Preclinical models of middle cerebral artery occlusion: new imaging approaches to a classic technique

Experimental digital atlas of blood supply zones of the internal carotid artery

Background: The compilation of a neuroanatomic atlas based on a large sample is essentially a fundamental research work, but compiling a digital atlas during the epoch of wide usage of radiodiagnostics methods in the clinical and experimental practice along with using the artificial intelligence systems brings a significant applied relevance to the research. Rats are the main species of laboratory animals, in which the studies of modeling the ischemic stroke, of testing the cerebroprotective drugs and of developing new strategies of regenerative therapy of stroke consequences are carried out. At the present moment, there is no available and comprehensive digital atlas of the arterial blood supply of the rat brain, while single research works are based on small groups of animals and their histological description. Within this context, it is deemed very interesting and important to take the first step in addressing this issue. AIM: to compile an atlas of blood supply zones within the intracranial branches of the internal carotid artery in the settings of experimentally induced occlusion of the medial cerebral artery. METHODS: The archived data were used from the magnetic resonance imaging scans in rats with modeling the transient occlusion of the medial cerebral artery with a monofilament (n=243). The system of automatic brain segmentation based on artificial intelligence was used for objective mapping of the cerebral infarction area, the obtained data were added to a single coordinate space, unified and analyzed for highlighting the arterial blood supply zones. RESULTS: A digital atlas of the arterial circulation was compiled based on the intravitam data of high-resolution magnetic resonance imaging with an isotropic voxel. CONCLUSION: The compiled atlas may be used for increasing the quality of modeling the cerebral infarction by means of transient occlusion of the medial cerebral artery with a monofilament and it allows for using the additional objective parameters in the evaluation of the treatment effects in cases of experimentally induced ischemic stroke. The methodology developed by us is applicable for high-performance retrospective analysis of the neurovisualization data from the ischemic stroke patients, obtained within a framework of the implementation of the Vascular Medicine Program in the Russian Federation.

Healing of ischemic injury in the retina

Neuro- and retinal degenerative diseases, including Alzheimer's, age-related macular degeneration, stroke, and central retinal artery occlusion, rob millions of their independence. Studying these diseases in human retinas has been hindered by the immediate loss of neuronal activity postmortem. While recent studies restored limited activity in postmortem CNS tissues, synchronized neuronal transmission >30 minutes postmortem remained elusive. Our study overcomes this barrier by reviving and sustaining light signal transmission in human retinas recovered up to four hours and stored 48 hours postmortem. We also establish infrared-based ex vivo imaging for precise sampling, a closed perfusion system for drug testing, and an ex vivo ischemia-reperfusion model in mouse and human retina. This platform enables testing of neuroprotective and neurotoxic effects of drugs targeting oxidative stress and glutamate excitotoxicity. Our advances question the irreversibility of ischemic injury, support preclinical vision restoration studies, offer new insights into treating ischemic CNS injuries, and pave the way for transplantation of human donor eyes.

Teaser

Reviving light signaling in postmortem human retinas challenges the irreversibility of ischemic injury and advances research to restore vision.