Angiopep-2 Research Articles

Combined Delivery of Temozolomide and siPLK1 Using Targeted Nanoparticles to Enhance Temozolomide Sensitivity in Glioma.

IntroductionTemozolomide (TMZ) is the first-line chemotherapeutic option to treat glioma; however, its efficacy and clinical application are limited by its drug resistance properties. Polo-like kinase 1 (PLK1)-targeted therapy causes G2/M arrest and increases the sensitivity of glioma to TMZ. Therefore, to limit TMZ resistance in glioma, an angiopep-2 (A2)-modified polymeric micelle (A2PEC) embedded with TMZ and a small interfering RNA (siRNA) targeting PLK1 (siPLK1) was developed (TMZ-A2PEC/siPLK).Materials and MethodsTMZ was encapsulated by A2-PEG-PEI-PCL (A2PEC) through the hydrophobic interaction, and siPLK1 was complexed with the TMZ-A2PEC through electrostatic interaction. Then, an angiopep-2 (A2) modified polymeric micelle (A2PEC) embedding TMZ and siRNA targeting polo-like kinase 1 (siPLK1) was developed (TMZ-A2PEC/siPLK).ResultsIn vitro experiments indicated that TMZ-A2PEC/siPLK effectively enhanced the cellular uptake of TMZ and siPLK1 and resulted in significant cell apoptosis and cytotoxicity of glioma cells. In vivo experiments showed that glioma growth was inhibited, and the survival time of the animals was prolonged remarkably after TMZ-A2PEC/siPLK1 was injected via their tail vein.DiscussionThe results demonstrate that the combination of TMZ and siPLK1 in A2PEC could enhance the efficacy of TMZ in treating glioma.

Angiopep2-Conjugated Star-Shaped Polyprodrug Amphiphiles for Simultaneous Glioma-Targeting Therapy and MR Imaging.

The development of valuable theranostic agents for overcoming the blood-brain barrier (BBB) to achieve efficient imaging-guided glioma-targeting delivery of therapeutics remains a great challenge for personalized glioma therapy. We herein developed a novel functional star-shaped polyprodrug amphiphile (denoted as CPP-2) via a combination of successive reversible addition-fragmentation chain transfer (RAFT) polymerization and click functionalization. In a diluted solution, the star amphiphile existed as structurally stable unimolecular micelles, containing hydrophobic cores conjugated with reduction-responsive camptothecin prodrugs Camptothecin (CPT) prodrug monomer (CPTM) and a tertiary amine monomer (2-(diethylamine) ethyl methacrylate, DEA) and hydrophilic oligo-(ethylene glycol) monomethyl ether methacrylat (OEGMA) outer coronas covalently decorated with dual-targeting moieties Angiopep2 (ANG) and small magnetic resonance imaging (MRI) contrast agents DOTA-Gd. In vitro and in vivo data in this study demonstrated that the ANG-modified micelles were capable of efficiently penetrating the BBB and delivering loaded cargoes such as CPT and Gd3+ contrast agents to glioma cells, leading to a considerably enhanced t1 relaxivity as well as antiglioma efficacy. Simultaneously, the targeted antiglioma efficacy and noninvasive MR imaging for a visualized therapy were realized. These collective findings augured well for the star polyprodrug amphiphiles to be utilized as a novel theranostic platform for clinical application in glioma therapy.

Angiopep-2 conjugated nanoparticles loaded with doxorubicin for the treatment of primary central nervous system lymphoma.

Primary central nervous system lymphoma (PCNSL) is a rare brain tumor. Its therapeutic efficacy is much lower than that of traditional lymphoma, largely due to the presence of the blood-brain barrier (BBB), which hinders the effective drug delivery and deposition on the disease site. Angiopep-2 (ANG) can target low-density lipoprotein receptor-related protein (LRP) on the surface of brain capillary endothelial cells (BCECs) and exhibits high BBB transport capability. In this study, we designed an ANG conjugated poly(ethylene glycol)-b-poly(ε-caprolactone) (PEG-b-PCL) (APP) nanoparticle to deliver doxorubicin (DOX) for the treatment of PCNSL. Our data indicated that the targeted APP nanoparticles showed significantly increased cellular uptake by BCECs compared with the control nanoparticles. In the intracranial SU-DHL-2-LUC lymphoma xenograft mice model, APP enhanced drug deposition in tumor tissues, and DOX-loaded APP (APP@DOX) exhibited a better therapeutic effect than free DOX and nontargeted PP@DOX, which significantly prolonged the survival time of mice.

Angiopep-2 Modified Cationic Lipid-Poly-Lactic-Co-Glycolic Acid Delivery Temozolomide and DNA Repair Inhibitor Dbait to Achieve Synergetic Chemo-Radiotherapy Against Glioma.

The therapeutic treatment of glioblastoma multiforme (GBM) remains a major challenge. Synergistic chemotherapy and radiotherapy (RT) have been considered the standard clinical therapy for malignant glioma, but there are some outstanding problems. First, gliomas are deemed exceedingly radio-resistant tumors, owing to efficient DNA double-strand break repair. In addition, the first-line chemotherapeutic agent (temozolomide, TMZ) for glioma shows extensive side effects and low accumulation in brain tumors. Therefore, we designed and constructed an Angiopep-2 modified cationic lipid-Poly-lactic-co-glycolic acid (PLGA), Angiopep-2 (A2)/DSPE-PEG2000/DOTAP/PLGA (APDP), to transport TMZ and a DNA repair inhibitor (Dbait) into glioblastoma cells, achieving concomitant chemo-radiotherapy treatment of glioma. At the cellular level, the APDP+TMZ/Dbait can be well endocytosed and enhance accumulation of the agent in brain tumors. Furthermore, the nanoparticle combined with Dbait improves the efficiency of radiotherapy in GBM. Our experimental data demonstrate that APDP+TMZ/Dbait has great potential as a multipurpose nanomedicine for the synergistic chemo-radiotherapy and radio-sensitization of malignant glioma in precise medical applications.

Co-delivery of GOLPH3 siRNA and gefitinib by cationic lipid-PLGA nanoparticles improves EGFR-targeted therapy for glioma.

Glioblastoma is one of the most aggressive types of brain tumor. Epidermal growth factor receptors (EGFRs) are overexpressed in glioma, and EGFR amplifications and mutations lead to rapid proliferation and invasion. EGFR-targeted therapy might be an effective treatment for glioma. Gefitinib (Ge) is an EGFR tyrosine kinase inhibitor (TKI), and Golgi phosphoprotein 3 (GOLPH3) expression is associated with worse glioma prognosis. Downregulation of GOLPH3 could promote EGFR degradation. Here, an angiopep-2 (A2)-modified cationic lipid-poly (lactic-co-glycolic acid) (PLGA) nanoparticle (A2-N) was developed that can release Ge and GOLPH3 siRNA (siGOLPH3) upon entering glioma cells and therefore acts as a combinatorial anti-tumor therapy. The in vitro and in vivo studies proved that A2-N/Ge/siGOLPH3 successfully crossed the blood-brain barrier (BBB) and targeted glioma. Released siGOLPH3 effectively silenced GOLPH3 mRNA expression and further promoted EGFR and p-EGFR degradation. Released Ge also markedly inhibited EGFR signaling. This combined EGFR-targeted action achieved remarkable anti-glioma effects and could be a safe and effective treatment for glioma. KEY MESSAGES: Angiopep-2-modified cationic lipid polymer can penetrate the BBB. Gefitinib can inhibit EGFR signaling and block the autophosphorylation of critical tyrosine residues on EGFR. GOLPH3 siRNA can be transfected into glioma and downregulate GLOPH3 expression. A2-N/Ge/siGOLPH3 can inhibit glioma growth.

Recombinant expressing angiopep-2 fused anti-VEGF single chain Fab (scFab) could cross blood\u2013brain barrier and target glioma

In 2009, the FDA approved bevacizumab for the treatment of adult patients diagnosed with recurrent glioblastoma. However, the poor permeability of the macromolecules across the blood–brain barrier, determined by multifactorial anatomical and physiological milieu, restricts the clinical therapeutic effect of bevacizumab. The low-density lipoprotein receptor related protein 1 (LRP1) is highly expressed in the endothelial cells of the brain capillary and the glioma cells. Angiopep-2 (ANG) is a 19-aa oligopeptide that can bind to LRP1 and penetrate the blood–brain barrier by receptor-mediated transport. Therefore, ANG can be used as a dual-targeting drug delivery carrier into the brain and the glioma sites. In this study, ANG gene was fused with the C-terminal domain of single-chain antigen binding fragment (scFab) of the anti-VEGF antibody and recombinant scFab-ANG protein was expressed and purified using Rosatte (DE3) strain. We confirmed that ANG could carry anti-VEGF-scFab, penetrate a three-dimensional model of the brain tumor, and cross the hCMEC/D3 monolayer in the in vitro blood–brain barrier model. The animal experiments demonstrated that 3 h after the tail intravenous protein injection, the fluorescent signals in the brains of the mice in the scFab-ANG group were stronger than that in the scFab group. Furthermore, the study of the in situ rat glioma model shows that scFab-ANG could target glioma while anti-VEGF-scFab could not. These findings indicate that scFab-ANG had stronger transepithelial permeability and glioma targeting capacity. Thus, it can be a potential candidate drug for glioblastoma therapy.

Functionalised LRP1 targeted carbon nanotubes across the blood-brain barrier in vitro and in vivo after intravenous injection

Abstract Despite extensive research in drug development, brain cancer is still lacking an efficacious cure due to the inability to deliver current therapeutics to the brain across the blood-brain barrier (BBB). Chemically functionalized carbon nanotubes (f-CNT) constitute a novel class of nanomaterials with attractive physical, chemical and electronic properties. The key advantage of f-CNTs is the extremely high surface area to size ratio allowing a high degree of chemical functionalization making them invaluable tools for designing drug delivery systems to the brain. One of the most interesting characteristics of f-CNTs is their ability to translocate across plasma membranes and enter the cells either passively by direct translocation across membranes or actively via endocytosis. Herein, we confirmed the ability of f-CNTs to cross the BBB and reach the brain in in vitro using a co-culture model of PBEC and primary rat astrocytes and in vivo after intravenous injection. Thanks to their unique optical properties, the uptake of f-CNT in brain was confirmed using state-of-the-art spectroscopic imaging techniques such as multi-photon luminescence imaging, fluorescence lifetime microscopy and Raman spectroscopy. Conjugation with angiopep-2 (ANG), a small peptide targeting the LRP1 receptor overexpressed in the BBB and glioma cells, further enhanced brain parenchyma accumulation in healthy brains. Higher uptake in glioma than brain parenchyma was also observed in glioma-bearing mice after intravenous administration. The inherent brain accumulation ability of f-CNTs coupled with improved brain-targeting by ANG favours the future clinical applications of f-CNTs-ANG to deliver active therapeutics for brain glioma therapy.

Hypoxic Radiosensitizer-Lipid Coated Gold Nanoparticles Enhance the Effects of Radiation Therapy on Tumor Growth.

Radiotherapy (RT) has become one of the most effective treatments for malignant tumor. Intra-tumoral hypoxia is recognized as a chief reason that induces resistance to radiation. Moreover, the toxicities of RT to normal tissues limits the usage of high doses of radiation to eliminate cancer cells. Therefore, developing an effective radiosensitizer is critical for improving the curative effects of RT. In the present study, we developed angiopep-2 (A2) modified hypoxic lipid radiosensitizer (HLR) coated gold nanoparticles (GNPs) (referred to as A2-HRGNPs) to increase the RT sensitivity of tumors. The A2-HRGNPs are comprised of the following two functional components: (1) HLR enhances the RT sensitivity on hypoxic tumor cells; (2) alkylthiol modified GNPs (DGNPs) increase radiation effects by a dose enhancing effect in RT. Our findings suggest that the synergistic radiosensitizing effects of A2-HRGNPs can significantly enhance radiosensitization effects and thus, inhibit tumor growth in vivo.

Development of dual drug loaded PLGA based mesoporous silica nanoparticles and their conjugation with Angiopep-2 to treat glioma

Chemotherapy most of the time fails in the treatment of glioma, because of blood-brain barrier (BBB) which prevents the penetration of drug molecules. This paper addresses the synthesis of mesoporous silica nanoparticles (MSNs) by suitably controlling the size of the particles. These nanoparticles were loaded with doxorubicin (DOX) as an anticancer drug and further modified with poly(lactic-co-glycolic acid) (PLGA) in order to incorporate paclitaxel (PTX) as another anticancer drug. The resulting drug-loaded nanoparticles were subsequently conjugated with Angiopep-2 (ANG) to bind selectively to low-density lipoprotein receptor-related protein 1 (LRP-1 receptors) to enable trans-endocytosis across BBB. The in-vitro cytotoxicity results revealed that a combined effect of DOX and PTX greatly enhanced the anticancer efficacy. The ANG-PTX-PLGA-DOX-MSNs-75 exhibited the significant IC50 value (0.0265 μg/mL) as compared to other nanoparticles. To mimic the transport mechanism of drugs across BBB, an in-vitro BBB model was developed using human brain microvascular endothelial (HBME) cells. Among the functionalized drugs loaded nanocarriers, ANG-PTX-PLGA-DOX-MSNs-75 recognized selectively and bound to LRP-1 receptors, and thereby enhanced the cellular uptake. From the results, we concluded that by tailoring the size of the MSNs and loading of dual drugs, one could effectively antagonize the glioblastoma by crossing the BBB.

A Combination of Tri-Leucine and Angiopep-2 Drives a Polyanionic Polymalic Acid Nanodrug Platform Across the Blood-Brain Barrier.

One of the major problems facing the treatment of neurological disorders is the poor delivery of therapeutic agents into the brain. Our goal is to develop a multifunctional and biodegradable nanodrug delivery system that crosses the blood-brain barrier (BBB) to access brain tissues affected by neurological disease. In this study, we synthesized a biodegradable nontoxic β-poly(l-malic acid) (PMLA or P) as a scaffold to chemically bind the BBB crossing peptides Angiopep-2 (AP2), MiniAp-4 (M4), and the transferrin receptor ligands cTfRL and B6. In addition, a trileucine endosome escape unit (LLL) and a fluorescent marker (rhodamine or rh) were attached to the PMLA backbone. The pharmacokinetics, BBB penetration, and biodistribution of nanoconjugates were studied in different brain regions and at multiple time points via optical imaging. The optimal nanoconjugate, P/LLL/AP2/rh, produced significant fluorescence in the parenchyma of cortical layers II/III, the midbrain colliculi, and the hippocampal CA1-3 cellular layers 30 min after a single intravenous injection; clearance was observed after 4 h. The nanoconjugate variant P/LLL/rh lacking AP2, or the variant P/AP2/rh lacking LLL, showed significantly less BBB penetration. The LLL moiety appeared to stabilize the nanoconjugate, while AP2 enhanced BBB penetration. Finally, nanoconjugates containing the peptides M4, cTfRL, and B6 displayed comparably little and/or inconsistent infiltration of brain parenchyma, likely due to reduced trans-BBB movement. P/LLL/AP2/rh can now be functionalized with intra-brain targeting and drug treatment moieties that are aimed at molecular pathways implicated in neurological disorders.

Self-assembled angiopep-2 modified lipid-poly (hypoxic radiosensitized polyprodrug) nanoparticles delivery TMZ for glioma synergistic TMZ and RT therapy

The addition of temozolomide (TMZ) to radiotherapy (RT) improves survival of patients with glioblastoma (GBM). However, TMZ + RT causes excess toxicity in patients. In this study, we prepared angiopep-2 (A2) modified lipid-poly (hypoxic radiosensitized polyprodrug) nanoparticles for TMZ delivery (A2-P(MIs)25/TMZ) to achieve synergistic effects against glioma. This A2-P(MIs)25/TMZ display highly promising advantages: (1) a hydrophobic P-(MIs)25 core where poorly water-soluble TMZ can be encapsulated; (2) nitro groups of the hydrophobic P-(MIs)25 core that are converted into hydrophilic amino groups (P(NH2s)25) under low oxygen conditions to mimic the oxygen-increased sensitization to RT; (3) a lipid monolayer at the interface of the core and the shell to modify the A2 (a specific ligand for low-density lipoprotein receptor-related protein-1 (LRP-1), which are expressed in the blood-brain barrier (BBB) and human glioma cells), thereby enhancing the drug encapsulation efficiency in glioma. These nanoparticles appear as a promising and robust nanoplatforms for TMZ and hypoxic cell radiosensitization delivery.

A Novel Delivery System of Cyclovirobuxine D for Brain Targeting: Angiopep-Conjugated Polysorbate 80-Coated Liposomes via Intranasal Administration.

The blood-brain barrier (BBB) poses a challenge for the treatment of cerebrovascular diseases including cerebral ischemia-reperfusion injury, Parkinson's syndrome, and cerebral tumors. Nanotechnology has developed as a promising strategy for drug delivery applications to the brain, especially liposomes (Lps) that have shown an intrinsic ability to cross the BBB. Angiopep-2 (ANG), a ligand for low-density lipoprotein receptor-related protein-1 (LRP1), is a good prospect for use as a targeting ligand for brain delivery using Lps. It was also reported that Polysorbate 80 (Tween 80, T80) plays a special role in brain targeting. Moreover, the nasal drug delivery method has attracted increased attention with its brain targeting capability in the clinical treatment of cerebrovascular diseases. The aim of this work was to evaluate the capability of Angiopep-conjugated Polysorbate 80-Coated Liposomes in the delivery of cyclovirobuxine D across the BBB in vitro and in vivo. For this purpose, we first synthesized DSPE-PEG2000-Angiopep-2 then cyclovirobuxine D was encapsulated in Angiopep-conjugated Polysorbate 80-Coated Liposomes (T80-An2-CVB-D-Lps) prepared by thin film evaporation and an ultrasonic technique. Formulations were characterized in terms of encapsulation efficiency, transmission electron microscope (TEM) morphology, size distribution, and zeta potential. Angiopep-conjugated Polysorbate 80-Coated Liposomes enhanced in vitro BBB transport of CVB-D compared to the nontargeted liposomes and the CVB-D solution in the BBB model consisting of brain microvascular endothelial (bEnd.3) cells. To evaluate the brain targeting of T80-An2-CVB-D-Lps in vivo, microdialysis samples were collected from the striatum and blood simultaneously. Rats were dosed with brain-targeting liposomes, CVB-D liposomes and CVB-D solution by intranasal administration and with brain-targeting liposomes by intravenous injection. The results showed that T80-An2-CVB-D-Lps were spherical, small (approximately 80 nm), homogeneously dispersed, negatively charged and possessed a high encapsulation efficiency. T80-An2-CVB-D-Lps crossed the BBB model better than the other treatments did. In addition, in a pharmacodynamic study, there was a higher AUC in the brain after T80-An2-CVB-D-Lps by intranasal administration. In conclusion, T80-An2-Lps can enhance the BBB permeability and improve the transport of CVB-D to the brain. This coadministration strategy can be utilized to enhance the brain accumulation in other cerebrovascular diseases.

MRI compatible MS2 nanoparticles designed to cross the blood–brain-barrier: providing a path towards tinnitus treatment

Fundamental challenges of targeting specific brain regions for treatment using pharmacotherapeutic nanoparticle (NP) carriers include circumventing the blood–brain-barrier (BBB) and tracking delivery. Angiopep-2 (AP2) has been shown to facilitate the transport of large macromolecules and synthetic nanoparticles across the BBB. Thus, conjugation of AP2 to an MS2 bacteriophage based NP should also permit transport across the BBB. We have fabricated and tested a novel MS2 capsid-based NP conjugated to the ligand AP2. The reaction efficiency was determined to be over 70%, with up to two angiopep-2 conjugated per MS2 capsid protein. When linked with a porphyrin ring, manganese (Mn2+) remained stable within MS2 and was MRI detectable. Nanoparticles were introduced intracerebroventricularly or systemically. Systemic delivery yielded dose dependent, non-toxic accumulation of NPs in the midbrain. Design of a multifunctional MRI compatible NP platform provides a significant step forward for the diagnosis and treatment of intractable brain conditions, such as tinnitus.

Targeted Imaging of Brain Tumors with a Framework Nucleic Acid Probe.

Development of agents for delivering drugs and imaging probes across the blood-brain barrier (BBB) remains a major challenge. In this study, we designed a biocompatible framework nucleic acid (FNA)-based imaging probe for brain tumor-targeting. We employed a typical type of FNAs, tetrahedral DNA nanostructures (TDNs), as the building block, which were modified with angiopep-2 (ANG), a 19-mer peptide derived from human Kunitz domain of aprotinin. This probe exhibited high binding efficiency with low-density lipoprotein receptor-related protein-1 (LRP-1) of BBB and glioma. We found that ANG-functionalized TDNs (ANG-TDNs) stayed intact for at least 12 h in serum, and that ANG modification effectively enhanced cellular uptake of TDNs in brain capillary endothelial cells and Uppsala 87 malignant glioma (U87MG) cells. Remarkably, studies in both in vitro and in vivo models revealed that ANG-TDNs could cross the BBB. Especially, in vivo imaging showed strong fluorescent signals in U87MG human glioblastoma xenograft in nude mice. This study establishes that the FNA-based platform provides a new theranostic tool for the study and therapy of brain tumors.

Electroresponsive Nanoparticles Improve Antiseizure Effect of Phenytoin in Generalized Tonic-Clonic Seizures.

Previously, we developed electroresponsive hydrogel nanoparticles (ERHNPs) modified with angiopep-2 (ANG) to facilitate the delivery of the antiseizure drug phenytoin sodium (PHT). However, the electroresponsive characteristics were not verified directly in epileptic mice and the optimal preparation formula for electroresponsive ability is still unclear. Here, we further synthesized PHT-loaded ANG-ERHNPs (ANG-PHT-HNPs) and PHT-loaded nonelectroresponsive hydrogel nanoparticles (ANG-PHT-HNPs) by changing the content of sodium 4-vinylbenzene sulfonate in the preparation formulae. In vivo microdialysis analysis showed that ANG-PHT-ERHNPs not only have the characteristics of a higher distribution in the central nervous system, but also have electroresponsive ability, which resulted in a strong release of nonprotein-bound PHT during seizures. In both electrical- (maximal electrical shock) and chemical-induced (pentylenetetrazole and pilocarpine) seizure models, ANG-PHT-ERHNPs lowered the effective therapeutic doses of PHT and demonstrated the improved antiseizure effects compared with ANG-PHT-HNPs or PHT solution. These results demonstrate that ANG-ERHNPs are able to transport PHT into the brain efficiently and release them when epileptiform activity occurred, which is due to the content of sodium 4-vinylbenzene sulfonate in formula. This may change the therapeutic paradigm of existing drug treatment for epilepsy into a type of on-demand control for epilepsy in the future.

Translocation of LRP1 targeted carbon nanotubes of different diameters across the blood–brain barrier in vitro and in vivo

Brain glioblastoma and neurodegenerative diseases are still largely untreated due to the inability of most drugs to cross the blood–brain barrier (BBB). Nanoparticles have emerged as promising tools for drug delivery applications to the brain; in particular carbon nanotubes (CNTs) that have shown an intrinsic ability to cross the BBB in vitro and in vivo. Angiopep-2 (ANG), a ligand for the low-density lipoprotein receptor-related protein-1 (LRP1), has also shown promising results as a targeting ligand for brain delivery using nanoparticles (NPs). Here, we investigate the ability of ANG-targeted chemically-functionalised multi-walled carbon nanotubes (f-MWNTs) to cross the BBB in vitro and in vivo. ANG was conjugated to wide and thin f-MWNTs creating w-MWNT-ANG and t-MWNT-ANG, respectively. All f-MWNTs were radiolabelled to facilitate quantitative analyses by γ-scintigraphy. ANG conjugation to f-MWNTs enhanced BBB transport of w- and t-MWNTs-ANG compared to their non-targeted equivalents using an in vitro co-cultured BBB model consisting of primary porcine brain endothelial cells (PBEC) and primary rat astrocytes. Additionally, following intravenous administration w-MWNTs-ANG showed significantly higher whole brain uptake than the non-targeted w-MWNT in vivo reaching ~2% injected dose per g of brain (%ID/g) within the first hour post-injection. Furthermore, using a syngeneic glioma model, w-MWNT-ANG showed enhanced uptake in glioma brain compared to normal brain at 24h post-injection. t-MWNTs-ANG, on the other hand, showed higher brain accumulation than w-MWNTs. However, no significant differences were observed between t-MWNT and t-MWNT-ANG indicating the importance of f-MWNTs diameter towards their brain accumulation. The inherent brain accumulation ability of f-MWNTs coupled with improved brain-targeting by ANG favours the future clinical applications of f-MWNT-ANG to deliver active therapeutics for brain glioma therapy.

Co-delivery of doxorubicin and siRNA for glioma therapy by a brain targeting system: angiopep-2-modified poly(lactic-co-glycolic acid) nanoparticles

It is very challenging to treat brain cancer because of the blood–brain barrier (BBB) restricting therapeutic drug or gene to access the brain. In this research project, angiopep-2 (ANG) was used as a brain-targeted peptide for preparing multifunctional ANG-modified poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs), which encapsulated both doxorubicin (DOX) and epidermal growth factor receptor (EGFR) siRNA, designated as ANG/PLGA/DOX/siRNA. This system could efficiently deliver DOX and siRNA into U87MG cells leading to significant cell inhibition, apoptosis and EGFR silencing in vitro. It demonstrated that this drug system was capable of penetrating the BBB in vivo, resulting in more drugs accumulation in the brain. The animal study using the brain orthotopic U87MG glioma xenograft model indicated that the ANG-targeted co-delivery of DOX and EGFR siRNA resulted in not only the prolongation of the life span of the glioma-bearing mice but also an obvious cell apoptosis in glioma tissue.

Angiopep-2-Mediated Delivery of Human Manganese Superoxide Dismutase in Brain Endothelial Cells and its Protective Effect Against Oxidative Stress

Oxidative stress has been considered as the leading cause of blood–brain barrier disruption which implicates many neurological disorders. Manganese superoxide dismutase (MnSOD or SOD2) is one of the crucial antioxidant enzymes that can provide substantial protection against oxidative damage. However, the therapeutic effect of the enzyme in such neurological diseases is limited due to poor transduction into brain microvascular endothelial cells. In the present study, a fusion protein of human SOD2 and a brain targeting peptide, Angiopep-2 (AP-2), was generated by genetic engineering. The SOD2-AP-2 and control SOD2 were successfully expressed in Escherichia coli and purified using immobilized metal affinity chromatography. Purified SOD2-AP-2 exhibited 1,090 μ/mg of specific SOD activity, which retained a significant activity in the same order of magnitude as that of native SOD2. The in vitro transduction demonstrated that 1 µM of SOD2-AP-2 delivered efficiently to immortalized mouse brain endothelial cell line within 30 min whereas, control SOD2 did not. Moreover, pretreatment with 50 units of SOD2-AP-2 for 1 h could significantly protect cells against paraquat up to 2 mM but control SOD2 pretreatment did not show a protective effect. Taken together, our findings pave the way for SOD2-AP-2 to be a potential therapeutic candidate for neurological diseases.

Angiopep-conjugated electro-responsive hydrogel nanoparticles: therapeutic potential for epilepsy.

A safe and effective therapy for epilepsy requires a drug delivery system that can penetrate the blood-brain barrier and subsequently release antiepileptic drugs rapidly to suppress neuronal discharges in a timely manner. We have developed electro-responsive hydrogel nanoparticles (ERHNPs) modified with angiopep-2 (ANG) to facilitate the delivery of the antiepileptic drug phenytoin sodium. The resulting ANG-ERHNPs had an average diameter of (102.3±16.8) nm and were electro-sensitive with regard to particle size and drug release in vitro. ANG-ERHNPs have the characteristics of penetrate the BBB easily, resulting in a higher distribution in the central system. The improved antiepileptic effects were investigated with the amygdala kindling model. The results demonstrate that the ANG-ERHNPs were able to transport antiepileptic drugs into the brain and release them under electroencephalograph epileptiform abnormalities to greatly improve the therapeutic index of existing drugs in clinical use.

Angiopep‐Conjugated Electro‐Responsive Hydrogel Nanoparticles: Therapeutic Potential for Epilepsy

AbstractA safe and effective therapy for epilepsy requires a drug delivery system that can penetrate the blood–brain barrier and subsequently release antiepileptic drugs rapidly to suppress neuronal discharges in a timely manner. We have developed electro‐responsive hydrogel nanoparticles (ERHNPs) modified with angiopep‐2 (ANG) to facilitate the delivery of the antiepileptic drug phenytoin sodium. The resulting ANG‐ERHNPs had an average diameter of (102.3±16.8) nm and were electro‐sensitive with regard to particle size and drug release in vitro. ANG‐ERHNPs have the characteristics of penetrate the BBB easily, resulting in a higher distribution in the central system. The improved antiepileptic effects were investigated with the amygdala kindling model. The results demonstrate that the ANG‐ERHNPs were able to transport antiepileptic drugs into the brain and release them under electroencephalograph epileptiform abnormalities to greatly improve the therapeutic index of existing drugs in clinical use.