Behavior of osteobalsts on multi-grooved surface in vitro

Objectives: This study evaluated the behavior of osteoblast-like cells on multi-grooved surfaces consisting of a combination of micro-grooves and macro-grooves. Methods: A polystyrene substrate was fabricated with multi-grooves with 90-degree, V-shaped micro-grooves with a 2-µm pitch cut on trapezoidal macro-grooves, which had a 50-µm ridge width, a 50-µm wall width, a 50-µm bottom width, and a 25-µm depth. Smooth polystyrene substrates were also prepared as controls. Rat bone marrow cells were cultured as osteoblast-like cells on the substrates. For morphological evaluation, scanning electron microscope (SEM) images after 8 and 16 days of incubation were observed and cellular orientation and cellular spreading ratios were measured using SEM images of 8 days of incubation. For biochemical evaluation, the quantitative RT-PCR technique for osteopontin and osteocalcin mRNA expression was evaluated. Results: The mean angle of cellular orientation on the multi-grooved surface was 11.45 ± 11.18 degrees, and on the smooth surfaces was 43.95 ± 41.05. The ratio of cellular spreading on multi-grooved surfaces was 2.41 ± 0.59, and on smooth surfaces was 1.23 ± 0.32. The ratio of cellular spreading on the multi-grooved surfaces was significantly greater than that on the smooth surfaces (p<0.05). After 16 days of incubation, a dense mineralized extra-cellular matrix (ECM) was produced along the multi-grooves. The ECM on the multi-grooved surface appeared oriented more in the direction of the grooves than on the smooth surface, and trapezoid-shaped macro-grooves of the ECM were cast upside down. Although there were not significant differences, the osteopontin and osteocalcin mRNA expressions of the osteoblast-like cells on the multi-grooved surfaces tended to be higher than on smooth surfaces. Conclusion: These results suggest that multi-grooves could be used to control the behavior of osteoblasts and to form mineralized ECM three-dimensionally.