Targeting senescent immune cells to rejuvenate the aging skeleton.

Accumulation of senescent cells in the bone marrow leads to age-related bone degeneration. Identifying the key senescent cell types and the factors they release that are responsible for skeletal aging is of keen interest. In a new study by Li et al. (2021), it is shown that immune cells, including neutrophils and macrophages, are critical cell types in this aging process, and that they secrete grancalcin to promote such aging.