The Behavior of Human Osteoblast under Tension in 3D Matrix

Objectives: The purpose of this study was to test the effect of tensile force on the primary human osteobalstic cell cultured in a 3-D environment, which was a more physiological situation. Mechanical strain was known to have potential anabolic effects on the skeleton and bone homeostasis and well-documented osteoblast proliferating effects both in vivo and in vitro. These studies had analyzed the effects of 3D growth environments on osteoblast differentiation using established osteoblast cell lines and had demonstrated increased cellular aggregation and osteoblast differentiation, but whether the primary cell culture model reacted different or not was not yet investigated. Methods: Bone cells from primary culture and undergone mechanical stimulation in a 3D collagen scoffold, 25x3x3mm in size by using Tissue Train culture system. The force was given in sine waveform shape, 10% elongation rate and 0.1Hz in frequency 6 hours per day. After tensile force applied, the level of ALP, osteocalcin and cell proliferation rate were evaluated. As mechanical strain probably conducted surface proteins interacting with ECM and cytoskeleton, the changes in morphology and alignment were also observed. Result: In this study, osteoblast could survive in a 3D tensile environment and the proliferation rates were not significantly different whether the cells were under tension or not. Besides, cells which were under tension had morphological and cytoskeletal changes including flattened appearance and spindled in shape and aligned parallel to the direction of force. As for bone differentiation related protein, ALP and osteocalcin were all raised by tension application. Conclusion: This 3-D model is suitable to investigate the physiological reaction of the primary osteoblastic cell culture and the tensile force promotes the differentiation of the cells.