Estimation of the Ischemic Lesion in the Experimental Stroke Studies Using Magnetic Resonance Imaging (Review).

In translational animal study aimed at evaluation of the effectiveness of innovative methods for treating cerebral stroke, including regenerative cell technologies, of particular importance is evaluation of the dynamics of changes in the volume of the cerebral infarction in response to therapy. Among the methods for assessing the focus of infarction, MRI is the most effective and convenient tool for use in preclinical studies. This review provides a description of MR pulse sequences used to visualize cerebral ischemia at various stages of its development, and a detailed description of the MR semiotics of cerebral infarction. A comparison of various methods for morphometric analysis of the focus of a cerebral infarction, including systems based on artificial intelligence for a more objective measurement of the volume of the lesion, is also presented.

Therapeutic Efficacy and Migration of Mesenchymal Stem Cells after Intracerebral Transplantation in Rats with Experimental Ischemic Stroke.

We studied therapeutic efficacy and migration characteristics of mesenchymal stem cells isolated from the human placenta after their intracerebral (stereotactic) administration to rats with the experimental ischemic stroke. It was shown that cell therapy significantly improved animal survival rate and reduced the severity of neurological deficit. New data on the migration pathways of transplanted cells in the brain were obtained.

Dose-Dependent Effects of Intravenous Mesenchymal Stem Cell Transplantation in Rats with Acute Focal Cerebral Ischemia.

Intravenous transplantation of mesenchymal stem (stromal) cells (MSC) is a promising approach to the treatment of ischemic stroke. In the published reports of the already completed preclinical and clinical studies the dosages of transplanted MSC greatly vary. However, the optimal dosage has not been determined. The dose-dependent effect of intravenous MSC transplantation was studied, in rats with experimental cerebral infarction. To this end, 5×105 and 2×106 MSC were intravenously administered 24 h after modeling of acute focal ischemia followed by complex assessment of the therapeutic efficacy over 60 days. The rate and degree of the recovery of neurological functions in rats increased with increasing the dose of injected cells, which confirms the dose-dependent effect of intravenous MSC transplantation.

MRI-Based and Histologically Verified 3D Modeling of Spatial Distribution of Intra-Arterially Transplanted Cells in Rat Brain.

Visualization of transplanted stem cells in the brain is an important issue in the study of the mechanisms of their therapeutic action. MRI allowing visualization of single transplanted cells previously labeled with superparamagnetic iron oxide particles is among the most informative methods of non-invasive intravital imaging. Verification of MRI data using pathomorphological examination at the microscopic level helps to avoid errors in data interpretation. However, making serial sections of the whole brain and searching for transplanted cells under the microscope is laborious and time-consuming. We have developed a method for 3D modeling of the distribution of transplanted cells in the brain allowing navigating through various brain structures and identifying the areas of accumulation of transplanted cells, which significantly increases the efficiency and reduces the time of histological examination.

Interrelations of Cerebral Hemodynamics with Parameters of Cardiac Function and Brain Tissue in Patients with Ischemic Stroke.

We analyzed interrelations between the cerebral blood flow, cardiac output, and condition of the brain substance in 530 patients with ischemic stroke. Dependencies between the linear blood flow velocities in all arteries supplying the brain, as well as between the total volume blood flow through the internal carotid arteries and left ventricular stroke volume were revealed. The severity of atrophy was maximum in the parietal lobes (median 1.5 (1.0; 2.0)) and minimum in the occipital lobes (median 0.5 (0; 1.0)). Temporal lobes cortical atrophy significantly correlated with changes in the limbic system and in the periventricular and deep white matter; a significant weak inverse correlation of this parameter with blood flow in the middle cerebral artery was also found. Changes in the periventricular white matter (but not in deep white matter) demonstrated a significant inverse correlation with blood flow in the middle and anterior cerebral arteries.

Brain Changes in the White Matter of the Brain White Matter Changes and Cognitive Functions in Asymptomatic Patients.

We analyzed the relationship between white matter hyperintensities in T2-weighted MR-images (according to Fazekas score) and the state of cognitive functions (total MOCA score) in 65 asymptomatic individuals. A relationship between the presence/number of lesions in the deep white matter of the brain and cognitive status according to the total MOCA score was revealed. The results of cognitive functions assessment also correlated with MRI evaluation of the severity of brain cortex atrophy. The severity of deep white matter lesions according to the Fazekas scale were also associated with end-diastolic blood flow velocities in the middle cerebral, vertebral, and basilar arteries.

Development of a motor and somatosensory evoked potentials-guided spinal cord Injury model in non-human primates.

Background Nonhuman primates (NHP) may provide the most adequate (in terms of neuroanatomy and neurophysiology) model of spinal cord injury (SCI) for testing regenerative therapies, but bioethical considerations exclude their use in severe SCI. New Method A reproducible model of SCI at the lower thoracic level has been developed in Rhesus macaques. The model comprises surgical resection of 25% of the spinal cord in the projection of the dorsal funiculus and dorsolateral corticospinal pathways, controlled via registration of intraoperative evoked potentials (EPs). The animals were evaluated using the modified Hindlimb score, MRI, SSEP, and MEP over a time period of 8-12 weeks post-SCI, followed by histological examination. Results Complete disappearance of intraoperative EPs from distal hindlimb muscles without restoration within two weeks post-SCI was an indicator for irreversible disruption of the abovementioned pathways. As a result, controlled damage to the spinal cord was achieved in three NHPs, clinically manifested as irreversible lower monoplegia. No significant functional restoration was observed in these NHPs up to 12 weeks post-SCI. Demyelination of the damaged ascending tracts was detected. Disturbances in pelvic organ function were not observed in all animals. Comparison with existing methods The new method of EPs-guided SCI allows a more controlled and irreversible damage to the spinal cord compared with contusion and other transection approaches. Conclusions This method to induce complete SCI in NHP is well tolerated, reproducible and ethically acceptable: these are valuable attributes in a preclinical model that will hopefully help advance testing of new regenerative therapies in SCI.

[Cell therapy for ischemic stroke. Stem cell types and results of pre-clinical trials]. / Kletochnaia terapiia ishemicheskogo insul'ta. Tipy stvolovykh kletok i rezul'taty doklinicheskikh issledovanii.

The literature review addresses the use of stem cells (SC) in ischemic stroke (IS). Part 1 of the paper overviews the results of experimental animal studies. Characteristics of different SC types and results of their studies in experimental models of IS are presented in the first section, the second section considers pros and cons of the methods of SC injection.

Multilayer polyion complex nanoformulations of superoxide dismutase 1 for acute spinal cord injury.

As one of the most devastating forms of trauma, spinal cord injury (SCI) remains a challenging clinical problem. The secondary processes associated with the primary injury, such as overproduction of reactive oxygen species (ROS) and inflammation, lead to concomitant compression of the injured spinal cord and neuronal death. Delivery of copper-zinc superoxide dismutase (SOD1), an efficient ROS scavenger, to the site of injury can mitigate SCI-induced oxidative stress and tissue damage. Towards this goal catalytically active nanoformulations of SOD1 ("nanozymes") are developed as a modality for treatment of SCI. Along with the cross-linked polyion complex of SOD1 with polycation poly(ethylene glycol) (PEG)-polylysine (single-coat (SC) nanozyme), we introduce for the first time the chemically cross-linked multilayer polyion complex in which SOD1 is first incorporated into a polyion complex with polycation, then coated by anionic block copolymer, PEG-polyglutamic acid (double-coat (DC) nanozyme). We developed DC nanozymes with high enzymatic activity and ability to retain and protect SOD1 under physiological conditions. Pharmacokinetic study revealed that DC nanozymes significantly prolonged circulation of active SOD1 in the blood stream compared to free SOD1 or SC nanozymes (half-life was 60 vs 6min). Single intravenous injection of DC nanozymes (5kU of SOD1/kg) improved the recovery of locomotor functions in rats with moderate SCI, along with reduction of swelling, concomitant compression of the spinal cord and formation of post-traumatic cysts. Thus, based on the testing in a rodent model the SOD1 DC nanozymes are promising modality for scavenging ROS, decreasing inflammation and edema, and improving recovery after SCI.

[Cell therapy for ischemic stroke. Results of clinical trials and perspectives of clinical application in the Russian Federation]. / Kletochnaia terapiia ishemicheskogo insul'ta. Rezul'taty klinicheskikh issledovanii i perspektivy primeneniia v Rossiiskoi Federatsii.

The first part of the review summarized the results of preclinical animal studies using stroke models that demonstrated the efficacy of cell therapy. The second part presents the proposed mechanisms of action of stem cells, optimal therapeutic window for cell transplantation, the results of completed clinical trials on humans in the period from 2010 to 2017, as well as the legal aspects of the use of cell technologies in the Russian Federation.

Luciferase Expression Allows Bioluminescence Imaging But Imposes Limitations on the Orthotopic Mouse (4T1) Model of Breast Cancer.

Implantation of reporter-labeled tumor cells in an immunocompetent host involves a risk of their immune elimination. We have studied this effect in a mouse model of breast cancer after the orthotopic implantation of mammary gland adenocarcinoma 4T1 cells genetically labelled with luciferase (Luc). Mice were implanted with 4T1 cells and two derivative Luc-expressing clones 4T1luc2 and 4T1luc2D6 exhibiting equal in vitro growth rates. In vivo, the daughter 4T1luc2 clone exhibited nearly the same, and 4T1luc2D6, a lower growth rate than the parental cells. The metastatic potential of 4T1 variants was assessed by magnetic resonance, bioluminescent imaging, micro-computed tomography, and densitometry which detected 100-µm metastases in multiple organs and bones at the early stage of their development. After 3-4 weeks, 4T1 generated 11.4 ± 2.1, 4T1luc2D6, 4.5 ± 0.6; and 4T1luc2, <1 metastases per mouse, locations restricted to lungs and regional lymph nodes. Mice bearing Luc-expressing tumors developed IFN-γ response to the dominant CTL epitope of Luc. Induced by intradermal DNA-immunization, such response protected mice from the establishment of 4T1luc2-tumors. Our data show that natural or induced cellular response against the reporter restricts growth and metastatic activity of the reporter-labelled tumor cells. Such cells represent a powerful instrument for improving immunization technique for cancer vaccine applications.