Microgravity-Related Changes in Bone Density and Treatment Options: A Systematic Review

Abstract

Space travelers are exposed to microgravity (µg), which induces enhanced bone loss compared to the age-related bone loss on Earth. Microgravity promotes an increased bone turnover, and this obstructs space exploration. This bone loss can be slowed down by exercise on treadmills or resistive apparatus. The objective of this systematic review is to provide a current overview of the state of the art of the field of bone loss in space and possible treatment options thereof. A total of 482 unique studies were searched through PubMed and Scopus, and 37 studies met the eligibility criteria. The studies showed that, despite increased bone formation during µg, the increase in bone resorption was greater. Different types of exercise and pharmacological treatments with bisphosphonates, RANKL antibody (receptor activator of nuclear factor κβ ligand antibody), proteasome inhibitor, pan-caspase inhibitor, and interleukin-6 monoclonal antibody decrease bone resorption and promote bone formation. Additionally, recombinant irisin, cell-free fat extract, cyclic mechanical stretch-treated bone mesenchymal stem cell-derived exosomes, and strontium-containing hydroxyapatite nanoparticles also show some positive effects on bone loss.

Recombinant irisin prevents cell death and mineralization defects induced by random positioning machine exposure in primary cultures of human osteoblasts: A promising strategy for the osteoporosis treatment

“…Interestingly, the bone mass loss is a condition that also characterizes the elderly with osteoporosis and, in this context, the use of r-irisin has already been suggested as a potential therapeutic tool ( Baran et al, 2022 ). However, the mechanism by which this hormone preserves the bone mass loss due to osteoporosis has not been well elucidated, nor have the molecular pathways common to the weightlessness-induced loss of bone mass and the pathological condition been determined.…”

Translation from Microgravity Research to Earth Application

“…The topic “Translation from Microgravity Research to Earth Application” comprises publications focusing on space life sciences, gravitational biology and space medicine [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. It covers publications reporting the impact of altered environmental conditions, such as microgravity (µ g ), cosmic radiation and isolation on organisms down to the level of cells [ 3 , 4 , 5 , 7 , 8 , 10 , 11 , 12 , 13 , 14 ].…”

“…The topic “Translation from Microgravity Research to Earth Application” comprises publications focusing on space life sciences, gravitational biology and space medicine [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. It covers publications reporting the impact of altered environmental conditions, such as microgravity (µ g ), cosmic radiation and isolation on organisms down to the level of cells [ 3 , 4 , 5 , 7 , 8 , 10 , 11 , 12 , 13 , 14 ]. In addition, the topic collects studies validating causal diagrams of human health risks for spaceflight [ 1 ], hypergravity studies [ 2 ] and investigations about the impact of extreme isolation in the Antarctica on the human body [ 6 ].…”

“…Humans in space experience µ g , which enhances bone loss by 0.5–1.5% and reduces bone mineral density per month in space. One reason for this finding is, among others, the inhibition of the Wnt/β-catenin signaling pathway [ 3 ]. Different types of exercise and pharmacological treatments are available and discussed in [ 3 ].…”

“…One reason for this finding is, among others, the inhibition of the Wnt/β-catenin signaling pathway [ 3 ]. Different types of exercise and pharmacological treatments are available and discussed in [ 3 ]. A second review highlighted the different mechanisms and factors regulating the humoral crosstalk between muscle and bone [ 8 ].…”