Near infrared light amplifies endothelial progenitor cell accumulation after stroke

Area of Science:

• Neuroscience
• Biomedical Engineering
• Regenerative Medicine

Background:

• Damage-associated molecular patterns (DAMPs) are implicated in non-cell autonomous conditioning effects.
• Astrocytes play crucial roles in neurovascular unit signaling and response to injury.

Purpose of the Study:

• To investigate the potential of near-infrared (NIR) light as a conditioning tool.
• To explore NIR-induced astrocytic signaling and its effect on endothelial progenitor cell (EPC) accumulation post-stroke.

Main Methods:

• In vitro studies using conditioned media from NIR-stimulated astrocytes.
• In vivo transcranial NIR irradiation in a mouse model of focal ischemia.
• Assessment of HMGB1 secretion, GFAP expression, and EPC accumulation.
• siRNA-mediated blockade of HMGB1.

Main Results:

• NIR light stimulation increased calcium-dependent HMGB1 secretion from astrocytes.
• Conditioned media from NIR-stimulated astrocytes enhanced EPC proliferation in vitro.
• Transcranial NIR penetrated scalp and skull, increasing GFAP expression in vivo.
• Repeated NIR irradiation in stroke models increased peri-infarct HMGB1 and EPC accumulation.

Conclusions:

• NIR light effectively stimulates astrocytic release of HMGB1, a key DAMP.
• NIR-induced signaling promotes EPC accumulation, suggesting a therapeutic potential for stroke.
• NIR light shows promise as a non-invasive conditioning strategy to enhance neurovascular repair after stroke.