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The relationship between ischemic penumbra progression and the oxygen content of cortex microcirculation in acute ischemic stroke. | LitMetric

AI Article Synopsis

  • The study investigates the oxygen content thresholds that are critical in ischemic brain conditions, particularly how low oxygen levels transform the ischemic penumbra into an infarct core.
  • Using advanced techniques, including a fiber-optic oxygen meter and a new probe, the research involved a mouse model to analyze stroke severity post-reperfusion.
  • Results showed a decline in oxygen levels and worsening stroke symptoms, suggesting the potential to rescue hypoxic tissue within 3 hours of ischemia, but indicating limited reversibility after 6 hours.

Article Abstract

The precise oxygen content thresholds of ischemic deep parenchymal (OCIDP) and that in cortical microcirculation (OCCM), which leads to ischemic penumbra converting into the infarcted core, remain uncertain. This study employed an invasive fiber-optic oxygen meter and a newly developed oxygen-responsive probe called RuA-Cy5-rtPA (RC-rtPA) based on recombinant tissue-type plasminogen activator (rtPA) to examine the oxygen content thresholds. A mouse model of middle cerebral artery occlusion was generated and animals were randomly divided into a sham, 24-h reperfusion after 3-h ischemia (IR 3-h), and IR 6-h groups, all of which were sacrificed following reperfusion. Stroke severity was evaluated based on the infarction area, neurological symptoms, microcirculation perfusion, and microemboli in microcirculation. OCIDP was characterized based on its extent and distribution, whereas OCCM was measured using RC-rtPA. During ischemia, stroke severity escalation manifested as increasing infarction area, severe neurologic symptoms, and poorer microcirculation perfusion with more microthrombi depositions. OCIDP presented rapid decline following artery occlusion along with a gradual increase in the hypoxic area. Within 3 ​h following ischemia induction, the ischemic tissue that experienced hypoxia could be rescued, and this reversibility would disappear after 6 ​h. Within 6 ​h, OCCM continued to decrease. A significant decrease in oxygen content in cortical venules and cortical parenchyma was observed. These findings assist in establishing the extent of the ischemic penumbra at the microcirculation level and offer a foundation for assessing the ischemic penumbra that could respond positively to reperfusion therapy beyond the typical time window.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC11579870PMC
http://dx.doi.org/10.1016/j.neurot.2024.e00387DOI Listing

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