NEUROPROTECTIVE AND IMMUNOMODULATORY EFFECTS OF NEAR-INFRARED PHOTOBIOMODULATION IN IN VITRO MODELS OF HYPOXIC–ISCHEMIC ENCEPHALOPATHY

Hypoxic–ischemic encephalopathy (HIE) is a severe neonatal disorder resulting from insufficient oxygen and blood supply to the brain leading to high mortality and long-term neurological impairments. Hypothermia remains the only approved treatment, but its efficacy is limited. Thus, identifying adjunct therapies to boost neuroprotection remains a critical priority. Photobiomodulation (PBM) has emerged as a promising non-invasive strategy for brain injury, with effects on mitochondrial metabolism, neurogenesis, synaptic plasticity, and neuroinflammation.
We investigated the neuroprotective and immunomodulatory potential of near-infrared (NIR) laser therapy using Multiwave Locked System in in vitro HIE models. Immature organotypic hippocampal and corticostriatal slice cultures were subjected to oxygen–glucose deprivation (OGD) for 30 or 60 minutes, respectively. After OGD, the slices were irradiated with NIR (808 nm and 905 nm), 3.82, 7.65, or 14.66 J/cm². Neuronal damage and survival were assessed after 24 hours by propidium iodide staining, lactate dehydrogenase release, and NeuN/IBA1 immunofluorescence. Transmission electron microscopy was employed to examine cellular ultrastructure and anatomical features, with particular focus on autophagic compartments. To further investigate the mechanisms by NIR laser irradiation affects microglial cells, BV2 microglia were subjected to 6 h OGD, followed by laser treatment and tubulin immunofluorescence analysis.
Our findings demonstrate that NIR exposure significantly enhanced neuronal survival following OGD, while modulating microglial activation. Higher NIR doses induced morphological alterations that warrant further investigation. TEM analysis suggests that laser treatment may delay autophagic processes. These results support NIR photobiomodulation as a promising adjunct therapy for HIE, enhancing the neuroprotective effects of hypothermia.