Focused ultrasound-mediated brain genome editing

Advancements and challenges in brain cancer therapeutics

Treating brain tumors requires a nuanced understanding of the brain, a vital and delicate organ. Location, size, tumor type, and surrounding tissue health are crucial in developing treatment plans. This review comprehensively summarizes various treatment options that are available or could be potentially available for brain tumors, including physical therapies (radiotherapy, ablation therapy, photodynamic therapy, tumor-treating field therapy, and cold atmospheric plasma therapy) and non-physical therapies (surgical resection, chemotherapy, targeted therapy, and immunotherapy). Mechanisms of action, potential side effects, indications, and latest developments, as well as their limitations, are highlighted. Furthermore, the requirements for personalized, multi-modal treatment approaches in this rapidly evolving field are discussed, emphasizing the balance between efficacy and patient safety.

Exosomes-mediated delivery of miR-486-3p alleviates neuroinflammation via SIRT2-mediated inhibition of mitophagy after subarachnoid hemorrhage

BACKGROUND

Neuroinflammation participates in the pathogenesis of subarachnoid haemorrhage (SAH); however, no effective treatments exist. MicroRNAs regulate several aspects of neuronal dysfunction. In a previous study, we found that exosomal miR-486-3p is involved in the pathophysiology of SAH. Targeted delivery of miR-486-3p without blood-brain barrier (BBB) restriction to alleviate SAH is a promising neuroinflammation approach.

METHODS

In this study, we modified exosomes (Exo) to form an RVG-miR-486-3p-Exo (Exo/miR) to achieve targeted delivery of miR-486-3p to the brain. Neurological scores, brain water content, BBB damage, flow cytometry and FJC staining were used to determine the effect of miR-486-3p on SAH. Western blot analysis, ELISA and RT-qPCR were used to measure relevant protein and mRNA levels. Immunofluorescence staining and laser confocal detection were used to measure the expression of mitochondria, lysosomes and autophagosomes, and transmission electron microscopy was used to observe the level of mitophagy in the brain tissue of mice after SAH.

RESULTS

Tail vein injection of Exo/miR improved targeting of miR-486-3p to the brains of SAH mice. The injection reduced levels of neuroinflammation-related factors by changing the phenotype switching of microglia, inhibiting the expression of sirtuin 2 (SIRT2) and enhancing mitophagy. miR-486-3p treatment alleviated neurobehavioral disorders, brain oedema, BBB damage and neurodegeneration. Further research found that the mechanism was achieved by regulating the acetylation level of peroxisome proliferator-activated receptor γ coactivator l alpha (PGC-1α) after SIRT2 enters the nucleus.

CONCLUSION

Exo/miR treatment attenuates neuroinflammation after SAH by inhibiting SIRT2 expression and stimulating mitophagy, suggesting potential clinical applications.

Brain Nucleic Acid Delivery and Genome Editing via Focused Ultrasound-Mediated Blood-Brain Barrier Opening and Long-Circulating Nanoparticles

We introduce a two-pronged strategy comprising focused ultrasound (FUS)-mediated blood-brain barrier (BBB) opening and long-circulating biodegradable nanoparticles (NPs) for systemic delivery of nucleic acids to the brain. Biodegradable poly(β-amino ester) polymer-based NPs were engineered to stably package various types of nucleic acid payloads and enable prolonged systemic circulation while retaining excellent serum stability. FUS was applied to a predetermined coordinate within the brain to transiently open the BBB, thereby allowing the systemically administered long-circulating NPs to traverse the BBB and accumulate in the FUS-treated brain region, where plasmid DNA or mRNA payloads produced reporter proteins in astrocytes and neurons. In contrast, poorly circulating and/or serum-unstable NPs, including the lipid NP analogous to a platform used in clinic, were unable to provide efficient nucleic acid delivery to the brain regardless of the BBB-opening FUS. The marriage of FUS-mediated BBB opening and the long-circulating NPs engineered to copackage mRNA encoding CRISPR-associated protein 9 and single-guide RNA resulted in genome editing in astrocytes and neurons precisely in the FUS-treated brain region. The combined delivery strategy provides a versatile means to achieve efficient and site-specific therapeutic nucleic acid delivery to and genome editing in the brain via a systemic route.

Ultrasound-Based Micro-/Nanosystems for Biomedical Applications

Due to the intrinsic non-invasive nature, cost-effectiveness, high safety, and real-time capabilities, besides diagnostic imaging, ultrasound as a typical mechanical wave has been extensively developed as a physical tool for versatile biomedical applications. Especially, the prosperity of nanotechnology and nanomedicine invigorates the landscape of ultrasound-based medicine. The unprecedented surge in research enthusiasm and dedicated efforts have led to a mass of multifunctional micro-/nanosystems being applied in ultrasound biomedicine, facilitating precise diagnosis, effective treatment, and personalized theranostics. The effective deployment of versatile ultrasound-based micro-/nanosystems in biomedical applications is rooted in a profound understanding of the relationship among composition, structure, property, bioactivity, application, and performance. In this comprehensive review, we elaborate on the general principles regarding the design, synthesis, functionalization, and optimization of ultrasound-based micro-/nanosystems for abundant biomedical applications. In particular, recent advancements in ultrasound-based micro-/nanosystems for diagnostic imaging are meticulously summarized. Furthermore, we systematically elucidate state-of-the-art studies concerning recent progress in ultrasound-based micro-/nanosystems for therapeutic applications targeting various pathological abnormalities including cancer, bacterial infection, brain diseases, cardiovascular diseases, and metabolic diseases. Finally, we conclude and provide an outlook on this research field with an in-depth discussion of the challenges faced and future developments for further extensive clinical translation and application.

Strategies for enhanced gene delivery to the central nervous system

The delivery of genes to the central nervous system (CNS) has been a persistent challenge due to various biological barriers. The blood-brain barrier (BBB), in particular, hampers the access of systemically injected drugs to parenchymal cells, allowing only a minimal percentage (<1%) to pass through. Recent scientific insights highlight the crucial role of the extracellular space (ECS) in governing drug diffusion. Taking into account advancements in vectors, techniques, and knowledge, the discussion will center on the most notable vectors utilized for gene delivery to the CNS. This review will explore the influence of the ECS - a dynamically regulated barrier-on drug diffusion. Furthermore, we will underscore the significance of employing remote-control technologies to facilitate BBB traversal and modulate the ECS. Given the rapid progress in gene editing, our discussion will also encompass the latest advances focused on delivering therapeutic editing in vivo to the CNS tissue. In the end, a brief summary on the impact of Artificial Intelligence (AI)/Machine Learning (ML), ultrasmall, soft endovascular robots, and high-resolution endovascular cameras on improving the gene delivery to the CNS will be provided.

Acoustically targeted noninvasive gene therapy in large brain volumes

Focused Ultrasound Blood-Brain Barrier Opening (FUS-BBBO) can deliver adeno-associated viral vectors (AAVs) to treat genetic disorders of the brain. However, such disorders often affect large brain regions. Moreover, the applicability of FUS-BBBO in the treatment of brain-wide genetic disorders has not yet been evaluated. Herein, we evaluated the transduction efficiency and safety of opening up to 105 sites simultaneously. Increasing the number of targeted sites increased gene delivery efficiency at each site. We achieved transduction of up to 60% of brain cells with comparable efficiency in the majority of the brain regions. Furthermore, gene delivery with FUS-BBBO was safe even when all 105 sites were targeted simultaneously without negative effects on animal weight or neuronal loss. To evaluate the application of multi-site FUS-BBBO for gene therapy, we used it for gene editing using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated 9 (Cas9) system and found effective gene editing, but also a loss of neurons at the targeted sites. Overall, this study provides a brain-wide map of transduction efficiency, shows the synergistic effect of multi-site targeting on transduction efficiency, and is the first example of large brain volume gene editing after noninvasive gene delivery with FUS-BBBO.

Treating the Brain With Focused Ultrasound

Focused ultrasound is an early stage, noninvasive therapy with the potential to treat a range of medical conditions. Like diagnostic ultrasound, it uses sound waves above the range of human hearing. But its purpose is to interact with tissues in the body, rather than just produce images of them. In focused ultrasound, multiple, intersecting beams of high frequency sound are aimed to converge on specific targets deep within the body. There, the ultrasound energy can act in multiple ways to either modify or destroy tissue.