Long- and short-term intravital imaging reveals differential spatiotemporal recruitment and function of myelomonocytic cells after spinal cord injury

J Physiol, 2013 · DOI: 10.1113/jphysiol.2013.256388 · Published: August 5, 2013

Simple Explanation

After spinal cord injury (SCI), the body recruits immune cells called myelomonocytic cells to the injury site. These cells can either help clear debris or worsen the injury by affecting axon growth. Using advanced microscopy, researchers tracked two types of myelomonocytic cells: infiltrating LysM(+) cells and resident CD11c(+) cells. They found these cells arrive at different times and locations within the injured spinal cord. The infiltrating cells were linked to the collapse of damaged axon terminals, potentially hindering recovery. In contrast, the resident cells were associated with clearing axon debris, which might promote axon regrowth and recovery.

Study Duration

Not specified

Participants

Adult transgenic mice

Evidence Level

Level 2: Experimental study using intravital two-photon microscopy in mice.

Key Findings

1
Infiltrating LysM(+) cells are rapidly recruited to injury sites and are associated with the collapse of distended axon terminals (DATs) caudal of injury sites.
2
Resident CD11c(+) cells peaked at the injury site later and are more closely associated with clearing axon debris rostral of injury sites.
3
DAT collapse occurs during close appositions with lysozyme M (LysM(+)) cells.

Research Summary

This study investigates the spatiotemporal dynamics of myelomonocytic cells following spinal cord injury (SCI) using intravital two-photon microscopy. The research identifies distinct recruitment profiles and functions for infiltrating LysM(+) and resident CD11c(+) cells, with LysM(+) cells associated with axon terminal collapse and CD11c(+) cells associated with debris clearance. The findings highlight the importance of precise timing and targeting of specific cell populations in developing effective therapies for SCI.

Practical Implications

Targeted Therapies

Developing therapies that specifically target different immune cell populations at precise times post-injury could improve SCI outcomes.

Understanding Cell Roles

Further research is needed to fully understand the roles of different myelomonocytic cell subpopulations in SCI to optimize therapeutic strategies.

Controlled Modulation

Strategies to repair the injured spinal cord by modulating macrophages need a precise knowledge of their recruitment and function to be effective.

Study Limitations

1
LysM-GFP and CD11c-EYFP markers may not reveal all infiltrating and resident macrophages.
2
The study cannot exclude the presence of other subpopulations of macrophages.
3
A more thorough characterization of these cells using tools such as multi-parametric ﬂow cytometry during the course of spinal cord healing is warranted in future studies.

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