Osteoprogenitor cell
Also known as: osteogenic cell, osteoprogenitor, skeletal stem cell
Mitotically active stem/progenitor cells of mesenchymal origin, found in the periosteum, endosteum and canal linings, that differentiate into osteoblasts.
Overview
Osteoprogenitor cells are flattened, spindle-shaped cells derived from mesenchymal stromal (stem) cells. They are the only bone cells capable of significant division and are therefore essential for growth, remodelling and fracture healing. Commitment to the osteoblast lineage requires the transcription factors RUNX2 (CBFA1) and osterix (Sp7), driven by Wnt/β-catenin signalling and bone morphogenetic proteins (BMPs). Under low oxygen and high movement (as in an unstable fracture gap) the same precursors tend instead to form chondroblasts, which explains cartilage in fracture callus.
In bone marrow, mesenchymal stromal cells can also become adipocytes; with ageing and glucocorticoid exposure the balance shifts towards fat (yellow marrow) at the expense of bone formation.
- Location
Inner cambium layer of periosteum, endosteum, linings of central and perforating canals, bone marrow stroma.
Anatomy
- Development
Derived from mesoderm (and neural crest in the skull and face).
Function
- Self-renewing source of osteoblasts
- Supplies new bone-forming cells for growth, remodelling and fracture repair
Clinical significance
Cleidocranial dysplasia
RUNX2 haploinsufficiency impairs osteoblast differentiation: absent/hypoplastic clavicles (shoulders can meet in the midline), delayed fontanelle closure, wormian bones and dental anomalies.
Compiled from standard anatomy and physiology references — see the Skeletal System sources. For education only; not medical advice.