Spatiotemporal Dynamics of Neuroinflammation Relate to Behavioral Recovery in Rats with Spinal Cord Injury

Area of Science:

• Neuroscience
• Biomedical Imaging
• Regenerative Medicine

Background:

• Neuroinflammation is critical in spinal cord injury (SCI) severity and recovery.
• Longitudinal monitoring of neuroinflammation is essential for understanding SCI progression and treatment efficacy.

Purpose of the Study:

• To validate Chemical Exchange Saturation Transfer (CEST) Magnetic Resonance Imaging (MRI) metrics for monitoring neuroinflammation post-SCI.
• To correlate dynamic neuroinflammation changes with behavioral recovery in a rat SCI model.
• To establish imaging biomarkers for evaluating SCI therapies.

Main Methods:

• 12 rats with SCI and 4 sham controls underwent weekly CEST MRI and Positron Emission Tomography (PET)-Translocator Protein (TSPO) scans for 8 weeks.
• CEST Z-spectra were analyzed using a 5-Lorentzian pool model.
• Behavioral tests (motor and somatosensory) were correlated with imaging data and validated with post-mortem histology (iba-1, GFAP).

Main Results:

• PET-TSPO confirmed widespread inflammation, corroborated by histological analysis of activated microglia.
• CEST and Nuclear Overhauser Effect (NOE) peaks showed significant changes within the first week post-injury, particularly in rostral segments.
• These imaging indices of neuroinflammation temporally correlated with the recovery of locomotor and somatosensory functions in rats with moderate SCI.

Conclusions:

• CEST MRI provides sensitive, noninvasive indices of dynamic neuroinflammation in SCI.
• Understanding the spatiotemporal progression of neuroinflammation is key for developing targeted neuroprotective and anti-inflammatory therapies.
• Noninvasive MRI biomarkers can accelerate clinical trials for SCI treatments.