Tracing notochord-derived cells using a Noto-cre mouse: implications for intervertebral disc development.

Area of Science:

• Developmental Biology
• Cell Biology
• Musculoskeletal Research

Background:

• Intervertebral disc degeneration causes widespread back pain, yet its developmental origins remain unclear.
• Effective treatments for disc degeneration are limited by a poor understanding of disc development and maintenance.
• The notochord's role in intervertebral disc formation is not fully elucidated.

Purpose of the Study:

• To determine the developmental origin of nucleus pulposus cells within the intervertebral disc.
• To trace the fate of notochordal cells during spinal development and intervertebral disc formation.
• To establish a tool for investigating notochordal cell contributions to disc development and degeneration.

Main Methods:

• Generated a novel notochord-specific Cre mouse line by targeting the Noto homeobox gene.
• Crossed Noto-cre mice with a conditional lacZ reporter for lineage tracing.
• Performed fate mapping experiments from embryonic day 12.5 to 9 months in mice.

Main Results:

• Fate mapping confirmed the notochord is the embryonic precursor to nucleus pulposus cells.
• Notochordal cells and chondrocyte-like nucleus pulposus cells were both shown to derive from the embryonic notochord.
• The Noto-cre mouse model successfully visualized notochordal cell contribution to the intervertebral disc.

Conclusions:

• Notochordal cells are conclusively identified as the embryonic precursors for all cells in the mature intervertebral disc nucleus pulposus.
• Notochordal cells may function as tissue-specific progenitor cells within the intervertebral disc.
• The Noto-cre mouse is a valuable tool for studying intervertebral disc development and degeneration.