Role of rhBMP-2 and rhBMP-7 in the Metabolism and Differentiation of Osteoblast-Like Cells Cultured on Chemically Modified Titanium Surfaces
This study analyzed the role of recombinant human bone morphogenetic protein 2 (rhBMP-2) and recombinant human bone morphogenetic protein 7 (rhBMP-7) in the adhesion and differentiation of rat osteoblast-like (osteo-1) cells cultured on chemically modified titanium surfaces. Osteo-1 cells were cultured on chemically modified (modified sandblasted and acid-etched) titanium surfaces in 3 different types of medium: control, medium supplemented with 20 ng/mL rhBMP-2, and medium supplemented with 20 ng/mL rhBMP-7. The following parameters were evaluated: cell adhesion after 24 hours; total protein content; collagen content and alkaline phosphatase (AP) activity after 7, 14, and 21 days; and calcified nodule formation after 21 days. The addition of rhBMP-2 or rhBMP-7 did not influence cell adhesion (P = .1175). Cell differentiation was influenced by rhBMP-2, as demonstrated by a significant increase in collagen content after 7 days of culture (P < .0001) and a significant decrease in AP activity after 21 days (P < .0001). The addition of rhBMP-7 only influenced AP activity, and a significant increase was observed after 21 days (P < .0001). Within the limitations of the study, we conclude that the presence of rhBMP-2 or rhBMP-7 did not influence cell adhesion to chemically modified titanium surfaces but provided an additional stimulus during the differentiation of rat osteo-1 cells cultured on this type of surface.
Figure 1. Effect of rhBMP-2 and rhBMP-7 on the number of osteo-1 cells cultured on the modSLA surface for 24 hours. Results are reported as the mean ± standard error of one experiment carried out in quadruplicate (analysis of variance [ANOVA], P = .1175). Figure 2. Total protein content (μg protein/mL) of osteo-1 cells evaluated after 7, 14, and 21 days of culture. Results are reported as the mean ± standard error of one experiment carried out in triplicate (ANOVA complemented by the Tukey test, P < .0001). Different letters indicate significant differences (P < .05). Figure 3. Collagen content (μg collagen/mg protein) of osteo-1 cells evaluated after 7, 14, and 21 days of culture. The data were normalized to total protein content and are reported as the mean ± standard error of one experiment carried out in quadruplicate (ANOVA complemented by the Tukey test, P < .0001). Different letters indicate significant differences (P < .05). Figure 4. Alkaline phosphatase activity (μmol thymolphthalein/mg protein) of osteo-1 cells evaluated after 7, 14, and 21 days of culture. The data were normalized to total protein content and are reported as the mean ± standard error of one experiment carried out in quadruplicate (ANOVA complemented by the Tukey test, P < .0001). Different letters indicate significant differences (P < .05). Figure 5. Formation of calcified nodules by osteo-1 cells evaluated after 21 days of culture. Results are reported as the mean ± standard error of one experiment carried out in quadruplicate (ANOVA, P = .21) and are expressed as percent mineralized area.
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