Nanotherapeutic approaches for brain cancer management

Neurodegenerative disorders: Mechanisms of degeneration and therapeutic approaches with their clinical relevance

Neurodegenerative disorders (NDs) are expected to pose a significant challenge for both medicine and public health in the upcoming years due to global demographic changes. NDs are mainly represented by degeneration/loss of neurons, which is primarily accountable for severe mental illness. This neuronal degeneration leads to many neuropsychiatric problems and permanent disability in an individual. Moreover, the tight junction of the brain, blood-brain barrier (BBB)has a protective feature, functioning as a biological barrier that can prevent medicines, toxins, and foreign substances from entering the brain. However, delivering any medicinal agent to the brain in NDs (i.e., Multiple sclerosis, Alzheimer's, Parkinson's, etc.) is enormously challenging. There are many approved therapies to address NDs, but most of them only help treat the associated manifestations. The available therapies have failed to control the progression of NDs due to certain factors, i.e., BBB and drug-associated undesirable effects. NDs have extremely complex pathology, with many pathogenic mechanisms involved in the initiation and progression; thereby, a limited survival rate has been observed in ND patients. Hence, understanding the exact mechanism behind NDs is crucial to developing alternative approaches for improving ND patients' survival rates. Thus, the present review sheds light on different cellular mechanisms involved in NDs and novel therapeutic approaches with their clinical relevance, which will assist researchers in developing alternate strategies to address the limitations of conventional ND therapies. The current work offers the scope into the near future to improve the therapeutic approach of NDs.

Demystifying the potential of lipid-based nanocarriers in targeting brain malignancies

Drug targeting for brain malignancies is restricted due to the presence of the blood-brain barrier (BBB) and blood-brain tumor barrier (BBTB), which act as barriers between the blood and brain parenchyma. Certainly, the limited therapeutic options for brain malignancies have made notable progress with enhanced biological understanding and innovative approaches, such as targeted therapies and immunotherapies. These advancements significantly contribute to improving patient prognoses and represent a promising shift in the landscape of brain malignancy treatments. A more comprehensive understanding of the histology and pathogenesis of brain malignancies is urgently needed. Continued research focused on unraveling the intricacies of brain malignancy biology holds the key to developing innovative and tailored therapies that can improve patient outcomes. Lipid nanocarriers are highly effective drug delivery systems that significantly improve their solubility, bioavailability, and stability while also minimizing unwanted side effects. Surface-modified lipid nanocarriers (liposomes, niosomes, solid lipid nanoparticles, nanostructured lipid carriers, lipid nanocapsules, lipid-polymer hybrid nanocarriers, lipoproteins, and lipoplexes) are employed to improve BBB penetration and uptake through various mechanisms. This systematic review illuminates and covers various topics related to brain malignancies. It explores the different methods of drug delivery used in treating brain malignancies and delves into the benefits, limitations, and types of brain-targeted lipid-based nanocarriers. Additionally, this review discusses ongoing clinical trials and patents related to brain malignancy therapies and provides a glance into future perspectives for treating this condition.

A, Gota V, Goda JS. Insight into lipid-based nanoplatform-mediated drug and gene delivery in neuro-oncology and their clinical prospects

Tumors of the Central nervous System (CNS) are a spectrum of neoplasms that range from benign lesions to highly malignant and aggressive lesions. Despite aggressive multimodal treatment approaches, the morbidity and mortality are high with dismal survival outcomes in these malignant tumors. Moreover, the non-specificity of conventional treatments substantiates the rationale for precise therapeutic strategies that selectively target infiltrating tumor cells within the brain, and minimize systemic and collateral damage. With the recent advancement of nanoplatforms for biomaterials applications, lipid-based nanoparticulate systems present an attractive and breakthrough impact on CNS tumor management. Lipid nanoparticles centered immunotherapeutic agents treating malignant CNS tumors could convene the clear need for precise treatment strategies. Immunotherapeutic agents can selectively induce specific immune responses by active or innate immune responses at the local site within the brain. In this review, we discuss the therapeutic applications of lipid-based nanoplatforms for CNS tumors with an emphasis on revolutionary approaches in brain targeting, imaging, and drug and gene delivery with immunotherapy. Lipid-based nanoparticle platforms represent one of the most promising colloidal carriers for chemotherapeutic, and immunotherapeutic drugs. Their current application in oncology especially in brain tumors has brought about a paradigm shift in cancer treatment by improving the antitumor activity of several agents that could be used to selectively target brain tumors. Subsequently, the lab-to-clinic transformation and challenges towards translational feasibility of lipid-based nanoplatforms for drug and gene/immunotherapy delivery in the context of CNS tumor management is addressed.

Advances in nanotechnology for the treatment of GBM

Glioblastoma (GBM), a highly malignant glioma of the central nervous system, is the most dread and common brain tumor with a high rate of therapeutic resistance and recurrence. Currently, the clinical treatment methods are surgery, radiotherapy, and chemotherapy. However, owning to the highly invasive nature of GBM, it is difficult to completely resect them due to the unclear boundary between the edges of GBM and normal brain tissue. Traditional radiotherapy and the combination of alkylating agents and radiotherapy have significant side effects, therapeutic drugs are difficult to penetrate the blood brain barrier. Patients receiving treatment have a high postoperative recurrence rate and a median survival of less than 2 years, Less than 5% of patients live longer than 5 years. Therefore, it is urgent to achieve precise treatment through the blood brain barrier and reduce toxic and side effects. Nanotechnology exhibit great potential in this area. This article summarizes the current treatment methods and shortcomings of GBM, and summarizes the research progress in the diagnosis and treatment of GBM using nanotechnology.

Nose-to-Brain Targeting via Nanoemulsion: Significance and Evidence

Background: Non-invasive and patient-friendly nose-to-brain pathway is the best-suited route for brain delivery of therapeutics as it bypasses the blood–brain barrier. The intranasal pathway (olfactory and trigeminal nerves) allows the entry of various bioactive agents, delivers a wide array of hydrophilic and hydrophobic drugs, and circumvents the hepatic first-pass effect, thus targeting neurological diseases in both humans and animals. The olfactory and trigeminal nerves make a bridge between the highly vascularised nasal cavity and brain tissues for the permeation and distribution, thus presenting a direct pathway for the entry of therapeutics into the brain. Materials: This review portrays insight into recent research reports (spanning the last five years) on the nanoemulsions developed for nose-to-brain delivery of actives for the management of a myriad of neurological disorders, namely, Parkinson’s disease, Alzheimer’s, epilepsy, depression, schizophrenia, cerebral ischemia and brain tumours. The information and data are collected and compiled from more than one hundred Scopus- and PubMed-indexed articles. Conclusions: The olfactory and trigeminal pathways facilitate better biodistribution and bypass BBB issues and, thus, pose as a possible alternative route for the delivery of hydrophobic, poor absorption and enzyme degradative therapeutics. Exploring these virtues, intranasal nanoemulsions have proven to be active, non-invasiveand safe brain-targeting cargos for the alleviation of the brain and other neurodegenerative disorders.

Polydopamine-based loaded temozolomide nanoparticles conjugated by peptide-1 for glioblastoma chemotherapy and photothermal therapy

Purpose: Nanoparticles (NPs) of the polydopamine (PDA)-based,loaded with temozolomide (TMZ) and conjugated with Pep-1 (Peptide-1) as a feasible nano-drug delivery system were constructed and utilized for chemotherapy (CT) and photothermal therapy (PTT) of glioblastoma (GBM). Method: PDA NPs were synthesized from dopamine (DA) hydrochloride and reacted with TMZ to obtain the PDA-TMZ NPs and then the PDA NPs and the PDA-TMZ NPs were conjugated and modified by Pep-1 to obtain the Pep-1@PDA NPs and Pep-1@PDA-TMZ NPs via the Schiff base reaction (SBR), respectively.Their dimensions, charge, and shape were characterized by dynamic light scattering (DLS) and scanning electron microscope (SEM). The assembly of TMZ was verified by Fourier-transform infrared spectroscopy (FT-IR) and ultraviolet and visible spectroscopy (UV-Vis). The biostability of both the nanocarrier and the synthetic NPs were validated using water and fetal bovine serum (FBS). The antitumor activities of the PDA-TMZ NPs and Pep-1@PDA-TMZ NPs were verified in U87 cells and tumor-bearing nude mice. Results: The prepared PDA NPs, PDA-TMZ NPs, Pep-1@PDA NPs, and Pep-1@PDA-TMZ NPs were regular and spherical, with dimension of approximately 122, 131, 136, and 140 nm, respectively. The synthetic nanoparticles possessed good dispersity, stability,solubility, and biocompatibility. No obvious toxic side effects were observed, and the loading rate of TMZ was approximately 50%.In vitro research indicated that the inhibition ratio of the Pep-1@PDA-TMZ NPs combined with 808 nm laser was approximately 94% for U87 cells and in vivo research was approximately 77.13%, which was higher than the ratio of the other groups (p < 0.05). Conclusion: Pep-1 was conjugated and modified to PDA-TMZ NPs, which can serve as a new targeted drug nano-delivery system and can offer a CT and PTT integration therapy against GBM. Thus, Pep-1@PDA-TMZ NPs could be a feasible approach for efficient GBM therapy, and further provide some evidence and data for clinical transformation so that gradually conquer GBM.

Polydopamine-based loaded temozolomide nanoparticles conjugated by peptide-1 for glioblastoma chemotherapy and photothermal therapy

Purpose: Nanoparticles (NPs) of the polydopamine (PDA)-based,loaded with temozolomide (TMZ) and conjugated with Pep-1 (Peptide-1) as a feasible nano-drug delivery system were constructed and utilized for chemotherapy (CT) and photothermal therapy (PTT) of glioblastoma (GBM).

Method: PDA NPs were synthesized from dopamine (DA) hydrochloride and reacted with TMZ to obtain the PDA-TMZ NPs and then the PDA NPs and the PDA-TMZ NPs were conjugated and modified by Pep-1 to obtain the Pep-1@PDA NPs and Pep-1@PDA-TMZ NPs via the Schiff base reaction (SBR), respectively.Their dimensions, charge, and shape were characterized by dynamic light scattering (DLS) and scanning electron microscope (SEM). The assembly of TMZ was verified by Fourier-transform infrared spectroscopy (FT-IR) and ultraviolet and visible spectroscopy (UV-Vis). The biostability of both the nanocarrier and the synthetic NPs were validated using water and fetal bovine serum (FBS). The antitumor activities of the PDA-TMZ NPs and Pep-1@PDA-TMZ NPs were verified in U87 cells and tumor-bearing nude mice.

Results: The prepared PDA NPs, PDA-TMZ NPs, Pep-1@PDA NPs, and Pep-1@PDA-TMZ NPs were regular and spherical, with dimension of approximately 122, 131, 136, and 140 nm, respectively. The synthetic nanoparticles possessed good dispersity, stability,solubility, and biocompatibility. No obvious toxic side effects were observed, and the loading rate of TMZ was approximately 50%.In vitro research indicated that the inhibition ratio of the Pep-1@PDA-TMZ NPs combined with 808 nm laser was approximately 94% for U87 cells and in vivo research was approximately 77.13%, which was higher than the ratio of the other groups (p &lt; 0.05).

Conclusion: Pep-1 was conjugated and modified to PDA-TMZ NPs, which can serve as a new targeted drug nano-delivery system and can offer a CT and PTT integration therapy against GBM. Thus, Pep-1@PDA-TMZ NPs could be a feasible approach for efficient GBM therapy, and further provide some evidence and data for clinical transformation so that gradually conquer GBM.

Enhancing Photothermal Therapy Efficacy by In Situ Self-Assembly in Glioma

The residence time of some small molecular imaging and therapeutic agents in tumor tissue is short and the molecules can be easily dispersed, which decreases treatment efficacy. Therefore, methods that enhance oncotherapy performance are of significant importance. Here, we report an in situ self-assembly strategy aimed at enhancing the photothermal therapy of glioblastomas. The probe, ICG-PEP-c(RGD)fk, consisted of a glutathione-reactive self-assembling polypeptide as the skeleton, indocyanine green (ICG) as a theranostic agent, and cyclic Arg-Gly-Asp [c(RGD)fk] peptides as the targeting group. ICG-PEP-c(RGD)fk was synthesized and found to be assembled in the glutathione environment at 9.446 μM in vitro. Human glioblastoma cell line U87MG-luc with high integrin αvβ3 expression was applied to invivo experiments. ICG-PEP-c(RGD)fk provided clearer tumor imaging and had a tumor retention time of 6.12 times longer than that of ICG-c(RGD)fk. In therapeutic experiments, ICG-PEP-c(RGD)fk significantly suppressed glioblastoma growth and the tumor volume was 2.61 times smaller than in the ICG-c(RGD)fk group at the end of the observation period. Moreover, the median survival time of ICG-PEP-c(RGD)fk group was significantly improved by 2.78 times compared with that of the control group. In conclusion, glutathione-reactive self-assembling peptides are capable of increasing the tumor retention time and improving the photothermal therapeutic effect. The in situ self-assembly strategy is a potential and feasible method to enhance oncotherapy.

Oncolytic Newcastle Disease Virus Co-Delivered with Modified PLGA Nanoparticles Encapsulating Temozolomide against Glioblastoma Cells: Developing an Effective Treatment Strategy

Glioblastoma multiforme (GBM) is considered to be one of the most serious version of primary malignant tumors. Temozolomide (TMZ), an anti-cancer drug, is the most common chemotherapeutic agent used for patients suffering from GBM. However, due to its inherent instability, short biological half-life, and dose-limiting characteristics, alternatives to TMZ have been sought. In this study, the TMZ-loaded PLGA nanoparticles were prepared by employing the emulsion solvent evaporation technique. The prepared TMZ-PLGA-NPs were characterized using FT-IR, zeta potential analyses, XRD pattern, particle size estimation, TEM, and FE-SEM observations. The virotherapy, being safe, selective, and effective in combating cancer, was employed, and TMZ-PLGA-NPs and oncolytic Newcastle Disease Virus (NDV) were co-administered for the purpose. An AMHA1-attenuated strain of NDV was propagated in chicken embryos, and the virus was titrated in Vero-slammed cells to determine the infective dose. The in vitro cytotoxic effects of the TMZ, NDV, and the TMZ-PLGA-NPs against the human glioblastoma cancer cell line, AMGM5, and the normal cell line of rat embryo fibroblasts (REFs) were evaluated. The synergistic effects of the nano-formulation and viral strain combined therapy was observed on the cell lines in MTT viability assays, together with the Chou–Talalay tests. The outcomes of the in vitro investigation revealed that the drug combinations of NDV and TMZ, as well as NDV and TMZ-PLGA-NPs exerted the synergistic enhancements of the antitumor activity on the AMGM5 cell lines. The effectiveness of both the mono, and combined treatments on the capability of AMGM5 cells to form colonies were also examined with crystal violet dyeing tests. The morphological features, and apoptotic reactions of the treated cells were investigated by utilizing the phase-contrast inverted microscopic examinations, and acridine orange/propidium iodide double-staining tests. Based on the current findings, the potential for the use of TMZ and NDV as part of a combination treatment of GBM is significant, and may work for patients suffering from GBM.

Emerging roles of ferroptosis in glioma

Glioma is the most common primary malignant tumor in the central nervous system, and directly affects the quality of life and cognitive function of patients. Ferroptosis, is a new form of regulated cell death characterized by iron-dependent lipid peroxidation. Ferroptosis is mainly due to redox imbalance and involves multiple intracellular biology processes, such as iron metabolism, lipid metabolism, and antioxidants synthesis. Induction of ferroptosis could be a new target for glioma treatment, and ferroptosis-related processes are associated with chemoresistance and radioresistance in glioma. In the present review, we provide the characteristics, key regulators and pathways of ferroptosis and the crosstalk between ferroptosis and other programmed cell death in glioma, we also proposed the application and prospect of ferroptosis in the treatment of glioma.

Progress in cancer drug delivery based on AS1411 oriented nanomaterials

Targeted cancer therapy has become one of the most important medical methods because of the spreading and metastatic nature of cancer. Based on the introduction of AS1411 and its four-chain structure, this paper reviews the research progress in cancer detection and drug delivery systems by modifying AS1411 aptamers based on graphene, mesoporous silica, silver and gold. The application of AS1411 in cancer treatment and drug delivery and the use of AS1411 as a targeting agent for the detection of cancer markers such as nucleoli were summarized from three aspects of active targeting, passive targeting and targeted nucleic acid apharmers. Although AS1411 has been withdrawn from clinical trials, the research surrounding its structural optimization is still very popular. Further progress has been made in the modification of nanoparticles loaded with TCM extracts by AS1411.

Transferrin Receptor-Targeted Nanocarriers: Overcoming Barriers to Treat Glioblastoma

Glioblastoma multiforme (GBM) is the most common and lethal type of brain tumor, and the clinically available approaches for its treatment are not curative. Despite the intensive research, biological barriers such as the blood–brain barrier (BBB) and tumor cell membranes are major obstacles to developing novel effective therapies. Nanoparticles (NPs) have been explored as drug delivery systems (DDS) to improve GBM therapeutic strategies. NPs can circumvent many of the biological barriers posed by this devastating disease, enhancing drug accumulation in the target site. This can be achieved by employing strategies to target the transferrin receptor (TfR), which is heavily distributed in BBB and GBM cells. These targeting strategies comprise the modification of NPs’ surface with various molecules, such as transferrin (Tf), antibodies, and targeting peptides. This review provides an overview and discussion on the recent advances concerning the strategies to target the TfR in the treatment of GBM, as their benefits and limitations.

Computer simulation of tumour resection-induced brain deformation by a meshless approach

Tumour resection requires precise planning and navigation to maximise tumour removal while simultaneously protecting nearby healthy tissues. Neurosurgeons need to know the location of the remaining tumour after partial tumour removal before continuing with the resection. Our approach to the problem uses biomechanical modelling and computer simulation to compute the brain deformations after the tumour is resected. In this study, we use meshless Total Lagrangian explicit dynamics as the solver. The problem geometry is extracted from the patient-specific magnetic resonance imaging (MRI) data and includes the parenchyma, tumour, cerebrospinal fluid and skull. The appropriate non-linear material formulation is used. Loading is performed by imposing intra-operative conditions of gravity and reaction forces between the tumour and surrounding healthy parenchyma tissues. A finite frictionless sliding contact is enforced between the skull (rigid) and parenchyma. The meshless simulation results are compared to intra-operative MRI sections. We also calculate Hausdorff distances between the computed deformed surfaces (ventricles and tumour cavities) and surfaces observed intra-operatively. Over 80% of points on the ventricle surface and 95% of points on the tumour cavity surface were successfully registered (results within the limits of two times the original in-plane resolution of the intra-operative image). Computed results demonstrate the potential for our method in estimating the tissue deformation and tumour boundary during the resection.

Modeling the blood-brain barrier for treatment of central nervous system (CNS) diseases

The blood-brain barrier (BBB) is the most specialized biological barrier in the body. This configuration of specialized cells protects the brain from invasion of molecules and particles through formation of tight junctions. To learn more about transport to the brain, in vitro modeling of the BBB is continuously advanced. The types of models and cells selected vary with the goal of each individual study, but the same validation methods, quantification of tight junctions, and permeability assays are often used. With Transwells and microfluidic devices, more information regarding formation of the BBB has been observed. Disease models have been developed to examine the effects on BBB integrity. The goal of modeling is not only to understand normal BBB physiology, but also to create treatments for diseases. This review will highlight several recent studies to show the diversity in model selection and the many applications of BBB models in in vitro research.

Development of Polymer-Based Nanoformulations for Glioblastoma Brain Cancer Therapy and Diagnosis: An Update

Brain cancers, mainly high-grade gliomas/glioblastoma, are characterized by uncontrolled proliferation and recurrence with an extremely poor prognosis. Despite various conventional treatment strategies, viz., resection, chemotherapy, and radiotherapy, the outcomes are still inefficient against glioblastoma. The blood–brain barrier is one of the major issues that affect the effective delivery of drugs to the brain for glioblastoma therapy. Various studies have been undergone in order to find novel therapeutic strategies for effective glioblastoma treatment. The advent of nanodiagnostics, i.e., imaging combined with therapies termed as nanotheranostics, can improve the therapeutic efficacy by determining the extent of tumour distribution prior to surgery as well as the response to a treatment regimen after surgery. Polymer nanoparticles gain tremendous attention due to their versatile nature for modification that allows precise targeting, diagnosis, and drug delivery to the brain with minimal adverse side effects. This review addresses the advancements of polymer nanoparticles in drug delivery, diagnosis, and therapy against brain cancer. The mechanisms of drug delivery to the brain of these systems and their future directions are also briefly discussed.

Temozolomide nano enabled medicine: promises made by the nanocarriers in glioblastoma therapy

Glioblastoma multiforme (GBM) is abnormal cell proliferation of glial cells. GBM is the grade IV glioma brain cancer which is life-threatening to many individuals affected by this cancer. The DNA alkylating agent Temozolomide (TMZ) has the distinctiveness of being FDA approved anticancer drug for the first line treatment for GBM. However, treatment of GBM still remains a challenge. This is attributed to TMZ's toxic nature, severe side effects, and fast degradation in vivo. In addition, the lack of targeting ability increases the chances of systemic toxicities. A nano enabled targeted delivery system not only improves the efficiency of TMZ by making it cross the blood brain barrier, have specificity to target, but also reduces toxicity to healthy tissues. Over the last decade the significant advances in the area of nanotechnology applied to medicine have developed many multifunctional therapeutics. In this context, the present review article comprehends the significant progress in the field of TMZ loaded nanocarriers showing promise for futuristic nanomedicine therapies in treating GBM.

The application of multifunctional nanomaterials in Alzheimer's disease: A potential theranostics strategy

By virtue of their small size, nanomaterials can cross the blood-brain barrier and, when modified to target specific cells or regions, can achieve high bioavailability at the intended site of action. Modified nanomaterials are therefore promising agents for the diagnosis and treatment of neurodegenerative diseases such as Alzheimer's disease (AD). Here we review the roles and mechanisms of action of nanomaterials in AD. First, we discuss the general characteristics of nanomaterials and their application to nanomedicine. Then, we summarize recent studies on the diagnosis and treatment of AD using modified nanomaterials. These studies indicate that using nanomaterials is a potential strategy for AD treatment by slowing the progression of AD through enhanced therapeutic effects.

Vancomycin-loaded nanoparticles against vancomycin intermediate and methicillin resistant Staphylococcus aureus strains

Bacterial infections represent one of the leading causes of mortality in the world. Among causative pathogens, S. aureus is prominently known as the underlying cause of many multidrug resistant infections that are often treated with the first-line choice antibiotic vancomycin (VCM). Loading antibiotics into polymeric nanoparticles (Np) displays promise as an alternative method to deliver therapy due to the greater access and accumulation of the antibiotic at the site of the infection as well as reducing toxicity, irritation and degradation. The aim of this work was to prepare, characterize and evaluate VCM-loaded nanoparticles (VNp) for use against S. aureus strains. Moreover, conjugation of Nps with holo-transferrin (h-Tf) was investigated as an approach for improving targeted drug delivery. VNp were prepared by double emulsion solvent evaporation method using PLGA and PVA or DMAB as surfactants. The particles were characterized for size distribution, Zeta Potential, morphology by transmission electron microscopy, encapsulation yield and protein conjugation efficiency. Process yield and drug loading were also investigated along with an in vitro evaluation of VNp antimicrobial effects against S. aureus strains. Results showed that Np were spontaneously formed with a mean diameter lower than 300 nm in a narrow size distribution that presented a spherical shape. The bioconjugation with h-Tf did not appear to increase the antimicrobial effect of VNp. However, non-bioconjugated Np presented a minimal inhibitory concentration lower than free VCM against a MRSA (Methicillin-resistant S. aureus) strain, and slightly higher against a VISA (VCM intermediate S. aureus) strain. VNp without h-Tf showed potential to assist in the development of new therapies against S. aureus infections.

Formulation and in vitro evaluation of upconversion nanoparticle-loaded liposomes for brain cancer

Aim: This work focused on the development of transferrin-conjugated theranostic liposomes consisting of docetaxel (DXL) and upconversion nanoparticles for the diagnosis and treatment of gliomas. Materials & methods: Upconversion nanoparticles and docetaxel-loaded theranostic liposomes were prepared by a solvent injection method. Formulations were analyzed for physicochemical properties, encapsulation efficiency, drug release, elemental analysis, cytotoxicity and fluorescence. Results: The particle size was around 200 nm with spherical morphology and an encapsulation efficiency of up to 75.93%, was achieved for liposomes with an in vitro drug release of 71.10%. The IC₅₀ values demonstrated enhanced cytotoxicity on C6 glioma cells with targeted liposomes in comparison with nontargeted liposomes. Conclusion: Prepared theranostic liposomes may be promising for clinical validation after an in vitro and in vivo evaluation on cell lines and animals, respectively.

Autophagy in cancers including brain tumors: role of MicroRNAs

Autophagy has a crucial role in many cancers, including brain tumors. Several types of endogenous molecules (e.g. microRNAs, AKT, PTEN, p53, EGFR, and NF1) can modulate the process of autophagy. Recently miRNAs (small non-coding RNAs) have been found to play a vital role in the regulation of different cellular and molecular processes, such as autophagy. Deregulation of these molecules is associated with the development and progression of different pathological conditions, including brain tumors. It was found that miRNAs are epigenetic regulators, which influence the level of proteins coded by the targeted mRNAs with any modification of the genetic sequences. It has been revealed that various miRNAs (e.g., miR-7-1-3p, miR-340, miR-17, miR-30a, miR-224-3p, and miR-93), as epigenetic regulators, can modulate autophagy pathways within brain tumors. A deeper understanding of the underlying molecular targets of miRNAs, and their function in autophagy pathways could contribute to the development of new treatment methods for patients with brain tumors. In this review, we summarize the various miRNAs, which are involved in regulating autophagy in brain tumors. Moreover, we highlight the role of miRNAs in autophagy-related pathways in different cancers.

Nasal Drug Delivery of Anticancer Drugs for the Treatment of Glioblastoma: Preclinical and Clinical Trials

Glioblastoma (GBM) is the most lethal form of brain tumor, being characterized by the rapid growth and invasion of the surrounding tissue. The current standard treatment for glioblastoma is surgery, followed by radiotherapy and concurrent chemotherapy, typically with temozolomide. Although extensive research has been carried out over the past years to develop a more effective therapeutic strategy for the treatment of GBM, efforts have not provided major improvements in terms of the overall survival of patients. Consequently, new therapeutic approaches are urgently needed. Overcoming the blood–brain barrier (BBB) is a major challenge in the development of therapies for central nervous system (CNS) disorders. In this context, the intranasal route of drug administration has been proposed as a non-invasive alternative route for directly targeting the CNS. This route of drug administration bypasses the BBB and reduces the systemic side effects. Recently, several formulations have been developed for further enhancing nose-to-brain transport, mainly with the use of nano-sized and nanostructured drug delivery systems. The focus of this review is to provide an overview of the strategies that have been developed for delivering anticancer compounds for the treatment of GBM while using nasal administration. In particular, the specific properties of nanomedicines proposed for nose-to-brain delivery will be critically evaluated. The preclinical and clinical data considered supporting the idea that nasal delivery of anticancer drugs may represent a breakthrough advancement in the fight against GBM.

Evaluation of Targeted Delivery to the Brain Using Magnetic Immunoliposomes and Magnetic Force

Magnetic nanoparticles have great prospects for drug delivery purposes, as they can be designed with various surface coatings and conjugated with drugs and targeting moieties. They also have a unique potential for precise delivery when guided by magnetic force. The blood-brain barrier (BBB) denotes the interface between the blood and brain parenchyma and hinders the majority of drugs from entering the brain. Red fluorescent magnetic nanoparticles were encapsulated in liposomes and conjugated to antibodies targeting the rat transferrin receptor (OX26) to form magnetic immunoliposomes. These magnetic immunoliposomes enhanced the uptake by rat brain capillary endothelial cells (BCECs) in vitro. In situ brain perfusion in young rats high in the endogenous expression of transferrin receptors by BCECs, revealed enhanced uptake of magnetic immunoliposomes when compared to naked magnetic nanoparticles or non-targeted magnetic liposomes. When applying the external magnetic force, the magnetic nanoparticles were detected in the brain parenchyma, suggesting transport across the BBB. Ultrastructural examination of the immunoliposomes, unfortunately, was unable to confirm a complete encapsulation of all naked nanoparticles within the liposomes, suggesting that the data on the brain could derive from particles being released from the liposomes under influence of external magnetic force; hence hypothesizes on external magnetic force as a qualifier for dragging targeted magnetic immunoliposomes through the BBB. In conclusion, our results suggest that transport of magnetic nanoparticles present in BCECs by targeted delivery to the transferrin receptor may undergo further transport into the brain when applying magnetic force. While magnetic immunoliposomes are targetable to BCECs, their design to enable further transport across the BBB when applying external magnetic force needs further improvement.

Improved Drug Delivery to Brain Metastases by Peptide-Mediated Permeabilization of the Blood-Brain Barrier

Patients with melanoma have a high risk of developing brain metastasis, which is associated with a dismal prognosis. During early stages of metastasis development, the blood-brain barrier (BBB) is likely intact, which inhibits sufficient drug delivery into the metastatic lesions. We investigated the ability of the peptide, K16ApoE, to permeabilize the BBB for improved treatment with targeted therapies preclinically. Dynamic contrast enhanced MRI (DCE-MRI) was carried out on NOD/SCID mice to study the therapeutic window of peptide-mediated BBB permeabilization. Further, both in vivo and in vitro assays were used to determine K16ApoE toxicity and to obtain mechanistic insight into its action on the BBB. The therapeutic impact of K16ApoE on metastases was evaluated combined with the mitogen-activated protein kinase pathway inhibitor dabrafenib, targeting BRAF mutated melanoma cells, which is otherwise known not to cross the intact BBB. Our results from the DCE-MRI experiments showed effective K16ApoE-mediated BBB permeabilization lasting for up to 1 hour. Mechanistic studies showed a dose-dependent effect of K16ApoE caused by induction of endocytosis. At concentrations above IC₅₀, the peptide additionally showed nonspecific disturbances on plasma membranes. Combined treatment with K16ApoE and dabrafenib reduced the brain metastatic burden in mice and increased animal survival, and PET/CT showed that the peptide also facilitated the delivery of compounds with molecular weights as large as 150 kDa into the brain. To conclude, we demonstrate a transient permeabilization of the BBB, caused by K16ApoE, that facilitates enhanced drug delivery into the brain. This improves the efficacy of drugs that otherwise do not cross the intact BBB.

Transferrin receptors-targeting nanocarriers for efficient targeted delivery and transcytosis of drugs into the brain tumors: a review of recent advancements and emerging trends

Treatment of glioblastoma multiforme (GBM) is a predominant challenge in chemotherapy due to the existence of blood-brain barrier (BBB) which restricts delivery of chemotherapeutic agents to the brain together with the problem of drug penetration through hard parenchyma of the GBM. With the structural and mechanistic elucidation of the BBB under both physiological and pathological conditions, it is now viable to target central nervous system (CNS) disorders utilizing the presence of transferrin (Tf) receptors (TfRs). However, overexpression of these TfRs on the GBM cell surface can also help to avoid restrictions of GBM cells to deliver chemotherapeutic agents within the tumor. Therefore, targeting of TfR-mediated delivery could counteract drug delivery issues in GBM and create a delivery system that could cross the BBB effectively to utilize ligand-conjugated drug complexes through receptor-mediated transcytosis. Hence, approach towards successful delivery of antitumor agents to the gliomas has been making possible through targeting these overexpressed TfRs within the CNS and glioma cells. This review article presents a thorough analysis of current understanding on Tf-conjugated nanocarriers as efficient drug delivery system.

Stealth and Cationic Nanoliposomes as Drug Delivery Systems to Increase Andrographolide BBB Permeability

(1) Background: Andrographolide (AG) is a natural compound effective for the treatment of inflammation-mediated neurodegenerative disorders. The aim of this investigation was the preparation of liposomes to enhance the penetration into the brain of AG, by modifying the surface of the liposomes by adding Tween 80 (LPs-AG) alone or in combination with Didecyldimethylammonium bromide (DDAB) (CLPs-AG). (2) Methods: LPs-AG and CLPs-AG were physically and chemically characterized. The ability of liposomes to increase the permeability of AG was evaluated by artificial membranes (PAMPA) and hCMEC/D3 cells. (3) Results: Based on obtained results in terms of size, homogeneity, ζ-potential and EE%. both liposomes are suitable for parenteral administration. The systems showed excellent stability during a month of storage as suspensions or freeze-dried products. Glucose resulted the best cryoprotectant agent. PAMPA and hCMEC/D3 transport studies revealed that LPs-AG and CLPs-AG increased the permeability of AG, about an order of magnitude, compared to free AG without alterations in cell viability. The caveolae-mediated endocytosis resulted the main mechanism of up-take for both formulations. The presence of positive charge increased the cellular internalization of nanoparticles. (4) Conclusions: This study shows that developed liposomes might be ideal candidates for brain delivery of AG.

Focused Ultrasound Enabled Trans-Blood Brain Barrier Delivery of Gold Nanoclusters: Effect of Surface Charges and Quantification Using Positron Emission Tomography

Focused ultrasound (FUS) technology is reported to enhance the delivery of ⁶⁴ Cu-integrated ultrasmall gold nanoclusters (⁶⁴ Cu-AuNCs) across the blood-brain barrier (BBB) as measured by positron emission tomography (PET). To better define the optimal physical properties for brain delivery, ⁶⁴ Cu-AuNCs with different surface charges are synthesized and characterized. In vivo biodistribution studies are performed to compare the individual organ uptake of each type of ⁶⁴ Cu-AuNCs. Quantitative PET imaging post-FUS treatment shows site-targeted brain penetration, retention, and diffusion of the negative, neutral, and positive ⁶⁴ Cu-AuNCs. Autoradiography is performed to compare the intrabrain distribution of these nanoclusters. PET Imaging demonstrates the effective BBB opening and successful delivery of ⁶⁴ Cu-AuNCs into the brain. Of the three ⁶⁴ Cu-AuNCs investigated, the neutrally charged nanostructure performs the best and is the candidate platform for future theranostic applications in neuro-oncology.

Nanotheranostics: Emerging Strategies for Early Diagnosis and Therapy of Brain Cancer

Nanotheranostics have demonstrated the development of advanced platforms that can diagnose brain cancer at early stages, initiate first-line therapy, monitor it, and if needed, rapidly start subsequent treatments. In brain nanotheranostics, therapeutic as well as diagnostic entities are loaded in a single nanoplatform, which can be further developed as a clinical formulation for targeting various modes of brain cancer. In the present review, we concerned about theranostic nanosystems established till now in the research field. These include gold nanoparticles, carbon nanotubes, magnetic nanoparticles, mesoporous silica nanoparticles, quantum dots, polymeric nanoparticles, upconversion nanoparticles, polymeric micelles, solid lipid nanoparticles and dendrimers for the advanced detection and treatment of brain cancer with advanced features. Also, we included the role of three-dimensional models of the BBB and cancer stem cell concept for the advanced characterization of nanotheranostic systems for the unification of diagnosis and treatment of brain cancer. In future, brain nanotheranostics will be able to provide personalized treatment which can make brain cancer even remediable or at least treatable at the primary stages.

Prevention of Synaptic Alterations and Neurotoxic Effects of PAMAM Dendrimers by Surface Functionalization

One of the most studied nanocarriers for drug delivery are polyamidoamine (PAMAM) dendrimers. However, the alterations produced by PAMAM dendrimers in neuronal function have not been thoroughly investigated, and important aspects such as effects on synaptic transmission remain unexplored. We focused on the neuronal activity disruption induced by dendrimers and the possibility to prevent these effects by surface chemical modifications. Therefore, we studied the effects of fourth generation PAMAM with unmodified positively charged surface (G4) in hippocampal neurons, and compared the results with dendrimers functionalized in 25% of their surface groups with folate (PFO₂₅) and polyethylene glycol (PPEG₂₅). G4 dendrimers significantly reduced cell viability at 1 µM, which was attenuated by both chemical modifications, PPEG₂₅ being the less cytotoxic. Patch clamp recordings demonstrated that G4 induced a 7.5-fold increment in capacitive currents as a measure of membrane permeability. Moreover, treatment with this dendrimer increased intracellular Ca²⁺ by 8-fold with a complete disruption of transients pattern, having as consequence that G4 treatment increased the synaptic vesicle release and frequency of synaptic events by 2.4- and 3-fold, respectively. PFO₂₅ and PPEG₂₅ treatments did not alter membrane permeability, total Ca²⁺ intake, synaptic vesicle release or synaptic activity frequency. These results demonstrate that cationic G4 dendrimers have neurotoxic effects and induce alterations in normal synaptic activity, which are generated by the augmentation of membrane permeability and a subsequent intracellular Ca²⁺ increase. Interestingly, these toxic effects and synaptic alterations are prevented by the modification of 25% of PAMAM surface with either folate or polyethylene glycol.

Inhibition of bcl-2 and cox-2 Protein Expression after Local Application of a New Carmustine-Loaded Clinoptilolite-Based Delivery System in a Chemically Induced Skin Cancer Model in Mice

Our research has focused on in vitro and in vivo evaluations of a new Carmustine (BCNU)-loaded clinoptilolite-based delivery system. Two clinoptilolite ionic forms-hydrogen form (HCLI) and sodium form (NaCLI)-were prepared, allowing a loading degree of about 5-6 mg BCNU/g of zeolite matrix due to the dual porous feature of clinoptilolite. Clinoptilolite-based delivery systems released 35.23% of the load in 12 h for the BCNU@HCLI system and only 10.82% for the BCNU@NaCLI system. The BCNU@HCLI system was chosen to develop gel and cream semisolid dosage forms. The cream (C_BCNU@HCLI) released 29.6% of the loaded BCNU after 12 h in the Nylon synthetic membrane test and 31.6% in the collagen membrane test, higher by comparison to the gel. The new cream was evaluated in vivo in a chemically induced model of skin cancer in mice. Quantitative immunohistochemistry analysis showed stronger inhibition of B-cell lymphoma-2 (bcl-2) and cyclooxygenase 2 (cox-2) protein expression, known markers for cancer survival and aggressiveness, after the treatment with C_BCNU@HCLI by comparison to all the control treatment types, including an off-label magistral formula commercially available Carmustine cream as reference, bringing evidence that a clinoptilolite-based delivery systems could be used as a cancer drug carriers and controlled release systems (skin-targeted topical delivery systems).

Targeted Magnetic Nanotheranostics of Cancer

Current advances in targeted magnetic nanotheranostics are summarized in this review. Unique structural, optical, electronic and thermal properties of magnetic materials in nanometer scale are attractive in the field of biomedicine. Magnetic nanoparticles functionalized with therapeutic molecules, ligands for targeted delivery, fluorescent and other chemical agents can be used for cancer diagnostic and therapeutic purposes. High selectivity, small size, and low immunogenicity of synthetic nucleic acid aptamers make them attractive delivery agents for therapeutic purposes. Properties, production and functionalization of magnetic nanoparticles and aptamers as ligands for targeted delivery are discussed herein. In recent years, magnetic nanoparticles have been widely used in diagnostic methods, such as scintigraphy, single photon emission computed tomography (SPECT), positron emission tomography (PET), magnetic resonance imaging (MRI), and Raman spectroscopy. Therapeutic purposes of magnetic nanoconstructions are also promising. They are used for effective drug delivery, magnetic mediated hypertermia, and megnetodynamic triggering of apoptosis. Thus, magnetic nanotheranostics opens a new venue for complex differential diagnostics, and therapy of metastatic cancer.

A Novel Approach on Drug Delivery: Investigation of A New Nano-Formulation of Liposomal Doxorubicin and Biological Evaluation of Entrapped Doxorubicin on Various Osteosarcoma Cell Lines

OBJECTIVE

In this study we prepared a novel formulation of liposomal doxorubicin (L- DOX). The drug dose was optimized by analyses of cellular uptake and cell viability of osteosarcoma (OS) cell lines upon exposure to nanoliposomes that contained varying DOX concentrations. We intended to reduce the cytotoxicity of DOX and improve characteristics of the nanosystems.

MATERIALS AND METHODS

In this experimental study, we prepared liposomes by the pH gradient hydration method. Various characterization tests that included dynamic light scattering (DLS), cryogenic transmission electron microscopy (Cryo-TEM) imaging, and UV- Vis spectrophotometry were employed to evaluate the quality of the nanocarriers. In addition, the CyQUANT® assay and fluorescence microscope imaging were used on various OS cell lines (MG-63, U2-OS, SaOS-2, SaOS-LM7) and Human primary osteoblasts cells, as novel methods to determine cell viability and in vitro transfection efficacy.

RESULTS

We observed an entrapment efficiency of 84% for DOX within the optimized liposomal formulation (L-DOX) that had a liposomal diameter of 96 nm. Less than 37% of DOX released after 48 hours and L-DOX could be stored stably for 14 days. L-DOX increased DOX toxicity by 1.8-4.6 times for the OS cell lines and only 1.3 times for Human primary osteoblasts cells compared to free DOX, which confirmed a higher sensitivity of the OS cell lines versus Human primary osteoblasts cells for L-DOX. We deduced that L- DOX passed more freely through the cell membrane compared to free DOX.

CONCLUSION

We successfully synthesized a stealth L-DOX that contained natural phospholipid by the pH gradient method, which could encapsulate DOX with 84% efficiency. The resulting nanoparticles were round, with a suitable particle size, and stable for 14 days. These nanoparticles allowed for adequately controlled DOX release, increased cell permeability compared to free DOX, and increased tumor cell death. L-DOX provided a novel, more effective therapy for OS treatment.

Self-Assembly of Gold Nanoparticles Shows Microenvironment-Mediated Dynamic Switching and Enhanced Brain Tumor Targeting

Inorganic nanoparticles with unique physical properties have been explored as nanomedicines for brain tumor treatment. However, the clinical applications of the inorganic formulations are often hindered by the biological barriers and failure to be bioeliminated. The size of the nanoparticle is an essential design parameter which plays a significant role to affect the tumor targeting and biodistribution. Here, we report a feasible approach for the assembly of gold nanoparticles into ~80 nm nanospheres as a drug delivery platform for enhanced retention in brain tumors with the ability to be dynamically switched into the single formulation for excretion. These nanoassemblies can target epidermal growth factor receptors on cancer cells and are responsive to tumor microenvironmental characteristics, including high vascular permeability and acidic and redox conditions. Anticancer drug release was controlled by a pH-responsive mechanism. Intracellular L-glutathione (GSH) triggered the complete breakdown of nanoassemblies to single gold nanoparticles. Furthermore, in vivo studies have shown that nanospheres display enhanced tumor-targeting efficiency and therapeutic effects relative to single-nanoparticle formulations. Hence, gold nanoassemblies present an effective targeting strategy for brain tumor treatment.

A novel biocompatible drug delivery system of chitosan/temozolomide nanoparticles loaded PCL-PU nanofibers for sustained delivery of temozolomide

In the present study, the anticancer drug temozolomide (TMZ) was initially loaded into the chitosan (CS) nanoparticles and synthesized CS/TMZ nanoparticles were incorporated into the synthesized poly (ε-caprolactone diol) based polyurethane (PCL-Diol-b-PU) nanofibers. The synthesized nanoparticles and nanofibers were characterized using dynamic light scattering, transmission electron microscopy, X-ray powder diffraction and scanning electron microscopy. The obtained results revealed that the CS/TMZ nanoparticles were successfully embedded into the PCL-Diol-b-PU nanofibers. The gold nanoparticles with average particle size of 18nm were synthesized and coated on the nanofibers surface to enhance the antitumor activity of CS/TMZ loaded nanofibers against inhibiting the growth of U-87 MG human glioblastoma cells. The sustained TMZ release for 30days with the zero order kinetic model were achieved from both CS/TMZ loaded PCL-Diol-b-PU and gold-coated nanofibers. The cell viability results indicated that the gold-coated nanofibers can effectively inhibit the growth of U-87 glioblastoma cells. Therefore, the prepared gold-coated CS/TMZ loaded PCL-Diol-b-PU nanofibers would be a potential candidate for glioblastoma cancer treatment.

Plant Food Residues as a Source of Nutraceuticals and Functional Foods

This chapter describes the use of different plant and vegetable food residues as nutraceuticals and functional foods. Different nutraceuticals are mentioned and explained. Their uses are well addressed along with their disease management and their action as nutraceutical delivery vehicles.

Peptides as a therapeutic avenue for nanocarrier-aided targeting of glioma

INTRODUCTION

Very few successful interventions have been possible in glioma therapy owing to its aggressive nature as well as its hindrance of targeted therapy together with the limited access afforded by the blood-brain barrier (BBB). With the advent of nanotechnology based delivery vehicles such as micelles, dendrimers, polymer-based nanoparticles and nanogels, the breach of the BBB has been facilitated. However, there remains the issue of targeted therapy for glioma cells. Peptide-mediated surface modification of nanocarriers serves this purpose, extending the ability to target glioma further than the enhanced permeability and retention effect. Areas covered: Here we have tried to re-establish the significance of peptides that could be used in various ways for treating glioma. Peptide-embellished nanocarriers used to deliver anticancer drugs; nucleic acids (siRNA, miRNA); micelles or dendrimers grafted with immunogenic glioma-derived peptides used for stimulating active immunity in vaccine therapy, glioma targets for cell penetrating peptides and homing to specific receptors are reviewed. Expert opinion: Peptides have multifunctional potential in targeting, BBB and cell penetration, and can serve as antagonists of various ligands and agonists of particular over-expressed receptors as discussed in this review. Using peptides in targeted personalized therapy would be one step forward and may offer new avenues for glioma therapeutics.

Transferrin liposomes of docetaxel for brain-targeted cancer applications: formulation and brain theranostics

Diagnosis and therapy of brain cancer was often limited due to low permeability of delivery materials across the blood-brain barrier (BBB) and their poor penetration into the brain tissue. This study explored the possibility of utilizing theranostic d-alpha-tocopheryl polyethylene glycol 1000 succinate mono-ester (TPGS) liposomes as nanocarriers for minimally invasive brain-targeted imaging and therapy (brain theranostics). The aim of this work was to formulate transferrin conjugated TPGS coated theranostic liposomes, which contain both docetaxel and quantum dots (QDs) for imaging and therapy of brain cancer. The theranostic liposomes with and without transferrin decoration were prepared and characterized for their particle size, polydispersity, morphology, drug encapsulation efficiency, in-vitro release study and brain theranostics. The particle sizes of the non-targeted and targeted theranostic liposomes were found below 200 nm. Nearly, 71% of drug encapsulation efficiency was achieved with liposomes. The drug release from transferrin conjugated theranostic liposomes was sustained for more than 72 h with 70% of drug release. The in-vivo results indicated that transferrin receptor-targeted theranostic liposomes could be a promising carrier for brain theranostics due to nano-sized delivery and its permeability which provided an improved and prolonged brain targeting of docetaxel and QDs in comparison to the non-targeted preparations.

Low oxygen tension reverses antineoplastic effect of iron chelator deferasirox in human glioblastoma cells

BACKGROUND

Overcoming resistance to treatment is an essential issue in many cancers including glioblastoma (GBM), the deadliest primary tumor of the central nervous system. As dependence on iron is a key feature of tumor cells, using chelators to reduce iron represents an opportunity to improve conventional GBM therapies. The aim of the present study was, therefore, to investigate the cytostatic and cytotoxic impact of the new iron chelator deferasirox (DFX) on human GBM cells in well-defined clinical situations represented by radiation therapy and mild-hypoxia.

RESULTS

Under experimental normoxic condition (21% O2), deferasirox (DFX) used at 10 μM for 3 days reduced proliferation, led cell cycle arrest in S and G2-M phases and induced cytotoxicity and apoptosis in U251 and U87 GBM cells. The abolition of the antineoplastic DFX effects when cells were co-treated with ferric ammonium sulfate supports the hypothesis that its effects result from its ability to chelate iron. As radiotherapy is the main treatment for GBM, the combination of DFX and X-ray beam irradiation was also investigated. Irradiation at a dose of 16 Gy repressed proliferation, cytotoxicity and apoptosis, but only in U251 cells, while no synergy with DFX was observed in either cell line. Importantly, when the same experiment was conducted in mild-hypoxic conditions (3% O2), the antiproliferative and cytotoxic effects of DFX were abolished, and its ability to deplete iron was also impaired.

CONCLUSIONS

Taken together, these in vitro results could raise the question of the benefit of using iron chelators in their native forms under the hypoxic conditions often encountered in solid tumors such as GBM. Developing new chemistry or a new drug delivery system that would keep DFX active in hypoxic cells may be the next step toward their application.

Intravenous administration of trans-resveratrol-loaded TPGS-coated solid lipid nanoparticles for prolonged systemic circulation, passive brain targeting and improved in vitro cytotoxicity against C6 glioma cell lines

trans-Resveratrol (RSV), a natural molecule isolated from red wine, is widely known for several therapeutic potentials.

Therapeutic strategies to improve drug delivery across the blood-brain barrier

Resection of brain tumors is followed by chemotherapy and radiation to ablate remaining malignant cell populations. Targeting these populations stands to reduce tumor recurrence and offer the promise of more complete therapy. Thus, improving access to the tumor, while leaving normal brain tissue unscathed, is a critical pursuit. A central challenge in this endeavor lies in the limited delivery of therapeutics to the tumor itself. The blood-brain barrier (BBB) is responsible for much of this difficulty but also provides an essential separation from systemic circulation. Due to the BBB's physical and chemical constraints, many current therapies, from cytotoxic drugs to antibody-based proteins, cannot gain access to the tumor. This review describes the characteristics of the BBB and associated changes wrought by the presence of a tumor. Current strategies for enhancing the delivery of therapies across the BBB to the tumor will be discussed, with a distinction made between strategies that seek to disrupt the BBB and those that aim to circumvent it.

Transferrin receptor-targeted vitamin E TPGS micelles for brain cancer therapy: preparation, characterization and brain distribution in rats

The effective treatment of brain cancer is hindered by the poor transport across the blood-brain barrier (BBB) and the low penetration across the blood-tumor barrier (BTB). The objective of this work was to formulate transferrin-conjugated docetaxel (DTX)-loaded d-alpha-tocopheryl polyethylene glycol 1000 succinate (vitamin E TPGS or TPGS) micelles for targeted brain cancer therapy. The micelles with and without transferrin conjugation were prepared by the solvent casting method and characterized for their particle size, polydispersity, drug encapsulation efficiency, drug loading, in vitro release study and brain distribution study. Particle sizes of prepared micelles were determined at 25 °C by dynamic light scattering technique. The external surface morphology was determined by transmission electron microscopy analysis and atomic force microscopy. The encapsulation efficiency was determined by spectrophotometery. In vitro release studies of micelles and control formulations were carried out by dialysis bag diffusion method. The particle sizes of the non-targeted and targeted micelles were <20 nm. About 85% of drug encapsulation efficiency was achieved with micelles. The drug release from transferrin-conjugated micelles was sustained for >24 h with 50% of drug release. The in vivo results indicated that transferrin-targeted TPGS micelles could be a promising carrier for brain targeting due to nano-sized drug delivery, solubility enhancement and permeability which provided an improved and prolonged brain targeting of DTX in comparison to the non-targeted micelles and marketed formulation.