CREKA peptide-conjugated dendrimer nanoparticles for glioblastoma multiforme delivery

Nanocarriers for the treatment of glioblastoma multiforme: A succinct review of conventional and repositioned drugs in the last decade

Glioblastoma multiforme is a very combative and threatening type of cancer. The standard course of treatment involves excising the tumor surgically, then administering chemotherapy and radiation therapy. Because of the presence of the blood-brain barrier and the unique characteristics of the tumor microenvironment, chemotherapy is extremely difficult and has a high incidence of relapse. With their capacity to precisely target and transport therapeutic medications to the tumor while overcoming the challenges provided by invasive and infiltrative gliomas, nanocarriers offer a potentially beneficial treatment option for gliomas. Drug repositioning or, in other words, finding novel therapeutic uses for medications that have received approval for previous uses has also recently emerged to provide alternative treatments for many diseases, with glioblastoma being among them. In this article, our goal is to shed light on the pathogenesis of glioma and summarize the proposed treatment approaches in the last decade, highlighting how combining repositioned drugs and nanocarriers technology can reduce drug resistance and improve therapeutic efficacy in primary glioma.

Dual electro-/pH-responsive nanoparticle/hydrogel system for controlled delivery of anticancer peptide

An electro-chemo-responsive carrier has been engineered for the controlled release of a highly hydrophilic anticancer peptide, CR(NMe)EKA (Cys-Arg- N-methyl-Glu-Lys-Ala). Remotely controlled on demand release of CR(NMe)EKA, loaded in electro-responsive poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles, has been achieved by applying electrical stimuli consisting of constant positive (+0.50 V) or negative voltages (-0.50 V) at pre-defined time intervals. In addition, after loading CR(NMe)EKA/PEDOT nanoparticles into an injectable pH responsive hydrogel formed by phenylboronic acid grafted to chitosan (PBA-CS), the efficiency of the controlled peptide release has increased approximately by a factor of 2.6. The hydration ratio of such hydrogel is significantly lower in acidic environments than in neutral and basic media, which has been attributed to the dissociation of the boronate bonds between polymer chains. Hence, the electro-controlled peptide release from PBA-CS/CR(NMe)EKA/PEDOT hydrogels, in the acidic environment of tumors, combines the effects of the oxidation and reduction of PEDOT chains on the interactions with the peptide and the carrier, with the peptide concentration gradient at the interface between the collapsed hydrogel and the release medium. Furthermore, the peptide released by electro-stimulation preserved its bioactivity assessed by promoting human prostate cancer cells death. Overall, this work is a promising attempt to develop a carrier platform for small hydrophilic anticancer peptides, which delivery rationale is synergistically regulated by the electrical and pH responsiveness of the carrier.

New insights into targeted therapy of glioblastoma using smart nanoparticles

In recent times, the intersection of nanotechnology and biomedical research has given rise to nanobiomedicine, a captivating realm that holds immense promise for revolutionizing diagnostic and therapeutic approaches in the field of cancer. This innovative fusion of biology, medicine, and nanotechnology aims to create diagnostic and therapeutic agents with enhanced safety and efficacy, particularly in the realm of theranostics for various malignancies. Diverse inorganic, organic, and hybrid organic-inorganic nanoparticles, each possessing unique properties, have been introduced into this domain. This review seeks to highlight the latest strides in targeted glioblastoma therapy by focusing on the application of inorganic smart nanoparticles. Beyond exploring the general role of nanotechnology in medical applications, this review delves into groundbreaking strategies for glioblastoma treatment, showcasing the potential of smart nanoparticles through in vitro studies, in vivo investigations, and ongoing clinical trials.

Blood-brain barrier-crossing dendrimers for glioma theranostics

Glioma, as a disease of the central nervous system, is difficult to be treated due to the presence of the blood-brain barrier (BBB) that can severely hamper the efficacy of most therapeutic agents. Hence, drug delivery to glioma in an efficient, safe, and specifically targeted manner is the key to effective treatment of glioma. With the advances in nanotechnology, targeted drug delivery systems have been extensively explored to deliver chemotherapeutic agents, nucleic acids, and contrast agents. Among these nanocarriers, dendrimers have played a significant role since they possess highly branched structures, and are easy to be decorated, thus offering numerous binding sites for various drugs and ligands. Dendrimers can be designed to cross the BBB for glioma targeting, therapy or theranostics. In this review, we provide a concise overview of dendrimer-based carrier designs including dendrimer surface modification with hydroxyl termini, peptides, and transferrin etc. for glioma imaging diagnostics, chemotherapy, gene therapy, or imaging-guided therapy. Finally, the future perspectives of dendrimer-based glioma theraputics are also briefly discussed.

Improving the Treatment Effect of Carotenoids on Alzheimer's Disease through Various Nano-Delivery Systems

Natural bioactive compounds have recently emerged as a current strategy for Alzheimer's disease treatment. Carotenoids, including astaxanthin, lycopene, lutein, fucoxanthin, crocin and others are natural pigments and antioxidants, and can be used to treat a variety of diseases, including Alzheimer's disease. However, carotenoids, as oil-soluble substances with additional unsaturated groups, suffer from low solubility, poor stability and poor bioavailability. Therefore, the preparation of various nano-drug delivery systems from carotenoids is a current measure to achieve efficient application of carotenoids. Different carotenoid delivery systems can improve the solubility, stability, permeability and bioavailability of carotenoids to a certain extent to achieve Alzheimer's disease efficacy. This review summarizes recent data on different carotenoid nano-drug delivery systems for the treatment of Alzheimer's disease, including polymer, lipid, inorganic and hybrid nano-drug delivery systems. These drug delivery systems have been shown to have a beneficial therapeutic effect on Alzheimer's disease to a certain extent.

Nanomaterial-based contrast agents

Medical imaging, which empowers the detection of physiological and pathological processes within living subjects, has a vital role in both preclinical and clinical diagnostics. Contrast agents are often needed to accompany anatomical data with functional information or to provide phenotyping of the disease in question. Many newly emerging contrast agents are based on nanomaterials as their high payloads, unique physicochemical properties, improved sensitivity and multimodality capacity are highly desired for many advanced forms of bioimaging techniques and applications. Here, we review the developments in the field of nanomaterial-based contrast agents. We outline important nanomaterial design considerations and discuss the effect on their physicochemical attributes, contrast properties and biological behaviour. We also describe commonly used approaches for formulating, functionalizing and characterizing these nanomaterials. Key applications are highlighted by categorizing nanomaterials on the basis of their X-ray, magnetic, nuclear, optical and/or photoacoustic contrast properties. Finally, we offer our perspectives on current challenges and emerging research topics as well as expectations for future advancements in the field.

Dendrimer: An update on recent developments and future opportunities for the brain tumors diagnosis and treatment

A brain tumor is an uncontrolled cell proliferation, a mass of tissue composed of cells that grow and divide abnormally and appear to be uncontrollable by the processes that normally control normal cells. Approximately 25,690 primary malignant brain tumors are discovered each year, 70% of which originate in glial cells. It has been observed that the blood-brain barrier (BBB) limits the distribution of drugs into the tumour environment, which complicates the oncological therapy of malignant brain tumours. Numerous studies have found that nanocarriers have demonstrated significant therapeutic efficacy in brain diseases. This review, based on a non-systematic search of the existing literature, provides an update on the existing knowledge of the types of dendrimers, synthesis methods, and mechanisms of action in relation to brain tumours. It also discusses the use of dendrimers in the diagnosis and treatment of brain tumours and the future possibilities of dendrimers. Dendrimers are of particular interest in the diagnosis and treatment of brain tumours because they can transport biochemical agents across the BBB to the tumour and into the brain after systemic administration. Dendrimers are being used to develop novel therapeutics such as prolonged release of drugs, immunotherapy, and antineoplastic effects. The use of PAMAM, PPI, PLL and surface engineered dendrimers has proven revolutionary in the effective diagnosis and treatment of brain tumours.

A Glimpse into Dendrimers Integration in Cancer Imaging and Theranostics

Cancer is a result of abnormal cell proliferation. This pathology is a serious health problem since it is a leading cause of death worldwide. Current anti-cancer therapies rely on surgery, radiation, and chemotherapy. However, these treatments still present major associated problems, namely the absence of specificity. Thus, it is urgent to develop novel therapeutic strategies. Nanoparticles, particularly dendrimers, have been paving their way to the front line of cancer treatment, mostly for drug and gene delivery, diagnosis, and disease monitoring. This is mainly derived from their high versatility, which results from their ability to undergo distinct surface functionalization, leading to improved performance. In recent years, the anticancer and antimetastatic capacities of dendrimers have been discovered, opening new frontiers to dendrimer-based chemotherapeutics. In the present review, we summarize the intrinsic anticancer activity of different dendrimers as well as their use as nanocarriers in cancer diagnostics and treatment.

Recent advances of CREKA peptide-based nanoplatforms in biomedical applications

Nanomedicine technology is a rapidly developing field of research and application that uses nanoparticles as a platform to facilitate the diagnosis and treatment of diseases. Nanoparticles loaded with drugs and imaging contrast agents have already been used in clinically, but they are essentially passive delivery carriers. To make nanoparticles smarter, an important function is the ability to actively locate target tissues. It enables nanoparticles to accumulate in target tissues at higher concentrations, thereby improving therapeutic efficacy and reducing side effects. Among the different ligands, the CREKA peptide (Cys-Arg-Glu-Lys-Ala) is a desirable targeting ligand and has a good targeting ability for overexpressed fibrin in different models, such as cancers, myocardial ischemia-reperfusion, and atherosclerosis. In this review, the characteristic of the CREKA peptide and the latest reports regarding the application of CREKA-based nanoplatforms in different biological tissues are described. In addition, the existing problems and future application perspectives of CREKA-based nanoplatforms are also addressed.

Dendrimer Technology in Glioma: Functional Design and Potential Applications

Novel therapeutic and diagnostic methods are sorely needed for gliomas, which contribute yearly to hundreds of thousands of cancer deaths worldwide. Despite the outpouring of research efforts and funding aimed at improving clinical outcomes for patients with glioma, the prognosis for high-grade glioma, and especially glioblastoma, remains dire. One of the greatest obstacles to improving treatment efficacy and destroying cancer cells is the safe delivery of chemotherapeutic drugs and biologics to the tumor site at a high enough dose to be effective. Over the past few decades, a burst of research has leveraged nanotechnology to overcome this obstacle. There has been a renewed interest in adapting previously understudied dendrimer nanocarriers for this task. Dendrimers are small, highly modifiable, branched structures featuring binding sites for a variety of drugs and ligands. Recent studies have demonstrated the potential for dendrimers and dendrimer conjugates to effectively shuttle therapeutic cargo to the correct tumor location, permeate the tumor, and promote apoptosis of tumor cells while minimizing systemic toxicity and damage to surrounding healthy brain tissue. This review provides a primer on the properties of dendrimers; outlines the mechanisms by which they can target delivery of substances to the site of brain pathology; and delves into current trends in the application of dendrimers to drug and gene delivery, and diagnostic imaging, in glioma. Finally, future directions for translating these in vitro and in vivo findings to the clinic are discussed.

A Review on Increasing the Targeting of PAMAM as Carriers in Glioma Therapy

Glioma is an invasive brain cancer, and it is difficult to achieve desired therapeutic effects due to the high postoperative recurrence rate and limited efficacy of drug therapy hindered by the biological barrier of brain tissue. Nanodrug delivery systems are of great interest, and many efforts have been made to utilize them for glioma treatment. Polyamidoamine (PAMAM), a starburst dendrimer, provides malleable molecular size, functionalized molecular structure and penetrable brain barrier characteristics. Therefore, PAMAM-based nanodrug delivery systems (PAMAM DDS) are preferred for glioma treatment research. In this review, experimental studies on PAMAM DDS for glioma therapy were focused on and summarized. Emphasis was given to three major topics: methods of drug loading, linkers between drug/ligand and PAMAM and ligands of modified PAMAM. A strategy for well-designed PAMAM DDS for glioma treatment was proposed. Purposefully understanding the physicochemical and structural characteristics of drugs is necessary for selecting drug loading methods and achieving high drug loading capacity. Additionally, functional ligands contribute to achieving the brain targeting, brain penetration and low toxicity of PAMAM DDS. Furthermore, a brilliant linker facilitates multidrug combination and multifunctional PAMAM DDS. PAMAM DDS show excellent promise as drug vehicles and will be further studied for product development and safety evaluation.

Surface Engineered Dendrimers: A Potential Nanocarrier for the Effective Management of Glioblastoma Multiforme

Gliomas are the most prevailing intracranial tumors, which account for approximately 36% of the primary brain tumors of glial cells. Glioblastoma multiforme (GBM) possesses a higher degree of malignancy among different gliomas. The blood-brain barrier (BBB) protects the brain against infections and toxic substances by preventing foreign molecules or unwanted cells from entering the brain parenchyma. Nano-carriers such as liposomes, nanoparticles, dendrimers, etc. boost the brain permeability of various anticancer drugs or other drugs. The favorable properties like small size, better solubility, and the modifiable surface of dendrimers have proven their broad applicability in the better management of GBM. However, in vitro and in vivo toxicities caused by dendrimers have been a significant concern. The presence of multiple functionalities on the surface of dendrimers enables the grafting of target ligand and/or therapeutic moieties. Surface engineering improves certain properties like targeting efficiency, pharmacokinetic profile, therapeutic effect, and toxicity reduction. This review will be focused on the role of different surface-modified dendrimers in the effective management of GBM.

Efficacy of Polymer-Based Nanomedicine for the Treatment of Brain Cancer

Malignant brain tumor is a life-threatening disease with a low survival rate. The therapies available for the treatment of brain tumor is limited by poor uptake via the blood-brain barrier. The challenges with the chemotherapeutics used for the treatment of brain tumors are poor distribution, drug toxicity, and their inability to pass via the blood-brain barrier, etc. Several researchers have investigated the potential of nanomedicines for the treatment of brain cancer. Nanomedicines are designed with nanosize particle sizes with a large surface area and are loaded with bioactive agents via encapsulation, immersion, conjugation, etc. Some nanomedicines have been approved for clinical use. The most crucial part of nanomedicine is that they promote drug delivery across the blood-brain barrier, display excellent specificity, reduce drug toxicity, enhance drug bioavailability, and promote targeted drug release mechanisms. The aforementioned features make them promising therapeutics for brain targeting. This review reports the in vitro and in vivo results of nanomedicines designed for the treatment of brain cancers.

Recent advances in targeted drug delivery for the treatment of pancreatic ductal adenocarcinoma

INTRODUCTION

Pancreatic ductal adenocarcinoma (PDAC) has become a serious health problem with high impact worldwide. The heterogeneity of PDAC makes it difficult to apply drug delivery systems (DDS) used in other cancer models, for example, the poorly developed vascular system makes anti-angiogenic therapy ineffective. Due to its various malignant pathological changes, drug delivery against PDAC is a matter of urgent concern. Based on this situation, various drug delivery strategies specially designed for PDAC have been generated.

AREAS COVERED

This review will briefly describe how delivery systems can be designed through nanotechnology and formulation science. Most research focused on penetrating the stromal barrier, exploiting and alleviating the hypoxic microenvironment, targeting immune cells, or designing vaccines, and combination therapies. This review will summarize the ways to reverse the malignant pathological features of PDAC and hopefully provide ideas for subsequent studies.

EXPERT OPINION

Drug delivery systems designed to achieve penetrating functions or to alleviate hypoxia and activate immunity have achieved good therapeutic results in animal models in several studies. In future studies, there is a need to deliver PDAC therapeutics in a more precise manner, or the use of drug carriers for multiple functions simultaneously, are potential therapeutic strategy.

Nanoscale Drug Delivery Systems in Glioblastoma

Glioblastoma is the most aggressive cerebral tumor in adults. However, the current pharmaceuticals in GBM treatment are mainly restricted to few chemotherapeutic drugs and have limited efficacy. Therefore, various nanoscale biomaterials that possess distinct structure and unique property were constructed as vehicles to precisely deliver molecules with potential therapeutic effect. In this review, nanoparticle drug delivery systems including CNTs, GBNs, C-dots, MOFs, Liposomes, MSNs, GNPs, PMs, Dendrimers and Nanogel were exemplified. The advantages and disadvantages of these nanoparticles in GBM treatment were illustrated.

Homing peptide combined with DNAzyme-based ELISA-like assay for highly specific and sensitive detection of fibrin

A highly sensitive and specific ELISA-like chemiluminescence method for detection of fibrin has been developed. In the sensing platform, the homing peptide (CREKA), as recognition molecule, which can specially recognize the fibrin on microtiter plate, combined with G-quadruplex-based DNAzyme to form the probe of G-quadruplex-hemin DNAzyme-CREKA. After the sample solution was coated on the plates, the probe was crosslinked with fibrin through the interaction of CREKA and fibrin. Finally, luminol-H₂O₂ chemiluminesecence (CL) reaction was exploited for quantitative analysis of fibrin. The liner range for fibrin detection was from 0.112 pmol L^-1 to 5.6 pmol L^-1 with the detection limit of fibrin as low as 0.04 pmol L^-1, based on a signal-to-noise ratio (S/N) of 3. Furthermore, on the basis of the high amplification efficiency of the rolling circle amplification (RCA) reaction, the method enabled to analyze fibrin with a detection limit corresponding to 0.06 fmol L^-1, whose sensitivity increased 3 orders of magnitude than that of above method in the absence of RCA reaction. In particular, combined with the separation and washing steps of ELISA, the proposed method possessed higher selectivity, high-throughput and low cost, which shows promise for applications in clinical diagnosis.

Pegylated LyeTx I-b peptide is effective against carbapenem-resistant Acinetobacter baumannii in an in vivo model of pneumonia and shows reduced toxicity

The World Health Organization (WHO) has been warning about the importance of developing new drugs against superbugs. Antimicrobial peptides are an alternative in this context, most of them being involved in innate immunity, acting in various ways, and some even showing synergism with commercial antimicrobial agents. LyeTx I-b is a synthetic peptide derived from native LyeTx I, originally isolated from Lycosa erythrognatha spider venom. Although LyeTx I-b is active against several multidrug-resistant bacteria, it shows some hemolytic and cytotoxic effects. To overcome this hindrance, in the present study we PEGylated LyeTx I-b and evaluated its toxicity and in vitro and in vivo activities on pneumonia caused by multi-resistant Acinetobacter baumannii. PEGylated LyeTx I-b (LyeTx I-bPEG) maintained the same MIC value as the non- PEGylated peptide, showed anti-biofilm activity, synergistic effect with commercial antimicrobial agents, and did not induce resistance. Moreover, in vivo experiments showed its activity against pneumonia. Additionally, LyeTx I-bPEG reduced hemolysis up to 10 times, was approximately 2 times less cytotoxic to HEK-293 cells and 4 times less toxic to mice in acute toxicity models, compared to LyeTx I-b. Our results show LyeTx I-bPEG as a promising antimicrobial candidate, significantly active against pneumonia caused by multidrug-resistant A. baumannii.

The MEK 1/2 inhibitor PD98059 exhibits synergistic anti-endometrial cancer activity with paclitaxel in vitro and enhanced tissue distribution in vivo when formulated into PAMAM-coated PLGA-PEG nanoparticles

Endometrial cancer is the most common gynecological cancer that affects the female reproductive organs. The standard therapy for EC for the past two decades has been chemotherapy and/or radiotherapy. PD98059 is a reversible MEK inhibitor that was found in these studies to increase the cytotoxicity of paclitaxel (PTX) against human endometrial cancer cells (Hec50co) in a synergistic and dose-dependent manner. Additionally, while PD98059 arrested Hec50co cells at the G₀/G₁ phase, and PTX increased accumulation of cells at the G₂/M phase, the combination treatment increased accumulation at both the G₀/G₁ and G₂/M phases at low PTX concentrations. We recently developed poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) modified with polyethylene glycol (PEG) and coated with polyamidoamine (PAMAM) (referred to here as PGM NPs) which have favorable biodistribution profiles in mice, compared to PD98059 solution. Here, in order to enhance tissue distribution of PD98059, PD98059-loaded PGM NPs were prepared and characterized. The average size, zeta potential, and % encapsulation efficiency (%EE) of these NPs was approximately 184 nm, + 18 mV, and 23%, respectively. The PD98059-loaded PGM NPs released ~ 25% of the total load within 3 days in vitro. In vivo murine studies revealed that the pharmacokinetics and biodistribution profile of intravenous (IV) injected PD98059 was improved when delivered as PD98059-loaded PGM NPs as opposed to soluble PD98059. Further investigation of the in vivo efficacy and safety of this formulation is expected to emphasize the potential of its clinical application in combination with commercial PTX formulations against different cancers.

Anti-Tumor Metastasis via Platelet Inhibitor Combined with Photothermal Therapy under Activatable Fluorescence/Magnetic Resonance Bimodal Imaging Guidance

Photothermal therapy (PTT) is a promising tumor therapy strategy; however, heterogeneous heat distribution over the tumor often exists, resulting in insufficient photothermal ablation and potential risk of cancer metastasis, which has been demonstrated to be associate with platelets. Herein, a near-infrared (NIR) photothermal agent of IR780 was conjugated with MRI agent of Gd-DOTA via a disulfide linkage (ICD-Gd), which was coassembly with lipid connecting tumor-homing pentapeptide CREKA (Cys-Arg-Glu-Lys-Ala) (DSPE-PEG-CREKA) to encapsulate a platelet inhibitor of ticagrelor (Tic), affording a multistimuli-responsive nanosystem (DPC@ICD-Gd-Tic). The nanosystem with completely quenching fluorescence could specifically target the tumor-associated platelets and showed pH/reduction/NIR light-responsive drug release, which simultaneously resulting in dis-assembly of nanoparticle and fluorescence recovery, enabling the drug delivery visualization in tumor in situ via activatable NIR fluorescence/MR bimodal imaging. Finally, DPC@ICD-Gd-Tic further integrated the photoinduced hyperthermia and platelet function inhibitor to achieve synergistic anticancer therapy, leading to ablation of primary tumor cells and effectively suppressed their distant metastasis. The number of lung metastases in 4T1 tumor bearing mice was reduced by about 90%, and the size of tumor was reduced by about 70%, while half of the mouse was completely cured by this smart nanosystem.

Bioscaffold-based study of glioblastoma cell behavior and drug delivery for tumor therapy

Glioblastoma multiforme (GBM) is a severe form of brain cancer with an average five-year survival rate of 6.7%. Current treatment strategies include surgical resection of the tumor area and lining the lesion site with therapeutics, which offer only a moderate impact on increasing survival rates. Drug-testing models based on the monolayer cell culture method may partially explain the lack of advancement in effective GBM treatment, because this model is limited in its ability to show heterogeneous cell-cell and cell-environment interactions as tumor cells in the in vivo state. The development of bioscaffold-based culture models is an important improvement in GBM research, preclinical trials, and targeted drug testing, through better mimicking of the heterogeneity of tumor environmental conditions. A major hurdle towards better GBM outcomes is in delivering medication across the blood-brain barrier (BBB), which normally prevents the crossing of materials into the treatment site. The delivery of therapeutics using bioscaffolds is a potential means of overcoming the BBB and could potentially facilitate long-lasting drug release. A number of natural and synthetic materials have been studied for their biodegradability, toxicity, distribution, and pharmaceutical stability, which are needed to determine the overall effectiveness and safety of glioblastoma treatment. This review summarizes advancements in the research of bioscaffold-based GBM cell growth systems and the potential of using bioscaffolds as a carrier for drug delivery.

Photoacoustic Imaging of Myocardial Infarction Region Using Non-Invasive Fibrin-Targeted Nanoparticles in a Rat Myocardial Ischemia-Reperfusion Model

BACKGROUND AND PURPOSE

Myocardial infarction (MI) is a serious threat to public health. The early identification of MI is important to promote appropriate treatment strategies for patients. Recently, strategies targeting extracellular matrix (ECM) components have gained attention. Fibrin is an ECM protein involved after MI. In this work, we constructed fibrin-targeted nanoparticles (NPs) by co-assembling a fibrin-targeted peptide (CREKA) and indocyanine green (ICG) and used them to enhance photoacoustic (PA) imaging for noninvasive detection of the infarct region to help diagnose MI.

METHODS

ICG NPs modified with CREKA were prepared (CREKA-ICG-LIP NPs). Then, the fundamental characteristics, stability, safety, and targeting ability of the NPs were detected. Finally, in an ischemia-reperfusion (IR) injury model, the performance of the NPs in detecting the infarct region in the model on PA imaging was evaluated.

RESULTS

CREKA-ICG-LIP NPs were successfully constructed and showed excellent basic characteristics, a high safety level, and an excellent targeting ability. After intravenous injection, the CREKA-ICG-LIP NPs accumulated in the injured region in the IR model. Then, the PA signal in the infarct region could be detected by the ultrasound transducer of the Vevo LAZR Photoacoustic Imaging System.

CONCLUSION

This work provides new insights for non-invasive, real-time imaging techniques to detect the region of myocardial injury and help diagnose MI based on a PA imaging system with high sensitivity in optical imaging and deep penetration in ultrasound imaging.

Enhancement of Therapies for Glioblastoma (GBM) Using Nanoparticle-based Delivery Systems

Glioblastoma multiforme (GBM) is the most aggressive type of malignant brain tumor. Current FDA-approved treatments include surgical resection, radiation, and chemotherapy, while hyperthermia, immunotherapy, and most relevantly, nanoparticle (NP)-mediated delivery systems or combinations thereof have shown promise in preclinical studies. Drug-carrying NPs are a promising approach to brain delivery as a result of their potential to facilitate the crossing of the blood-brain barrier (BBB) via two main types of transcytosis mechanisms: adsorptive-mediated transcytosis (AMT) and receptor-mediated transcytosis (RMT). Their ability to accumulate in the brain can thus provide local sustained release of tumoricidal drugs at or near the site of GBM tumors. NP-based drug delivery has the potential to significantly reduce drug-related toxicity, increase specificity, and consequently improve the lifespan and quality of life of patients with GBM. Due to significant advances in the understanding of the molecular etiology and pathology of GBM, the efficacy of drugs loaded into vectors targeting this disease has increased in both preclinical and clinical settings. Multitargeting NPs, such as those incorporating multiple specific targeting ligands, are an innovative technology that can lead to decreased off-target effects while simultaneously having increased accumulation and action specifically at the tumor site. Targeting ligands can include antibodies, or fragments thereof, and peptides or small molecules, which can result in a more controlled drug delivery system compared to conventional drug treatments. This review focuses on GBM treatment strategies, summarizing current options and providing a detailed account of preclinical findings with prospective NP-based approaches aimed at improving tumor targeting and enhancing therapeutic outcomes for GBM patients.

Targeting the brain lesions using peptides: A review focused on the possibility of targeted drug delivery to multiple sclerosis lesions

As described by Jean Martin Charcot in 1868, multiple sclerosis (MS) is an inflammatory, demyelinating and neurodegenerative disease of the central nervous system (CNS) which leads to permanent disability in patients. Following CNS insults, astrocytes and microglial cells undergo changes, which lead to scar formation in the site of injury. Owning to the pathophysiology of MS lesions, changes in both cellular and extracellular matrix (ECM) components occur over the progression of disease. In spite of advances in therapeutic approaches, drug delivery to MS lesions appears of great interest with big challenges and limitations. Targeting with peptides is a novel promising approach in the field of drug delivery. Recently peptides have been used for active targeting of different pathological disorders in which specific peptides make targeted accumulation of cargos to enhance local drug concentration at the pathological area, lead to increased therapeutic efficacy and decreased side effects. However, specific approaches for targeting the lesion in MS are still lacking. In this review, we discuss the changes of the ECM components as well as the cellular characteristics of demyelinated lesions and emphasis on opportunities for peptide based targeted drug delivery to highlight the possibility of such approaches for neurodegenerative disease with specific focus on MS.

Vascular-targeted micelles as a specific MRI contrast agent for molecular imaging of fibrin clots and cancer cells

Molecular medical imaging is intended to increase the accuracy of diagnosis, particularly in cardiovascular and cancer-related diseases, where early detection could significantly increase the treatment success rate. In this study, we present mixed micelles formed from four building blocks as a magnetic resonance imaging targeted contrast agent for the detection of atheroma and cancer cells. The building blocks are a gadolinium-loaded DOTA ring responsible for contrast enhancement, a fibrin-specific CREKA pentapeptide responsible for targeting, a fluorescent dye and DSPE-PEG₂₀₀₀. The micelles were fully characterized in terms of their size, zeta potential, stability, relaxivity and toxicity. Target binding assays performed on fibrin clots were quantified by fluorescence and image signal intensities and proved the binding power. An additional internalization assay showed that the micelles were also designed to specifically enter into cancer cells. Overall, these multimodal mixed micelles represent a potential formulation for MRI molecular imaging of atheroma and cancer cells.

Dendrimers as Modulators of Brain Cells

Nanostructured hyperbranched macromolecules have been extensively studied at the chemical, physical and morphological levels. The cellular structural and functional complexity of neural cells and their cross-talk have made it rather difficult to evaluate dendrimer effects in a mixed population of glial cells and neurons. Thus, we are at a relatively early stage of bench-to-bedside translation, and this is due mainly to the lack of data valuable for clinical investigations. It is only recently that techniques have become available that allow for analyses of biological processes inside the living cells, at the nanoscale, in real time. This review summarizes the essential properties of neural cells and dendrimers, and provides a cross-section of biological, pre-clinical and early clinical studies, where dendrimers were used as nanocarriers. It also highlights some examples of biological studies employing dendritic polyglycerol sulfates and their effects on glia and neurons. It is the aim of this review to encourage young scientists to advance mechanistic and technological approaches in dendrimer research so that these extremely versatile and attractive nanostructures gain even greater recognition in translational medicine.

Dendrimer size effects on the selective brain tumor targeting in orthotopic tumor models upon systemic administration

Malignant gliomas are the most common and aggressive form of primary brain tumors, with a median survival of 15-20 months for patients receiving maximal interventions. Advances in nanomedicine have provided tumor-specific delivery of chemotherapeutics to potentially overcome their off-target toxicities. Recent advances in dendrimer-based nanomedicines have established that hydroxyl-terminated poly(amidoamine) dendrimers can intrinsically target neuroinflammation and brain tumors from systemic administration without the need for targeting moieties. The size of nanocarriers is a critical parameter that determines their tumor-targeting efficiency, intratumor distribution, and clearance mechanism. In this study, we explore the dendrimer size effects on brain tumor targeting capability in two clinically relevant orthotopic brain tumor models, the 9L rat and GL261 mouse models, which capture differing aspects of gliomas. We show that increasing dendrimers from Generation 4 to Generation 6 significantly enhances their tumor accumulation (~10-fold greater at 24 hr), tumor specificity (~2-3 fold higher), and tumor retention. The superior tumor targeting effect of G6 dendrimers is associated with its reduced renal clearance rate, resulting in longer circulation time compared to G4 dendrimers. Additionally, the increase in dendrimer generation does not compromise its homogeneous tumor distribution and intrinsic targeting of tumor-associated macrophages. These results validate the potential for these dendrimers as an effective, clinically translatable platform for effectively targeting tumor-associated macrophages in malignant gliomas.

PAMAM Dendrimer Nanomolecules Utilized as Drug Delivery Systems for Potential Treatment of Glioblastoma: A Systematic Review

Glioblastoma (GB) is a grade IV astrocytoma that maintains a poor prognosis with respect to current treatment options. Despite major advancements in the fields of surgery and chemoradiotherapy over the last few decades, the life expectancy for someone with glioblastoma remains virtually unchanged and warrants a new approach for treatment. Poly(amidoamine) (PAMAM) dendrimers are a type of nanomolecule that ranges in size (between 1 and 100 nm) and shape and can offer a new viable solution for the treatment of intracranial tumors, including glioblastoma. Their ability to deliver a variety of therapeutic cargo and penetrate the blood-brain barrier (BBB), while preserving low cytotoxicity, make them a favorable candidate for further investigation into the treatment of glioblastoma. Here, we present a systematic review of the current advancements in PAMAM dendrimer technology, including the wide spectrum of dendrimer generations formulated, surface modifications, core modifications, and conjugations developed thus far to enhance tumor specificity and tumor penetration for treatment of glioblastoma. Furthermore, we highlight the extensive variety of therapeutics capable of delivery by PAMAM dendrimers for the treatment of glioblastoma, including cytokines, peptides, drugs, siRNAs, miRNAs, and organic polyphenols. While there have been prolific results stemming from aggressive research into the field of dendrimer technology, there remains a nearly inexhaustible amount of questions that remain unanswered. Nevertheless, this technology is rapidly developing and is nearing the cusp of use for aggressive tumor treatment. To that end, we further highlight future prospects in focus as researchers continue developing more optimal vehicles for the delivery of therapeutic cargo.

Glioblastoma multiforme: a glance at advanced therapies based on nanotechnology

Glioblastoma multiforme (GBM, grade IV) is the most common malignant and invasive central nervous system tumor with poor survival outcome. Various pathogenesis signatures such as genetic mutation, hypoxia, necrosis and neo-angiogenesis are involved in GBM. Standard treatment includes surgical resection along with radiation therapy and temozolomide (TMZ) chemotherapy that do not improve the overall survival of patients. In this review, we focused on the diagnosis, risk factors and novel therapies, using advanced therapies such as nanotechnology in drug delivery, gene therapy and hyperthermia that have promising roles in the treatment of aggressive brain tumors.

Targeting hemostasis-related moieties for tumor treatment

Under normal conditions, the hemostatic system, that includes the involvement of the coagulation response and platelets, is anatomically and functionally inseparable from the vasculature. However, the hemostatic response always occurs in a wide range of tumors because of the high expression of coagulation initiator tissue factor (TF) in many tumor tissues, and due to the leakage of coagulation factors and platelets from the circulation system into the tumor interstitium through abnormal tumor vessels. Therefore, in addition to TF, these coagulation factors, platelets, the central moiety thrombin, the final product fibrin, and fibronectin, which is capable of stabilizing coagulation clots, are also abundant in tumors. These hemostasis-related moieties (HRMs), including TF, thrombin, fibrin, fibronectin, and platelets, are also closely associated with tumor progression, e.g., primary tumor growth and distal metastasis. The hemostatic response only occurs under pathological conditions, such as tumors, thrombosis, and atherosclerosis other than in normal tissues. The HRMs within tumors are also highly specific, establishing functional and therapeutic targets for tumor treatment. Therefore, strategies including active targeting to these moieties, modulation of HRMs deposited in the tumor microenvironment to improve tumor drug delivery, activation of prodrug by the coagulation complex formed during coagulation response, and direct inhibition of the tumor-promoting activity of HRMs could be designed for tumor therapy. In this review, we summarize various strategies that target HRMs for tumor treatment.

Dendrimer-Based Drug Delivery Systems for Brain Targeting

Human neuroscience has made remarkable progress in understanding basic aspects of functional organization; it is a renowned fact that the blood-brain barrier (BBB) impedes the permeation and access of most drugs to central nervous system (CNS) and that many neurological diseases remain undertreated. Therefore, a number of nanocarriers have been designed over the past few decades to deliver drugs to the brain. Among these nanomaterials, dendrimers have procured an enormous attention from scholars because of their nanoscale uniform size, ease of multi-functionalization, and available internal cavities. As hyper-branched 3D macromolecules, dendrimers can be maneuvered to transport diverse therapeutic agents, incorporating small molecules, peptides, and genes; diminishing their cytotoxicity; and improving their efficacy. Herein, the present review will give exhaustive details of extensive researches in the field of dendrimer-based vehicles to deliver drugs through the BBB in a secure and effectual manner. It is also a souvenir in commemorating Donald A. Tomalia on his 80th birthday.

Targeted and effective glioblastoma therapy via aptamer-modified tetrahedral framework nucleic acid-paclitaxel nanoconjugates that can pass the blood brain barrier

Targeted DNA nanoparticles have been identified as one of the most promising nanocarriers in anti-glioma drug delivery. We established a multifunctional nanosystem for targeted glioma therapy. Tetrahedral framework nucleic acid (tFNA), entering U87MG cells and bEnd.3 cells, was chosen to deliver two aptamers, GMT8 and Gint4.T, and paclitaxel. GMT8 and Gint4.T, which specifically bind with U87MG cells and with PDGFRβ, were linked with tFNA, to form Gint4.T-tFNA-GMT8 (GTG). GTG was efficiently internalized by U87MG and bEnd.3 cells and penetrated an in-vitro blood-brain-barrier model. GTG loaded with paclitaxel (GPC) had potentiated anti-glioma efficacy. It inhibited the proliferation, migration, and invasion of U87MG cells, and enhanced apoptosis induction in these cells. The expression of apoptosis-related proteins was significantly changed after treatment with GPC, confirming apoptosis induction. Our study demonstrated that the combination of GTG and paclitaxel has great potential for glioma treatment and tFNA shows great promise for use in drug delivery.

Nanotechnology-based strategies as novel therapies in gliomas

Gliomas are the most common malignancies of the brain and have a mean survival of 12 months with only 5-10% of the patients surviving for more than 5 years, independent of treatment after diagnosis. Conventional treatment modalities have found the modest success in reducing tumor burden and metastases. Presence of different biological barriers and drug-resistance efflux transporters are crucial for tumor recurrence and treatment failure. Nanotechnology may amend these circumstances by targeting residual infiltrating malignant cells with minimal damage to normal cells, on-demand release and an improved cellular uptake by tumor cells. This review highlights the current status and advances in nanotechnology for treatment of gliomas.

Targeted Theranostic Nanoparticles for Brain Tumor Treatment

The poor prognosis and rapid recurrence of glioblastoma (GB) are associated to its fast-growing process and invasive nature, which make difficult the complete removal of the cancer infiltrated tissues. Additionally, GB heterogeneity within and between patients demands a patient-focused method of treatment. Thus, the implementation of nanotechnology is an attractive approach considering all anatomic issues of GB, since it will potentially improve brain drug distribution, due to the interaction between the blood⁻brain barrier and nanoparticles (NPs). In recent years, theranostic techniques have also been proposed and regarded as promising. NPs are advantageous for this application, due to their respective size, easy surface modification and versatility to integrate multiple functional components in one system. The design of nanoparticles focused on therapeutic and diagnostic applications has increased exponentially for the treatment of cancer. This dual approach helps to understand the location of the tumor tissue, the biodistribution of nanoparticles, the progress and efficacy of the treatment, and is highly useful for personalized medicine-based therapeutic interventions. To improve theranostic approaches, different active strategies can be used to modulate the surface of the nanotheranostic particle, including surface markers, proteins, drugs or genes, and take advantage of the characteristics of the microenvironment using stimuli responsive triggers. This review focuses on the different strategies to improve the GB treatment, describing some cell surface markers and their ligands, and reports some strategies, and their efficacy, used in the current research.

Nanosensors for the Chemical Imaging of Acetylcholine Using Magnetic Resonance Imaging

A suite of imaging tools for detecting specific chemicals in the central nervous system could accelerate the understanding of neural signaling events critical to brain function and disease. Here, we introduce a class of nanoparticle sensors for the highly specific detection of acetylcholine in the living brain using magnetic resonance imaging. The nanosensor is composed of acetylcholine-catalyzing enzymes and pH-sensitive gadolinium contrast agents co-localized onto the surface of polymer nanoparticles, which leads to changes in T₁ relaxation rate (1/ T₁). The mechanism of the sensor involves the enzymatic hydrolysis of acetylcholine leading to a localized decrease in pH which is detected by the pH-sensitive gadolinium chelate. The concomitant change in 1/ T₁ in vitro measured a 20% increase from 0 to 10 μM acetylcholine concentration. The applicability of the nanosensors in vivo was demonstrated in the rat medial prefrontal cortex showing distinct changes in 1/ T₁ induced by pharmacological stimuli. The highly specific acetylcholine nanosensor we present here offers a promising strategy for detection of cholinergic neurotransmission and will facilitate our understanding of brain function through chemical imaging.

Optimization of the tumor microenvironment and nanomedicine properties simultaneously to improve tumor therapy

Effective delivery of nanomedicines to tumor tissues depends on both the tumor microenvironment and nanomedicine properties. Accordingly, tumor microenvironment modification or advanced design of nanomedicine was emerging to improve nanomedicine delivery to tumors. However, few studies have emphasized the necessity to optimize the tumor microenvironment and nanomedicine properties simultaneously to improve tumor treatment. In the present study, imatinib mesylate (IMA) was used to normalize the tumor microenvironment including platelet-derived growth factor receptor-β expression inhibition, tumor vessel normalization, and tumor perfusion improvement as demonstrated by immunofluorescence staining. In addition, the effect of tumor microenvironment normalization on tumor delivery of nanomedicines with different sizes was carefully investigated. It was shown that IMA treatment significantly reduced the accumulation of nanoparticles (NPs) around 110 nm but enhanced the accumulation of micelles around 23 nm by in vivo fluorescence imaging experiment. Furthermore, IMA treatment limited the distribution of NPs inside tumors but increased that of micelles with a more homogeneous pattern. Finally, the anti-tumor efficacy study displayed that IMA pretreatment could significantly increase the therapeutic effects of paclitaxel-loaded micelles. All-together, a new strategy to improve nanomedicine delivery to tumor was provided by optimizing both nanomedicine size and the tumor microenvironment simultaneously, and it will have great potential in clinics for tumor treatment.

Enhanced antitumor and anti-metastasis efficacy against aggressive breast cancer with a fibronectin-targeting liposomal doxorubicin

The chemotherapy of aggressive breast tumor is usually accompanied by a poor prognosis because of the metastasis of tumor cells. Thus, it is important to simultaneously enhance antitumor and anti-metastasis efficacy. Fibronectin and its complexes are expressed on the walls of tumor vessels and in tumor stroma. Moreover, the expression of fibronectin in metastatic sites is even higher than that in primary tumors. Herein, we designed a fibronectin-targeting CREKA-modified liposomal doxorubicin (CREKA-Lipo-Dox) for the therapy of metastatic breast tumor. CREKA-Lipo was uniformly formed with high entrapment efficiency. It exhibited longer blood circulation time compared with free Dox, and there was no significant change compared with PEG-Lipo-Dox. Immunofluorescence results revealed that the CREKA-Lipo-Dox could specifically bind to fibronectin in the tumor vessels and tumor stroma. The antitumor and anti-metastasis efficacy of CREKA-loaded liposome was more obvious than that of free Dox or unmodified Dox-Lipo. Taken together, binding fibronectin by CREKA could be an attractive therapeutic strategy for metastatic breast cancer in the future.

Glioma and microenvironment dual targeted nanocarrier for improved antiglioblastoma efficacy

Drug delivery systems based on nanoparticles (nano-DDS) have aroused attentions for the treatment of glioblastoma (GBM), the most malignant brain cancer with a dismal prognosis. However, there are still numerous unmet challenges for traditional nano-DDS, such as the poor nanoparticle penetration, short retention in the GBM parenchyma and low glioma targeting ability. Herein, we used Pep-1 and CREKA peptides to construct a novel multifunctional GBM targeting nano-DDS (PC-NP). Pep-1 was used to overcome the blood-brain tumor barrier (BBTB) and home to glioma cells via interleukin-13 receptor-α2-mediated endocytosis, and CREKA was used to bind to fibrin-fibronectin complexes abundantly expressed in tumor microenvironment for enhanced retention in the GBM. Biological studies showed that the cellular uptake of PC-NP by U87MG cells was significantly enhanced compared with the non-targeting NP. Furthermore, CREKA modification increased the binding capacity of PC-NP to fibrin-fibronectin complexes as confirmed by the competition experiment. In accordance with the increased cellular uptake, PC-NP remarkably increased the cytotoxicity of its payload paclitaxel (PTX) against U87MG cells with an IC₅₀ of 0.176 μg/mL. In vivo fluorescence imaging and antiglioma efficacy evaluation further confirmed that PC-NP accumulated effectively and penetrated deeply into GBM tissue. PC-NP-PTX exhibited a median survival time as long as 61 days in intracranial GBM-bearing mice. In conclusion, our findings indicated PC-NP as a promising nano-DDS for GBM targeting delivery of anticancer drugs.

Advances in the design of solid lipid nanoparticles and nanostructured lipid carriers for targeting brain diseases

Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) comprise a category of versatile drug delivery systems that have been used in the biomedical field for >25years. SLNs and NLCs have been used for the treatment of various diseases including cardiovascular and cerebrovascular, and are considered a standard treatment for the latter, due to their inherent ability to cross the blood brain barrier (BBB). In this review, a presentation of the most important brain diseases (brain cancer, ischemic stroke, Alzheimer's disease, Parkinson's disease and multiple sclerosis) is approached, followed by the basic fabrication techniques of SLNs and NLCs. A detailed description of the reported studies of the last seven years, of active and passive targeting SLNs and NLCs for the treatment of glioblastoma multiforme and of other brain cancers, as well as for the treatment of neurodegenerative diseases is also carried out. Finally, a brief description of the advantages, the disadvantages, and the future perspectives in the use of these nanocarriers is reported, aiming at giving an insight of the limitations that have to be overcome in order to result in a delivery system with high therapeutic efficacy and without the limitations of the existing nano-systems.

Nanocarriers for brain specific delivery of anti-retro viral drugs: challenges and achievements

HIV/AIDS is a global pandemic and the deleterious effects of human immunodeficiency virus in the brain cannot be overlooked. Though the current anti-retro viral therapy is able to reduce the virus load in the peripheral tissues of the body, the inability of the anti-retro viral drugs to cross the blood brain barrier, as such, limits its therapeutic effect in the brain. The development of newer, successful nanoparticulate drug delivery systems to enhance the feasibility of the anti-retro viral drugs to the brain, offers a novel strategy to treat the AIDS-related neuronal degradation. This review summarised the neuropathogenesis of neuroAIDS, the challenges and achievements made in the delivery of therapeutics across the BBB and the use of nanocarriers as a safe and effective way for delivering anti-retro viral drugs to the brain.

Nanomaterial applications for neurological diseases and central nervous system injury

The effectiveness of noninvasive treatment for neurological disease is generally limited by the poor entry of therapeutic agents into the central nervous system (CNS). Most CNS drugs cannot permeate into the brain parenchyma because of the blood-brain barrier thus, overcoming this problem has become one of the most significant challenges in the development of neurological therapeutics. Nanotechnology has emerged as an innovative alternative for treating neurological diseases. In fact, rapid advances in nanotechnology have provided promising solutions to this challenge. This review highlights the applications of nanomaterials in the developing neurological field and discusses the evidence for their efficacies.

Brain-Targeted Polymers for Gene Delivery in the Treatment of Brain Diseases

Gene therapies have become a promising strategy for treating neurological disorders, such as brain cancer and neurodegenerative diseases, with the help of molecular biology interpreting the underlying pathological mechanisms. Successful cellular manipulation against these diseases requires efficient delivery of nucleic acids into brain and further into specific neurons or cancer cells. Compared with viral vectors, non-viral polymeric carriers provide a safer and more flexible way of gene delivery, although suffering from significantly lower transfection efficiency. Researchers have been devoted to solving this defect, which is attributed to the multiple barriers existing for gene therapeutics in vivo, such as systemic degradation, blood-brain barrier, and endosome trapping. This review will be mainly focused on systemically administrated brain-targeted polymers developed so far, including PEI, dendrimers, and synthetic polymers with various functions. We will discuss in detail how they are designed to overcome these barriers and how they efficiently deliver therapeutic nucleic acids into targeted cells.

Crossing the Blood-Brain Barrier: Recent Advances in Drug Delivery to the Brain

CNS disorders are on the rise despite advancements in our understanding of their pathophysiological mechanisms. A major hurdle to the treatment of these disorders is the blood-brain barrier (BBB), which serves as an arduous janitor to protect the brain. Many drugs are being discovered for CNS disorders, which, however fail to enter the market because of their inability to cross the BBB. This is a pronounced challenge for the pharmaceutical fraternity. Hence, in addition to the discovery of novel entities and drug candidates, scientists are also developing new formulations of existing drugs for brain targeting. Several approaches have been investigated to allow therapeutics to cross the BBB. As the molecular structure of the BBB is better elucidated, several key approaches for brain targeting include physiological transport mechanisms such as adsorptive-mediated transcytosis, inhibition of active efflux pumps, receptor-mediated transport, cell-mediated endocytosis, and the use of peptide vectors. Drug-delivery approaches comprise delivery from microspheres, biodegradable wafers, and colloidal drug-carrier systems (e.g., liposomes, nanoparticles, nanogels, dendrimers, micelles, nanoemulsions, polymersomes, exosomes, and quantum dots). The current review discusses the latest advancements in these approaches, with a major focus on articles published in 2015 and 2016. In addition, we also cover the alternative delivery routes, such as intranasal and convection-enhanced diffusion methods, and disruption of the BBB for brain targeting.