Development of a 3D Collagen Model for the In Vitro Evaluation of Magnetic-assisted Osteogenesis

Abstract Magnetic stimulation has been applied to bone regeneration, however, the cellular and molecular mechanisms of repair still require a better understanding. A three-dimensional (3D) collagen model was developed using plastic compression, which produces dense, cellular, mechanically strong native collagen structures. Osteoblast cells (MG-63) and magnetic iron oxide nanoparticles (IONPs) were incorporated into collagen gels to produce a range of cell-laden models. A magnetic bio-reactor to support cell growth under static magnetic fields (SMFs) was designed and fabricated by 3D printing. The influences of SMFs on cell proliferation, differentiation, extracellular matrix production, mineralisation and gene expression were evaluated. Polymerase chain reaction (PCR) further determined the effects of SMFs on the expression of runt-related transcription factor 2 (Runx2), osteonectin (ON), and bone morphogenic proteins 2 and 4 (BMP-2 and BMP-4). Results demonstrate that SMFs, IONPs and the collagen matrix can stimulate the proliferation, alkaline phosphatase production and mineralisation of MG-63 cells, by influencing matrix/cell interactions and encouraging the expression of Runx2, ON, BMP-2 and BMP-4. Therefore, the collagen model developed here not only offers a novel 3D bone model to better understand the effect of magnetic stimulation on osteogenesis, but also paves the way for further applications in tissue engineering and regenerative medicine

In search of an osteoblast cell model for in vitro research

The process of bone formation, remodelling and healing involves a coordinated action of various cell types. Advances in understanding the biology of osteoblast cells during these processes have been enabled through the use of various in vitro culture models from different origins. In an era of intensive bone tissue engineering research, these cell models are more and more often applied due to limited availability of primary human osteoblast cells. While they are a helpful tool in developing novel therapies or biomaterials; concerns arise regarding their phenotypic state and differences in relation to primary human osteoblast cells. In this review we discuss the osteoblastic development of some of the available cell models; such as primary human, rat, mouse, bovine, ovine and rabbit osteoblast cells; as well as MC3T3-E1, MG-63 and SaOs-2 cell lines, together with their advantages and disadvantages. Through this, we provide suggestions on the selection of the appropriate and most relevant osteoblast model for in vitro studies, with specific emphasis on cell-material based studies