THE ROLE OF BONE CELL MECHANICAL STIMULATION IN THE PROCESS OF OSTEOGENESIS

The main function of bones is to support soft tissues of the organisms and maintain vertical posture of a human body. Thus, skeletal tissue provides an important mechanical function and senses different mechanical forces. Mechanical stimulation affects bone remodelling, i.e. bone turnover. Bone remodeling takes place under physiological conditions and upon micro-and macro-bone injuries. Imbalance between bone formation and resorption affects the homeostasis of a whole organism. Treating large bone defects or bone degenerative diseases remains a challenging medical issue. Besides standard auto-or allogenic bone grafts, bone tissue engineering offers several innovating solutions by applying e.g. isolated osteoblast precursor cells that are stimulated to osteogenesis with selected growth factors, cultured in three-dimensional bone-like scaffolds and exposed to mechanical forces in vitro. In a body, bone precursors, osteoblasts and terminally differentiated osteocytes are exposed to e.g. shear stress, stretching, compression and vibrations, which may trigger bone remodelling. Different bioreactors facilitate mechanical stimulation of cells in vitro. In this manuscript we review the current literature dealing with the most common mechanical forces applied in bone cell cultures and effectively stimulating the osteogenesis in vitro. Particular attention was paid to flow perfusion, stretching and vibrations and the role these forces play in mesenchymal stem cell and bone precursor cell osteogenesis in vitro.