant difference in mineralized ECM formation was observed on the ground substrate compared to the machined substrates. Physicochemical analysis confirmed the apatite-like nature of the deposited ECM on all substrates. On the basis of these findings, we concluded that our in vitro study could not clearly confirm the effect of surface roughness on the proliferation, differentiation and calcification of rat bone marrow cells.