Targeted drug delivery system to neural cells utilizes the nicotinic acetylcholine receptor

Receptor-Assisted Nanotherapeutics for Overcoming the Blood-Brain Barrier

Blood-brain barrier (BBB) is a distinguishing checkpoint that segregates peripheral organs from neural compartment. It protects the central nervous system from harmful ambush of antigens and pathogens. Owing to such explicit selectivity, the BBB hinders passage of various neuroprotective drug molecules that escalates into poor attainability of neuroprotective agents towards the brain. However, few molecules can surpass the BBB and gain access in the brain parenchyma by exploiting surface transporters and receptors. For successful development of brain-targeted therapy, understanding of BBB transporters and receptors is crucial. This review focuses on the transporter and receptor-based mechanistic pathway that can be manoeuvred for better comprehension of reciprocity of receptors and nanotechnological vehicle delivery. Nanotechnology has emerged as one of the expedient noninvasive approaches for brain targeting via manipulating the hurdle of the BBB. Various nanovehicles are being reported for brain-targeted delivery such as nanoparticles, nanocrystals, nanoemulsion, nanolipid carriers, liposomes and other nanovesicles. Nanotechnology-aided brain targeting can be a strategic approach to circumvent the BBB without altering the inherent nature of the BBB.

Nose-to-brain delivery of nanotherapeutics: Transport mechanisms and applications

The blood-brain barrier presents a key limitation to the administration of therapeutic molecules for the treatment of brain disease. While drugs administered orally or intravenously must cross this barrier to reach brain targets, the unique anatomical structure of the olfactory system provides a route to deliver drugs directly to the brain. Entering the brain via receptor, carrier, and adsorption-mediated transcytosis in the nasal olfactory and trigeminal regions has the potential to increase drug delivery. In this review, we introduce the physiological and anatomical structures of the nasal cavity, and summarize the possible modes of transport and the relevant receptors and carriers in the nose-to-brain pathway. Additionally, we provide examples of nanotherapeutics developed for intranasal drug delivery to the brain. Further development of nanoparticles that can be applied to intranasal delivery systems promises to improve drug efficacy and reduce drug resistance and adverse effects by increasing molecular access to the brain. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease.

Exploring Chinese herbal medicine for ischemic stroke: insights into microglia and signaling pathways

Ischemic stroke is a prevalent clinical condition affecting the central nervous system, characterized by a high mortality and disability rate. Its incidence is progressively rising, particularly among younger individuals, posing a significant threat to human well-being. The activation and polarization of microglia, leading to pro-inflammatory and anti-inflammatory responses, are widely recognized as pivotal factors in the pathogenesis of cerebral ischemia and reperfusion injury. Traditional Chinese herbal medicines (TCHMs) boasts a rich historical background, notable efficacy, and minimal adverse effects. It exerts its effects by modulating microglia activation and polarization, suppressing inflammatory responses, and ameliorating nerve injury through the mediation of microglia and various associated pathways (such as NF-κB signaling pathway, Toll-like signaling pathway, Notch signaling pathway, AMPK signaling pathway, MAPK signaling pathway, among others). Consequently, this article focuses on microglia as a therapeutic target, reviewing relevant pathway of literature on TCHMs to mitigate neuroinflammation and mediate IS injury, while also exploring research on drug delivery of TCHMs. The ultimate goal is to provide new insights that can contribute to the clinical management of IS using TCHMs.

Protein corona on brain targeted nanocarriers: Challenges and prospects

Safe and efficient medical therapy for brain diseases is still an unmet clinical need due to various barriers represented by the blood-brain barrier. Well-designed brain targeted nanocarriers are potential solutions for enhanced brain drug delivery; however, the complicated in vivo process attenuates performance of nanocarriers, which severely hampers clinical translation. The formation of protein corona (PC) is inevitable for nanocarriers circulation and transport in biofluids, acting as an important factor to regulate in vivo performance of nanocarriers. In this review, the reported strategies have been retrospected for better understanding current situation in developing brain targeted nanocarriers. The interplay between brain targeted nanocarriers and plasma proteins is emphasized to comprehend how the nanocarriers adsorb proteins by certain synthetic identity, and following regulations on in vivo performance of nanocarriers. More importantly, the mainstream methods to promote efficiency of nanocarriers by regulating PC, defined as in vitro functionalization and in vivo functionalization strategies, are also discussed. Finally, viewpoints about future development of brain targeted nanocarriers according to the understanding on nanocarriers-PC interaction are proposed.

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.

Non-Invasive, Targeted Nanoparticle-Mediated Drug Delivery across a Novel Human BBB Model

The blood-brain barrier (BBB) is a highly sophisticated system with the ability to regulate compounds transporting through the barrier and reaching the central nervous system (CNS). The BBB protects the CNS from toxins and pathogens but can cause major issues when developing novel therapeutics to treat neurological disorders. PLGA nanoparticles have been developed to successfully encapsulate large hydrophilic compounds for drug delivery. Within this paper, we discuss the encapsulation of a model compound Fitc-dextran, a large molecular weight (70 kDa), hydrophilic compound, with over 60% encapsulation efficiency (EE) within a PLGA nanoparticle (NP). The NP surface was chemically modified with DAS peptide, a ligand that we designed which has an affinity for nicotinic receptors, specifically alpha 7 nicotinic receptors, found on the surface of brain endothelial cells. The attachment of DAS transports the NP across the BBB by receptor-mediated transcytosis (RMT). Assessment of the delivery efficacy of the DAS-conjugated Fitc-dextran-loaded PLGA NP was studied in vitro using our optimal triculture in vitro BBB model, which successfully replicates the in vivo BBB environment, producing high TEER (≥230 ) and high expression of ZO1 protein. Utilising our optimal BBB model, we successfully transported fourteen times the concentration of DAS-Fitc-dextran-PLGA NP compared to non-conjugated Fitc-dextran-PLGA NP. Our novel in vitro model is a viable method of high-throughput screening of potential therapeutic delivery systems to the CNS, such as our receptor-targeted DAS ligand-conjugated NP, whereby only lead therapeutic compounds will progress to in vivo studies.

Norepinephrine transporter analog benzylguanidine-conjugated nanoparticles for the delivery of paclitaxel in neuroblastoma

Aim: We previously synthesized a polyethylene glycol-based norepinephrine transporter-targeted agent, BG-P-TAT, which has a benzylguanidine and a triazolyl-tetrac group. This targeted conjugate showed suppression of neuroblastoma tumor progression. In this study we aimed to synthesize nanoparticles to encapsulate the chemotherapeutic agent paclitaxel for targeting neuroblastoma tumors by using benzylguanidine so that it can compete with norepinephrine for uptake by neuroendocrine cells. Methods: Biocompatible poly(lactide-co-glycolic acid)-polyethylene glycol was chosen to prepare targeted nanoparticles for safe delivery of the chemotherapy agent paclitaxel. Result: Paclitaxel concentration was 60% higher in neuroblastoma tumors of mice treated with paclitaxel encapsulated in targeted nanoparticles than with non-targeted nanoparticles. Conclusion: These findings support the targeted delivery of paclitaxel as a chemotherapeutic agent for neuroblastoma.

Cytotoxicity of targeted PLGA nanoparticles: a systematic review

Recent advances in nanotechnology have contributed tremendously to the development and revolutionizing of drug delivery systems in the field of nanomedicine. In particular, targeting nanoparticles based on biodegradable poly(lactic-co-glycolic acid) (PLGA) polymers have gained much interest. However, PLGA nanoparticles remain of concern for their effectiveness against cancer cells and their toxicity to normal cells. The aim of this systematic review is to identify a promising targeting PLGA nanoformulation based on the comparison study of their cytotoxicity potency in different cell lines. A literature search was conducted through the databases of Google Scholar, PubMed, ScienceDirect, Scopus and SpringerLink. The sources studied were published between 2009 and 2019, and a variety of keywords were utilized. In total, 81 manuscripts that met the inclusion and exclusion criteria were selected for analysis based on their cytotoxicity, size, zeta potential, year of publication, type of ligand, active compounds and cell line used. The half maximal inhibitory concentration (IC50) for cytotoxicity was the main measurement in this data extraction, and the SI units were standardized to μg mL-1 for a better view of comparison. This systematic review also identified that cytotoxicity potency was inversely proportional to nanoparticle size. The PLGA nanoparticles predominantly exhibited a size of less than 300 nm and absolute zeta potential ∼20 mV. In conclusion, more comprehensive and critical appraisals of pharmacokinetic, pharmacokinetic, toxicokinetic, in vivo and in vitro tests are required for the investigation of the full value of targeting PLGA nanoparticles for cancer treatment.

An overview of nanomedicines for neuron targeting

Medical treatments of neuron-related disorders are limited due to the difficulty of targeting brain cells. Major drawbacks are the presence of the blood-brain barrier and the lack of specificity of the drugs for the diseased cells. Nanomedicine-based approaches provide promising opportunities for overcoming these limitations. Although many previous reviews are focused on brain targeting with nanomedicines in general, none of those are concerned explicitly on the neurons, while targeting neuronal cells in central nervous diseases is now one of the biggest challenges in nanomedicine and neuroscience. We review the most relevant advances in nanomedicine design and strategies for neuronal drug delivery that might successfully bridge the gap between laboratory and bedside treatment in neurology.

Nanomaterial-Based Approaches for Neural Regeneration

Mechanical, thermal, chemical, or ischemic injury of the central or peripheral nervous system results in neuron loss, neurite damage, and/or neuronal dysfunction, almost always accompanied by sensorimotor impairment which alters the patient's life quality. The regenerative strategies for the injured nervous system are currently limited and mainly allow partial functional recovery, so it is necessary to develop new and effective approaches for nervous tissue regenerative therapy. Nanomaterials based on inorganic or organic and composite or hybrid compounds with tunable physicochemical properties and functionality proved beneficial for the transport and delivery/release of various neuroregenerative-relevant biomolecules or cells. Within the following paragraphs, we will emphasize that nanomaterial-based strategies (including nanosized and nanostructured biomaterials) represent a promising alternative towards repairing and regenerating the injured nervous system.

Cannabidiol Enhances the Passage of Lipid Nanocapsules across the Blood-Brain Barrier Both in Vitro and in Vivo

Diseases affecting the central nervous system (CNS) should be regarded as a major health challenge due to the current lack of effective treatments given the hindrance to brain drug delivery imposed by the blood-brain barrier (BBB). Since efficient brain drug delivery should not solely rely on passive targeting, active targeting of nanomedicines into the CNS is being explored. The present study is devoted to the development of lipid nanocapsules (LNCs) decorated with nonpsychotropic cannabinoids as pioneering nonimmunogenic brain-targeting molecules and to the evaluation of their brain-targeting ability both in vitro and in vivo. Noticeably, both the permeability experiments across the hCMEC/D3 cell-based in vitro BBB model and the biodistribution experiments in mice consistently demonstrated that the highest brain-targeting ability was achieved with the smallest-sized cannabinoid-decorated LNCs. Importantly, the enhancement in brain targeting achieved with the conjugation of cannabidiol to LNCs outperformed by 6-fold the enhancement observed for the G-Technology (the main brain active strategy that has already entered clinical trials for the treatment of CNS diseases). As the transport efficiency across the BBB certainly determines the efficacy of the treatments for brain disorders, small cannabinoid-decorated LNCs represent auspicious platforms for the design and development of novel therapies for CNS diseases.

Targeted therapy of intracranial glioma model mice with curcumin nanoliposomes

Background

Glioma is the most aggressive and lethal brain tumor in humans, it comprises about 30 per cent of all brain tumors and central nervous system tumors.

Purpose

The objective of this study was to create novel brain-targeting nanoliposomes to encapsulate curcumin as a promising option for glioma therapy.

Patients and methods

Human glioma cells (U251MG) were used to determine cell uptake efficiency and possible internalization mechanism of the curcumin-loaded nanoliposomes modified by a brain-targeting peptide RDP. In addition, intracranial glioma mice model was prepared by transplantation of U251MG cells into the mice striatum, and then the liposomes were intravenously administered into the glioma-bearing mice to evaluate the anti-glioma activity.

Results

RDP-modified liposomes (RCL) could enter the brain and glioma region, and were internalized by the glioma cells perhaps through acetylcholine receptor-mediated endocytosis pathway. Furthermore, the RCL prolonged the survival time of the glioma-bearing mice from 23 to 33 days, and the inhibition mechanism of the RCL on glioma cell was partly due to cell cycle arrest at the S phase and induction of cell apoptosis.

Conclusion

This study would provide a potential approach for targeted delivery of drug-loaded liposomes for glioma treatment.

Promotion of SH-SY5Y Cell Growth by Gold Nanoparticles Modified with 6-Mercaptopurine and a Neuron-Penetrating Peptide

Much effort has been devoted to the discovery of effective biomaterials for nerve regeneration. Here, we reported a novel application of gold nanoparticles (AuNPs) modified with 6-mercaptopurine (6MP) and a neuron-penetrating peptide (RDP) as a neurophic agent to promote proliferation and neurite growth of human neuroblastoma (SH-SY5Y) cells. When the cells were treated with 6MP-AuNPs-RDP conjugates, they showed higher metabolic activity than the control. Moreover, SH-SY5Y cells were transplanted onto the surface coated with 6MP-AuNPs-RDP to examine the effect of neurite development. It can be concluded that 6MP-AuNPs-RDP attached to the cell surface and then internalized into cells, leading to a significant increase of neurite growth. Even though 6MP-AuNPs-RDP-treated cells were recovered from frozen storage, the cells still maintained constant growth, indicating that the cells have excellent tolerance to 6MP-AuNPs-RDP. The results suggested that the 6MP-AuNPs-RDP had promising potential to be developed as a neurophic nanomaterial for neuronal growth.

Targeted transport of nanocarriers into brain for theranosis with rabies virus glycoprotein-derived peptide

For successful theranosis of brain diseases, limited access of therapeutic molecules across blood-brain barrier (BBB) needs be overcome in brain delivery. Currently, peptide derivatives of rabies virus glycoprotein (RVG) have been exploited as delivery ligands to transport nanocarriers across BBB and specifically into the brain. The targeting peptides usually conjugate to the nanocarrier surface, and the cargoes, including siRNA, miRNA, DNA, proteins and small molecular chemicals, are complexed or encapsulated in the nanocarriers. The peptide ligand of the RVG-modified nanocarriers introduces the conjugated targeted-delivery into the brain, and the cargoes are involved in disease theranosis. The peptide-modified nanocarriers have been applied to diagnose and treat various brain diseases, such as glioma, Alzheimer's disease, ischemic injury, protein misfolding diseases etc. Since the targeting delivery system has displayed good biocompatibility and desirable therapeutic effect, it will raise a potential application in treating brain diseases.