Bone Mineral Density and Molecular-Genetic Markers of Bone Remodeling in Blood in Cosmonauts after Long-Term Missions to the International Space Station
We investigated the bone system in 24 cosmonauts after long-duration (124-199 days) ISS missions. It was found that the functional adaptations of the bone system involves some complex changes in the metabolic activity of osteoblasts and osteoclasts: serum concentrations of osteocalcin, tartrate-resistant acid phos-phatase (TRAP), osteoprotegerin, receptor activator of nuclear factor kappa-B ligand (RANKL) levels, and expression of genes regulating the development of skeletal system as well as bone mineral metabolism. Significant individual variability in the mineral density of femur neck and chosen molecular-genetic markers after longterm space flights indicates individual variability in the balance of processes of bone remodeling - bone formation and resorption. Significant bone mass losses in the femoral bone of subjects were associated with more pronounced changes in the markers of metabolic activity of osteoclasts.