Xiaoling Gao

Lactoferrin-conjugated PEG-PLA nanoparticles with improved brain delivery: in vitro and in vivo evaluations.

The lactoferrin (Lf) conjugated poly (ethyleneglycol)-poly (lactide) nanoparticle (Lf-NP) was constructed in this paper as a novel biodegradable brain drug delivery system with evaluation of its in vitro and in vivo delivery properties. Lf was thiolated and conjugated to the distal maleimide functions surrounding on the pegylated nanoparticles to form the Lf-NP. The existence of Lf on the surface of Lf-NP was verified by TEM observation and XPS analysis. The Lf ELISA results confirmed the biorecognitive activity of Lf after the coupling procedure and suggested the average number of Lf conjugated on each nanoparticle was around 55. To evaluate the brain delivery properties of the Lf-NP, a fluorescent probe, coumarin-6 was incorporated into it. The uptake of Lf-NP by bEnd.3 cells was shown significantly higher than that of unconjugated nanoparticle (NP). Following an intravenous administration, a near 3 folds of coumarin-6 were found in the mice brain carried by Lf-NP compared to that carried by NP. Cell viability experiment results confirmed good safety of the biodegradable Lf-NP. The significant in vitro and in vivo results suggest that Lf-NP is a promising brain drug delivery system with low toxicity.

Preparation and brain delivery property of biodegradable polymersomes conjugated with OX26.

A novel drug carrier for brain delivery, poly(ethyleneglycol)-poly(epsilon-caprolactone) (PEG-PCL) polymersomes conjugated with mouse-anti-rat monoclonal antibody OX26 (OX26-PO), was developed and its brain delivery property was evaluated. The diblock copolymers of methoxy-PEG-PCL and Maleimide-PEG-PCL were synthesized and applied to prepare polymersomes (PO) which were verified by direct cryogenic temperature transmission electron micrograph (Cryo-TEM) imaging. The TEM examination and dynamic light scattering results showed that OX26-PO had a round and vesicle-like shape with a mean diameter around 100 nm. Coupling of OX26 with PO was confirmed by immuno-gold labeling of OX26 visualized under the TEM and X-ray photoelectron spectroscopy test. The surface OX26 densities were obtained from enzyme-linked immunosorbant assay. The result of brain delivery in rats proved that the increase of surface OX26 density of OX26-PO decreased blood AUC. The optimized OX26 number conjugated per polymersome was 34, which can acquire the greatest blood-brain barrier (BBB) permeability surface area product and percentage of injected dose per gram brain (%ID/g brain). Furthermore, NC-1900, as a model peptide, was encapsulated into OX26(34)-PO and improved the scopolamine-induced learning and memory impairments in a water maze task via i.v. administration. These results indicated that OX26(34)-PO is a promising carrier for peptide brain delivery.

Aptamer-functionalized PEG–PLGA nanoparticles for enhanced anti-glioma drug delivery

Targeted delivery of therapeutic nanoparticles in a disease-specific manner represents a potentially powerful technology especially when treating infiltrative brain tumors such as gliomas. We developed a nanoparticulate drug delivery system decorated with AS1411 (Ap), a DNA aptamer specifically binding to nucleolin which was highly expressed in the plasma membrane of both cancer cells and endothelial cells in angiogenic blood vessels, as the targeting ligand to facilitate anti-glioma delivery of paclitaxel (PTX). Ap was conjugated to the surface of PEG-PLGA nanoparticles (NP) via an EDC/NHS technique. With the conjugation confirmed by Urea PAGE and XPS, the resulting Ap-PTX-NP was uniformly round with particle size at 156.0xa0±xa054.8xa0nm and zeta potential atxa0-32.93xa0±xa03.1xa0mV. Ap-nucleolin interaction significantly enhanced cellular association of nanoparticles in C6 glioma cells, and increased the cytotoxicity of its payload. Prolonged circulation and enhanced PTX accumulation at the tumor site was achieved for Ap-PTX-NP, which eventually obtained significantly higher tumor inhibition on mice bearing C6 glioma xenografts and prolonged animal survival on rats bearing intracranial C6 gliomas when compared with PTX-NP and Taxol(®). The results of this contribution demonstrated the potential utility of AS1411-functionalized nanoparticles for a therapeutic application in the treatment of gliomas.

Penetratin-functionalized PEG-PLA nanoparticles for brain drug delivery.

Nanoparticulate drug delivery system possesses distinct advantages for brain drug delivery. However, its amount that reach the brain is still not satisfied. Cell-penetrating peptides (CPPs), short peptides that facilitate cellular uptake of various molecular cargo, would be appropriate candidates for facilitating brain delivery of nanoparticles. However, such effect could be deprived by the rapid systemic clearance of CPPs-functionalized nanoparticles due to their positive surface charge. Penetratin (CPP with relatively low content of basic amino acids) was here functionalized to poly(ethylene glycol)-poly(lactic acid) nanoparticles (NP) to achieve desirable pharmacokinetic and biodistribution profiles for brain drug delivery. The obtained penetratin-NP showed a particle size of 100 nm and zeta potential of -4.42 mV. The surface conjugation of penetratin was confirmed by surface chemical compositions analysis via X-ray photo electron spectroscopy. In MDCK-MDR cell model, penetratin-NP presented enhanced cellular accumulation via both lipid raft-mediated endocytosis and direct translocation processes with the involvement of Golgi apparatus, lysosome and microtubules. In vivo pharmacokinetic and biodistribution studies showed that penetratin-NP exhibited a significantly enhanced brain uptake and reduced accumulation in the non-target tissues compared with low-molecular-weight protamine (CPP with high arginine content)-functionalized nanoparticles. These data strongly implicated that penetratin-NP might represent a promising brain-targeting drug delivery system. The findings also provided an important basis for the optimization of brain drug delivery systems via surface charge modulation.

Nose-to-Brain Transport Pathways of Wheat Germ Agglutinin Conjugated PEG-PLA Nanoparticles

PurposeTo investigate the possible pathways for transport of wheat germ agglutinin conjugated PEG-PLA nanoparticles (WGA-NP) into the brain after nasal administration.MethodsThe nose-to-brain pathways were investigated using WGA-NP containing 6-coumarin (as a fluorescent marker) and 125I-labeled WGA-NP. Ex vivo imaging analysis was also employed to visualize the transport process.ResultsNasal administration of WGA-NP to rats resulted in transcellular absorption across the olfactory epithelium and transfer to the olfactory bulb within 5xa0min. After entering the lamina propria, a proportion of WGA-NP were transferred from the olfactory nerve bundles and their surrounding connective tissue to the olfactory bulb. The trigeminal nerves also contributed to WGA-NP brain transfer, especially to WGA-NP distribution in the caudal brain areas. However, cerebrospinal fluid pathway may have little contribution to the process of transferring WGA-NP into the central nervous system (CNS) after intranasal administration.ConclusionsThese results demonstrated that intranasally administered WGA-NP reach the CNS via olfactory pathway and trigeminal nerve pathway, and extracellular transport along these nerves is the most possible mechanism.

F3 peptide-functionalized PEG-PLA nanoparticles co-administrated with tLyp-1 peptide for anti-glioma drug delivery.

The development of a drug delivery strategy which can mediate efficient tumor targeting together with high cellular internalization and extensive vascular extravasation is essential and important for glioma treatment. To achieve this goal, F3 peptide that specifically bind to nucleolin, which is highly expressed on the surface of both glioma cells and endothelial cells of glioma angiogenic blood vessels, is utilized to decorate a nanoparticulate drug delivery system to realize glioma cell and neovasculature dual-targeting and efficient cellular internalization. Tumor homing and penetrating peptide, tLyp-1 peptide, which contains the motif of (R/K)XX(R/K) and specially binds to neuropilin is co-administrated to improve the penetration of the nanoparticles across angiogenic vasculature into glioma parenchyma. The F3 conjugation via a maleimide-thiol coupling reaction was confirmed by XPS analysis with 1.03% nitrogen detected on the surface of the functionalized nanoparticles. Enhanced cellular interaction with C6 cells, improved penetration in 3D multicell tumor spheroids, and increased cytotoxicity of the loaded paclitaxel were achieved by the F3-functionalized nanoparticles (F3-NP). Following co-administration with tLyp-1 peptide, F3-NP displayed enhanced accumulation at the tumor site and deep penetration into the glioma parenchyma and achieved the longest survival in mice bearing intracranial C6 glioma. The findings here clearly indicated that the strategy by co-administrating a tumor homing and penetrating peptide with functionalized nanoparticles dual-targeting both glioma cells and neovasculature could significantly improve the anti-glioma drug delivery, which also hold a great promise for chemotherapy of other hard-to-cure cancers.

PEG-co-PCL nanoparticles modified with MMP-2/9 activatable low molecular weight protamine for enhanced targeted glioblastoma therapy.

By taking advantage of the dramatically upregulated expression of matrix metalloproteinases MMP-2 and MMP-9 in glioblastomas and the powerful transport ability of low molecular weight protamine (LMWP), we constructed an activatable low molecular weight protamine (ALMWP) and conjugated it to PEG-PCL nanoparticles (NP) to develop a smart drug delivery system for enhanced targeted glioblastoma therapy. Important parameters such as particle size distribution, zeta potential and surface content were determined, which confirmed the conjugation of ALMWP to the surface of nanoparticle. ALMWP-NP loaded with paclitaxel (PTX) exhibited a desirable pharmacokinetic and biodistribution profiles for anti-glioblastoma drug delivery. Cellular experiments showed that ALMWP-NP exhibited significantly elevated MMP-dependent cellular accumulation in C6 cells via lipid raft-mediated endocytosis and energy-dependent macropinocytosis, and improved the cytotoxicity of PTX. In vitro C6 tumor spheroid uptake confirmed the tumor penetrating ability of ALMWP-NP, in vivo imaging and glioma distribution justified its specific accumulation in the glioma. The improved glioma-targeting and tumor penetration led to an anticipated enhanced in vivo anti-glioblastoma effect: animals (nude mice bearing intracranial C6 glioma) treated with ALMWP-NP-PTX survive significantly longer than those treated with saline, Taxol(®) NP-PTX and LMWP-NP-PTX. The findings here offered strong evidence for the glioblastoma-targeting therapy of ALMWP-NP-PTX, and could also lead to a significant advancement in the application of CPPs for targeted therapy of glioma.

Low molecular weight protamine-functionalized nanoparticles for drug delivery to the brain after intranasal administration.

The development of new strategies for enhancing drug delivery to the brain is of great importance in diagnostics and therapeutics of central nervous diseases. Low-molecular-weight protamine (LMWP) as a cell-penetrating peptide possesses distinct advantages including high cell translocation potency, absence of toxicity of peptide itself, and the feasibility as an efficient carrier for delivering therapeutics. Therefore, it was hypothesized that brain delivery of nanoparticles conjugated with LMWP should be efficiently enhanced following intranasal administration. LMWP was functionalized to the surface of PEG-PLA nanoparticles (NP) via a maleimide-mediated covalent binding procedure. Important parameters such as particle size distribution, zeta potential and surface content were determined, which confirmed the conjugation of LMWP to the surface of nanoparticle. Using 16HBE14o- cells as the cell model, LMWP-NP was found to exhibit significantly enhanced cellular accumulation than that of unmodified NP via both lipid raft-mediated endocytosis and direct translocation processes without causing observable cytotoxic effects. Following intranasal administration of coumarin-6-loaded LMWP-NP, the AUC(0-8 h) of the fluorescent probe detected in the rat cerebrum, cerebellum, olfactory tract and olfactory bulb was found to be 2.03, 2.55, 2.68 and 2.82 folds, respectively, compared to that of coumarin carried by NP. Brain distribution analysis suggested LMWP-NP after intranasal administration could be delivered to the central nervous system along both the olfactory and trigeminal nerves pathways. The findings clearly indicated that the brain delivery of nanoparticles could be greatly facilitated by LMWP and the LMWP-functionalized nanoparticles appears as a effective and safe carrier for nose-to-brain drug delivery in potential diagnostic and therapeutic applications.

Glioma therapy using tumor homing and penetrating peptide-functionalized PEG–PLA nanoparticles loaded with paclitaxel

By taking advantage of the excessively upregulated expression of neuropilin (NRP) on the surface of both glioma cells and endothelial cells of angiogenic blood vessels, the ligand of NRP with high affinity - tLyp-1 peptide, which also contains a CendR motif ((R/K)XX(R/K)), was functionalized to the surface of PEG-PLA nanoparticles (tLyp-1-NP) to mediate its tumor homing, vascular extravasation and deep penetration into the glioma parenchyma. The tLyp-1-NP was prepared via a maleimide-thiol coupling reaction with uniformly spherical shape under TEM and particle size of 111.30 ± 15.64 nm. tLyp-1-NP exhibited enhanced cellular uptake in both human umbilical vein endothelial cells and Rat C6 glioma cells, increased cytotoxicity of the loaded PTX, and improved penetration and growth inhibition in avascular C6 glioma spheroids. Selective accumulation and deep penetration of tLyp-1-NP at the glioma site was confirmed by in vivo imaging and glioma distribution analysis. The longest survival was achieved by those mice bearing intracranial C6 glioma treated with PTX-loaded tLyp-1-NP. The findings here strongly indicate that tLyp-1 peptide-functionalized nanoparticulate DDS could significantly improve the efficacy of paclitaxel glioma therapy.

Quantum dots bearing lectin-functionalized nanoparticles as a platform for in vivo brain imaging.

Delivery of imaging agents to the brain is highly important for the diagnosis and treatment of central nervous system (CNS) diseases, as well as the elucidation of their pathophysiology. Quantum dots (QDs) provide a novel probe with unique physical, chemical, and optical properties, and become a promising tool for in vivo molecular and cellular imaging. However, their poor stability and low blood-brain barrier permeability severely limit their ability to enter into and act on their target sites in the CNS following parenteral administration. Here, we developed a QDs-based imaging platform for brain imaging by incorporating QDs into the core of poly(ethylene glycol)-poly(lactic acid) nanoparticles, which was then functionalized with wheat germ agglutinin and delivered into the brain via nasal application. The resulting nanoparticles, with high payload capacity, are water-soluble, stable, and showed excellent and safe brain targeting and imaging properties. With PEG functional terminal groups available on the nanoparticles surface, this nanoprobe allows for conjugation of various biological ligands, holding considerable potential for the development of specific imaging agents for various CNS diseases.