Skeletal stem and progenitor cells in bone development and repair.

Area of Science:

• Bone Biology
• Regenerative Medicine
• Stem Cell Research

Background:

• Bone development, growth, and repair involve complex cellular interactions, with skeletal stem and progenitor cells (SSPCs) playing central roles.
• Recent research has illuminated skeletal precursor populations involved in intramembranous and endochondral ossification.
• Fracture repair reactivates developmental mechanisms, with trauma-induced signals activating postnatal SSPCs.

Purpose of the Study:

• To review current understanding of skeletal progenitor cell origins, identities, and fates during bone development and repair.
• To discuss the roles of adult SSPC populations in fracture healing.
• To reflect on the dynamism and relationships among skeletal precursors and differentiated cell lineages.

Main Methods:

• In vivo lineage tracing
• Cell surface marker-based cell selection
• Single-cell molecular analyses
• High-resolution in situ imaging

Main Results:

• Evidence suggests considerable flexibility and dynamic fates for SSPCs and differentiated skeletal cells during injury.
• Multiple cell sources can function as progenitors, generating chondrocytes and osteoblasts.
• Advanced imaging and molecular techniques have improved insights into SSPC diversity, roles, dynamics, and relationships.

Conclusions:

• Findings challenge the classical dogma of a single primitive stem cell driving bone formation and regeneration.
• Lineage flexibility and plasticity among osteogenic cell sources are increasingly recognized.
• Further research into SSPC heterogeneity and regulatory cues is crucial for clinical translation in bone regenerative medicine.