Retinal Degeneration in a Murine Model of Retinal Ischemia by Unilateral Common Carotid Artery Occlusion

Retinal degeneration is a progressive retinal damage in ocular vascular diseases. There are several reasons for this, such as occlusion of arteries or veins, diabetic retinopathy, or hereditary retinal diseases. To study pathological mechanisms of retinal degeneration, it is required to develop experimentally reproducible and clinically relevant models. In our previous studies, we developed a murine model of retinal hypoperfusion by unilateral common carotid artery occlusion (UCCAO) which mimics the pathophysiology of ocular ischemic syndrome (OIS) in humans, and described broad pathological mechanisms in the retina after UCCAO. However, there still remain missing pieces of the ocular pathologic process by UCCAO. In this study, we examined those unfound mechanisms. UCCAO was performed on adult mice. Ocular dysfunctions, histological deficits, and inflammation were examined after UCCAO, compared with sham-operated mice. Evaluation values were analyzed by electrophysiological, histological, and molecular biological methods. Eyelid drooping was permanently seen after UCCAO. Induction time point of acute reversible cataract under anesthesia was shortened. Retinal/visual dysfunctions were detected 2-4 weeks after UCCAO. Specifically, scotopic b-wave was more affected than a-wave, with the dysfunction of photopic b-wave. Impaired oscillatory potentials and visual evoked potential were constantly observed. Pathological Müller gliosis/inflammation was featured with NeuN-positive cell loss in the ganglion cell layer. Axial length, intraocular pressure, pupillary light reflex, and retinal pigment epithelium/choroidal thickness were not changed by UCCAO. A murine model of retinal ischemia by UCCAO can be useful for studying a series of degenerative process in the ischemic retina.

Relation between the Severity of the Sensorimotor Cortical Edema with Cell Swelling and the Duration of Common Carotid Artery Occlusion in Rats (Morphometric Study)

The aim of the study. To examine the changes in structure and morphometry in sensorimotor cortical edema with cell swelling in mature white rats after common carotid artery occlusion of various durations.Material and methods. Acute ischemia was modeled on white adult Wistar rats by 20-, 30- and 40-min occlusion of the common carotid arteries (CCA). Histological (hematoxylin-eosin and Nissl staining), immunohistochemical (NSE, MAP-2, GFAP) and morphometric methods were used. Morphometry was assessed on hematoxylin and eosin-stained specimens using ImageJ 1.53 plug-ins (Find Maxima, Find Foci). Statistical hypothesis testing (nonparametric criteria) was performed using Statistica 8.0 software.Results. In the sensorimotor cortex (SMC) of white rats after 20, 30 and 40 minutes of CCA occlusion the signs of cytotoxic brain edema appeared, focal destructive and adaptive changes of neurons and astroglia evolved. The edema persisted throughout the observation period (7 days). The increase in the relative area, the number of cell swelling zones and their hydration (pixel brightness) was significant. On days 1 and 3 after CCA occlusion, some of the SMC astrocyte processes underwent destruction. Subpial and perivascular zones suffered to a greater extent. Mild and moderate (after unilateral 30-min CCA occlusion) to moderate and severe (after bilateral 40-min CCA occlusion) scattered structural and functional changes of the SMC with large areas of clearing in the «porous» neuropil, severe perivascular and perineuronal edema of the astrocyte processes developed. The latter was associated with a moderate reduction of the total neuronal density.Conclusion. After occlusion of CCA, signs of edema with cellular swelling appeared in the SMC amid dystrophic and necrotic pyramidal neurons and activated neuroglial cells. To a greater extent, the signs of brain swelling were evident three days after bilateral 40-min occlusion of CCA.

Electroacupuncture Promotes the Survival of the Grafted Human MGE Neural Progenitors in Rats with Cerebral Ischemia by Promoting Angiogenesis and Inhibiting Inflammation

Stem cells have the potential as a regenerative therapy for cerebral ischemia by improving functional outcomes. However, cell transplantation has some limitations, including a low rate of the grafted cell survival. There is still a major challenge of promoting the harmonious symbiosis between grafted cells and the host. Acupuncture can effectively improve the functional outcome after cerebral ischemia. The present study evaluated the therapeutic effects and explored the mechanism of combined medial ganglionic eminence (MGE) neural progenitors differentiated from human embryonic stem cells (hESCs) with electroacupuncture (EA) in a bilateral common carotid artery occlusion (2VO) rat model. The results showed that EA could promote the survival of the grafted MGE neural progenitors differentiated from hESCs and alleviate learning and memory impairment in rats with cerebral ischemia. This may have partially resulted from inhibited expression of TNF-α and IL-1β and increased vascular endothelial growth factor (VEGF) expression and blood vessel density in the hippocampus. Our findings indicated that EA could promote the survival of the grafted MGE neural progenitors and enhance transplantation therapy’s efficacy by promoting angiogenesis and inhibiting inflammation.

Anti-inflammatory efficacy of Berberine Nanomicelle for improvement of cerebral ischemia: formulation, characterization and evaluation in bilateral common carotid artery occlusion rat model

Background Berberine (BBR) is a plant alkaloid that possesses anti-inflammatory and anti-oxidant effects with low oral bioavailability. In this study, micelle formulation of BBR was investigated to improve therapeutic efficacy and examined its effect on the secretion of inflammatory cytokines in cerebral ischemia in the animal model. Material and methods Nano formulation was prepared by thin-film hydration method, and characterized by particle size, zeta potential, morphology, encapsulation efficacy, and drug release in Simulated Gastric Fluid (SGF) and Simulated Intestine Fluid (SIF). Then, Wistar rats were pretreated with the drug (100 mg/kg) and nano-drug (25, 50, 75, 100 mg/kg) for 14 days. Then, on the fourteenth day, stroke induction was accomplished by Bilateral Common Carotid Artery Occlusion (BCCAO); after that, Tumor Necrosis Factor - Alpha (TNF-α), Interleukin – 1 Beta (IL-1ß), and Malondialdehyde (MDA) levels were measured in the supernatant of the whole brain, then the anti-inflammatory effect of BBR formulations was examined. Result and discussion Micelles were successfully formed with appropriate characteristics and smaller sizes than 20 nm. The Poly Dispersity Index (PDI), zeta potential, encapsulation efficacy of micelles was 0.227, − 22 mV, 81%, respectively. Also, the stability of nano micelles was higher in SGF as compared to SIF. Our outcomes of TNF-a, IL-1B, and MDA evaluation show a significant ameliorating effect of the Berberine (BBR) and BBR-loaded micelles in pretreated groups. Conclusion Our experimental data show that pretreated groups in different doses (nano BBR 100, 75, 50 mg/kg, and BBR 100 mg/kg) successfully showed decreased levels of the inflammatory factors in cerebral ischemia compared with the stroke group and pretreated group with nano BBR in the dose of 25 mg/kg. Nano BBR formulation with a lower dose can be a better candidate than conventional BBR formulation to reduce oxidative and inflammatory factors in cerebral ischemia. Therefore, BBR-loaded micelle formulation could be a promising protective agent on cerebral ischemia.

Pemafibrate Prevents Retinal Dysfunction in a Mouse Model of Unilateral Common Carotid Artery Occlusion

Cardiovascular diseases lead to retinal ischemia, one of the leading causes of blindness. Retinal ischemia triggers pathological retinal glial responses and functional deficits. Therefore, maintaining retinal neuronal activities and modulating pathological gliosis may prevent loss of vision. Previously, pemafibrate, a selective peroxisome proliferator-activated receptor alpha modulator, was nominated as a promising drug in retinal ischemia. However, a protective role of pemafibrate remains untouched in cardiovascular diseases-mediated retinal ischemia. Therefore, we aimed to unravel systemic and retinal alterations by treating pemafibrate in a new murine model of retinal ischemia caused by cardiovascular diseases. Adult C57BL/6 mice were orally administered pemafibrate (0.5 mg/kg) for 4 days, followed by unilateral common carotid artery occlusion (UCCAO). After UCCAO, pemafibrate was continuously supplied to mice until the end of experiments. Retinal function (a-and b-waves and the oscillatory potentials) was measured using electroretinography on day 5 and 12 after UCCAO. Moreover, the retina, liver, and serum were subjected to qPCR, immunohistochemistry, or ELISA analysis. We found that pemafibrate enhanced liver function, elevated serum levels of fibroblast growth factor 21 (FGF21), one of the neuroprotective molecules in the eye, and protected against UCCAO-induced retinal dysfunction, observed with modulation of retinal gliosis and preservation of oscillatory potentials. Our current data suggest a promising pemafibrate therapy for the suppression of retinal dysfunction in cardiovascular diseases.