Temporal window for detection of inflammatory disease using dynamic cell tracking with time-lapse MRI

Area of Science:

• Neuroimaging
• Immunology
• Cell Biology

Background:

• Intravascular immune cell dynamics are crucial for understanding inflammatory responses.
• Non-invasive methods for tracking these cells in deep tissues are limited.
• Iron oxide nanoparticles (IONs) can label cells for MRI detection.

Purpose of the Study:

• To develop and validate time-lapse MRI for dynamic, non-invasive tracking of slowly moving intravascular immune cells.
• To assess immune cell dynamics in a mouse model of experimental autoimmune encephalomyelitis (EAE).

Main Methods:

• Repetitive MRI acquisition was used to dynamically observe ION-labeled cells.
• Simulations determined the detectable cell velocity threshold (<1 µm/s).
• Time-lapse MRI was performed on mice (naïve and EAE) after intravenous injection of IONs or ION-labeled monocytes.

Main Results:

• Time-lapse MRI successfully tracked ION-labeled cells in vivo.
• EAE mice exhibited a reduced number of slow-moving (patrolling) cells compared to naïve controls, both pre- and post-symptom onset.
• This suggests altered immune cell dynamics, potentially higher velocities, in the inflamed condition.

Conclusions:

• Time-lapse MRI is a viable tool for non-invasively assessing immune cell dynamics in deep tissues.
• The technique can potentially detect or monitor inflammatory responses by observing changes in immune cell movement patterns.