jsc2025e065390 (1/21/2022) --- A microscope image of osteoclasts, which are multinucleated cells responsible for breaking down bone tissue. The Microgravity Associated Bone Loss-B (MABL-B) investigation on the International Space Station uses this type of cell and human bone-forming stem cells from two human donors to examine the effects of microgravity. The investigation could provide a better understanding of the basic molecular mechanisms behind the bone loss that occurs during spaceflight and from normal aging and disease on Earth. Credit: Mayo Clinic