Targeting the central nervous system: In vivo experiments with peptide-derivatized nanoparticles loaded with Loperamide and Rhodamine-123

Targeting Neurological Aspects of Mucopolysaccharidosis Type II: Enzyme Replacement Therapy and Beyond

Mucopolysaccharidosis type II (MPS II) is a rare, pediatric, neurometabolic disorder due to the lack of activity of the lysosomal hydrolase iduronate 2-sulfatase (IDS), normally degrading heparan sulfate and dermatan sulfate within cell lysosomes. The deficit of activity is caused by mutations affecting the IDS gene, leading to the pathological accumulation of both glycosaminoglycans in the lysosomal compartment and in the extracellular matrix of most body districts. Although a continuum of clinical phenotypes is described, two main forms are commonly recognized-attenuated and severe-the latter being characterized by an earlier and faster clinical progression and by a progressive impairment of central nervous system (CNS) functions. However, attenuated forms have also been recently described as presenting some neurological involvement, although less deep, such as deficits of attention and hearing loss. The main treatment for the disease is represented by enzyme replacement therapy (ERT), applied in several countries since 2006, which, albeit showing partial efficacy on some peripheral organs, exhibited a very poor efficacy on bones and heart, and a total inefficacy on CNS impairment, due to the inability of the recombinant enzyme to cross the blood-brain barrier (BBB). Together with ERT, whose design enhancements, performed in the last few years, allowed a possible brain penetration of the drug through the BBB, other therapeutic approaches aimed at targeting CNS involvement in MPS II were proposed and evaluated in the last decades, such as intrathecal ERT, intracerebroventricular ERT, ex vivo gene therapy, or adeno-associated viral vector (AAV) gene therapy. The aim of this review is to summarize the main clinical aspects of MPS II in addition to current therapeutic options, with particular emphasis on the neurological ones and on the main CNS-targeted therapeutic approaches explored through the years.

Advances in Intrathecal Nanoparticle Delivery: Targeting the Blood-Cerebrospinal Fluid Barrier for Enhanced CNS Drug Delivery

The blood-cerebrospinal fluid barrier (BCSFB) tightly regulates molecular exchanges between the bloodstream and cerebrospinal fluid (CSF), creating challenges for effective central nervous system (CNS) drug delivery. This review assesses intrathecal (IT) nanoparticle (NP) delivery systems that aim to enhance drug delivery by circumventing the BCSFB, complementing approaches that target the blood-brain barrier (BBB). Active pharmaceutical ingredients (APIs) face hurdles like restricted CNS distribution and rapid clearance, which diminish the efficacy of IT therapies. NPs can be engineered to extend drug circulation times, improve CNS penetration, and facilitate sustained release. This review discusses key pharmacokinetic (PK) parameters essential for the effectiveness of these systems. NPs can quickly traverse the subarachnoid space and remain within the leptomeninges for extended periods, often exceeding three weeks. Some designs enable deeper brain parenchyma penetration. Approximately 80% of NPs in the CSF are cleared through the perivascular glymphatic pathway, with microglia-mediated transport significantly contributing to their paravascular clearance. This review synthesizes recent progress in IT-NP delivery across the BCSFB, highlighting critical findings, ongoing challenges, and the therapeutic potential of surface modifications and targeted delivery strategies.

Peptide Coated Polycaprolactone-Benzalkonium Chloride Nanocapsules for Targeted Drug Delivery to the Pancreatic β-Cell

Targeting of current therapies to treat or prevent loss of pancreatic islet β-cells in Type 1 Diabetes (T1D) may provide improved efficacy and reduce off target effects. Current efforts to target the β-cell are limited by a lack of β-cell specific targets and the inability to test multiple targeting moieties with the same delivery vehicle. Here we fabricate a novel tailorable polycaprolactone nanocapsule (NC) where multiple different targeting peptides can be interchangeably attached for β-cell specific delivery. Incorporation of a cationic surfactant in the NC shell allows for the attachment of Exendin-4 and an antibody for ectonucleoside triphosphate diphosphohydrolase 3 (ENTPD3) for β-cell specific targeting. The average NC size ranges from 250-300nm with a polydispersity index under 0.2. The NCs are non-toxic, stable in media culture, and can be lyophilized and reconstituted. NCs coated with targeting peptide were taken up by human cadaveric islet β-cells and human stem cell-derived β-like cells (sBC) in vitro with a high level of specificity. Furthermore, NCs successfully delivered both hydrophobic and hydrophilic cargo to human β-cells. Finally, Exendin-4 coated NCs were stable and targeted the mouse pancreatic islet β-cell in vivo . Our unique NC design allows for the interchangeable coating of targeting peptides for future screening of targets with improved cell specificity. The ability to target and deliver thera-peutics to human pancreatic β-cells opens avenues for improved therapies and treatments to help the delay onset, prevent, or reverse T1D.

Nose-to-Brain (N2B) Delivery: An Alternative Route for the Delivery of Biologics in the Management and Treatment of Central Nervous System Disorders

In recent years, there have been a growing number of small and large molecules that could be used to treat diseases of the central nervous system (CNS). Nose-to-brain delivery can be a potential option for the direct transport of molecules from the nasal cavity to different brain areas. This review aims to provide a compilation of current approaches regarding drug delivery to the CNS via the nose, with a focus on biologics. The review also includes a discussion on the key benefits of nasal delivery as a promising alternative route for drug administration and the involved pathways or mechanisms. This article reviews how the application of various auxiliary agents, such as permeation enhancers, mucolytics, in situ gelling/mucoadhesive agents, enzyme inhibitors, and polymeric and lipid-based systems, can promote the delivery of large molecules in the CNS. The article also includes a discussion on the current state of intranasal formulation development and summarizes the biologics currently in clinical trials. It was noted that significant progress has been made in this field, and these are currently being applied to successfully transport large molecules to the CNS via the nose. However, a deep mechanistic understanding of this route, along with the intimate knowledge of various excipients and their interactions with the drug and nasal physiology, is still necessary to bring us one step closer to developing effective formulations for nasal-brain drug delivery.

Molecular Trojan Horses for treating lysosomal storage diseases

Lysosomal storage diseases (LSDs) are caused by monogenic mutations in genes encoding for proteins related to the lysosomal function. Lysosome plays critical roles in molecule degradation and cell signaling through interplay with many other cell organelles, such as mitochondria, endoplasmic reticulum, and peroxisomes. Even though several strategies (i.e., protein replacement and gene therapy) have been attempted for LSDs with promising results, there are still some challenges when hard-to-treat tissues such as bone (i.e., cartilages, ligaments, meniscus, etc.), the central nervous system (mostly neurons), and the eye (i.e., cornea, retina) are affected. Consistently, searching for novel strategies to reach those tissues remains a priority. Molecular Trojan Horses have been well-recognized as a potential alternative in several pathological scenarios for drug delivery, including LSDs. Even though molecular Trojan Horses refer to genetically engineered proteins to overcome the blood-brain barrier, such strategy can be extended to strategies able to transport and deliver drugs to specific tissues or cells using cell-penetrating peptides, monoclonal antibodies, vesicles, extracellular vesicles, and patient-derived cells. Only some of those platforms have been attempted in LSDs. In this paper, we review the most recent efforts to develop molecular Trojan Horses and discuss how this strategy could be implemented to enhance the current efficacy of strategies such as protein replacement and gene therapy in the context of LSDs.

The translational potential of cholesterol-based therapies for neurological disease

Cholesterol is an important metabolite and membrane component and is enriched in the brain owing to its role in neuronal maturation and function. In the adult brain, cholesterol is produced locally, predominantly by astrocytes. When cholesterol has been used, recycled and catabolized, the derivatives are excreted across the blood-brain barrier. Abnormalities in any of these steps can lead to neurological dysfunction. Here, we examine how precise interactions between cholesterol production and its use and catabolism in neurons ensures cholesterol homeostasis to support brain function. As an example of a neurological disease associated with cholesterol dyshomeostasis, we summarize evidence from animal models of Huntington disease (HD), which demonstrate a marked reduction in cholesterol biosynthesis with clinically relevant consequences for synaptic activity and cognition. In addition, we examine the relationship between cholesterol loss in the brain and cognitive decline in ageing. We then present emerging therapeutic strategies to restore cholesterol homeostasis, focusing on evidence from HD mouse models.

Peptide-Based Agents for Cancer Treatment: Current Applications and Future Directions

Peptide-based strategies have received an enormous amount of attention because of their specificity and applicability. Their specificity and tumor-targeting ability are applied to diagnosis and treatment for cancer patients. In this review, we will summarize recent advancements and future perspectives on peptide-based strategies for cancer treatment. The literature search was conducted to identify relevant articles for peptide-based strategies for cancer treatment. It was performed using PubMed for articles in English until June 2023. Information on clinical trials was also obtained from ClinicalTrial.gov. Given that peptide-based strategies have several advantages such as targeted delivery to the diseased area, personalized designs, relatively small sizes, and simple production process, bioactive peptides having anti-cancer activities (anti-cancer peptides or ACPs) have been tested in pre-clinical settings and clinical trials. The capability of peptides for tumor targeting is essentially useful for peptide-drug conjugates (PDCs), diagnosis, and image-guided surgery. Immunomodulation with peptide vaccines has been extensively tested in clinical trials. Despite such advantages, FDA-approved peptide agents for solid cancer are still limited. This review will provide a detailed overview of current approaches, design strategies, routes of administration, and new technological advancements. We will highlight the success and limitations of peptide-based therapies for cancer treatment.

Chronic cholesterol administration to the brain supports complete and long-lasting cognitive and motor amelioration in Huntington's disease

Evidence that Huntington's disease (HD) is characterized by impaired cholesterol biosynthesis in the brain has led to strategies to increase its level in the brain of the rapidly progressing R6/2 mouse model, with a positive therapeutic outcome. Here we tested the long-term efficacy of chronic administration of cholesterol to the brain of the slowly progressing zQ175DN knock-in HD mice in preventing ("early treatment") or reversing ("late treatment") HD symptoms. To do this we used the most advanced formulation of cholesterol loaded brain-permeable nanoparticles (NPs), termed hybrid-g7-NPs-chol, which were injected intraperitoneally. We show that one cycle of treatment with hybrid-g7-NPs-chol, administered in the presymptomatic ("early treatment") or symptomatic ("late treatment") stages is sufficient to normalize cognitive defects up to 5 months, as well as to improve other behavioral and neuropathological parameters. A multiple cycle treatment combining both early and late treatments ("2 cycle treatment") lasting 6 months generates therapeutic effects for more than 11 months, without severe adverse reactions. Sustained cholesterol delivery to the brain of zQ175DN mice also reduces mutant Huntingtin aggregates in both the striatum and cortex and completely normalizes synaptic communication in the striatal medium spiny neurons compared to saline-treated HD mice. Furthermore, through a meta-analysis of published and current data, we demonstrated the power of hybrid-g7-NPs-chol and other strategies able to increase brain cholesterol biosynthesis, to reverse cognitive decline and counteract the formation of mutant Huntingtin aggregates. These results demonstrate that cholesterol delivery via brain-permeable NPs is a therapeutic option to sustainably reverse HD-related behavioral decline and neuropathological signs over time, highlighting the therapeutic potential of cholesterol-based strategies in HD patients. DATA AVAILABILITY: This study does not include data deposited in public repositories. Data are available on request to the corresponding authors.

Drug Delivery of Solid Lipid Nanoparticles (SLNs) and Nanostructured Lipid Carriers (NLCs) to Target Brain Tumors

Brain, predisposed to local and metastasized tumors, has always been the focus of oncological studies. Glioblastoma multiforme (GBM), the most common invasive primary tumor of the brain, is responsible for 4% of all cancer-related deaths worldwide. Despite novel technologies, the average survival rate is 2 years. Physiological barriers such as blood-brain barrier (BBB) prevent drug molecules penetration into brain. Most of the pharmaceuticals present in the market cannot infiltrate BBB to have their maximum efficacy and this in turn imposes a major challenge. This mini review discusses GBM and physiological and biological barriers for anticancer drug delivery, challenges for drug delivery across BBB, drug delivery strategies focusing on SLNs and NLCs and their medical applications in on-going clinical trials. Numerous nanomedicines with various characteristics have been introduced in the last decades to overcome the delivery challenge. Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) were introduced as oral drug delivery nanomedicines which can be encapsulated by both hydrophilic and lipophilic pharmaceutical compounds. Their biocompatibility, biodegradability, lower toxicity and side effects, enhanced bioavailability, solubility and permeability, prolonged half-life and stability and finally tissue-targeted drug delivery makes them unique among all.

Polymer-based drug delivery systems under investigation for enzyme replacement and other therapies of lysosomal storage disorders

Lysosomes play a central role in cellular homeostasis and alterations in this compartment associate with many diseases. The most studied example is that of lysosomal storage disorders (LSDs), a group of 60 + maladies due to genetic mutations affecting lysosomal components, mostly enzymes. This leads to aberrant intracellular storage of macromolecules, altering normal cell function and causing multiorgan syndromes, often fatal within the first years of life. Several treatment modalities are available for a dozen LSDs, mostly consisting of enzyme replacement therapy (ERT) strategies. Yet, poor biodistribution to main targets such as the central nervous system, musculoskeletal tissue, and others, as well as generation of blocking antibodies and adverse effects hinder effective LSD treatment. Drug delivery systems are being studied to surmount these obstacles, including polymeric constructs and nanoparticles that constitute the focus of this article. We provide an overview of the formulations being tested, the diseases they aim to treat, and the results observed from respective in vitro and in vivo studies. We also discuss the advantages and disadvantages of these strategies, the remaining gaps of knowledge regarding their performance, and important items to consider for their clinical translation. Overall, polymeric nanoconstructs hold considerable promise to advance treatment for LSDs.

PEG 400:Trehalose Coating Enhances Curcumin-Loaded PLGA Nanoparticle Internalization in Neuronal Cells

This work proposes a combination of polyethylene glycol 400 (PEG) and trehalose as a surface modification approach to enhance PLGA-based nanoparticles as a drug carrier for neurons. PEG improves nanoparticles' hydrophilicity, and trehalose enhances the nanoparticle's cellular internalization by inducing a more auspicious microenvironment based on inhibiting cell surface receptor denaturation. To optimize the nanoprecipitation process, a central composite design was performed; nanoparticles were adsorbed with PEG and trehalose. PLGA nanoparticles with diameters smaller than 200 nm were produced, and the coating process did not considerably increase their size. Nanoparticles entrapped curcumin, and their release profile was determined. The nanoparticles presented a curcumin entrapment efficiency of over 40%, and coated nanoparticles reached 60% of curcumin release in two weeks. MTT tests and curcumin fluorescence, with confocal imaging, were used to assess nanoparticle cytotoxicity and cell internalization in SH-SY5Y cells. Free curcumin 80 µM depleted the cell survival to 13% at 72 h. Contrariwise, PEG:Trehalose-coated curcumin-loaded and non-loaded nanoparticles preserved cell survival at 76% and 79% under the same conditions, respectively. Cells incubated with 100 µM curcumin or curcumin nanoparticles for 1 h exhibited 13.4% and 14.84% of curcumin's fluorescence, respectively. Moreover, cells exposed to 100 µM curcumin in PEG:Trehalose-coated nanoparticles for 1 h presented 28% fluorescence. In conclusion, PEG:Trehalose-adsorbed nanoparticles smaller than 200 nm exhibited suitable neural cytotoxicity and increased cell internalization proficiency.

Immunomodulation in age-related disorders and nanotechnology interventions

Recently, the aging population has increased exponentially around the globe bringing more challenges to improve quality of life in those populations while reducing the economic burden on healthcare systems. Aging is associated with changes in the immune system culminating in detrimental effects such as immune dysfunction, immunosenescence, and chronic inflammation. Age-related decline of immune functions is associated with various pathologies including cardiovascular, autoimmune, neurodegenerative, and infectious diseases to name a few. Conventional treatment addresses the onset of age-related diseases by early detection of risk factors, administration of vaccines as preventive care, immunomodulatory treatment, and other dietary supplements. However, these approaches often come with systemic side-effects, low bioavailability of therapeutic agents, and poor outcomes seen in the elderly. Recent innovations in nanotechnology have led to the development of novel biomaterials/nanomaterials, which explore targeted drug delivery and immunomodulatory interactions in vivo. Current nanotechnology-based immunomodulatory approaches that have the potential to be used as therapeutic interventions for some prominent age-related diseases are discussed here. Finally, we explore challenges and future aspects of nanotechnology in the treatments of age-related disorders to improve quality of life in the elderly. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Cardiovascular Disease Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Quantitative comparison of the protein corona of nanoparticles with different matrices

Nanoparticles (NPs) are paving the way for improved treatments for difficult to treat diseases diseases; however, much is unknown about their fate in the body. One important factor is the interaction between NPs and blood proteins leading to the formation known as the “protein corona” (PC). The PC, consisting of the Hard (HC) and Soft Corona (SC), varies greatly based on the NP composition, size, and surface properties. This highlights the need for specific studies to differentiate the PC formation for each individual NP system. This work focused on comparing the HC and SC of three NPs with different matrix compositions: a) polymeric NPs based on poly(lactic-co-glycolic) acid (PLGA), b) hybrid NPs consisting of PLGA and Cholesterol, and c) lipidic NPs made only of Cholesterol. NPs were formulated and characterized for their physico-chemical characteristics and composition, and then were incubated in human plasma. In-depth purification, identification, and statistical analysis were then performed to identify the HC and SC components. Finally, similar investigations demonstrated whether the presence of a targeting ligand on the NP surface would affect the PC makeup. These results highlighted the different PC fingerprints of these NPs, which will be critical to better understand the biological influences of the PC and improve future NP designs.

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NPs with different matrices were formulated: PLGA, Cholesterol, or mixed PLGA-Chol hybrids.

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The hard and soft corona of each formulation was quantified and compared.

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The PC seems to be more strongly affected by the polymer rather than the lipid in mixed NPs.

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The soft corona depends more on the hard corona composition than on the matrix.

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Surface modification with a targeting ligand did not influence PC composition.

Peptides as Pharmacological Carriers to the Brain: Promises, Shortcomings and Challenges

Central nervous system (CNS) diseases are among the most difficult to treat, mainly because the vast majority of the drugs fail to cross the blood-brain barrier (BBB) or to reach the brain at concentrations adequate to exert a pharmacological activity. The obstacle posed by the BBB has led to the in-depth study of strategies allowing the brain delivery of CNS-active drugs. Among the most promising strategies is the use of peptides addressed to the BBB. Peptides are versatile molecules that can be used to decorate nanoparticles or can be conjugated to drugs, with either a stable link or as pro-drugs. They have been used to deliver to the brain both small molecules and proteins, with applications in diverse therapeutic areas such as brain cancers, neurodegenerative diseases and imaging. Peptides can be generally classified as receptor-targeted, recognizing membrane proteins expressed by the BBB microvessels (e.g., Angiopep2, CDX, and iRGD), "cell-penetrating peptides" (CPPs; e.g. TAT_47-57, SynB1/3, and Penetratin), undergoing transcytosis through unspecific mechanisms, or those exploiting a mixed approach. The advantages of peptides have been extensively pointed out, but so far few studies have focused on the potential negative aspects. Indeed, despite having a generally good safety profile, some peptide conjugates may display toxicological characteristics distinct from those of the peptide itself, causing for instance antigenicity, cardiovascular alterations or hemolysis. Other shortcomings are the often brief lifetime in vivo, caused by the presence of peptidases, the vulnerability to endosomal/lysosomal degradation, and the frequently still insufficient attainable increase of brain drug levels, which remain below the therapeutically useful concentrations. The aim of this review is to analyze not only the successful and promising aspects of the use of peptides in brain targeting but also the problems posed by this strategy for drug delivery.

Formulation of intranasal surface engineered nanostructured lipid carriers of rotigotine: Full factorial design optimization, in vitro characterization, and pharmacokinetic evaluation

The objective of the present research was to develop, optimize, and evaluate rotigotine (RT)-loaded chitosan (CH) coated nanostructured lipid carriers (RT-CH-NLCs) for nose-to-brain delivery. The NLCs were prepared by homogenization and sonication technique as well as optimized by using three factors at three-level Box-Behnken design. The prepared NLCs were evaluated for particle size, zeta potential, entrapment efficiency, drug release, and ex vivo permeation. The pharmacokinetic study was conducted on albino Wistar rats to evaluate the bioavailability and neuropharmacokinetic parameters after intranasal administration of the optimized formulation (RT-CH-NLCs-OPT). The optimized formulation showed the particle size (170.48 ± 8.37 nm), PDI (0.19 ± 0.03), zeta potential (+ 26.73 mV), and entrapment efficiency (82.37 ± 2.48 %). In vitro drug release study displayed a sustained drug release pattern from RT-CH-NLCs-OPT (86.73±8.58 % in 24 h) in comparison to RT-Dis (98.61±7.24 % in 16 h). The permeability coefficient (PC) was found to be 11.39 ± 1.08×10^-4 cm.h^-1 and 2.34 folds higher than RT-Dis (4.85±1.53×10^-4 cm.h^-1). The relative bioavailability of RT from RT-CH-NLCs-OPT was 3.2-fold greater as compared to RT-Dis. The absolute bioavailability of RT after intranasal administration of RT-CH-NLCs-OPT was 2.1-fold higher than RT-CH-NLCs-OPT administered intravenously. The brain targeting and targeting potential was displayed by DTE (422.03 %) and DTP (76.03 %) after intranasal administration of RT-CH-NLCs-OPT as compared to RT-Dis (DTE 173.91 % and DTP 59.97 %). Furthermore, confocal laser scanning microscopy results confirmed better brain targeting for RT-CH-NLCs-OPT as compared to RT-Dis. From these findings, it could be concluded that RT-CH-NLCs could serve as a promising strategy for targeting RT through the intranasal route.

Chitosan - Polyphosphate nanoparticles for a targeted drug release at the absorption membrane

The aim of this study was to develop nanoparticles (NPs) providing a targeted drug release directly on the epithelium of the intestinal mucosa. NPs were prepared via ionic gelation between cationic chitosan (Cs) and anionic polyphosphate (PP). The resulting NPs were characterized by their size, polydispersity index (PDI) and zeta potential. Isolated and cell-associated intestinal alkaline phosphatase (IAP) was employed to trigger polyphosphate cleavage in Cs-PP NPs which was quantified via malachite green assay. In parallel, the shift in zeta potential was determined. In-vitro drug release studies were performed in Franz diffusion cells with Cs-PP NPs containing rhodamine 123 as model active ingredient. Furthermore, cytotoxicity of Cs-PP NPs was assessed via resazurin assay on Caco-2 cells as well as via hemolysis assay on red blood cells. Cs-PP NPs exhibited an average size of 144.17 ± 10.95 nm and zeta potential of -12.6 ± 0.50 mV. The encapsulation efficiency of rhodamine 123 by Cs-PP NPs was 86.8%. After incubation with isolated IAP for 3 h the polyphosphate of Cs-PP NPs was cleaved to monophosphate and zeta potential raised up to -2.3 ± 0.30 mV. Cs-PP NPs showed a non-toxic profile. Within 3 h, 62.0 ± 10.8% and 14.1 ± 2.2% of total rhodamine 123 was released from Cs-PP NPs upon incubation with isolated as well as porcine intestine derived intestinal alkaline phosphatase (IAP), respectively. According to these results, Cs-PP NPs are promising drug delivery systems to enable a drug targeted release at the absorption membrane.

Glioblastoma Multiforme Selective Nanomedicines for Improved Anti-Cancer Treatments

Glioblastoma Multiforme (GBM) is a devastating disease with a low survival rate and few efficacious treatment options. The fast growth, late diagnostics, and off-target toxicity of currently used drugs represent major barriers that need to be overcome to provide a viable cure. Nanomedicines (NMeds) offer a way to overcome these pitfalls by protecting and loading drugs, increasing blood half-life, and being targetable with specific ligands on their surface. In this study, the FDA-approved polymer poly (lactic-co-glycolic) acid was used to optimise NMeds that were surface modified with a series of potential GBM-specific ligands. The NMeds were fully characterised for their physical and chemical properties, and then in vitro testing was performed to evaluate cell uptake and GBM cell specificity. While all targeted NMeds showed improved uptake, only those decorated with the-cell surface vimentin antibody M08 showed specificity for GBM over healthy cells. Finally, the most promising targeted NMed candidate was loaded with the well-known chemotherapeutic, paclitaxel, to confirm targeting and therapeutic effects in C6 GBM cells. These results demonstrate the importance of using well-optimised NMeds targeted with novel ligands to advance delivery and pharmaceutical effects against diseased cells while minimising the risk for nearby healthy cells.

Nanoparticle delivery systems for substance use disorder

Innovative breakthroughs in nanotechnology are having a substantial impact in healthcare, especially for brain diseases where effective therapeutic delivery systems are desperately needed. Nanoparticle delivery systems offer an unmatched ability of not only conveying a diverse array of diagnostic and therapeutic agents across complex biological barriers, but also possess the ability to transport payloads to targeted cell types over a sustained period. In substance use disorder (SUD), many therapeutic targets have been identified in preclinical studies, yet few of these findings have been translated to effective clinical treatments. The lack of success is, in part, due to the significant challenge of delivering novel therapies to the brain and specific brain cells. In this review, we evaluate the potential approaches and limitations of nanotherapeutic brain delivery systems. We also highlight the examples of promising strategies and future directions of nanocarrier-based treatments for SUD.

Targeting nucleic acid-based therapeutics to tumors: Challenges and strategies for polyplexes

The current medical reality of cancer gene therapy is reflected by more than ten approved products on the global market, including oncolytic and other viral vectors and CAR T-cells as ex vivo gene-modified cell therapeutics. The development of synthetic antitumoral nucleic acid therapeutics has been proceeding at a lower but steady pace, fueled by a plethora of alternative nucleic acid platforms (from various antisense oligonucleotides, siRNA, microRNA, lncRNA, sgRNA, to larger mRNA and DNA) and several classes of physical and chemical delivery technologies. This review summarizes the challenges and strategies for tumor-targeted nucleic acid delivery. Focusing primarily on polyplexes (polycation complexes) as nanocarriers, delivery options across multiple barriers into tumor cells are illustrated.

Tunneling Nanotubes: A New Target for Nanomedicine?

Tunneling nanotubes (TNTs), discovered in 2004, are thin, long protrusions between cells utilized for intercellular transfer and communication. These newly discovered structures have been demonstrated to play a crucial role in homeostasis, but also in the spreading of diseases, infections, and metastases. Gaining much interest in the medical research field, TNTs have been shown to transport nanomedicines (NMeds) between cells. NMeds have been studied thanks to their advantageous features in terms of reduced toxicity of drugs, enhanced solubility, protection of the payload, prolonged release, and more interestingly, cell-targeted delivery. Nevertheless, their transfer between cells via TNTs makes their true fate unknown. If better understood, TNTs could help control NMed delivery. In fact, TNTs can represent the possibility both to improve the biodistribution of NMeds throughout a diseased tissue by increasing their formation, or to minimize their formation to block the transfer of dangerous material. To date, few studies have investigated the interaction between NMeds and TNTs. In this work, we will explain what TNTs are and how they form and then review what has been published regarding their potential use in nanomedicine research. We will highlight possible future approaches to better exploit TNT intercellular communication in the field of nanomedicine.

Analysis and comparison of metal-doped on Graphene-Genistein using QM/MM calculations

Genistein (5,7,4′-trihydroxyisoflavone) is an isoflavone abundantly found in soy and other legumes and acts as a selective estrogen receptor modulator (SERM). When testing for similar abilities among other flavonoids, it has been found to be a strong topoisomerase inhibitor. Similar to some high-dose chemotherapy drugs, it was strongly toxic to normal cells. In this study, the adsorption of genistein on the surface of exclusive graphene and Ni, Ti, Cr, and Se-doped graphene was theoretically evaluated by means of density functional theory calculation. Initially, we varied the position of genistein from the surface of pristine and decorated graphene by changing the distances between (1-5 Å) and gained the Ead and Egap for each situation. Our calculation indicated that adsorption energies (Ead) of pristine genistein to graphene with Ni decorated graphene, Ti-     decorated graphene, and Cr-decorated graphene and Se-decorated graphene are: 954.984, 318.168, 797.480, 946.725, 958.154 kcal/mole, respectively, and the calculated values of adsorption energy in the equilibrium distance (de=3.918OA.) of genistein to Ni-decorated graphene reveal that apparently genistein- Ni-decorated graphene as the most energetically favorable position was correctly selected in comparison with other atom     -decorated graphene. In consequence, we explain the density of states (Doss) and frontier molecular orbitals HOMO and LUMO for Ni-decorated graphene and complexes with genistein; therefore, data confirmed that a positive charge of Ni-decorated graphene for nucleophile molecules could be achieved. 

Manickam D. Targeting the blood-brain barrier for the delivery of stroke therapies

A variety of neuroprotectants have shown promise in treating ischemic stroke, yet their delivery to the brain remains a challenge. The endothelial cells lining the blood-brain barrier (BBB) are emerging as a dynamic factor in the response to neurological injury and disease, and the endothelial-neuronal matrix coupling is fundamentally neuroprotective. In this review, we discuss approaches that target the endothelium for drug delivery both across the BBB and to the BBB as a viable strategy to facilitate neuroprotective effects, using the example of brain-derived neurotrophic factor (BDNF). We highlight the advances in cell-derived extracellular vesicles (EVs) used for CNS targeting and drug delivery. We also discuss the potential of engineered EVs as a potent strategy to deliver BDNF or other drug candidates to the ischemic brain, particularly when coupled with internal components like mitochondria that may increase cellular energetics in injured endothelial cells.

Insights into kinetics, release, and behavioral effects of brain-targeted hybrid nanoparticles for cholesterol delivery in Huntington's disease

Supplementing brain cholesterol is emerging as a potential treatment for Huntington's disease (HD), a genetic neurodegenerative disorder characterized, among other abnormalities, by inefficient brain cholesterol biosynthesis. However, delivering cholesterol to the brain is challenging due to the blood-brain barrier (BBB), which prevents it from reaching the striatum, especially, with therapeutically relevant doses. Here we describe the distribution, kinetics, release, and safety of novel hybrid polymeric nanoparticles made of PLGA and cholesterol which were modified with an heptapeptide (g7) for BBB transit (hybrid-g7-NPs-chol). We show that these NPs rapidly reach the brain and target neural cells. Moreover, deuterium-labeled cholesterol from hybrid-g7-NPs-chol is released in a controlled manner within the brain and accumulates over time, while being rapidly removed from peripheral tissues and plasma. We confirm that systemic and repeated injections of the new hybrid-g7-NPs-chol enhanced endogenous cholesterol biosynthesis, prevented cognitive decline, and ameliorated motor defects in HD animals, without any inflammatory reaction. In summary, this study provides insights about the benefits and safety of cholesterol delivery through advanced brain-permeable nanoparticles for HD treatment.

Central nervous system delivery of molecules across the blood-brain barrier

Therapies targeting neurological conditions such as Alzheimer's or Parkinson's diseases are hampered by the presence of the blood-brain barrier (BBB). During the last decades, several approaches have been developed to overcome the BBB, such as the use of nanoparticles (NPs) based on biomaterials, or alternative methods to open the BBB. In this review, we briefly highlight these strategies and the most recent advances in this field. Limitations and advantages of each approach are discussed. Combination of several methods such as functionalized NPs targeting the receptor-mediated transcytosis system with the use of magnetic resonance imaging-guided focused ultrasound (FUS) might be a promising strategy to develop theranostic tools as well as to safely deliver therapeutic molecules, such as drugs, neurotrophic factors or antibodies within the brain parenchyma.

From adsorption to covalent bonding: Apolipoprotein E functionalization of polymeric nanoparticles for drug delivery across the blood-brain barrier

The blood-brain barrier (BBB) is composed of brain endothelial cells, pericytes, and astrocytes, which build a tight cellular barrier. Therapeutic (macro)molecules are not able to transit through the BBB in their free form. This limitation is bypassed by apolipoprotein E (ApoE)-functionalized polymeric nanoparticles (NPs) that are able to transport drugs (e.g. dalargin, loperamide, doxorubicin, nerve growth factor) across the BBB via low density lipoprotein (LDL) receptor mediated transcytosis. Coating with polysorbate 80 or poloxamer 188 facilitates ApoE adsorption onto polymeric NPs enabling recognition by LDL receptors of brain endothelial cells. This effect is even enhanced when NPs are directly coated with ApoE without surfactant anchor. Similarly, covalent coupling of ApoE to NPs that bear reactive groups on their surface leads to significantly improved brain uptake while avoiding the use of surfactants. Several in vitro BBB models using brain endothelial cells or co-cultures with astrocytes/pericytes/glioma cells are described which provide first insights regarding the ability of a drug delivery system to cross this barrier. In vivo models are employed to simulate central nervous system-relevant diseases such as Alzheimer's or Parkinson's disease and cerebral cancer.

A comparison of acyl-moieties for noncovalent functionalization of PLGA and PEG-PLGA nanoparticles with a cell-penetrating peptide

Noncovalent functionalization with acylated cell-penetrating peptides achieves an efficient cellular uptake of PLGA and PEG-PLGA nanoparticles.

Challenges in Biomaterial-Based Drug Delivery Approach for the Treatment of Neurodegenerative Diseases: Opportunities for Extracellular Vesicles

Biomaterials have been the subject of numerous studies to pursue potential therapeutic interventions for a wide variety of disorders and diseases. The physical and chemical properties of various materials have been explored to develop natural, synthetic, or semi-synthetic materials with distinct advantages for use as drug delivery systems for the central nervous system (CNS) and non-CNS diseases. In this review, an overview of popular biomaterials as drug delivery systems for neurogenerative diseases is provided, balancing the potential and challenges associated with the CNS drug delivery. As an effective drug delivery system, desired properties of biomaterials are discussed, addressing the persistent challenges such as targeted drug delivery, stimuli responsiveness, and controlled drug release in vivo. Finally, we discuss the prospects and limitations of incorporating extracellular vesicles (EVs) as a drug delivery system and their use for biocompatible, stable, and targeted delivery with limited immunogenicity, as well as their ability to be delivered via a non-invasive approach for the treatment of neurodegenerative diseases.

Drug-Loaded Lipid-Core Micelles in Mucoadhesive Films as a Novel Dosage Form for Buccal Administration of Poorly Water-Soluble and Biological Drugs

The aim of the study was to develop a novel buccal dosage form to transport rhodamine 123 and human insulin as models for poorly water-soluble and biological drugs, using lipid-core micelles (LCMs)-loaded mucoadhesive films. LCMs were synthesized by a low-energy hot emulsification process, yielding spherically shaped, small-sized, monodispersed and negatively charged carriers with high entrapment efficiency. In vitro release studies demonstrated a higher release of insulin rather than rhodamine from LCMs in simulated physiological conditions, due to an initial burst release effect; however, both release profiles are mainly explained by a diffusion mechanism. Furthermore, LCMs-loaded mucoadhesive films were manufactured and preserved with similar mechanical properties and optimal mucoadhesive behavior compared to nonloaded films. Ex vivo permeation experiments using excised porcine buccal epithelium reveal that both rhodamine and insulin-loaded LCM films elicited a significantly enhanced permeation effect compared to LCMs in suspension and free drugs in solution as controls. Hence, LCMs-loaded mucoadhesive films are suitable as buccal dosage form for the transport and delivery of rhodamine 123 and insulin, as models for poorly water-soluble and biological drugs, respectively.

Biocompatibility of Biomaterials for Nanoencapsulation: Current Approaches

Nanoencapsulation is an approach to circumvent shortcomings such as reduced bioavailability, undesirable side effects, frequent dosing and unpleasant organoleptic properties of conventional drug delivery systems. The process of nanoencapsulation involves the use of biomaterials such as surfactants and/or polymers, often in combination with charge inducers and/or ligands for targeting. The biomaterials selected for nanoencapsulation processes must be as biocompatible as possible. The type(s) of biomaterials used for different nanoencapsulation approaches are highlighted and their use and applicability with regard to haemo- and, histocompatibility, cytotoxicity, genotoxicity and carcinogenesis are discussed.

Nanotechnology in Chronic Pain Relief

Increasing awareness of chronic pain due to both injury and disease have encouraged drug companies and pharmaceutical researchers alike to design and fabricate better, more specific drugs for pain relief. However, overuse of clinically available pain medication has caused a multitude of negative repercussions, including drug tolerance, addiction, and other severe side effects, which can prolong suffering and reduce pain mediation. Applications of nanotechnology to the field of drug delivery has sought to enhance the treatment efficiency, lower side effects, and mitigate the formation of tolerance. The use of nanomaterials has several advantages for chronic pain relief, such as controlled release, prolonged circulation time, and limited side effects. With the development of nanotechnology, strategies for chronic pain relief have also bourgeoned utilizing a variety of nanomaterials and targeting surface modifications. In addition to using these materials as carriers for drug delivery, nanomaterials can also be designed to have inherent properties that relieve chronic pain. This minireview covers the current status of designed nanomaterials for pain relief and provides a discussion of future considerations for nanotechnology designed for relieving chronic pain.

PLGA-PEG-ANG-2 Nanoparticles for Blood-Brain Barrier Crossing: Proof-of-Concept Study

The treatment of diseases that affect the central nervous system (CNS) represents a great research challenge due to the restriction imposed by the blood-brain barrier (BBB) to allow the passage of drugs into the brain. However, the use of modified nanomedicines engineered with different ligands that can be recognized by receptors expressed in the BBB offers a favorable alternative for this purpose. In this work, a BBB-penetrating peptide, angiopep-2 (Ang-2), was conjugated to poly(lactic-co-glycolic acid) (PLGA)-based nanoparticles through pre- and post-formulation strategies. Then, their ability to cross the BBB was qualitatively assessed on an animal model. Proof-of-concept studies with fluorescent and confocal microscopy studies highlighted that the brain-targeted PLGA nanoparticles were able to cross the BBB and accumulated in neuronal cells, thus showing a promising brain drug delivery system.

Multifunctional Polymeric Nanoplatforms for Brain Diseases Diagnosis, Therapy and Theranostics

The blood-brain barrier (BBB) acts as a barrier to prevent the central nervous system (CNS) from damage by substances that originate from the blood circulation. The BBB limits drug penetration into the brain and is one of the major clinical obstacles to the treatment of CNS diseases. Nanotechnology-based delivery systems have been tested for overcoming this barrier and releasing related drugs into the brain matrix. In this review, nanoparticles (NPs) from simple to developed delivery systems are discussed for the delivery of a drug to the brain. This review particularly focuses on polymeric nanomaterials that have been used for CNS treatment. Polymeric NPs such as polylactide (PLA), poly (D, L-lactide-co-glycolide) (PLGA), poly (ε-caprolactone) (PCL), poly (alkyl cyanoacrylate) (PACA), human serum albumin (HSA), gelatin, and chitosan are discussed in detail.

Triazole Modified Tetraiodothyroacetic Acid Conjugated to Polyethylene Glycol: High Affinity Thyrointegrin αvβ3 Antagonist with Potent Anticancer Activities in Glioblastoma Multiforme

Discovery of bioactive molecules that target integrins has implicated their role in tumor angiogenesis, tumor growth, metastasis, and other pathological angiogenesis processes. Integrins are members of a family of cell surface receptors that play a critical role in the angiogenesis process. Tetraiodothyroacetic acid (tetrac), a deaminated derivative of l-thyroxine (T4), is a "thyrointegrin" antagonist that blocks the actions of l-triiodothyronine (T3) and T4 with an interaction site that is located at or near the RGD recognition site identified on integrin α_vβ₃'s binding pocket (thyrointegrin α_vβ₃ receptors). We have enhanced the biological activity of a tetrac-based inhibitor via significantly improving its α_vβ₃ receptor binding affinity by introducing a triazole ring on the outer ring of tetrac and covalently conjugating to polymer to increase the product's hydrophilicity via PEGylation. The product, P-bi-TAT, was restricted from nuclear translocation and demonstrated high blood brain barrier permeability and retention in contrast to the non-PEG conjugated derivative. Results of biological activity indicated that this macromolecule new chemical entity P-bi-TAT has greater than 400-fold potent integrin α_vβ₃ affinity versus the parent compound tetrac and has potent anticancer/anti-angiogenesis efficacy against glioblastoma multiforme (GBM). P-bi-TAT administered subcutaneously once daily for 21 days at 1-10 mg/kg mouse body weight resulted in a dose-dependent suppression of GBM tumor growth and viability as monitored with IVIS imaging (P < 0.001). GBM tumors had >95% volume loss and maximal loss of GBM cell viability during the 21 days ON-treatment experiment as well as in the 21 days ON followed by 21 days OFF-treatment experiment (P < 0.001). In conclusion, P-bi-TAT is a promising lead clinical candidate effective in the treatment of human GBM.

In vivo biodistribution of venlafaxine-PLGA nanoparticles for brain delivery: plain vs. functionalized nanoparticles

Background: Actually, no drugs provide therapeutic benefit to approximately one-third of depressed patients. Depression is predicted to become the first global disease by 2030. So, new therapeutic interventions are imperative.Research design and methods: Venlafaxine-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) were surface functionalized with two ligands against transferrin receptor to enhance access to brain. An in vitro blood-brain barrier model using hCMEC/D3 cell line was developed to evaluate permeability. In vivo biodistribution studies were performed using C57/bl6 mice. Particles were administered intranasal and main organs were analyzed.Results: Particles were obtained as a lyophilized powder easily to re-suspend. Internalization and permeability studies showed the following cell association sequence: TfRp-NPs>Tf-NPs>plain NPs. Permeability studies also showed that encapsulated VLF was not affected by P-gP pump efflux increasing its concentration in the basolateral side after 24 h. In vivo studies showed that 25% of plain NPs reach the brain after 30 min of one intranasal administration while less than 5% of functionalized NPs get the target.Conclusions: Plain NPs showed the highest ability to reach the brain vs. functionalized NPs after 30 min by intranasal administration. We suggest plain NPs probably travel via direct nose-to-brian route whereas functionalized NPs reach the brain by receptor-mediated endocytosis.

Nanoparticles as carriers for drug delivery of macromolecules across the blood-brain barrier

Introduction: Current therapies of neurodegenerative or neurometabolic diseases are, to a large extent, hampered by the inability of drugs to cross the blood-brain barrier (BBB). This very tight barrier severely restricts the entrance of molecules from the blood into the brain, especially macromolecular substances (i.e. neurotrophic factors, enzymes, proteins, as well as genetic materials). Due to their size, physicochemical properties, and instability, the delivery of these materials is particularly difficult.Areas covered: Recent research showed that biocompatible and biodegradable nanoparticles possessing tailored surface properties can enable a delivery of drugs and specifically of macromolecules across the blood-brain barrier by using carrier systems of the brain capillary endothelium (Trojan Horse strategy). In the present review, the state-of-art of nanoparticle-mediated drug delivery of different macromolecular substances into the brain following intravenous injection is summarized, and different nanomedicines that are used to enable the transport of neurotrophic factors and enzymes across the blood-brain barrier into the CNS are critically analyzed.Expert opinion: Brain delivery of macromolecules by an intravenous application using nanomedicines is now a growing area of interest which could be really translated into clinical application if dedicated effort will be given to industrial scale-up production.

3,3'-Diindolylmethane nanoencapsulation improves its antinociceptive action: Physicochemical and behavioral studies

This study aimed to characterize the physicochemical properties of 3,3'-diindolylmethane (DIM)-loaded nanocapsules (NCs) as well as the antinociceptive effect using distinct animal models (hot plate test, formalin-induced nociception and complete Freud's adjuvant induced paw inflammation). The DIM-loaded NCs (composed by primula oil and ethylcellulose) were characterized using differential scanning calorimetry, thermogravimetric analysis, Fourier-transformed infrared spectroscopy, X-ray diffractometry and scanning electron microscopy. The physicochemical characterization demonstrated that DIM could be molecularly dispersed into the NCs, whose size was nanometric with a spherical shape. An improvement in DIM thermal stability was achieved by its encapsulation and there were no interactions among the formula components. For the nociceptive evaluation, male adult Swiss mice were pretreated with the NCs or free DIM by the intragastric route at the dose of 10 mg/Kg (time-response curve), 5 or 2.5 mg/Kg (dose-response curve). The behavioral tests were performed over an experimental period of 0.5-8 h. Both free and nanoencapsulated DIM reduced the mechanical hypernociception induced by CFA, mitigated nociceptive behavior of formalin-induced neurogenic and inflammatory pain and increased paw withdrawal latency assessed by the hot-plate test. Importantly, the DIM nanoencapsulation promoted a rapid initiation and prolonged the bioactive antinociceptive action (up to 8 h) as well as reduced the effective dose in comparison to its free form. In summary, this study reported that the NCs had adequate nanometric size, increased DIM stability and its antinociceptive action in different animal models, suggesting that the formulation may be a possible therapeutic alternative to the management of pain and inflammatory-related pathologies.

Emerging role of nanomedicine in the treatment of neuropathic pain

Neuropathic pain (NeP) is a complex chronic pain condition associated with nerve injury. Approximately, 7-10% of the general population across the globe is suffering from this traumatic condition, but the existing treatment strategies are inadequate to deliver pain relief and are associated with severe adverse effects. To overcome these limitations, lot of research is focussed on developing new molecules with high potency and fewer side effects, novel cell and gene-based therapies and modification of the previously approved drugs by different formulation aspects. Nanomedicine has attracted a lot of attention in the treatment of many diverse pathological conditions because of their unique physiochemical and biological properties. In this manuscript, we highlighted the emerging role of nanomedicine in different therapies (drug, cell and gene), also we emphasised on the challenges associated with nanomedicine such as development of well-characterised nanoformulation, scaling of batches with reproducible results and toxicity along with this we discussed about the future of nanomedicine in the treatment of neuropathic pain.

Targeting Brain Disease in MPSII: Preclinical Evaluation of IDS-Loaded PLGA Nanoparticles

Mucopolysaccharidosis type II (MPSII) is a lysosomal storage disorder due to the deficit of the enzyme iduronate 2-sulfatase (IDS), which leads to the accumulation of glycosaminoglycans in most organ-systems, including the brain, and resulting in neurological involvement in about two-thirds of the patients. The main treatment is represented by a weekly infusion of the functional enzyme, which cannot cross the blood-brain barrier and reach the central nervous system. In this study, a tailored nanomedicine approach based on brain-targeted polymeric nanoparticles (g7-NPs), loaded with the therapeutic enzyme, was exploited. Fibroblasts from MPSII patients were treated for 7 days with NPs loaded with the IDS enzyme; an induced IDS activity like the one detected in healthy cells was measured, together with a reduction of GAG content to non-pathological levels. An in vivo short-term study in MPSII mice was performed by weekly administration of g7-NPs-IDS. Biochemical, histological, and immunohistochemical evaluations of liver and brain were performed. The 6-weeks treatment produced a significant reduction of GAG deposits in liver and brain tissues, as well as a reduction of some neurological and inflammatory markers (i.e., LAMP2, CD68, GFAP), highlighting a general improvement of the brain pathology. The g7-NPs-IDS approach allowed a brain-targeted enzyme replacement therapy. Based on these positive results, the future aim will be to optimize NP formulation further to gain a higher efficacy of the proposed approach.

Development of biodegradable polyesters based on a hydroxylated coumarin initiator towards fluorescent visible paclitaxel-loaded microspheres

In this work, we developed a facile end-functionalization method using hydroxylated coumarin to initiate the ring-opening polymerization of cyclic esters to synthesize a series of fluorescent biodegradable aliphatic polyesters with tailorable properties. The resulting fluorescent functionalized poly(l-lactide) (PLLA-COU), poly(ε-caprolactone) (PCL-COU) poly(δ-valerolactone) (PVL-COU) and poly(trimethylene carbonate) (PTMC-COU) were investigated to evaluate the dependence of fluorescence on the chemical structure and molecular weight of the materials. The differences in the electron withdrawing ability and the density of ester groups are responsible for the changes in the fluorescence quantum yield. Then, two representative biodegradable materials, namely, PLLA-COU and PCL-COU, were used to prepare fluorescent paclitaxel-loaded microspheres. During in vitro drug release, the release rate of the PCL-COU microspheres is dramatically faster than that of the PLLA-COU microspheres due to the difference in the material nature and their surface morphologies, possibly achieving a tunable degradation and release rate for the drug carriers. Fluorescent functionalized polyester microspheres can retain their fluorescence properties and emit bright blue light for fluorescence tracing during the degradation process. Biological evaluations showed that both fluorescent polyesters are devoid of any significant toxicity and have good biocompatibility. The results demonstrated that the obtained fluorescent polyesters are promising for use in traceable and controlled drug delivery with tunable drug release.

Nanomedicine in Alzheimer's disease: Amyloid beta targeting strategy

The treatment of Alzheimer's disease (AD) is up to today one of the most unsuccessful examples of biomedical science. Despite the high number of literature evidences detailing the multifactorial and complex etiopathology of AD, no cure is yet present on the market and the available treatments are only symptomatic. The reasons could be ascribed on two main factors: (i) lack of ability of the majority of drugs to cross the blood-brain barrier (BBB), thus excluding the brain for any successful therapy; (ii) lack of selectivity and specificity of drugs, decreasing the efficacy of even potent anti-AD drugs. The exploitation of specifically engineered nanomedicines planned to cross the BBB and to target the most "hot" site of action (i.e., β-amyloid) is one of the most interesting innovations in drug delivery and could reasonably represent an promising choice for possible treatments and even early-diagnosis of AD. In this chapter, we therefore outline the most talented approaches in AD treatment with a specific focus on the main advantages/drawbacks and future possible translation to clinic application.

Biocompatible Polymer Nanoparticles for Drug Delivery Applications in Cancer and Neurodegenerative Disorder Therapies

Polymer nanoparticles (NPs) represent one of the most innovative non-invasive approaches for drug delivery applications. NPs main objective is to convey the therapeutic molecule be they drugs, proteins, or nucleic acids directly into the target organ or tissue. Many polymers are used for the synthesis of NPs and among the currently most employed materials several biocompatible synthetic polymers, namely polylactic acid (PLA), poly lactic-co-glycolic acid (PLGA), and polyethylene glycol (PEG), can be cited. These molecules are made of simple monomers which are naturally present in the body and therefore easily excreted without being toxic. The present review addresses the different approaches that are most commonly adopted to synthetize biocompatible NPs to date, as well as the experimental strategies designed to load them with therapeutic agents. In fact, drugs may be internalized in the NPs or physically dispersed therein. In this paper the various types of biodegradable polymer NPs will be discussed with emphasis on their applications in drug delivery. Close attention will be devoted to the treatment of cancer, where both active and passive targeting is used to enhance efficacy and reduce systemic toxicity, and to diseases affecting the central nervous system, inasmuch as NPs can be modified to target specific cells or cross membrane barriers.

Biodegradable polyanhydride-based nanomedicines for blood to brain drug delivery

An urgent need to deliver therapeutics across the blood-brain barrier (BBB) underlies a paucity of effective therapies currently available for treatment of degenerative, infectious, traumatic, chemical, and metabolic disorders of the nervous system. With an eye toward achieving this goal, an in vitro BBB model was employed to simulate biodegradable polyanhydride nanoparticle-based drug delivery to the brain. Using a combination of confocal microscopy, flow cytometry, and high performance liquid chromatography, we examined the potential of polyanhydride nanoparticles containing the anti-oxidant, mito-apocynin, to be internalized and then transferred from monocytes to human brain microvascular endothelial cells. The efficacy of this nanoparticle-based delivery platform was demonstrated by neuronal protection against oxidative stress. Taken together, this polyanhydride nanoparticle-based delivery system holds promise for enhancing neuroprotection by facilitating drug transport across the BBB. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2881-2890, 2018.