Neuroprotective effect of low-intensity transcranial ultrasound stimulation in endothelin-1-induced middle cerebral artery occlusion in rats

Low-Intensity Ultrasound Facilitation of Intranasal Drug Delivery to Olfactory Bulb and Trigeminal Nerves

OBJECTIVE

Nasal-to-brain (NtoB) delivery is a noninvasive approach that uses the nasal cavity as a pathway to transport therapeutic agents directly to the brain. This approach bypasses systemic circulation and avoids the blood-brain barrier (BBB). Transcranial ultrasound, coupled with microbubbles (MB), is a technique used to oscillate and generate acoustic cavitation to open the capillary tight junctions of BBB temporarily. Its efficacy in facilitating NtoB delivery has been demonstrated in vivo. However, while opening the BBB, sonication with MB poses the risk of cerebral microhemorrhage or brain tissue damage due to sonication-induced physical injury. This study aimed to assess the effectiveness of low-intensity ultrasound treatment to facilitate NtoB delivery in a mouse model without using MB.

METHODS

In this study, 10-kDa dextran was administered intranasally (IN), and transcranial planar US was applied to the entire mouse brain without MB assistance. Ex-vivo whole brain imaging via fluorescence macroscopy, brain slice analysis with fluorescence microscope, and quantification of dextran concentration in distinct brain regions were conducted to compare the IN-only, IN combined with US (IN+US), and sham groups. For the trigeminal nerves (TN), fluorescence macroscopy, microscopy, and TN concentration quantification were performed to compare the three groups.

RESULTS

Whole brain imaging revealed that US facilitated the IN delivery of dextran to the olfactory bulb (OB) in the IN+US group compared with that in the IN-only and sham groups; however, this difference was not observed after a 24 h follow-up. Conversely, brain slice images showed that the tracer was delivered to the OB, cerebral cortex, striatum and brainstem in the IN+US group, but this finding was not observed in the IN-only group at the 4 h mark. The quantification of fluorescence intensity at two follow-up time points revealed no significant difference between the IN and IN+US groups in these specific regions. Dextran concentration analysis for distinct brain areas and TN showed that ultrasound significantly increased the tracer concentration delivered to the OB and TN in the IN+US group at the 4 h mark compared with that in the IN-only and sham groups; however, this effect was not sustained at 24 h. Confocal microscopy indicated that the dextran tracer accumulated in the perivascular space along the microvascular structures.

CONCLUSION

We demonstrated the efficacy of low-intensity ultrasound without using MB, in enhancing nose-to-OB and nose-to-TN drug delivery, and proposed the potential for future clinical application. Thus, we showed that this approach was safe, without evidence of microhemorrhage or brain tissue damage.

Targeting MAPK14 in microglial cells: neuroimmune implications of Panax ginseng in post-stroke inflammation

AIM

This study investigates the molecular mechanisms through which Panax ginseng and Panax notoginseng saponin (PNS) mitigate neuroinflammatory damage and promote neural repair postischemic stroke, utilizing bioinformatics, and experimental approaches.

BACKGROUND

Cerebral infarction significantly contributes to disability worldwide, with chronic neuroinflammation worsening cognitive impairments and leading to neurodegenerative diseases. Addressing neuroimmune interactions is crucial for slowing disease progression and enhancing patient recovery, highlighting the need for advanced research in neuroimmune regulatory mechanisms and therapeutic strategies.

OBJECTIVE

To elucidate the effects of the traditional Chinese medicine components Panax ginseng and PNS on neuroinflammatory damage following ischemic stroke, focusing on the molecular pathways involved in mitigating inflammation and facilitating neural repair.

METHODS

The study employs single-cell sequencing and transcriptomic analysis to investigate gene expression changes associated with cerebral infarction. Gene set enrichment analysis and weighted gene co-expression network analysis are used to identify key molecular markers and core genes. Furthermore, pharmacological profiling, including functional assays, assesses the impact of Ginsenoside-Rc, a PNS derivative, on microglial cell viability, cytokine production, and reactive oxygen species (ROS) levels.

RESULTS

Our analysis revealed that MAPK14 is a critical mediator in the neuroinflammatory response to ischemic stroke. Ginsenoside-Rc potentially targets and modulates MAPK14 activity to suppress inflammation. Experimental validation showed that Ginsenoside-Rc treatment, combined with MAPK14 silencing, significantly alters MAPK14 expression and mitigates neuroinflammatory damage, evidenced by reduced microglial cell death, inflammatory factor secretion, and ROS production.

CONCLUSION

Ginsenoside-Rc's modulation of MAPK14 offers a promising therapeutic strategy for reducing neuroinflammation and potentially improving cognitive recovery post-ischemic stroke. This supports the therapeutic application of the traditional Chinese medicine Sanqi in ischemic stroke care, providing a theoretical and experimental foundation for its use.

OTHERS

Future work will focus on extending these findings through clinical trials to evaluate the efficacy and safety of Ginsenoside-Rc in human subjects, aiming to translate these promising preclinical results into practical therapeutic interventions for ischemic stroke recovery.

Human neural stem cells transplanted during the sequelae phase alleviate motor deficits in a rat model of cerebral palsy

AIMS

Cerebral palsy (CP) is the most common physical disability in children, yet lacks an ideal animal model or effective treatment. This study aimed to develop a reliable CP model in neonatal rats and explore the effectiveness and underlying mechanisms of human neural stem cells (hNSCs) transplantation during the sequelae phase of CP.

METHODS

Vasoconstrictor endothelin-1 (ET-1) was administered intracranially to the motor cortex and striatum of rats on postnatal day 5 to establish a CP model. hNSCs (5 × 105/5 μL) pretreated with hypoxia (5% O2 for 24 h) were transplanted near the infarct 3 weeks after ET-1 injury (the sequelae phase). The distribution and differentiation of hNSCs were observed after transplantation. Changes in neurotrophic factors, neurogenesis, angiogenesis, axonal plasticity, and motor function were analyzed.

RESULTS

Neurobehavioral tests showed poor muscle strength and postural control in young ET-1 rats. Motor deficits of the left forelimb and gait abnormalities persisted into adulthood. Histopathological findings and MRI indicated the atrophy of the cortex, striatum, and adjacent corpus callosum in ET-1 rats. At 56 days after transplantation, hNSCs were widely distributed in the ipsilateral hemisphere, and differentiated into neurons, oligodendrocytes and astrocytes. Transplantation of hNSCs increased BDNF and VEGF expression, EdU+ cell number in the SVZ area, RECA-1+ vessel density and GAP-43 intensity around the lesion in ET-1 rats. The cylinder test revealed a significant increase in the left forelimb motor function from 28 days after transplantation, and the staircase and CatWalk tests showed improvements in fine motor function and gait parameters.

CONCLUSIONS

Intracerebral injection of ET-1 modelled key functional and histopathological features of CP. hNSCs transplanted during the sequelae phase of CP resulted in long-term improvement in motor performance, possibly attributed to its capacity to stimulate neurotrophic factors, facilitate neurogenesis, angiogenesis, and promote axonal plasticity.

The effect of combined ultrasound stimulation and gastrodin on seizures in mice

Both physiotherapy and medicine play essential roles in the treatment of epilepsy. The purpose of this research was to evaluate the efficacy of the combined therapy with focus ultrasound stimulation (FUS) and gastrodin (GTD) on seizures in a mouse model. Kainic acid-induced seizure mice were divided into five groups randomly: sham, FUS, saline + sham, GTD + sham and GTD + FUS. The results showed that combined therapy with ultrasound stimulation and gastrodin can significantly reduce the number and duration of seizures in GTD + FUS group. 9.4T magnetic resonance imaging and histologic staining results revealed the underlying mechanism of the combined therapy may be that ultrasound stimulation increases cell membrane permeability to increase GTD concentration in brain. In addition, we verified the safety of FUS combined with GTD therapy. This research provides a new strategy for neurological disorders combining treatment of physical neuromodulation and medicine.

Progress in Noninvasive Low-Intensity Focused Ultrasound Neuromodulation

Low-intensity focused ultrasound represents groundbreaking medical advancements, characterized by its noninvasive feature, safety, precision, and broad neuromodulatory capabilities. This technology operates through mechanisms, for example, acoustic radiation force, cavitation, and thermal effects. Notably, with the evolution of medical technology, ultrasound neuromodulation has been gradually applied in treating central nervous system diseases, especially stroke. Furthermore, burgeoning research areas such as sonogenetics and nanotechnology show promising potential. Despite the benefit of low-intensity focused ultrasound the precise biophysical mechanism of ultrasound neuromodulation still need further exploration. This review discusses the recent and ongoing developments of low-intensity focused ultrasound for neurological regulation, covering the underlying rationale to current utility and the challenges that impede its further development and broader adoption of this promising alternative to noninvasive therapy.

Insight into the pathophysiological advances and molecular mechanisms underlying cerebral stroke: current status

Molecular pathways involved in cerebral stroke are diverse. The major pathophysiological events that are observed in stroke comprises of excitotoxicity, oxidative stress, mitochondrial damage, endoplasmic reticulum stress, cellular acidosis, blood-brain barrier disruption, neuronal swelling and neuronal network mutilation. Various biomolecules are involved in these pathways and several major proteins are upregulated and/or suppressed following stroke. Different types of receptors, ion channels and transporters are activated. Fluctuations in levels of various ions and neurotransmitters have been observed. Cells involved in immune responses and various mediators involved in neuro-inflammation get upregulated progressing the pathogenesis of the disease. Despite of enormity of the problem, there is not a single therapy that can limit infarction and neurological disability due to stroke. This is because of poor understanding of the complex interplay between these pathophysiological processes. This review focuses upon the past to present research on pathophysiological events that are involved in stroke and various factors that are leading to neuronal death following cerebral stroke. This will pave a way to researchers for developing new potent therapeutics that can aid in the treatment of cerebral stroke.

Multimodal evaluation of the effects of low-intensity ultrasound on cerebral blood flow after traumatic brain injury in mice

Traumatic brain injury (TBI) is one of the leading causes of death and disability worldwide, and destruction of the cerebrovascular system is a major factor in the cascade of secondary injuries caused by TBI. Laser speckle imaging (LSCI)has high sensitivity in detecting cerebral blood flow. LSCI can visually show that transcranial focused ultrasound stimulation (tFUS) treatment stimulates angiogenesis and increases blood flow. To study the effect of tFUS on promoting angiogenesis in Controlled Cortical impact (CCI) model. tFUS was administered daily for 10 min and for 14 consecutive days after TBI. Cerebral blood flow was measured by LSCI at 1, 3, 7 and 14 days after trauma. Functional outcomes were assessed using LSCI and neurological severity score (NSS). After the last test, Nissl staining and vascular endothelial growth factor (VEGF) were used to assess neuropathology. TBI can cause the destruction of cerebrovascular system. Blood flow was significantly increased in TBI treated with tFUS. LSCI, behavioral and histological findings suggest that tFUS treatment can promote angiogenesis after TBI.

The Emergence of Functional Ultrasound for Noninvasive Brain-Computer Interface

A noninvasive brain-computer interface is a central task in the comprehensive analysis and understanding of the brain and is an important challenge in international brain-science research. Current implanted brain-computer interfaces are cranial and invasive, which considerably limits their applications. The development of new noninvasive reading and writing technologies will advance substantial innovations and breakthroughs in the field of brain-computer interfaces. Here, we review the theory and development of the ultrasound brain functional imaging and its applications. Furthermore, we introduce latest advancements in ultrasound brain modulation and its applications in rodents, primates, and human; its mechanism and closed-loop ultrasound neuromodulation based on electroencephalograph are also presented. Finally, high-frequency acoustic noninvasive brain-computer interface is prospected based on ultrasound super-resolution imaging and acoustic tweezers.

Noninvasive Brain Stimulation for Neurorehabilitation in Post-Stroke Patients

Characterized by high morbidity, mortality, and disability, stroke usually causes symptoms of cerebral hypoxia due to a sudden blockage or rupture of brain vessels, and it seriously threatens human life and health. Rehabilitation is the essential treatment for post-stroke patients suffering from functional impairments, through which hemiparesis, aphasia, dysphagia, unilateral neglect, depression, and cognitive dysfunction can be restored to various degrees. Noninvasive brain stimulation (NIBS) is a popular neuromodulatory technology of rehabilitation focusing on the local cerebral cortex, which can improve clinical functions by regulating the excitability of corresponding neurons. Increasing evidence has been obtained from the clinical application of NIBS, especially repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS). However, without a standardized protocol, existing studies on NIBS show a wide variation in terms of stimulation site, frequency, intensity, dosage, and other parameters. Its application for neurorehabilitation in post-stroke patients is still limited. With advances in neuronavigation technologies, functional near-infrared spectroscopy, and functional MRI, specific brain regions can be precisely located for stimulation. On the basis of our further understanding on neural circuits, neuromodulation in post-stroke rehabilitation has also evolved from single-target stimulation to co-stimulation of two or more targets, even circuits and the network. The present study aims to review the findings of current research, discuss future directions of NIBS application, and finally promote the use of NIBS in post-stroke rehabilitation.

The Feasibility Mechanism of Nerve Interventional Thrombectomy for Occlusion of Cranial Artery M1 and M2 Segments

This study was aimed at exploring the feasibility and clinical efficacy of nerve interventional thrombectomy (NIT) to treat occlusion of cranial artery M1 and M2 segments. 80 patients were selected and rolled into a control group (intravenous thrombolysis) and an experimental group (NIT). Patients' vascular recanalization rates following therapy were compared, and the National Institutes of Health Stroke Scale (NIHSS) was used to measure neurological function. The improvement in hemodynamics and the occurrence of adverse responses were compared. The results showed that the experimental group's recanalization rate was up to 74.23%, which was significantly greater than the control group's (P < 0.05). One week after treatment, the neurological function scores in both groups decreased, and the score in the experimental group was only 15.23, which was much lower than that in the control group (P < 0.05). The peak systolic flow rates of the basilar artery, internal carotid artery, and common carotid artery in the experimental group were 132 cm/s, 147 cm/s, and 114 cm/s, respectively, which were lower greatly than those in the control group (P < 0.05). There was no significant difference in incidence of adverse reactions between the two groups (P > 0.05). In summary, NIT showed a significant therapeutic effect on cranial artery occlusion of M1 and M2 segments, can dredge the occluded blood vessels, and effectively improve the neurological deficits of patients, showing reliable feasibility.

Noninvasive Low-Intensity Focused Ultrasound Mediates Tissue Protection following Ischemic Stroke

Objective and Impact Statement. This study examined the efficacy and safety of pulsed, low-intensity focused ultrasound (LIFU) and determined its ability to provide neuroprotection in a murine permanent middle cerebral artery occlusion (pMCAO) model. Introduction. Focused ultrasound (FUS) has emerged as a new therapeutic strategy for the treatment of ischemic stroke; however, its nonthrombolytic properties remain ill-defined. Therefore, we examined how LIFU influenced neuroprotection and vascular changes following stroke. Due to the critical role of leptomeningeal anastomoses or pial collateral vessels, in cerebral blood flow restoration and tissue protection following ischemic stroke, we also investigated their growth and remodeling. Methods. Mice were exposed to transcranial LIFU (fundamental frequency: 1.1 MHz, sonication duration: 300 ms, interstimulus interval: 3 s, pulse repetition frequency: 1 kHz, duty cycle per pulse: 50%, and peak negative pressure: -2.0 MPa) for 30 minutes following induction of pMCAO and then evaluated for infarct volume, blood-brain barrier (BBB) disruption, and pial collateral remodeling at 24 hrs post-pMCAO. Results. We found significant neuroprotection in mice exposed to LIFU compared to mock treatment. These findings correlated with a reduced area of IgG deposition in the cerebral cortex, suggesting attenuation of BBB breakdown under LIFU conditions. We also observed increased diameter of CD31-postive microvessels in the ischemic cortex. We observed no significant difference in pial collateral vessel size between FUS and mock treatment at 24 hrs post-pMCAO. Conclusion. Our data suggests that therapeutic use of LIFU may induce protection through microvascular remodeling that is not related to its thrombolytic activity.

The Value of First-Order Features Based on the Apparent Diffusion Coefficient Map in Evaluating the Therapeutic Effect of Low-Intensity Pulsed Ultrasound for Acute Traumatic Brain Injury With a Rat Model

Purpose

In order to evaluate the neuroprotective effect of low-intensity pulsed ultrasound (LIPUS) for acute traumatic brain injury (TBI), we studied the potential of apparent diffusion coefficient (ADC) values and ADC-derived first-order features regarding this problem.

Methods

Forty-five male Sprague Dawley rats (sham group: 15, TBI group: 15, LIPUS treated: 15) were enrolled and underwent magnetic resonance imaging. Scanning layers were acquired using a multi-shot readout segmentation of long variable echo trains (RESOLVE) to decrease distortion. The ultrasound transducer was applied to the designated region in the injured cortical areas using a conical collimator and was filled with an ultrasound coupling gel. Regions of interest were manually delineated in the center of the damaged cortex on the diffusion weighted images (b = 800 s/mm²) layer by layer for the TBI and LIPUS treated groups using the open-source software ITK-SNAP. Before analysis and modeling, the features were normalized using a z-score method, and a logistic regression model with a backward filtering method was employed to perform the modeling. The entire process was completed using the R language.

Results

During the observation time, the ADC values ipsilateral to the trauma in the TBI and LIPUS groups increased rapidly up to 24 h. After statistical analysis, the 10th percentile, 90th percentile, mean, skewness, and uniformity demonstrated a significant difference among three groups. The receiver operating characteristic curve (ROC) analysis shows that the combined LR model exhibited the highest area under the curve value (AUC: 0.96).

Conclusion

The combined LR model of first-order features based on the ADC map can acquire a higher diagnostic performance than each feature only in evaluating the neuroprotective effect of LIPUS for TBI. Models based on first-order features may have potential value in predicting the therapeutic effect of LIPUS in clinical practice in the future.

The Updated Role of Transcranial Ultrasound Neuromodulation in Ischemic Stroke: From Clinical and Basic Research

Ischemic stroke is a common cause of death and disability worldwide, which leads to serious neurological and physical dysfunction and results in heavy economic and social burdens. For now, timely and effective dissolution of thrombus, and ultimately improvement in the recovery of neurological functions, is the treatment strategy focus. Recently, many studies have reported that transcranial ultrasound stimulation (TUS), as a non-invasive method, can dissolve thrombus, improve cerebral blood circulation, and exert a neuroprotective effect post-stroke. TUS can promote functional recovery and improve rehabilitation efficacy among patients with ischemic stroke. This mini-review summarizes the potential mechanism and limitation of TUS in stroke aims to provide a new strategy for the future treatment of patients with ischemic stroke.

New Insights Into the Roles of Microglial Regulation in Brain Plasticity-Dependent Stroke Recovery

Stroke remains the leading cause of long-term disability worldwide with significant long-term sequelae. However, there is no highly effective treatment to enhance post-stroke recovery despite extensive efforts in exploring rehabilitative therapies. Neurorehabilitation is recognized as the cornerstone of functional restoration therapy in stroke, where treatments are focused on neuroplastic regulation to reverse neural structural disruption and improve neurofunctional networks. Post-stroke neuroplasticity changes begin within hours of symptom onset and reaches a plateau by 3 to 4 weeks within the global brain in animal studies. It plays a determining role in spontaneous stroke recovery. Microglia are immediately activated following cerebral ischemia, which has been found both proximal to the primary ischemic injury and at the remote brain regions which have functional connections to the primary injury area. Microglia exhibit different activation profiles based on the microenvironment and adaptively switch their phenotypes in a spatiotemporal manner in response to brain injuries. Microglial activation coincides with neuroplasticity after stroke, which provides the fundamental base for the microglia-mediated inflammatory responses involved in the entire neural network rewiring and brain repair. Microglial activation exerts important effects on spontaneous recovery after stroke, including structural and functional reestablishment of neurovascular networks, neurogenesis, axonal remodeling, and blood vessel regeneration. In this review, we focus on the crosstalk between microglial activation and endogenous neuroplasticity, with a special focus on the plastic alterations in the whole brain network and their implications for structural and functional restoration after stroke. We then summarize recent advances in the impacts of microglial phenotype polarization on brain plasticity, trying to discuss the potential efficacy of microglia-based extrinsic restorative interventions in promoting post-stroke recovery.