Influence factors on and potential strategies to amplify receptor-mediated nanodrug delivery across the blood-brain barrier

Ultrasonic head-mounted device spatiotemporal opening blood-brain barrier enhances the brain permeation of drugs for treatment of radiation-induced brain injury

The field of physical therapy is advancing and using focused ultrasound to deliver drugs into the brain gains growing interest. However, the blood-brain barrier makes it difficult for drugs to enter. Finding safe and efficient physical therapy strategies to complement drug treatments is essential. Here, the rule and molecular mechanisms of spatiotemporal opening blood-brain barrier of ultrasound were explored using a Bluetooth-controlled ultrasonic head-mounted device which was used to enhance the brain permeation of drugs for the treatment of radiation-induced brain injury. The falling-off of tight junction proteins in the blood-brain barrier was the key to spatiotemporally opening under ultrasound. Evans blue and Rhodamine B represented macromolecules and small molecules, respectively, which were intravenously injected into the circulation. Their brain permeation was promoted by brain ultrasound and the smaller molecules required the lower sound intensity that also affected the speed of drug-passing. During the blood-brain barrier restoration after ultrasound, biomarkers like enzymes and growth factors changed, which could be used for selection of dosing window. After the use of the helmet, the blood-brain barrier was restored after 24 h, and the efficacy of water-soluble drugs for the treatment of radiation brain injury was increased. It was suitable for non-invasive external use and enhanced the treating effect when cooperating with drugs. This study provides a research basis for applying ultrasound technology into physio-pharmacotherapy.

Nanoparticles modified with glucose analogs to enhance the permeability of the blood-brain barrier and their accumulation in the epileptic brain

Drug delivery for epilepsy treatment faces enormous challenges, where the sole focus on enhancing the ability of drugs to penetrate the blood-brain barrier (BBB) through ligand modification is insufficient because of the absence of seizure-specific drug accumulation. In this study, an amphipathic drug carrier with a glucose transporter (GLUT)-targeting capability was synthesised by conjugating 2-deoxy-2-amino-D-glucose (2-DG) to the model carrier DSPE-PEG2k. A 2-DG-modified nano drug delivery system (NDDS) possessing robust stability and favourable biocompatibility was then fabricated using the nanoprecipitation method. The results showed that the 2-DG-modified NDDS exhibited enhanced cellular uptake by brain capillary endothelial cells and neuronal cells. Most importantly, the 2-DG-modified NDDS exhibited enhanced BBB penetration and brain accumulation, especially in the epileptic brain, thus achieving seizure-based on-demand drug delivery. Our study provides a simple and smart strategy for the delivery of anti-seizure medicines.

Biomimetic membrane-coated nanoparticles specially permeate the inflammatory blood-brain barrier to deliver plasmin therapy for brain metastases

Many brain-targeting drug delivery strategies have been reported to permeate the blood-brain barrier (BBB) via hijacking receptor-mediated transport. However, these receptor-based strategies could mediate whole-brain BBB crossing due to the wide intracranial expression of target receptors and lead to unwanted accumulation and side effects on healthy brain tissues. Inspired by brain metastatic processes and the selectivity of brain metastatic cancer cells for the inflammatory BBB, a biomimetic nanoparticle was developed by coating drug-loaded core with the inflammatory BBB-seeking erythrocyte-brain metastatic hybrid membrane, which can resist homotypic aggregation and specially bind and permeate the inflammatory BBB for specific drug delivery. Dexamethasone and embelin were used as model drugs to be loaded in the biomimetic nanoparticles to restore plasmin-mediated attacks against brain metastases. The drug-loaded nanoparticles were proved to inhibit tumor serpin secretion to restore local plasmin production, which could inactivate tumor cell surface L1CAM to inhibit vessel-spreading-dependent tumor growth and produce lethal soluble factor-related apoptosis ligands (sFasL) to induce tumor cell apoptosis, leading to the suppression of the intracranial metastatic nodule development and prolonged survival of mice with brain metastases. The inflammatory BBB-seeking biomimetic approach represents an effective regimen for potent therapy against brain metastases.

Brain targeted polymeric micelles as drug carriers for ischaemic stroke treatment

Ischaemic stroke is a central nervous system disease with high morbidity, recurrence and mortality rates. Thrombolytic and neuroprotective therapies are the main therapeutic strategies for ischaemic stroke, however, the poor delivery efficiency of thrombolytic and neuroprotective drugs to the brain limits their clinical application. So far, the development of nanomedicine has brought opportunities for the above challenges, which can not only realise the effective accumulation of drugs in the target site, but also improve the pharmacokinetic behaviour of the drugs. Among the most rapidly developing nanoparticles, micelles gradually emerging as an effective strategy for ischaemic stroke treatment due to their own unique advantages. This review provided an overview of targeted and response-release micelles based on the physicochemical properties of the ischaemic stroke microenvironment, summarised the targeting strategies for delivering micellar formulations to the thrombus, blood-brain barrier, and brain parenchyma, and finally described the potentials and challenges of polymeric micelles in the treatment of ischaemic stroke.

Enhanced BBB penetration and microglia-targeting nanomodulator for the two-pronged modulation of chronically activated microglia-mediated neuroinflammation in Alzheimer's disease

Intervention in chronically activated microglia-mediated neuroinflammation is a novel approach to treat Alzheimer's disease (AD). The low permeability of the blood‒brain barrier (BBB) and non-selective distribution in the brain severely restrict AD drugs' disease-modifying efficacy. Here, an immunosuppressant TREM2-lowing antisense oligonucleotides (ASOs) and resveratrol co-loaded cationic liposome is developed as an immune reprogramming nanomodulator modified by acid-cleavable BBB-targeting peptide and microglia-targeting peptide (Res@TcMNP/ASO) for AD management. Res@TcMNP/ASO can enter brain endothelial cells via D-T7 peptides. Then D-T7 undergoes an acid-responsive cleavage, facilitating the escape of Res@MNP/ASO from endo/lysosomes to cross the BBB. The detached Res@MNP/ASO specifically targets M1-phenotype microglia via exposed MG1 peptides to prompt the simultaneous delivery of two drugs into activated microglia. This nanomodulator can not only restore the immune function of microglia through TREM2-lowing ASO but also mitigate the immune stimulation to microglia caused by reactive oxygen species (ROS) through resveratrol, thereby synergistically inhibiting the chronic activation of microglia to alleviate neuroinflammation in AD. Our results indicate that this combination treatment can achieve significant behavioral and cognitive improvements in late APP/PS1 mice.

Transcytosis: an effective mechanism to enhance nanoparticle extravasation and infiltration through biological barriers

Nanoparticles (NPs)1have been explored as drugs carriers for treating tumors and central nervous system (CNS)2diseases and for oral administration. However, they lack satisfactory clinical efficacy due to poor extravasation and infiltration through biological barriers to target tissues. Most clinical antitumor NPs have been designed based on enhanced permeability and retention effects which are insufficient and heterogeneous in human tumors. The tight junctions33TJs: tight junctionsof the blood-brain barrier44BBB: blood-brain barrierand the small intestinal epithelium severely impede NPs from being transported into the CNS and blood circulation, respectively. By contrast, transcytosis enables NPs to bypass these physiological barriers and enhances their infiltration into target tissues by active transport. Here, we systematically review the mechanisms and putative application of NP transcytosis for targeting tumor and CNS tissues, explore oral NP administration, and propose future research directions in the field of NP transcytosis.

Counteracting Alzheimer's disease via normalizing neurovascular unit with a self-regulated multi-functional nano-modulator

The neurovascular unit (NVU) is highly responsible for cerebral homeostasis and its dysfunction emerges as a critical contributor to Alzheimer's disease (AD) pathology. Hence, rescuing NVU dysfunction might be a viable approach to AD treatments. Here, we fabricated a self-regulated muti-functional nano-modulator (siR/PIO@RP) that can intelligently navigate to damaged blood-brain barrier and release therapeutical cargoes for synergetic AD therapy. The resulting siR/PIO@RP enables self-regulation of its distribution in accordance with the physio/pathological state (low/high RAGE expression) of the target site via a feedback loop. siR/PIO@RP is capable of performing intricate tasks and goes beyond the capabilities of single-target therapeutic agents utilized in AD therapy, such as reducing cerebral Aβ load, relieving neuroinflammation, and alleviating the dysfunction of NVU. Overall, the current study provides proof of concept that normalizing NVU holds promise as a means of alleviating AD symptoms.

Lactoferrin/CD133 antibody conjugated nanostructured lipid carriers for dual targeting of blood-brain-barrier and glioblastoma stem cells

The main reasons for the difficulty in curing and high recurrence rate of glioblastoma multiforme (GBM) include: 1. The difficulty of chemotherapy drugs in penetrating the blood-brain barrier (BBB) to target tumor cells; 2. The presence of glioma stem cells (GSCs) leading to chemotherapy resistance. Therefore, breaking through the limitations of the BBB and overcoming the drug resistance caused by GSCs are the main strategies to address this problem. This study presents our results on the development of lactoferrin (Lf)/CD133 antibody conjugated nanostructured lipid carriers (Lf/CD133-NLCS) for simultaneously targeting BBB and GSCs. Temozolomide (TMZ) loaded Lf/CD133-NLCS (Lf/CD133-NLCS-TMZ) exhibited high-efficiencyin vitroanti-tumor effects toward malignant glioma cells (U87-MG) and GSCs, while demonstrating no significant toxicity to normal cells at concentrations lower than 200 μg ml-1. The results of thein vitrotargeting GBM study revealed a notably higher cellular uptake of Lf/CD133-NLCS-TMZ in U87-MG cells and GSCs in comparison to Lf/CD133 unconjugated counterpart (NLCS-TMZ). In addition, increased BBB permeability were confirmed for Lf/CD133-NLCS-TMZ compared to NLCS-TMZ bothin vitroandin vivo. Taking together, Lf/CD133-NLCS-TMZ show great potential for dual targeting of BBB and GSCs, as well as GBM therapy based on this strategy.

Brain-targeted Tet-1 peptide-PLGA nanoparticles for berberine delivery against STZ-induced Alzheimer's disease in a rat model: Alleviation of hippocampal synaptic dysfunction, Tau pathology, and amyloidogenesis

Alzheimer's disease (AD) is an age-related neurodegenerative disorder that causes severe dementia and memory loss. Surface functionalized poly(lactic-co-glycolic acid) nanoparticles have been reported for better transport through the blood-brain barrier for AD therapy. This study investigated the improved therapeutic potential of berberine-loaded poly(lactic-co-glycolic acid)/Tet-1 peptide nanoparticles (BBR/PLGA-Tet NPs) in a rat model of sporadic AD. BBR was loaded into the PLGA-Tet conjugate. BBR/PLGA-Tet NPs were physicochemically and morphologically characterized. AD was achieved by bilateral intracerebroventricular (ICV) injection of streptozotocin (STZ). Cognitively impaired rats were divided into STZ, STZ + BBR, STZ + BBR/PLGA-Tet NPs, and STZ + PLGA-Tet NPs groups. Cognitive improvement was assessed using the Morris Water Maze. Brain acetylcholinesterase and monoamine oxidase activities, amyloid β42 (Aβ42), and brain glycemic markers were estimated. Further, hippocampal neuroplasticity (BDNF, pCREB, and pERK/ERK), Tau pathogenesis (pGSK3β/GSK3β, Cdk5, and pTau), inflammatory, and apoptotic markers were evaluated. Finally, histopathological changes were monitored. ICV-STZ injection produces AD-like pathologies evidenced by Aβ42 deposition, Tau hyperphosphorylation, impaired insulin signaling and neuroplasticity, and neuroinflammation. BBR and BBR/PLGA-Tet NPs attenuated STZ-induced hippocampal damage, enhanced cognitive performance, and reduced Aβ42, Tau phosphorylation, and proinflammatory responses. BBR/PLGA-Tet NPs restored neuroplasticity, cholinergic, and monoaminergic function, which are critical for cognition and brain function. BBR/PLGA-Tet NPs may have superior therapeutic potential in alleviating sporadic AD than free BBR due to their bioavailability, absorption, and brain uptake.

Precise Modulation of Pericyte Dysfunction by a Multifunctional Nanoprodrug to Ameliorate Alzheimer's Disease

Pericyte dysfunction severely undermines cerebrovascular integrity and exacerbates neurodegeneration in Alzheimer's disease (AD). However, pericyte-targeted therapy is a yet-untapped frontier for AD. Inspired by the elevation of vascular cell adhesion molecule-1 (VCAM-1) and reactive oxygen species (ROS) levels in pericyte lesions, we fabricated a multifunctional nanoprodrug by conjugating the hybrid peptide VLC, a fusion of the VCAM-1 high-affinity peptide VHS and the neuroprotective apolipoprotein mimetic peptide COG1410, to curcumin (Cur) through phenylboronic ester bond (VLC@Cur-NPs) to alleviate complex pericyte-related pathological changes. Importantly, VLC@Cur-NPs effectively homed to pericyte lesions via VLC and released their contents upon ROS stimulation to maximize their regulatory effects. Consequently, VLC@Cur-NPs markedly increased pericyte regeneration to form a positive feedback loop and thus improved neurovascular function and ultimately alleviated memory defects in APP/PS1 transgenic mice. We present a promising therapeutic strategy for AD that can precisely modulate pericytes and has the potential to treat other cerebrovascular diseases.

Lipid-mediated protein corona regulation with increased apolipoprotein A-I recruitment for glioma targeting

Protein corona has long been a source of concern, as it might impair the targeting efficacy of targeted drug delivery systems. However, engineered up-regulating the adsorption of certain functional serum proteins could provide nanoparticles with specific targeting drug delivery capacity. Herein, apolipoprotein A-I absorption increased nanoparticles (SPC-PLGA NPs), composed with the Food and Drug Administration approved intravenously injectable soybean phosphatidylcholine (SPC) and poly (DL-lactide-co-glycolide) (PLGA), were fabricated for enhanced glioma targeting. Due to the high affinity of SPC and apolipoprotein A-I, the percentage of apolipoprotein A-I in the protein corona of SPC-PLGA NPs was 2.19-fold higher than that of nanoparticles without SPC, which made SPC-PLGA NPs have superior glioma targeting ability through binding to scavenger receptor class BI on blood-brain barrier and glioma cells both in vitro and in vivo. SPC-PLGA NPs loaded with paclitaxel could effectively reduce glioma invasion and prolong the survival time of glioma-bearing mice. In conclusion, we provided a good example of the direction of achieving targeting drug delivery based on protein corona regulation.

Potential of Nanocarrier-Associated Approaches for Better Therapeutic Intervention in the Management of Glioblastoma

Glioblastoma, commonly known as glioblastoma multiforme (GBM), is one of the deadliest and most invasive types of brain cancer. Two factors account for the majority of the treatment limitations for GBM. First, the presence of the blood-brain barrier (BBB) renders malignancy treatment ineffective, leading to recurrence without full recovery. Second, several adverse effects are associated with the drugs used in conventional GBM treatment. Recent studies have developed nanocarrier systems, such as liposomes, polymeric micelles, dendrimers, nanosuspensions, nanoemulsions, nanostructured lipid carriers, solid lipid nanocarriers, metal particles, and silica nanoparticles, which allow drug-loaded formulations to penetrate the BBB more effectively. This has opened up new possibilities for overcoming therapy issues. Extensive and methodical searches of databases such as PubMed, Science Direct, Google Scholar, and others were conducted to gather relevant literature for this work, using precise keyword combinations such as "GBM," "brain tumor," and "nanocarriers." This review provides deep insights into the administration of drugs using nanocarriers for the management of GBM and explores new advancements in nanotechnology. It also highlights how scientific developments can be explained in connection with hopeful findings about the potential of nanocarriers for the future successful management of GBM.