Preparation of Angiopep-2 Peptide-Modified Bubble Liposomes for Delivery to the Brain

Angiopep-2-Functionalized Lipid Cubosomes for Blood-Brain Barrier Crossing and Glioblastoma Treatment

Glioblastoma multiforme (GBM) is an aggressive brain cancer with high malignancy and resistance to conventional treatments, resulting in a bleak prognosis. Nanoparticles offer a way to cross the blood-brain barrier (BBB) and deliver precise therapies to tumor sites with reduced side effects. In this study, we developed angiopep-2 (Ang2)-functionalized lipid cubosomes loaded with cisplatin (CDDP) and temozolomide (TMZ) for crossing the BBB and providing targeted glioblastoma therapy. Developed lipid cubosomes showed a particle size of around 300 nm and possessed an internal ordered inverse primitive cubic phase, a high conjugation efficiency of Ang2 to the particle surface, and an encapsulation efficiency of more than 70% of CDDP and TMZ. In vitro models, including BBB hCMEC/D3 cell tight monolayer, 3D BBB cell spheroid, and microfluidic BBB/GBM-on-a-chip models with cocultured BBB and glioblastoma cells, were employed to study the efficiency of the developed cubosomes to cross the BBB and showed that Ang2-functionalized cubosomes can penetrate the BBB more effectively. Furthermore, Ang2-functionalized cubosomes showed significantly higher uptake by U87 glioblastoma cells, with a 3-fold increase observed in the BBB/GBM-on-a-chip model as compared to that of the bare cubosomes. Additionally, the in vivo biodistribution showed that Ang2 modification could significantly enhance the brain accumulation of cubosomes in comparison to that of non-functionalized particles. Moreover, CDDP-loaded Ang2-functionalized cubosomes presented an enhanced toxic effect on U87 spheroids. These findings suggest that the developed Ang2-cubosomes are prospective for improved BBB crossing and enhanced delivery of therapeutics to glioblastoma and are worth pursuing further as a potential application of nanomedicine for GBM treatment.

RNAi therapies: Expanding applications for extrahepatic diseases and overcoming delivery challenges

The era of RNA medicine has become a reality with the success of messenger RNA (mRNA) vaccines against COVID-19 and the approval of several RNA interference (RNAi) agents in recent years. Particularly, therapeutics based on RNAi offer the promise of targeting intractable and previously undruggable disease genes. Recent advances have focused in developing delivery systems to enhance the poor cellular uptake and insufficient pharmacokinetic properties of RNAi therapeutics and thereby improve its efficacy and safety. However, such approach has been mainly achieved via lipid nanoparticles (LNPs) or chemical conjugation with N-Acetylgalactosamine (GalNAc), thus current RNAi therapy has been limited to liver diseases, most likely to encounter liver-targeting limitations. Hence, there is a huge unmet medical need for intense evolution of RNAi therapeutics delivery systems to target extrahepatic tissues and ultimately extend their indications for treating various intractable diseases. In this review, challenges of delivering RNAi therapeutics to tumors and major organs are discussed, as well as their transition to clinical trials. This review also highlights innovative and promising preclinical RNAi-based delivery platforms for the treatment of extrahepatic diseases.

An update on dual targeting strategy for cancer treatment

The key issue in the treatment of solid tumors is the lack of efficient strategies for the targeted delivery and accumulation of therapeutic cargoes in the tumor microenvironment (TME). Targeting approaches are designed for more efficient delivery of therapeutic agents to cancer cells while minimizing drug toxicity to normal cells and off-targeting effects, while maximizing the eradication of cancer cells. The highly complicated interrelationship between the physicochemical properties of nanoparticles, and the physiological and pathological barriers that are required to cross, dictates the need for the success of targeting strategies. Dual targeting is an approach that uses both purely biological strategies and physicochemical responsive smart delivery strategies to increase the accumulation of nanoparticles within the TME and improve targeting efficiency towards cancer cells. In both approaches, either one single ligand is used for targeting a single receptor on different cells, or two different ligands for targeting two different receptors on the same or different cells. Smart delivery strategies are able to respond to triggers that are typical of specific disease sites, such as pH, certain specific enzymes, or redox conditions. These strategies are expected to lead to more precise targeting and better accumulation of nano-therapeutics. This review describes the classification and principles of dual targeting approaches and critically reviews the efficiency of dual targeting strategies, and the rationale behind the choice of ligands. We focus on new approaches for smart drug delivery in which synthetic and/or biological moieties are attached to nanoparticles by TME-specific responsive linkers and advanced camouflaged nanoparticles.

Mechanistic Insights and Therapeutic Delivery through Micro/Nanobubble-Assisted Ultrasound

Ultrasound with low frequency (20–100 kHz) assisted drug delivery has been widely investigated as a non-invasive method to enhance the permeability and retention effect of drugs. The functional micro/nanobubble loaded with drugs could provide an unprecedented opportunity for targeted delivery. Then, ultrasound with higher intensity would locally burst bubbles and release agents, thus avoiding side effects associated with systemic administration. Furthermore, ultrasound-mediated destruction of micro/nanobubbles can effectively increase the permeability of vascular membranes and cell membranes, thereby not only increasing the distribution concentration of drugs in the interstitial space of target tissues but also promoting the penetration of drugs through cell membranes into the cytoplasm. These advancements have transformed ultrasound from a purely diagnostic utility into a promising theragnostic tool. In this review, we first discuss the structure and generation of micro/nanobubbles. Second, ultrasound parameters and mechanisms of therapeutic delivery are discussed. Third, potential biomedical applications of micro/nanobubble-assisted ultrasound are summarized. Finally, we discuss the challenges and future directions of ultrasound combined with micro/nanobubbles.

Angiopep-2-Modified Nanoparticles for Brain-Directed Delivery of Therapeutics: A Review

Nanotechnology has opened up a world of possibilities for the treatment of brain disorders. Nanosystems can be designed to encapsulate, carry, and deliver a variety of therapeutic agents, including drugs and nucleic acids. Nanoparticles may also be formulated to contain photosensitizers or, on their own, serve as photothermal conversion agents for phototherapy. Furthermore, nano-delivery agents can enhance the efficacy of contrast agents for improved brain imaging and diagnostics. However, effective nano-delivery to the brain is seriously hampered by the formidable blood–brain barrier (BBB). Advances in understanding natural transport routes across the BBB have led to receptor-mediated transcytosis being exploited as a possible means of nanoparticle uptake. In this regard, the oligopeptide Angiopep-2, which has high BBB transcytosis capacity, has been utilized as a targeting ligand. Various organic and inorganic nanostructures have been functionalized with Angiopep-2 to direct therapeutic and diagnostic agents to the brain. Not only have these shown great promise in the treatment and diagnosis of brain cancer but they have also been investigated for the treatment of brain injury, stroke, epilepsy, Parkinson’s disease, and Alzheimer’s disease. This review focuses on studies conducted from 2010 to 2021 with Angiopep-2-modified nanoparticles aimed at the treatment and diagnosis of brain disorders.

Homogeneous antibody-angiopep 2 conjugates for effective brain targeting

Antibody-based therapy has shown great success in the treatment of many diseases, including cancers. While antibodies and antibody-drug conjugates (ADCs) have also been evaluated for central nervous system (CNS) disorders as well as brain tumors, their therapeutic efficacy can be substantially limited due to low permeability across the blood-brain barrier (BBB). Thus, improving BBB permeability of therapeutic antibodies is critical in establishing this drug class as a reliable clinical option for CNS diseases. Here, we report that, compared with a conventional heterogeneous conjugation, homogeneous conjugation of the synthetic BBB shuttle peptide angiopep-2 (Ang2) to a monoclonal antibody (mAb) provides improved binding affinity for brain microvascular endothelial cells in vitro and accumulation into normal brain tissues in vivo. In a mouse model, we also demonstrate that the homogeneous anti-EGFR mAb-Ang2 conjugate administered intravenously efficiently accumulates in intracranial tumors. These findings suggest that homogeneous conjugation of BBB shuttle peptides such as Ang2 is a promising approach to enhancing the therapeutic efficacy of antibody agents for CNS diseases.

Design and characterization of a novel dimeric blood-brain barrier penetrating TNFα inhibitor

Tumor necrosis factor-alpha (TNFα) inhibitors could prevent neurological disorders systemically, but their design generally relies on molecules unable to cross the blood-brain barrier (BBB). This research was aimed to design and characterize a novel TNFα inhibitor based on the angiopeptide-2 as a BBB shuttle molecule fused to the extracellular domain of human TNFα receptor 2 and a mutated vascular endothelial growth factor (VEGF) dimerization domain. This new chimeric protein (MTV) would be able to trigger receptor-mediated transcytosis across the BBB via low-density lipoprotein receptor-related protein-1 (LRP-1) and inhibit the cytotoxic effect of TNFα more efficiently because of its dimeric structure. Stably transformed CHO cells successfully expressed MTV, and its purification by Immobilized-Metal Affinity Chromatography (IMAC) rendered high purity degree. Mutated VEGF domain included in MTV did not show cell proliferation or angiogenic activities measured by scratch and aortic ring assays, which corroborate that the function of this domain is restricted to dimerization. The pairs MTV-TNFα (Kd 279 ± 40.9 nM) and MTV-LRP1 (Kd 399 ± 50.5 nM) showed high affinity by microscale thermophoresis, and a significant increase in cell survival was observed after blocking TNFα with MTV in a cell cytotoxicity assay. Also, the antibody staining in CHOK1 and bEnd3 cells demonstrated the adhesion of MTV to the LRP1 receptor located in the cell membrane. These results provide compelling evidence for the proper functioning of the three main domains of MTV individually, which encourage us to continue the research with this new molecule as a potential candidate for the systemic treatment of neurological disorders.

A Spontaneous Membrane-Adsorption Approach to Enhancing Second Near-Infrared Deep-Imaging-Guided Intracranial Tumor Therapy

Herein, a functional class of microenvironment-associated nanomaterials is reported for improving the second near-infrared (NIR-II) imaging and photothermal therapeutic effect on intracranial tumors via a spontaneous membrane-adsorption approach. Specific peptides, photothermal agents, and biological alkylating agents were designed to endow the nanogels with high targeting specificity, photothermal properties, and pharmacological effects. Importantly, the frozen scanning electron microscopy technology (cryo-SEM) was utilized to observe the self-association of nanomaterials on tumor cells. Interestingly, the spontaneous membrane-adsorption behavior of nanomaterials was captured through direct imaging evidence. Histological analysis showed that the cross-linking adhesion in intracranial tumor and monodispersity in normal tissues of the nanogels not only enhanced the retention time but also ensured excellent biocompatibility. Impressively, in vivo data confirmed that the microenvironment-associated nanogels could significantly enhance brain tumor clearance rate within a short treatment timeframe (only two weeks). In short, utilizing the spontaneous membrane-adsorption strategy can significantly improve NIR-II diagnosis and phototherapy in brain diseases while avoiding high-risk complications.

Advancements in liposome technology: Preparation techniques and applications in food, functional foods, and bioactive delivery: A review

Liposomes play a significant role in encapsulation of various bioactive compounds (BACs), including functional food ingredients to improve the stability of core. This technology can be used for promoting an effective application in functional food and nutraceuticals. Incorporation of traditional and emerging methods for the developments of liposome for loading BACs resulted in viable and stable liposome formulations for industrial applications. Thus, the advance technologies such as supercritical fluidic methods, microfluidization, ultrasonication with traditional methods are revisited. Liposomes loaded with plant and animal BACs have been introduced for functional food and nutraceutical applications. In general, application of liposome systems improves stability, delivery, and bioavailability of BACs in functional food systems and nutraceuticals. This review covers the current techniques and methodologies developed and practiced in liposomal preparation and application in functional foods.

Think Big, Start Small: How Nanomedicine Could Alleviate the Burden of Rare CNS Diseases

The complexity and organization of the central nervous system (CNS) is widely modulated by the presence of the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSFB), which both act as biochemical, dynamic obstacles impeding any type of undesirable exogenous exchanges. The disruption of these barriers is usually associated with the development of neuropathologies which can be the consequence of genetic disorders, local antigenic invasions, or autoimmune diseases. These disorders can take the shape of rare CNS-related diseases (other than Alzheimer's and Parkinson's) which a exhibit relatively low or moderate prevalence and could be part of a potential line of treatments from current nanotargeted therapies. Indeed, one of the most promising therapeutical alternatives in that field comes from the development of nanotechnologies which can be divided between drug delivery systems and diagnostic tools. Unfortunately, the number of studies dedicated to treating these rare diseases using nanotherapeutics is limited, which is mostly due to a lack of interest from industrial pharmaceutical companies. In the present review, we will provide an overview of some of these rare CNS diseases, discuss the physiopathology of these disorders, shed light on how nanotherapies could be of interest as a credible line of treatment, and finally address the major issues which can hinder the development of efficient therapies in that area.

Microbubbles and Nanobubbles with Ultrasound for Systemic Gene Delivery

The regulation of gene expression is a promising therapeutic approach for many intractable diseases. However, its use in clinical applications requires the efficient delivery of nucleic acids to target tissues, which is a major challenge. Recently, various delivery systems employing physical energy, such as ultrasound, magnetic force, electric force, and light, have been developed. Ultrasound-mediated delivery has particularly attracted interest due to its safety and low costs. Its delivery effects are also enhanced when combined with microbubbles or nanobubbles that entrap an ultrasound contrast gas. Furthermore, ultrasound-mediated nucleic acid delivery could be performed only in ultrasound exposed areas. In this review, we summarize the ultrasound-mediated nucleic acid systemic delivery system, using microbubbles or nanobubbles, and discuss its possibilities as a therapeutic tool.

I6P7 peptide modified superparamagnetic iron oxide nanoparticles for magnetic resonance imaging detection of low-grade brain gliomas

Glioma, the most severe primary brain malignancy, has very low survival rates and a high level of recurrence. Nowadays, conventional treatments for these patients are suffering a similar plight owing to the distinctive features of the malignant gliomas, for example chemotherapy is limited by the blood-brain barrier while surgery and radiation therapy are affected by the unclear boundaries of tumor from normal tissue. In the present study, a novel superparamagnetic iron oxide (SPIO) nanoprobe for enhanced T2-weighted magnetic resonance imaging (MRI) was developed. A frequently used MRI probe, SPIO nanoparticles, was coated with a silica outer layer and for the first time was covalently modified with interleukin-6 receptor targeting peptides (I6P7) to promote transportation through the blood-brain barrier and recognition of low-grade gliomas. The efficiency of transcytosis across the blood-brain barrier was examined in vitro using a transwell invasion model and in vivo in nude mice with orthotopic low-grade gliomas. The targeting nanoprobe showed significant MRI enhancement and has potential for use in the diagnosis of low-grade gliomas.

Nanotechnology as a Platform for the Development of Injectable Parenteral Formulations: A Comprehensive Review of the Know-Hows and State of the Art

Within recent decades, the development of nanotechnology has made a significant contribution to the progress of various fields of study, including the domains of medical and pharmaceutical sciences. A substantially transformed arena within the context of the latter is the development and production of various injectable parenteral formulations. Indeed, recent decades have witnessed a rapid growth of the marketed and pipeline nanotechnology-based injectable products, which is a testimony to the remarkability of the aforementioned contribution. Adjunct to the ability of nanomaterials to deliver the incorporated payloads to many different targets of interest, nanotechnology has substantially assisted to the development of many further facets of the art. Such contributions include the enhancement of the drug solubility, development of long-acting locally and systemically injectable formulations, tuning the onset of the drug’s release through the endowment of sensitivity to various internal or external stimuli, as well as adjuvancy and immune activation, which is a desirable component for injectable vaccines and immunotherapeutic formulations. The current work seeks to provide a comprehensive review of all the abovementioned contributions, along with the most recent advances made within each domain. Furthermore, recent developments within the domains of passive and active targeting will be briefly debated.

Modification of graphene oxide by angiopep-2 enhances anti-glioma efficiency of the nanoscaled delivery system for doxorubicin

OBJECTIVE

This study aimed to evaluate the efficacy of the improved nanoscaled delivery system for doxorubicin (Dox) based on angiopep (ANG)-2 modified graphene oxide (GO), the so-called ANG-Dox-GO, in suppressing the growth and and metastasis of glioma cells.

RESULTS

Modification of GO by angiopep-2 significantly increased the cellular uptake of Dox. In addition, ANG-Dox-GO treatment of U87 MG cells significantly inhibited cell viability, decreased clone number, cell migration and invasion andinduced cell apoptosis, with superior efficiency over that of Dox-GO and free Dox. Similar results were observed in in vivo experiments-tumor size and weight of glioma xenograft mice were obviously decreased after treatments with ANG-Dox-GO, Dox-GO and Dox, respectively, as compared with control group, and the efficiency was the highest in ANG-Dox-GO, followed by Dox-Go and Dox.

CONCLUSIONS

ANG-Dox-GO exhibited superior anti-glioma effects over Dox-GO both in vitro and in vivo experiments.

METHODS

The morphology of ANG-Dox-GO was analyzed by UV visible absorption spectroscopy and atomic force microscopy and its in vitro cellular uptake was measured using confocal imaging analysis. The antitumor effects of GO, unbound Dox, Dox-GO and ANG-Dox-GO were evaluated by MTT assay, colony-forming assay, cell apoptosis assay and Transwell assay in U87 malignant glioma (MG) cells.

Manipulation of Mitophagy by "All-in-One" nanosensitizer augments sonodynamic glioma therapy

Limited penetration of chemotherapeutic drugs through the blood brain barrier (BBB), and the increased chemo-resistance of glioma cells due to macroautophagy/autophagy, result in high tumor recurrence and extremely limited survival of glioma patients. Ultrasound-targeted microbubble destruction (UTMD) is a technique of transient and reversible BBB disruption, which greatly facilitates intracerebral drug delivery. In addition, sonodynamic therapy (SDT) based on ultrasound stimulation and a sonosensitizer, can be a safe and noninvasive strategy for treating glioma. We innovatively designed a smart "all-in-one" nanosensitizer platform by incorporating the sonoactive chlorin e6 (Ce6) and an autophagy inhibitor-hydroxychloroquine (HCQ) into angiopep-2 peptide-modified liposomes (designated as ACHL), which integrates multiple diagnostic and therapeutic functions. ACHL selectively accumulated in the brain tumors during the optimal time-window of transient UTMD-mediated BBB opening. The nanosensitizer then responded to a second ultrasonic stimulation, and simultaneously unloaded HCQ and generated ROS in the glioma cells. The sonotherapy triggered apoptosis as well as MAPK/p38-PINK1-PRKN-dependent mitophagy, in which the antioxidant relieved the sonotoxicity and MAPK/p38 activation, while the inhibition of MAPK/p38 attenuated the progression toward mitophagy by compromising redistribution of PRKN. Moreover, HCQ blocking autophagosome degradation, augmented intracellular ROS production and resulted in an oxidative-damage regenerative loop. ACHL-SDT treatment using this construct significantly inhibited the xenograft-tumor growth and prolonged the survival time of tumor-bearing mice, exhibiting an improved therapeutic efficiency. All together, we demonstrated a precision sonotherapy with simultaneous apoptosis induction and mitophagy inhibition, which served as an intelligently strategic sense of working alongside, providing new insights into the theranostics of brain tumors.

ABBREVIATIONS

ACHL: Angiopep-2-modified liposomes loaded with Ce6 and hydroxychloroquine; ACL: Angiopep-2-modified liposomes loaded with Ce6; BBB: blood brain barrier; Ce6: chlorin e6; CHL: liposomes loaded with Ce6 and hydroxychloroquine; CL: liposomes loaded with Ce6; CNS: central nervous system; DDS: drug delivery system; EB: Evans blue; FUS: focused ultrasound; HCQ: hydroxychloroquine; LRP1: low density lipoprotein receptor-related protein 1; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MAPK: mitogen-activated protein kinase; MBs: microbubbles; MTG: MitoTracker Green; MTR: MitoTracker Red; MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; PBS: phosphate-buffered saline; PDI: polydispersity index; PINK1: PTEN induced kinase 1; PRKN/parkin: parkin RBR E3 ubiquitin protein ligase; ROS: reactive oxygen species; SDT: sonodynamic therapy; SQSTM1: sequestome 1; TA: terephthalic acid; TEM: transmission electron microscopy; TUNEL: terminal deoxynucleotidyl transferase mediated dUTP nick-end labeling; US: ultrasound; UTMD: ultrasound-targeted microbubble destruction.

Development of Antibody-Modified Nanobubbles Using Fc-Region-Binding Polypeptides for Ultrasound Imaging

Ultrasound (US) imaging is a widely used imaging technique. The use of US contrast agents such as microbubbles, which consist of phospholipids and are filled with perfluorocarbon gases, has become an indispensable component of clinical US imaging, while molecular US imaging has recently attracted significant attention in combination with efficient diagnostics. The avidin–biotin interaction method is frequently used to tether antibodies to microbubbles, leading to the development of a molecular targeting US imaging agent. However, avidin still has limitations such as immunogenicity. We previously reported that lipid-based nanobubbles (NBs) containing perfluorocarbon gas are suitable for US imaging and gene delivery. In this paper, we report on the development of a novel antibody modification method for NBs using Fc-region-binding polypeptides derived from protein A/G. First, we prepared anti-CD146 antibody-modified NBs using this polypeptide, resulting in high levels of attachment to human umbilical vein endothelial cells expressing CD146. To examine their targeting ability and US imaging capability, the NBs were administered to tumor-bearing mice. The contrast imaging of antibody-modified NBs was shown to be prolonged compared with that of non-labeled NBs. Thus, this antibody modification method using an Fc-binding polypeptide may be a feasible tool for developing a next-generation antibody-modified US imaging agent.

Peptide and protein nanoparticle conjugates: versatile platforms for biomedical applications

Peptide- and protein-nanoparticle conjugates have emerged as powerful tools for biomedical applications, enabling the treatment, diagnosis, and prevention of disease. In this review, we focus on the key roles played by peptides and proteins in improving, controlling, and defining the performance of nanotechnologies. Within this framework, we provide a comprehensive overview of the key sequences and structures utilised to provide biological and physical stability to nano-constructs, direct particles to their target and influence their cellular and tissue distribution, induce and control biological responses, and form polypeptide self-assembled nanoparticles. In doing so, we highlight the great advances made by the field, as well as the challenges still faced in achieving the clinical translation of peptide- and protein-functionalised nano-drug delivery vehicles, imaging species, and active therapeutics.

Peptide Mediated Brain Delivery of Nano- and Submicroparticles: A Synergistic Approach

The brain is a complex, regulated organ with a highly controlled access mechanism: The Blood-Brain Barrier (BBB). The selectivity of this barrier is a double-edged sword, being both its greatest strength and weakness. This weakness is evident when trying to target therapeutics against diseases within the brain. Diseases such as metastatic brain cancer have extremely poor prognosis due to the poor permeability of many therapeutics across the BBB. Peptides can be designed to target BBB receptors and gain access to the brain by transcytosis. These peptides (known as BBB-shuttles) can carry compounds, usually excluded from the brain, across the BBB. BBB-shuttles are limited by poor loading of therapeutics and degradation of the peptide and cargo. Likewise, nano- submicro- and microparticles can be fine-tuned to limit their degradation and with high loading of therapeutics. However, most nano- and microparticles' core materials completely lack efficient targeting, with a few selected materials able to cross the BBB passively. Combining the selectivity of peptides with the high loading potential of nano-, microparticles offers an exciting strategy to develop novel, targeted therapeutics towards many brain disorders and diseases. Nevertheless, at present the field is diverse, in both scope and nomenclature, often with competing or contradictory names. In this review, we will try to address some of these issues and evaluate the current state of peptide mediated nano,-microparticle transport to the brain, analyzing delivery vehicle type and peptide design, the two key components that must act synergistically for optimal therapeutic impact.

Recent Advances in Endogenous and Exogenous Stimuli-Responsive Nanocarriers for Drug Delivery and Therapeutics

Significant progress has been achieved in the development of stimuli-responsive nanocarriers for drug delivery, diagnosis, and therapy. Various types of triggers are utilized in the development of nanocarrier delivery. Endogenous factors such as changes in pH, redox, gradient, and enzyme concentration which are linked to disease progression have been utilized for controlling biodistribution and releasing drugs from nanocarriers, as well as increasing subsequent pharmacological activity at the disease site. Nanocarriers which respond to artificially-induced exogenous factors (such as temperature, light, magnetic field, and ultrasound) have also been developed. This review aims to discuss recent advances in the design of stimuli-responsive nanocarriers which appear to have a promising future in medicine.

Blood-brain barrier peptide shuttles

Brain delivery is hampered by the presence of the blood-brain barrier (BBB), a natural defence of the brain that protects it and allows the entrance of nutrients by several mechanisms. Taking advantage of these mechanisms is an opportunity to treat brain related diseases. Among the different alternatives, BBB peptide shuttles are gaining attention to increase brain delivery of therapeutics. The most recent advances in the field are analysed here.