NGF-p75 signaling coordinates skeletal cell migration during bone repair.

Area of Science:

• Orthopedics
• Regenerative Medicine
• Cell Biology

Background:

• Bone regeneration involves inflammation and nerve infiltration, but the precise mechanisms linking these processes remain unclear.
• The coordination of angiogenesis, tissue reprogramming, immune signaling, and osteogenesis is essential for effective bone healing.

Purpose of the Study:

• To elucidate the mechanism by which immune signals are coupled to reinnervation and osteogenesis during bone repair.
• To investigate the role of nerve growth factor (NGF) and its signaling pathway in coordinating skeletal cell migration during early bone healing.

Main Methods:

• Utilized mouse models with genetic deficiencies in NGF and p75 signaling.
• Employed single-cell transcriptomics to analyze mesenchymal subpopulations.
• Observed osteogenic precursor cell migration to cranial bone injury sites.

Main Results:

• Nerve growth factor (NGF) is expressed after cranial bone injury and signals via p75 in osteogenic precursors, promoting their migration.
• Mice lacking NGF in myeloid cells showed reduced osteogenic precursor migration and delayed bone healing.
• Deletion of p75 in osteoblast precursors phenocopied these defects, highlighting the p75 signaling pathway's importance.
• Single-cell transcriptomics revealed altered mesenchymal subpopulations involved in cell migration and immune response upon p75 deletion.

Conclusions:

• The p75 signaling pathway plays a critical role in coordinating skeletal cell migration during the early stages of bone repair.
• NGF signaling is a key mediator in guiding osteogenic precursors to injury sites, essential for successful bone regeneration.