Endosteal stem cells at the bone-blood interface: A double-edged sword for rapid bone formation

Endosteal stem cells are a subclass of bone marrow skeletal stem cell populations that are particularly important for rapid bone formation occurring in growth and regeneration. These stem cells are strategically located near the bone surface in a specialized microenvironment of the endosteal niche. These stem cells are abundant in young stages but eventually depleted and replaced by other stem cell types residing in a non-endosteal perisinusoidal niche. Single-cell molecular profiling and in vivo cell lineage analyses play key roles in discovering endosteal stem cells. Importantly, endosteal stem cells can transform into bone tumor-making cells when deleterious mutations occur in tumor suppressor genes. The emerging hypothesis is that osteoblast-chondrocyte transitional identities confer a special subset of endosteal stromal cells with stem cell-like properties, which may make them susceptible for tumorigenic transformation. Endosteal stem cells are likely to represent an important therapeutic target of bone diseases caused by aberrant bone formation. Endosteal stem cells are a new subclass of bone marrow skeletal stem cell populations. These cells are particularly abundant in the young bone marrow and possess osteoblast-chondrocyte transitional identity. Endosteal stem cells coordinate active osteogenesis in homeostasis and regeneration. These cells can also dictate tumorigenesis when they lose the tumor suppressor gene p53, a known driver gene for osteosarcoma.image