Lipoprotein-Inspired Nanoscavenger for the Three-Pronged Modulation of Microglia-Derived Neuroinflammation in Alzheimer's Disease Therapy

Ischemic Microenvironment-Targeted Bioinspired Lipoprotein Sequentially Penetrates Cerebral Ischemic Lesions to Rescue Ischemic Stroke

Reperfusion injury represents a significant impediment to recovery after recanalization in an ischemic stroke and can be alleviated by neuroprotectants. However, inadequate drug delivery to ischemic lesions impairs the therapeutic effects of neuroprotectants. To address this issue, an ischemic microenvironment-targeted bioinspired lipoprotein system encapsulating lipoic acid (LA@PHDL) is herein designed to sequentially penetrate ischemic lesions and be readily taken up by neurons and microglia. In transient middle cerebral artery occlusion (tMCAO) mouse models, LA@PHDL accumulates rapidly and preferentially in the ischemic brain, with a 2.29-fold higher than the nontargeted nanoplatform in the early stage. Furthermore, LA@PHDL effectively restores neurological function, reduces infarct volume to 17.70%, prevents brain cell necrosis and apoptosis, and attenuates inflammation in tMCAO mouse models. This design presents new opportunities for delivering neuroprotectants to cerebral ischemic lesions to improve the outcome of an ischemic stroke.

Harnessing nanomedicine for modulating microglial states in the central nervous system disorders: Challenges and opportunities

Microglia are essential for maintaining homeostasis and responding to pathological events in the central nervous system (CNS). Their dynamic and multidimensional states in different environments are pivotal factors in various CNS disorders. However, therapeutic modulation of microglial states is challenging due to the intricate balance these cells maintain in the CNS environment and the blood-brain barrier's restriction of drug delivery. Nanomedicine presents a promising avenue for addressing these challenges, offering a method for the targeted and efficient modulation of microglial states. This review covers the challenges faced in microglial therapeutic modulation and potential use of nanoparticle-based drug delivery systems. We provide an in-depth examination of nanoparticle applications for modulating microglial states in a range of CNS disorders, encompassing neurodegenerative and autoimmune diseases, infections, traumatic injuries, stroke, tumors, chronic pain, and psychiatric conditions. This review highlights the recent advancements and future prospects in nanomedicine for microglial modulation, paving the way for future research and clinical applications of therapeutic interventions in CNS disorders.

Relationship of Curcumin with Aging and Alzheimer and Parkinson Disease, the Most Prevalent Age-Related Neurodegenerative Diseases: A Narrative Review

The elderly population is increasing worldwide every day. Age is a significant factor in the progression of neurological diseases, which can also cause cognitive decline and memory disorders. Inflammation and oxidative stress are primary drivers of senescence and disorders, particularly those associated with aging and neurodegenerative diseases. Bioactive phytochemicals are considered a promising therapeutic strategy in combating aging and age-related pathological conditions. One of the phytochemicals with diverse biological properties encompassing antioxidant, anti-inflammatory, antibacterial, antiviral, anticancer, antifungal, antidepressant, anti-allergic, and anti-aging properties is curcumin. Curcumin, a polyphenolic structure with a distinct orange hue and unique chemical properties, is derived from the roots of Curcuma longa, a member of the Zingiberaceae family, commonly known as turmeric. It has been noted that the incidence of neurodegenerative diseases is low in societies that consume curcumin widely. Therefore, this review investigates the effect of curcumin on aging and Alzheimer and Parkinson disease, which are the most prevalent age-related neurodegenerative diseases.

Exploring Curcumin-Loaded Lipid-Based Nanomedicine as Efficient Targeted Therapy for Alzheimer's Diseases

Alzheimer's disease (AD) is a neurological condition currently with 47 million people suffering from it globally. AD might have many reasons such as genetic issues, environmental factors, and Aβ accumulation, which is the biomarker of the disease. Since the primary reason is unknown, there is no targeted treatment at the moment, but ongoing research aims to slow its progression by managing amyloid-beta peptide production rather than symptomatic improvement. Since phytochemicals have been demonstrated to possess antioxidant, anti-inflammatory, and neuroprotective properties, they may target multiple pathological factors and can reduce the risk of the disease. Curcumin, as a phytochemical found in turmeric known for its antioxidant, free radical scavenging properties, and as an antiamyloid in treating AD, has come under investigation. Although its low bioavailability limits its efficacy, a prominent drug delivery system (DDS) is desired to overcome it. Hence, the potency of lipid-based nanoparticles encapsulating curcumin (LNPs-CUR) is considered in this study as a promising DDS. In vivo studies in animal models indicate LNPs-CUR effectively slow amyloid plaque formation, leading to cognitive enhancement and reduced toxicity compared to free CUR. However, a deeper understanding of CUR's pharmacokinetics and safety profile is crucial before LNPs-CUR can be considered as a medicine. Future investigations may explore the combination of NPs with other therapeutic agents to increase their efficacy in AD cases. This review provides the current position of CUR in the AD therapy paradigm, the DDS suggestions for CUR, and the previous research from the point of analytical view focused on the advantages and challenges.

Multifunctional Nanocarrier for Synergistic Treatment of Alzheimer's Disease by Inhibiting β-Amyloid Aggregation and Scavenging Reactive Oxygen Species

The excessive depositions of β-amyloid (Aβ) and abnormal level of reactive oxygen species (ROS) are considered as the important pathogenic factors of Alzheimer's disease (AD). Strategies targeting only one of them have no obvious effects in clinic. In this study, a multifunctional nanocarrier CICe@M-K that crosses the blood-brain barrier (BBB) efficiently was developed for inhibiting Aβ aggregation and scavenging ROS synchronously. Antioxidant curcumin (Cur) and photosensitizer IR780 were loaded in mesoporous silica nanomaterials (MSNs). Their surfaces were grafted with cerium oxide nanoparticles (CeO2 NPs) and a short peptide K (CKLVFFAED). Living imaging showed that CICe@M-K was mainly distributed in the brain, liver, and kidneys, indicating CICe@M-K crossed BBB efficiently and accumulated in brain. After the irradiation of 808 nm laser, Cur was continuously released. Both of Cur and the peptide K can recognize and bind to Aβ through multiple interaction including π-π stacking interaction, hydrophobic interaction, and hydrogen bond, inhibiting Aβ aggregation. On the other hand, Cur and CeO2 NPs cooperate to relieve the oxidative stress in the brains by scavenging ROS. In vivo assays showed that the CICe@M-K could diminish Aβ depositions, alleviate oxidative stress, and improve cognitive ability of the APP/PS1 AD mouse model, which demonstrated that CICe@M-K is a potential agent for AD treatment.

Biomimetic Nanovesicles as a Dual Gene Delivery System for the Synergistic Gene Therapy of Alzheimer's Disease

The association between dysfunctional microglia and amyloid-β (Aβ) is a fundamental pathological event and increases the speed of Alzheimer's disease (AD). Additionally, the pathogenesis of AD is intricate and a single drug may not be enough to achieve a satisfactory therapeutic outcome. Herein, we reported a facile and effective gene therapy strategy for the modulation of microglia function and intervention of Aβ anabolism by ROS-responsive biomimetic exosome-liposome hybrid nanovesicles (designated as TSEL). The biomimetic nanovesicles codelivery β-site amyloid precursor protein cleaving enzyme-1 (BACE1) siRNA (siBACE1) and TREM2 plasmid (pTREM2) gene drug efficiently penetrate the blood-brain barrier and enhance the drug accumulation at AD lesions with the help of exosomes homing ability and angiopep-2 peptides. Specifically, an upregulation of TREM2 expression can reprogram microglia from a pro-inflammatory M1 phenotype to an anti-inflammatory M2 phenotype while also restoring its capacity to phagocytose Aβ and its nerve repair function. In addition, siRNA reduces the production of Aβ plaques at the source by knocking out the BACE1 gene, which is expected to further enhance the therapeutic effect of AD. The in vivo study suggests that TSEL through the synergistic effect of two gene drugs can ameliorate APP/PS1 mice cognitive impairment by regulating the activated microglial phenotype, reducing the accumulation of Aβ, and preventing the retriggering of neuroinflammation. This strategy employs biomimetic nanovesicles for the delivery of dual nucleic acids, achieving synergistic gene therapy for AD, thus offering more options for the treatment of AD.

Injectable Fluorescent Neural Interfaces for Cell-Specific Stimulating and Imaging

Building on current explorations in chronic optical neural interfaces, it is essential to address the risk of photothermal damage in traditional optogenetics. By focusing on calcium fluorescence for imaging rather than stimulation, injectable fluorescent neural interfaces significantly minimize photothermal damage and improve the accuracy of neuronal imaging. Key advancements including the use of injectable microelectronics for targeted electrical stimulation and their integration with cell-specific genetically encoded calcium indicators have been discussed. These injectable electronics that allow for post-treatment retrieval offer a minimally invasive solution, enhancing both usability and reliability. Furthermore, the integration of genetically encoded fluorescent calcium indicators with injectable bioelectronics enables precise neuronal recording and imaging of individual neurons. This shift not only minimizes risks such as photothermal conversion but also boosts safety, specificity, and effectiveness of neural imaging. Embracing these advancements represents a significant leap forward in biomedical engineering and neuroscience, paving the way for advanced brain-machine interfaces.

Transthyretin-Penetratin: A Potent Fusion Protein Inhibitor against Alzheimer's Amyloid-β Fibrillogenesis with High Blood Brain Barrier Crossing Capability

The design of a potent amyloid-β protein (Aβ) inhibitor plays a pivotal role in the prevention and treatment of Alzheimer's disease (AD). Despite endogenous transthyretin (TTR) being recognized as an Aβ inhibitor, the weak inhibitory and blood brain barrier (BBB) crossing capabilities hinder it for Aβ aggregation inhibition and transport. Therefore, we have herein designed a recombinant TTR by conjugating a cationic cell penetrating peptide (penetratin, Pen), which not only enabled the fusion protein, TTR-Pen (TP), to present high BBB penetration but also greatly enhanced the potency of Aβ inhibition. Namely, the protein fusion made TP positively charged, leading to a potent suppression of Aβ40 fibrillization at a low concentration (1.5 μM), while a TTR concentration as high as 12.5 μM was required to gain a similar function. Moreover, TP could mitigate Aβ-induced neuronal death, increase cultured cell viability from 72% to 92% at 2.5 μM, and extend the lifespan of AD nematodes from 14 to 18 d. Thermodynamic studies revealed that TP, enriched in positive charges, presented extensive electrostatic interactions with Aβ40. Importantly, TP showed excellent BBB penetration performance, with a 10 times higher BBB permeability than TTR, which would allow TP to enter the brain of AD patients and participate in the transport of Aβ species out of the brain. Thus, it is expected that the fusion protein has great potential for drug development in AD treatment.

Current Anti-Amyloid-β Therapy for Alzheimer's Disease Treatment: From Clinical Research to Nanomedicine

Recent successive approval of anti-amyloid-β (Aβ) monoclonal antibodies as disease-modifying therapies against Alzheimer's disease (AD) has raised great confidence in the development of anti-AD therapies; however, the current therapies still face the dilemma of significant adverse reactions and limited effects. In this review, we summarized the therapeutic characteristics of the approved anti-Aβ immunotherapies and dialectically analyzed the gains and losses from clinical trials. The review further proposed the reasonable selection of animal models in preclinical studies from the perspective of different animal models of Aβ deposition and deals in-depth with the recent advances of exploring preclinical nanomedical application in Aβ targeted therapy, aiming to provide a reliable systematic summary for the development of novel anti-Aβ therapies. Collectively, this review comprehensively dissects the pioneering work of Aβ-targeted therapies and proposed perspective insight into AD-modified therapies.

Nano-Plumber Reshapes Glymphatic-Lymphatic System to Sustain Microenvironment Homeostasis and Improve Long-Term Prognosis after Traumatic Brain Injury

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. Long-term changes in the microenvironment of the brain contribute to the degeneration of neurological function following TBI. However, current research focuses primarily on short-term modulation during the early phases of TBI, not on the critical significance of long-term homeostasis in the brain microenvironment. Notably, dysfunction of the glymphatic-lymphatic system results in the accumulation of danger/damage-associated molecular patterns (DAMPs) in the brain, which is regarded as the leading cause of long-term microenvironmental disturbances following TBI. Here, a nanostructure, Nano-plumber, that co-encapsulates the microenvironment regulator pro-DHA and the lymphatic-specific growth factor VEGF-C is developed, allowing for a sustainable and orderly regulation of the microenvironment to promote long-term neurological recovery. Nano-plumber reverses the injury microenvironment by suppressing microglia and astrocytes activation and maintaining reduced activation via enhanced glymphatic-lymphatic drainage, and significantly improves the neurological function of rodents with TBI. This study demonstrates that glymphatic-lymphatic system reconstruction is essential for enhancing long-term prognosis following TBI, and that the Nano-plumber developed here may serve as a clinically translatable treatment option for TBI.

A Reactive Oxygen Species-Responsive Targeted Nanoscavenger to Promote Mitophagy for the Treatment of Alzheimer's Disease

Mitophagy modulators are proposed as potential therapeutic intervention that enhance neuronal health and brain homeostasis in Alzheimer's disease (AD). Nevertheless, the lack of specific mitophagy inducers, low efficacies, and the severe side effects of nonselective autophagy during AD treatment have hindered their application. In this study, the P@NB nanoscavenger is designed with a reactive-oxygen-species-responsive (ROS-responsive) poly(l-lactide-co-glycolide) core and a surface modified with the Beclin1 and angiopoietin-2 peptides. Notably, nicotinamide adenine dinucleotide (NAD+ ) and Beclin1, which act as mitophagy promoters, are quickly released from P@NB in the presence of high ROS levels in lesions to restore mitochondrial homeostasis and induce microglia polarization toward the M2-type, thereby enabling it to phagocytose amyloid-peptide (Aβ). These studies demonstrate that P@NB accelerates Aβ degradation and alleviates excessive inflammatory responses by restoring autophagic flux, which ameliorates cognitive impairment in AD mice. This multitarget strategy induces autophagy/mitophagy through synergy, thereby normalizing mitochondrial dysfunction. Therefore, the developed method provides a promising AD-therapy strategy.

Design of Self-Assembled Nanoparticles as a Potent Inhibitor and Fluorescent Probe for β-Amyloid Fibrillization

Alzheimer's disease (AD) remains incurable due to its complex pathogenesis. The deposition of β-amyloid (Aβ) in the brain appears much earlier than any clinical symptoms and plays an essential role in the occurrence and development of AD neuropathology, which implies the importance of early theranostics. Herein, we designed a self-assembled bifunctional nanoparticle (LC8-pCG-fLC8) for Aβ fluorescent diagnosis and inhibition. The nanoparticle was synthesized by click chemistry from Aβ-targeting peptide Ac-LVFFARKC-NH2 (LC8) and an Aβ fluorescent probe f with the zwitterionic copolymer poly(carboxybetaine methacrylate-glycidyl methacrylate) (p(CBMA-GMA), pCG). Owing to the high reactivity of epoxy groups, the peptide concentration of LC8-pCG-fLC8 nanoparticles reached about 4 times higher than that of the existing inhibitor LVFFARK@poly(carboxybetaine) (LK7@pCB). LC8-pCG-fLC8 exhibited remarkable inhibitory capability (suppression efficiency of 83.0% at 20 μM), altered the aggregation pathway of Aβ, and increased the survival rate of amyloid-induced cultured cells from 76.5% to 98.0% at 20 μM. Notably, LC8-pCG-fLC8 possessed excellent binding affinity, good biostability, and high fluorescence responsivity to β-sheet-rich Aβ oligomers and fibrils, which could be used for the early diagnosis of Aβ aggregation. More importantly, in vivo tests using transgenic C. elegans CL2006 stain showed that LC8-pCG-fLC8 could specifically image Aβ plaques, prolong the lifespan (from 13 to 17 days), and attenuate the AD-like symptoms (reducing paralysis and Aβ deposition). Therefore, self-assembled nanoparticles hold great potential in AD theranostics.

Nanotechnologies meeting natural sources: Engineered lipoproteins for precise brain disease theranostics

Biological nanotechnologies have provided considerable opportunities in the management of malignancies with delicate design and negligible toxicity, from preventive and diagnostic to therapeutic fields. Lipoproteins, because of their inherent blood-brain barrier permeability and lesion-homing capability, have been identified as promising strategies for high-performance theranostics of brain diseases. However, the application of natural lipoproteins remains limited owing to insufficient accumulation and complex purification processes, which can be critical for individual therapeutics and clinical translation. To address these issues, lipoprotein-inspired nano drug-delivery systems (nano-DDSs), which have been learned from nature, have been fabricated to achieve synergistic drug delivery involving site-specific accumulation and tractable preparation with versatile physicochemical functions. In this review, the barriers in brain disease treatment, advantages of state-of-the-art lipoprotein-inspired nano-DDSs, and bio-interactions of such nano-DDSs are highlighted. Furthermore, the characteristics and advanced applications of natural lipoproteins and tailor-made lipoprotein-inspired nano-DDSs are summarized. Specifically, the key designs and current applications of lipoprotein-inspired nano-DDSs in the field of brain disease therapy are intensively discussed. Finally, the current challenges and future perspectives in the field of lipoprotein-inspired nano-DDSs combined with other vehicles, such as exosomes, cell membranes, and bacteria, are discussed.

Curcumin, inflammation, and neurological disorders: How are they linked?

Background

Despite the extensive research in recent years, the current treatment modalities for neurological disorders are suboptimal. Curcumin, a polyphenol found in Curcuma genus, has been shown to mitigate the pathophysiology and clinical sequalae involved in neuroinflammation and neurodegenerative diseases.

Methods

We searched PubMed database for relevant publications on curcumin and its uses in treating neurological diseases. We also reviewed relevant clinical trials which appeared on searching PubMed database using 'Curcumin and clinical trials'.

Results

This review details the pleiotropic immunomodulatory functions and neuroprotective properties of curcumin, its derivatives and formulations in various preclinical and clinical investigations. The effects of curcumin on neurodegenerative diseases such as Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), brain tumors, epilepsy, Huntington's disorder (HD), ischemia, Parkinson's disease (PD), multiple sclerosis (MS), and traumatic brain injury (TBI) with a major focus on associated signalling pathways have been thoroughly discussed.

Conclusion

This review demonstrates curcumin can suppress spinal neuroinflammation by modulating diverse astroglia mediated cascades, ensuring the treatment of neurological disorders.

Modulation of engineered nanomaterial interactions with organ barriers for enhanced drug transport

The biomedical use of nanoparticles (NPs) has been the focus of intense research for over a decade. As most NPs are explored as carriers to alter the biodistribution, pharmacokinetics and bioavailability of associated drugs, the delivery of these NPs to the tissues of interest remains an important topic. To date, the majority of NP delivery studies have used tumor models as their tool of interest, and the limitations concerning tumor targeting of systemically administered NPs have been well studied. In recent years, the focus has also shifted to other organs, each presenting their own unique delivery challenges to overcome. In this review, we discuss the recent advances in leveraging NPs to overcome four major biological barriers including the lung mucus, the gastrointestinal mucus, the placental barrier, and the blood-brain barrier. We define the specific properties of these biological barriers, discuss the challenges related to NP transport across them, and provide an overview of recent advances in the field. We discuss the strengths and shortcomings of different strategies to facilitate NP transport across the barriers and highlight some key findings that can stimulate further advances in this field.

Pathological BBB Crossing Melanin-Like Nanoparticles as Metal-Ion Chelators and Neuroinflammation Regulators against Alzheimer's Disease

Inflammatory responses, manifested in excessive oxidative stress and microglia overactivation, together with metal ion-triggered amyloid-beta (Aβ) deposition, are critical hallmarks of Alzheimer's disease (AD). The intricate pathogenesis causes severe impairment of neurons, which, in turn, exacerbates Aβ aggregation and facilitates AD progression. Herein, multifunctional melanin-like metal ion chelators and neuroinflammation regulators (named PDA@K) were constructed for targeted treatment of AD. In this platform, intrinsically bioactive material polydopamine nanoparticles (PDA) with potent metal ion chelating and ROS scavenging effects were decorated with the KLVFF peptide, endowing the system with the capacity of enhanced pathological blood-brain barrier (BBB) crossing and lesion site accumulation via Aβ hitchhiking. In vitro and in vivo experiment revealed that PDA@K had high affinity toward Aβ and were able to hitch a ride on Aβ to achieve increased pathological BBB crossing. The engineered PDA@K effectively mitigated Aβ aggregate and alleviated neuroinflammation. The modulated inflammatory microenvironment by PDA@K promoted microglial polarization toward the M2-like phenotype, which restored their critical functions for neuron care and plaque removal. After 3-week treatment of PDA@K, spatial learning and memory deficit as well as neurologic changes of FAD^4T transgenic mice were largely rescued. Transcriptomics analysis further revealed the therapeutic mechanism of PDA@K. Our study provided an appealing paradigm for directly utilizing intrinsic properties of nanomaterials as therapeutics for AD instead of just using them as nanocarriers, which largely widen the application of nanomaterials in AD therapy.

Intranasal Pathway for Nanoparticles to Enter the Central Nervous System

Intranasal administration was previously proposed for delivering drugs for central nervous system (CNS) diseases. However, the delivery and elimination pathways, which are very imperative to know for exploring the therapeutic applications of any given CNS drugs, remain far from clear. Because lipophilicity has a high priority in the design of CNS drugs, the as-prepared CNS drugs tend to form aggregates. Therefore, a PEGylated Fe₃O₄ nanoparticle labeled with a fluorescent dye was prepared as a model drug and studied to elucidate the delivery pathways of intranasally administered nanodrugs. Through magnetic resonance imaging, the distribution of the nanoparticles was investigated in vivo. Through ex vivo fluorescence imaging and microscopy studies, more precise distribution of the nanoparticles across the entire brain was disclosed. Moreover, the elimination of the nanoparticles from cerebrospinal fluid was carefully studied. The temporal dose levels of intranasally delivered nanodrugs in different parts of the brain were also investigated.

ROS-responsive nanomodulators downregulate IFITM3 expression and eliminate ROS for Alzheimer's disease combination treatment

Neuronal damage caused by β-amyloid (Aβ) aggregates and excess reactive oxygen species (ROS) is a crucial pathogenic event in Alzheimer's disease (AD). However, current Aβ-targeting RNA interference (RNAi) treatments have shown limited therapeutic efficacy due to ineffective intracerebral siRNA delivery and overlooked crosstalk between excess ROS and Aβ aggregates in the brain. Herein, a ROS-responsive nanomodulator (NM/CM) was developed for the combinational treatment of RNAi and ROS elimination for AD. NM/CM was coated with 4T1 cell membranes, which endowed NM/CM with the capability to cross blood-brain barrier (BBB). After being internalized by neural cells, NM/CM releases curcumin (Cur) and siIFITM3 spontaneously into the cytoplasm. The released Cur can eliminate ROS, protecting neurons from oxidative damage and reducing the production of Aβ induced by ROS-related neuroinflammation. The released siIFITM3 can downregulate the expression of interferon-induced transmembrane protein 3 (IFITM3), thereby reducing the abnormal Aβ production mediated by IFITM3. As a result, NM/CM remarkably alleviated ROS- and Aβ aggregate-induced neurotoxicity in vitro, showing significant neuroprotective effects. This work demonstrates the potential of NM/CM in the development of novel and effective AD combination therapies.

Inactive Trojan Bacteria as Safe Drug Delivery Vehicles Crossing the Blood-Brain Barrier

Escherichia coli K1 (EC-K1) can bypass the blood-brain barrier (BBB) and cause meningitis. Excitingly, we find the "dead EC-K1" can safely penetrate the BBB because they retain the intact structure and chemotaxis of the live EC-K1, while losing their pathogenicity. Based on this, we develop a safe "dead EC-K1"-based drug delivery system, in which EC-K1 engulf the maltodextrin (MD)-modified therapeutics through the bacteria-specific MD transporter pathway, followed by the inactivation via UV irradiation. We demonstrate that the dead bacteria could carry therapeutics (e.g., indocyanine green (ICG)) and together bypass the BBB after intravenous injection into the mice, delivering ∼3.0-fold higher doses into the brain than free ICG under the same conditions. What is more, all mice remain healthy even after 14 days of intravenous injection of ∼10⁹ CFU of inactive bacteria. As a proof of concept, we demonstrate the developed strategy enables the therapy of bacterial meningitis and glioblastoma in mice.

Multivalent Nanobody Conjugate with Rigid, Reactive Oxygen Species Scavenging Scaffold for Multi-Target Therapy of Alzheimer's Disease

Efficient therapeutic strategies that concurrently target both Aβ aggregation and oxidative stress in the Alzheimer's disease (AD) microenvironment emerge as a cutting-edge tool to combat the intricate pathogenesis of AD. Here, a multivalent nanobody conjugate with rigid, reactive oxygen species (ROS) scavenging scaffold is developed to achieve simultaneous Aβ amyloidogenesis mitigation, ROS elimination, and Aβ plaque clearance. Grafting Aβ segment (33-GLMVGGVVIA-42) into the third complementary-determining region of a parent nanobody generates an engineered nanobody NB that can recognize Aβ and inhibit its aggregation through homotypic interactions. NB is further genetically modified with a fragment of human interleukin-1β (163-VQGEESNDK-171), so that the obtained fusion nanobody NBIL can also facilitate the Aβ clearance by microglia. Linking NBIL covalently onto a rigid, ROS scavenging scaffold poly(deca-4,6-diynedioic acid) (PDDA) creates the multivalent nanobody conjugate PNBIL, which not only boosts the binding affinity between NBIL and Aβ aggregates for nearly 100 times but also possesses a long-term capability of oxidative stress alleviation, inflammation reduction, and neuron protection. PNBIL has significantly attenuated symptoms on two AD mouse models through amyloidogenesis inhibition and AD microenvironment modulation, validating that the multivalent nanobody conjugate design based on combinatory nanobody and molecular engineering is a promising approach of multi-target therapeutic strategies.

Nucleic acid drug vectors for diagnosis and treatment of brain diseases

Nucleic acid drugs have the advantages of rich target selection, simple in design, good and enduring effect. They have been demonstrated to have irreplaceable superiority in brain disease treatment, while vectors are a decisive factor in therapeutic efficacy. Strict physiological barriers, such as degradation and clearance in circulation, blood-brain barrier, cellular uptake, endosome/lysosome barriers, release, obstruct the delivery of nucleic acid drugs to the brain by the vectors. Nucleic acid drugs against a single target are inefficient in treating brain diseases of complex pathogenesis. Differences between individual patients lead to severe uncertainties in brain disease treatment with nucleic acid drugs. In this Review, we briefly summarize the classification of nucleic acid drugs. Next, we discuss physiological barriers during drug delivery and universal coping strategies and introduce the application methods of these universal strategies to nucleic acid drug vectors. Subsequently, we explore nucleic acid drug-based multidrug regimens for the combination treatment of brain diseases and the construction of the corresponding vectors. In the following, we address the feasibility of patient stratification and personalized therapy through diagnostic information from medical imaging and the manner of introducing contrast agents into vectors. Finally, we take a perspective on the future feasibility and remaining challenges of vector-based integrated diagnosis and gene therapy for brain diseases.

Long-Term Repeatable In Vivo Monitoring of Amyloid-β Plaques and Vessels in Alzheimer's Disease Mouse Model with Combined TPEF/CARS Microscopy

Long-term, repeatable monitoring of the appearance and progress of Alzheimer's disease (AD) in real time can be extremely beneficial to acquire highly reliable diagnostic insights, which is crucial for devising apt strategies towards effective AD treatment. Herein, we present an optimized innovative cranial window imaging method for the long-term repeatable imaging of amyloid-β (Aβ) plaques and vessels in an AD mouse model. Basically, two-photon excitation fluorescence (TPEF) microscopy was used to monitor the fluorescently labeled Aβ plaques, whereas the label-free blood vessels were studied using coherent anti-Stokes Raman scattering (CARS) microscopy in the live in vivo AD mouse model. It was possible to clearly observe the Aβ deposition and vascular structure in the target cortex localization for 31 weeks in the AD mouse model using this method. The combined TPEF/CARS imaging studies were also instrumental in realizing the relationship between the tendency of Aβ deposition and ageing. Essentially, the progression of cerebral amyloid angiopathy (CAA) in the AD mouse model was quantitatively characterized, which revealed that the proportion Aβ deposition in the unit vessel can increase from 13.63% to 28.80% upon increasing the age of mice from 8 months old to 14 months old. The proposed imaging method provided an efficient, safe, repeatable platform with simple target localization aptitude towards monitoring the brain tissues, which is an integral part of studying any brain-related physiological or disease conditions to extract crucial structural and functional information.