Simultaneous Imaging of Cerebrovascular Structure and Function in Hypertensive Rats Using Synchrotron Radiation Angiography

Advanced rehabilitation in ischaemic stroke research

At present, due to the rapid progress of treatment technology in the acute phase of ischaemic stroke, the mortality of patients has been greatly reduced but the number of disabled survivors is increasing, and most of them are elderly patients. Physicians and rehabilitation therapists pay attention to develop all kinds of therapist techniques including physical therapy techniques, robot-assisted technology and artificial intelligence technology, and study the molecular, cellular or synergistic mechanisms of rehabilitation therapies to promote the effect of rehabilitation therapy. Here, we discussed different animal and in vitro models of ischaemic stroke for rehabilitation studies; the compound concept and technology of neurological rehabilitation; all kinds of biological mechanisms of physical therapy; the significance, assessment and efficacy of neurological rehabilitation; the application of brain-computer interface, rehabilitation robotic and non-invasive brain stimulation technology in stroke rehabilitation.

An updated review on animal models to study attention-deficit hyperactivity disorder

Attention-deficit hyperactivity disorder (ADHD) is a neuropsychiatric disorder affecting both children and adolescents. Individuals with ADHD experience heterogeneous problems, such as difficulty in attention, behavioral hyperactivity, and impulsivity. Recent studies have shown that complex genetic factors play a role in attention-deficit hyperactivity disorders. Animal models with clear hereditary traits are crucial for studying the molecular, biological, and brain circuit mechanisms underlying ADHD. Owing to their well-managed genetic origins and the relative simplicity with which the function of neuronal circuits is clearly established, models of mice can help learn the mechanisms involved in ADHD. Therefore, in this review, we highlighting the important genetic animal models that can be used to study ADHD.

Real-time X-ray imaging of mouse cerebral microvessels in vivo using a pixel temporal averaging method

Rodents are used extensively as animal models for the preclinical investigation of microvascular-related diseases. However, motion artifacts in currently available imaging methods preclude real-time observation of microvessels in vivo. In this paper, a pixel temporal averaging (PTA) method that enables real-time imaging of microvessels in the mouse brain in vivo is described. Experiments using live mice demonstrated that PTA efficiently eliminated motion artifacts and random noise, resulting in significant improvements in contrast-to-noise ratio. The time needed for image reconstruction using PTA with a normal computer was 250 ms, highlighting the capability of the PTA method for real-time angiography. In addition, experiments with less than one-quarter of photon flux in conventional angiography verified that motion artifacts and random noise were suppressed and microvessels were successfully identified using PTA, whereas conventional temporal subtraction and averaging methods were ineffective. Experiments performed with an X-ray tube verified that the PTA method could also be successfully applied to microvessel imaging of the mouse brain using a laboratory X-ray source. In conclusion, the proposed PTA method may facilitate the real-time investigation of cerebral microvascular-related diseases using small animal models.

Sensitive imaging of intact microvessels in vivo with synchrotron radiation

Early stages of diseases, including stroke, hypertension, angiogenesis of tumours, spinal cord injuries, etc., are closely associated with the lesions of microvasculature. Rodent models of human vascular diseases are extensively used for the preclinical investigation of the disease evolution and therapy with synchrotron radiation. Therefore, non-invasive and in vivo X-ray imaging with high sensitivity and clarity is desperately needed to visualize the microvessels in live-animal models. Contrast agent is essential for the in vivo X-ray imaging of vessels and angiomatous tissue. Because of the non-rigid motion of adjacent tissues, the short circulation time and the intermittent flow of contrast agents in vessels, it is a great challenge for the traditional X-ray imaging methods to achieve well defined images of microvessels in vivo. In this article, move contrast X-ray imaging (MCXI) based on high-brightness synchrotron radiation is developed to overcome the intrinsic defects in conventional methods. Experiments with live rodents demonstrate the practicability of the MCXI method for sensitive and intact imaging of microvessels in vivo.

Synchrotron radiation micro-tomography for high-resolution neurovascular network morphology investigation

There has been increasing interest in using high-resolution micro-tomography to investigate the morphology of neurovascular networks in the central nervous system, which remain difficult to characterize due to their microscopic size as well as their delicate and complex 3D structure. Synchrotron radiation X-ray imaging, which has emerged as a cutting-edge imaging technology with a high spatial resolution, provides a novel platform for the non-destructive imaging of microvasculature networks at a sub-micrometre scale. When coupled with computed tomography, this technique allows the characterization of the 3D morphology of vasculature. The current review focuses on recent progress in developing synchrotron radiation methodology and its application in probing neurovascular networks, especially the pathological changes associated with vascular abnormalities in various model systems. Furthermore, this tool represents a powerful imaging modality that improves our understanding of the complex biological interactions between vascular function and neuronal activity in both physiological and pathological states.

Cerebral Blood Flow in SHR Rats after Transplantation of Mesenchymal Stem Cells

Intracerebral transplantation of mesenchymal stem cells to 6- and 12-month-old SHR rats induced angiogenesis in the pia mater. In 6-months-old SHR rats, perfusion in the brain tissue after cell transplantation considerably increased, while in 12-month-old rats it remained practically unchanged. We also observed marked activation of regulatory processes in the cerebral vascular system, most pronounced in 12-month-old rats. Neurogenic and myogenic tone of cerebral vessels increased significantly, while endothelium-dependent tone slightly decreased. The increase in neurogenic and myogenic tone of blood vessels in SHR rats at the age of 6 and 12 months after transplantation of stem cells can be explained by the formation of new smooth muscle cells in the pre-existing arteries walls. Greater muscle mass developed stronger force and contributed to narrowing of the arterial lumen, as a result, there was no increase in blood flow despite the downstream angiogenesis. A slight decrease in endothelium-dependent tone can be explained by increased production of vasodilators by newly formed endothelial cells.

Dl-3-N-butylphthalide promotes angiogenesis and upregulates sonic hedgehog expression after cerebral ischemia in rats

INTRODUCTION

Dl-3-N-butylphthalide (NBP), a small molecule drug used clinically in the acute phase of ischemic stroke, has been shown to improve functional recovery and promote angiogenesis and collateral vessel circulation after experimental cerebral ischemia. However, the underlying molecular mechanism is unknown.

AIMS

To explore the potential molecular mechanism of angiogenesis induced by NBP after cerebral ischemia.

RESULTS

NBP treatment attenuated body weight loss, reduced brain infarct volume, and improved neurobehavioral outcomes during focal ischemia compared to the control rats (P < 0.05). NBP increased the number of CD31⁺ microvessels, the number of CD31⁺ /BrdU⁺ proliferating endothelial cells, and the functional vascular density (P < 0.05). Further study demonstrated that NBP also promoted the expression of vascular endothelial growth factor and angiopoietin-1 (P < 0.05), which was accompanied by upregulated sonic hedgehog expression in astrocytes in vivo and in vitro.

CONCLUSION

NBP treatment promoted the expression of vascular endothelial growth factor and angiopoietin-1, induced angiogenesis, and improved neurobehavioral recovery. These effects were associated with increased sonic hedgehog expression after NBP treatment. Our results broadened the clinical application of NBP to include the later phase of ischemia.

Dynamic Detection of Thrombolysis in Embolic Stroke Rats by Synchrotron Radiation Angiography

A rodent model of embolic middle cerebral artery occlusion is used to mimic cerebral embolism in clinical patients. Thrombolytic therapy is the effective treatment for this ischemic injury. However, it is difficult to detect thrombolysis dynamically in living animals. Synchrotron radiation angiography may provide a novel approach to directly monitor the thrombolytic process and assess collateral circulation after embolic stroke. Thirty-six adult Sprague-Dawley rats underwent the embolic stroke model procedure and were then treated with tissue plasminogen activator. The angiographic images were obtained in vivo by synchrotron radiation angiography. Synchrotron radiation angiography confirmed the successful establishment of occlusion and detected the thrombolysis process after the thrombolytic treatment. The time of thrombolytic recanalization was unstable during embolic stroke. The infarct volume increased as the recanalization time was delayed from 2 to 6 h (p < 0.05). The collateral circulation of the internal carotid artery to the ophthalmic artery, the olfactory artery to the ophthalmic artery, and the posterior cerebral artery to the middle cerebral artery opened after embolic stroke and manifested different opening rates (59%, 24%, and 75%, respectively) in the rats. The opening of the collateral circulation from the posterior cerebral artery to the middle cerebral artery alleviated infarction in rats with successful thrombolysis (p < 0.05). The cerebral vessels of the circle of Willis narrowed after thrombolysis (p < 0.05). Synchrotron radiation angiography provided a unique tool to dynamically detect and assess the thrombolysis process and the collateral circulation during thrombolytic therapy.