Drug targeting

TMZ-BioShuttle--a reformulated temozolomide

There is a large number of effective cytotoxic drugs whose side effect profile, efficacy, and long-term use in man are well understood and documented over decades of use in clinical routine e.g. in the treatment of recurrent glioblastoma multiforme (GBM) and the hormone-refractory prostate cancer (HRPC). Both cancers are insensitive against most chemotherapeutic interventions; they have low response rates and poor prognoses. Some cytotoxic agents can be significantly improved by using modern technology of drug delivery or formulation. We succeeded to enhance the pharmacologic potency with simultaneous reduction of unwanted adverse reactions of the highly efficient chemotherapeutic temozolomide (TMZ) as an example. The TMZ connection to transporter molecules (TMZ-BioShuttle) resulted in a much higher pharmacological effect in glioma cell lines while using reduced doses. This permits the conclusion that a suitable chemistry could realize the ligation of pharmacologically active, but sensitive and highly unstable pharmaceutical ingredients without functional deprivation. The re-formulation of TMZ to TMZ-BioShuttle achieved a nearly 10-fold potential of the established pharmaceutic TMZ far beyond the treatment of brain tumors cells and results in an attractive reformulated drug with enhanced therapeutic index.

Epithelial barrier modulation by a channel forming peptide

NC-1059 is a synthetic channel-forming peptide that provides for ion transport across, and transiently reduces the barrier integrity of, cultured epithelial monolayers derived from canine kidney (MDCK cells). Experiments were conducted to determine whether epithelial cells derived from other sources were similarly affected. Epithelial cells derived from human intestine (T-84), airway (Calu-3), porcine intestine (IPEC-J2) and reproductive duct (PVD9902) were grown on permeable supports. Basal short circuit current (Isc) was <3 microA cm(-2) for T-84, IPEC-J2 and PVD9902 cell monolayers and <8 microA cm(-2) for Calu-3 cells. Apical NC-1059 exposure caused, in all cell types, an increase in Isc to >15 microA cm(-2), indicative of net anion secretion or cation absorption, which was followed by an increase in transepithelial conductance (in mS cm(-2): T-84, 1.6 to 62; PVD9902, 0.2 to 51; IPEC-J2, 0.3 to 26; Calu-3, 2.3 to 13). These results are consistent with the peptide affecting transcellular ion movement, with a likely effect also on the paracellular route. NC-1059 exposure increased dextran permeation when compared to basal permeation, which documents an effect on the paracellular pathway. In order to evaluate membrane ion channels, experiments were conducted to study the dose dependence and stability of the NC-1059-induced membrane conductance in Xenopus laevis oocytes. NC-1059 induced a dose-dependent increase in oocyte membrane conductance that remained stable for greater than 2 h. The results demonstrate that NC-1059 increases transcellular conductance and paracellular permeation in a wide range of epithelia. These effects might be exploited to promote drug delivery across barrier epithelia.

Exploiting lipid raft transport with membrane targeted nanoparticles: a strategy for cytosolic drug delivery

The ability to specifically deliver therapeutic agents to selected cell types while minimizing systemic toxicity is a principal goal of nanoparticle-based drug delivery approaches. Numerous cellular portals exist for cargo uptake and transport, but after targeting, intact nanoparticles typically are internalized via endocytosis prior to drug release. However, in this work, we show that certain classes of nanoparticles, namely lipid-coated liquid perfluorocarbon emulsions, undergo unique interactions with cells to deliver lipophilic substances to target cells without the need for entire nanoparticle internalization. To define the delivery mechanisms, fluorescently-labeled nanoparticles complexed with alphav beta 3-integrin targeting ligands were incubated with alphav beta 3-integrin expressing cells (C32 melanoma) under selected inhibitory conditions that revealed specific nanoparticle-to-cell interactions. We observed that the predominant mechanism of lipophilic delivery entailed direct delivery of lipophilic substances to the target cell plasma membrane via lipid mixing and subsequent intracellular trafficking through lipid raft-dependent processes. We suggest that local drug delivery to selected cell types could be facilitated by employing targeted nanoparticles designed specifically to utilize alternative membrane transport mechanisms.

Arg-Gly-Asp (RGD) peptide conjugated poly(lactic acid)-poly(ethylene oxide) micelle for targeted drug delivery

In this study, a new poly(lactic acid)-poly (ethylene oxide)-Arg-Gly-Asp (PLA-PEO-RGD) derivative was synthesized, and paclitaxel-loaded PLA-PEO-RGD micelles were prepared by this derivative. The solubility assay showed that micelles mixed with Pluronic F-68 as surfactant could increase the solubility of this hydrophobic paclitaxel in aqueous solution. The cell-binding assay showed that PLA-PEO-RGD micelle (IC(50) = 11.13 +/- 1.38 nmol/L) had about 3.6-fold higher integrin avidity than PLA-PEO-RGD conjugates (IC(50) = 40.33 +/- 3.12 nmol/L). The avidity of micelle was also higher than RGD4C peptide (IC(50) = 24.44 +/- 1.21 nmol/L). The in vitro drug release profile of drug-loaded PLA-PEO-RGD micelles exhibited initial burst release to 37% +/- 2% (w/w) during the first 12 h, and then the release rate became steady in a controlled release manner. Furthermore, treatment of the MDA-MB-435 breast cancer cell line with paclitaxel-loaded PLA-PEO-RGD micelles yielded cytotoxicities, with EC(50) values of approximately 30 mumol/L. The paclitaxel-loaded PLA-PEO-RGD micelles treated group showed the most dramatic tumor reduction in MDA-MB-435 tumor-bearing nude mice, and the final mean tumor load was 31 +/- 16 mm(3) (mean +/- SD; n = 8). (125)I-labeled micelles administration resulted in significant (p < 0.001) higher tumor uptake (2.68% +/- 0.14%, ID/g) of PLA-PEO-RGD micelles compared to PLA-PEO micelles (0.84% +/- 0.09%, ID/g) after 2.5 h postinjection. Biodistribution study showed the best blood clearance of PLA-PEO-RGD micelles after 4.5 h postinjection. The results of this study suggest that paclitaxel-loaded PLA-PEO-RGD micelles based on the specific recognition of alpha(V)beta(3) integrin represent a potential and powerful target delivery technology.

Pharmacokinetic characteristics and anticancer effects of 5-fluorouracil loaded nanoparticles

Background

It is expected that prolonged circulation of anticancer drugs will increase their anticancer activity while decreasing their toxic side effects. The purpose of this study was to prepare 5-fluorouracil (5-FU) loaded block copolymers, with poly(γ-benzyl-L-glutamate) (PBLG) as the hydrophobic block and poly(ethylene glycol) (PEG) as the hydrophilic block, and then examine the 5-FU release characteristics, pharmacokinetics, and anticancer effects of this novel compound.

Methods

5-FU loaded PEG-PBLG (5-FU/PEG-PBLG) nanoparticles were prepared by dialysis and then scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe the shape and size of the nanoparticles, and ultraviolet spectrophotometry was used to evaluate the 5-FU in vitro release characteristics. The pharmacokinetic parameters of 5-FU/PEG-PBLG nanoparticles in rabbit plasma were determined by measuring the 5-FUby high-performance liquid chromatography (HPLC). To study in vivo effects, LoVo cells (human colon cancer cell line) or Tca8113 cells (human oral squamous cell carcinoma cell line) were implanted in BALB/c nude mice that were subsequently treated with 5-FU or 5-FU/PEG-PBLG nanospheres.

Results

5-FU/PEG-PBLG nanoparticles had a core-shell spherical structure with a diameter of 200 nm and a shell thickness of 30 nm. The drug loading capacity was 27.1% and the drug encapsulation was 61.5%. Compared with 5-FU, 5-FU/PEG-PBLG nanoparticles had a longer elimination half-life (t_1/2, 33.3 h vs. 5 min), lower peak concentration (C, 4563.5 μg/L vs. 17047.3 μg/L), and greater distribution volume (V_D, 0.114 L vs. 0.069 L). Compared with a blank control, LoVo cell xenografts and Tca8113 cell xenografts treated with 5-FU or 5-FU/PEG-PBLG nanoparticles grew slower and had prolonged tumor doubling times. 5-FU/PEG-PBLG nanoparticles showed greater inhibition of tumor growth than 5-FU (p < 0.01). In the PEG-PBLG nanoparticle control group, there was no tumor inhibition (p > 0.05).

Conclusion

In our model system, 5-FU/PEG-PBLG nanoparticles changed the pharmacokinetic behavior of 5-FU, thus increasing its anticancer activity. 5-Fluorouracil loaded nanoparticles have potential as a novel anticancer drug that may have useful clinical applications.

Synthesis and cytotoxic properties of new fluorodeoxyglucose-coupled chlorambucil derivatives

Frequently used in the treatment of malignant cells, alkylating agents, like most anticancer substances, produce adverse side effects caused by the toxicity of the agents toward normal tissues and lose efficiency through poor distribution to target sites. Our approach to developing more selective drugs with low systemic toxicity is based on the premise that the body distribution and cell uptake of a drug can be altered by attaching a neoplastic cell-specific uptake enhancer, such as 2-fluoro-2-deoxyglucose (FDG), the radiotracer most frequently used in PET for tumor imaging. Two properties of deoxyglucose, namely preferential accumulation in neoplastic cells and inhibition of glycolysis, underpin this targeting approach. Here, we report the synthesis of 19 new chlorambucil glycoconjugates in which the alkylating drug is attached to the C-1 position of FDG, directly or via different linkages. This set of compounds was evaluated for in vitro cytotoxicity against different human normal and tumor cell lines. There was a significant improvement in the in vitro cytotoxicity of peracetylated glucoconjugates compared with the free substance. Four compounds were finally selected for further in vivo studies owing to their lack of oxidative stress-inducing properties.

Preparations of bifunctional polymeric beads simultaneously incorporated with fluorescent quantum dots and magnetic nanocrystals

Bifunctional polystyrene beads simultaneously incorporated with fluorescent CdTe quantum dots (Q-dots) and superparamagnetic Fe(3)O(4) nanocrystals were prepared by a modified mini-emulsion polymerization method, in which polymerizable surfactants were used as both phase transfer agent for aqueous colloidal nanoparticles and emulsifier. In addition, silica coating was also introduced to Fe(3)O(4) nanocrystals for regulating the internal structure of the composite beads. Transmission electron microscopy, confocal fluorescence microscopy and conventional spectroscopy were used to characterize the composite beads, as well as the polymerizable surfactant-coated CdTe Q-dots and silica-coated Fe(3)O(4) nanoparticles. Different mixing methods were also attempted in order to vary the size of the resultant bifunctional beads.

Poly(L-lysine)-modified iron oxide nanoparticles for stem cell labeling

New surface-modified iron oxide nanoparticles were developed by precipitation of Fe(II) and Fe(III) salts with ammonium hydroxide and oxidation of the resulting magnetite with sodium hypochlorite, followed by the addition of poly( L-lysine) (PLL) solution. PLL of several molecular weights ranging from 146 ( L-lysine) to 579 000 was tested as a coating to boost the intracellular uptake of the nanoparticles. The nanoparticles were characterized by TEM, dynamic light scattering, FTIR, and ultrasonic spectrometry. TEM revealed that the particles were ca. 6 nm in diameter, while FTIR showed that their surfaces were well-coated with PLL. The interaction of PLL-modified iron oxide nanoparticles with DMEM culture medium was verified by UV-vis spectroscopy. Rat bone marrow stromal cells (rMSCs) and human mesenchymal stem cells (hMSC) were labeled with PLL-modified iron oxide nanoparticles or with Endorem (control). Optical microscopy and TEM confirmed the presence of PLL-modified iron oxide nanoparticles inside the cells. Cellular uptake was very high (more than 92%) for PLL-modified nanoparticles that were coated with PLL (molecular weight 388 00) at a concentration of 0.02 mg PLL per milliliter of colloid. The cellular uptake of PLL-modified iron oxide was facilitated by its interaction with the negatively charged cell surface and subsequent endosomolytic uptake. The relaxivity of rMSCs labeled with PLL-modified iron oxide and the amount of iron in the cells were determined. PLL-modified iron oxide-labeled rMSCs were imaged in vitro and in vivo after intracerebral grafting into the contralateral hemisphere of the adult rat brain. The implanted cells were visible on magnetic resonance (MR) images as a hypointense area at the injection site and in the lesion. In comparison with Endorem, nanoparticles modified with PLL of an optimum molecular weight demonstrated a higher efficiency of intracellular uptake by MSC cells.

Immobilization of homing peptide on magnetite nanoparticles and its specificity in vitro

As a homing peptide, A54 is the most effective peptide specific to the human hepatocellular carcinoma cell. Homing peptide labeled with green fluorescent protein (A54-GFP) was successfully immobilized on the surfaces of magnetic nanoparticles and characterized by Fourier transform infrared spectroscopy as well as fluorescence microscopy. The binding efficiency was analyzed by performing adsorption equilibrium and SDS-PAGE electrophoresis. Specific binding of the nanoparticles functionalized with A54-GFP to human hepatocellular carcinoma cells in vitro was visualized using fluorescence microscopy. The results demonstrated the specificity of A54-GFP-coated magnetic nanoparticle to tumor cell, pointing to its great potential in magnetic cell separation and purification, magnetic resonance imaging (MRI), magnetic hyperthermia, and drug targeting.

Direct coprecipitation route to monodisperse dual-functionalized magnetic iron oxide nanocrystals without size selection

Water-soluble monodisperse superparamagnetic Fe3O4 nanocrystals decorated with two distinct functional groups are prepared in a single-step procedure by injecting iron precursors into a refluxing aqueous solution of a polymer ligand, trithiol-terminated poly(methacrylic acid) (PMAA-PTTM), bearing both carboxylate and thiol functionalities. The ratio of carboxylic acid groups in the polymer-protecting ligand to the iron precursors plays a key role in determining the particle size and particle size distribution. The surface functionalities of the ligands allow post-synthesis modification of the materials to produce water-soluble fluorescent magnetic nanocrystals.

Quantum dots – Nano-sized probes for the exploration of cellular and intracellular targeting

Nanoparticles emerged as promising tool in drug targeting, since, after appropriate modification, they are able to deliver their payload to specific sites, like tissues, cells, or even certain cellular organelles. In this context, the delivery of nanoparticles from the circulation into the target cells represents a crucial step. Here, model drug delivery systems such as quantum dots are ideal candidates to elucidate this process in more detail, since they provide outstanding features like a small and uniform size, unique optical properties for most sensitive detection and modifiable surfaces. Recent progress in the surface chemistry of quantum dots expanded their use in biological applications, reduced their cytotoxicity and rendered quantum dots a powerful tool for the investigation of distinct cellular processes, like uptake, receptor trafficking and intracellular delivery. In this review, we will not only describe the ideal attributes of QDs for biological applications and imaging but also their distinct specific and non-specific pathways into the cells as well as their intracellular fate.

Nanotechnology: a focus on nanoparticles as a drug delivery system

This review will provide an in-depth discussion on the previous development of nanoparticle-based drug delivery systems (DDS) and discuss original research data that includes the therapeutic enhancement of antiretroviral therapy. The use of nanoparticle DDS will allow practitioners to use drugs to target specific areas of the body. In the treatment of malignancies, the use of nanoparticles as a DDS is making measurable treatment impact. Medical imaging will also utilize DDS to illuminate tumors, the brain, or other cellular functions in the body. The utility of nanoparticle DDS to improve human health is potentially enormous.

Polycation-based nanoparticle delivery for improved RNA interference therapeutics

Small-interfering RNA (siRNA)-mediated silencing of genes implicated in disease by the process of RNA interference offers a novel genetic medicine approach. Polymeric nanoparticles (or polyplexes) formed by self-assembly of polycations with siRNA can be used for site-specific delivery, cellular uptake and intracellular trafficking as a strategy to improve the therapeutic potential of siRNA. This review describes the application of polyplexes for in vivo delivery of synthetic siRNA with focus given to systemic and mucosal routes and in vivo requirements. Issues including use of stimuli-responsive systems for intracellular trafficking of siRNA are discussed as part of necessary future directives towards the development of RNA-based clinical therapeutics.

A comprehensivein vitroinvestigation of a portable magnetic separator device for human blood detoxification

A portable magnetic separator device is being developed for a proposed magnetically based detoxification system. In this paper, the performance of this device was evaluated via preliminary in vitro flow experiments using simple fluids and a separator unit consisting of one tube and two metal wires, each at the top and bottom of the tube. The effects of the following factors were observed: mean flow velocity U(o) (0.14-45 cm s(-1)), magnetic field strength micro(o)H(o) (0.125-0.50 T), wire size R(w) (0.125, 0.250 and 0.500 mm), wire length L(w) (2, 5 and 10 cm), wire materials (nickel, stainless steel 304 and 430) and tube size (outer radius R(o) = 0.30 mm and inner radius R(i) = 0.25 mm; R(o) = 0.50 mm and R(i) = 0.375 mm; and R(o) = 2.0 mm and R(i) = 1.0 mm). Our observations showed that the experimental results fit well with the corresponding theoretical results from the model we previously developed at a low flow velocity area (for example, U(o) < or = 20 cm s(-1)), strong external magnetic field (for example, > or = 0.30 T) and long wire length (for example, L(w) = 10 cm). The experimental results also showed that more than 90% capture efficiency is indeed achievable under moderate systemic and operational conditions. Pressure drop measurements revealed that the device could work well under human physiological and clinical conditions, and sphere buildup would not have any considerable effect on the pressure drop of the device. The breakthrough experiments demonstrated that a lower flow rate V, higher applied magnetic field micro(o)H(o) and diluted sphere suspension, i.e. lower C(o), would delay the breakthrough. All the results indicate the promise of this portable magnetic separator device to efficiently in vivo sequestrate nano-/micro-spheres from blood flow in the future magnetically based detoxification system.

Influence of size, surface, cell line, and kinetic properties on the specific binding of A33 antigen-targeted multilayered particles and capsules to colorectal cancer cells

There has been increased interest in the use of polymer capsules formed by the layer-by-layer (LbL) technique as therapeutic carriers to cancer cells due to their versatility and ease of surface modification. We have investigated the influence of size, surface properties, cell line, and kinetic parameters such as dosage (particle concentration) and incubation time on the specific binding of humanized A33 monoclonal antibody (huA33 mAb)-coated LbL particles and capsules to colorectal cancer cells. HuA33 mAb binds to the A33 antigen present on almost all colorectal cancer cells and has demonstrated great promise in clinical trials as an immunotherapeutic agent for cancer therapy. Flow cytometry experiments showed the cell binding specificity of huA33 mAb-coated particles to be size-dependent, with the optimal size for enhanced selectivity at approximately 500 nm. The specific binding was improved by increasing the dosage of particles incubated with the cells. The level of specific versus nonspecific binding was compared for particles terminated with various polyelectrolytes to examine the surface dependency of antibody attachment and subsequent cell binding ability. The specific binding of huA33 mAb-coated particles is also reported for two colorectal cancer cell lines, with an enhanced binding ratio between 4 and 10 obtained for the huA33 mAb-functionalized particles. This investigation aims to improve the level of specific targeting of LbL particles, which is important in targeted drug and gene delivery applications.

A macrophage-nanozyme delivery system for Parkinson's disease

Selective delivery of antioxidants to the substantia nigra pars compacta (SNpc) during Parkinson's disease (PD) can potentially attenuate oxidative stress and as such increase survival of dopaminergic neurons. To this end, we developed a bone-marrow-derived macrophage (BMM) system to deliver catalase to PD-affected brain regions in an animal model of human disease. To preclude BMM-mediated enzyme degradation, catalase was packaged into a block ionomer complex with a cationic block copolymer, polyethyleneimine-poly(ethylene glycol) (PEI-PEG). The self-assembled catalase/PEI-PEG complexes, "nanozymes", were ca. 60 to 100 nm in size, stable in pH and ionic strength, and retained antioxidant activities. Cytotoxicity was negligible over a range of physiologic nanozyme concentrations. Nanozyme particles were rapidly, 40-60 min, taken up by BMM, retained catalytic activity, and released in active form for greater than 24 h. In contrast, "naked" catalase was rapidly degraded. The released enzyme decomposed microglial hydrogen peroxide following nitrated alpha-synuclein or tumor necrosis factor alpha activation. Following adoptive transfer of nanozyme-loaded BMM to 1-methyl 4-phenyl 1,2,3,6-tetrahydropyridine-intoxicated mice, ca. 0.6% of the injected dose were found in brain. We conclude that cell-mediated delivery of nanozymes can reduce oxidative stress in laboratory and animal models of PD.

Peritoneal macrophage uptake, pharmacokinetics and biodistribution of macrophage-targeted PEG-fMLF (N-formyl-methionyl-leucyl-phenylalanine) nanocarriers for improving HIV drug delivery

PURPOSE

To assess in vivo macrophage targeting potential of PEG-fMLF nanocarriers and to investigate their biodistribution, peritoneal macrophage uptake, and pharmacokinetics.

METHODS

Multiple copies of fMLF were conjugated to purchased and novel (branched, peptide-based) PEG nanocarriers. Peritoneal macrophage uptake was evaluated in mice 4 hours after IP administration of fluorescence-labeled PEG-fMLF nanocarriers. Pharmacokinetics and biodistribution were determined in rats after IV administration of tritiated PEG-fMLF nanocarriers.

RESULTS

Attachment of one, two, or four fMLF copies increased uptake in macrophages by 3.8-, 11.3-, and 23.6-fold compared to PEG without fMLF. Pharmacokinetic properties and tissue distribution also differed between nanocarriers with and without fMLF. Attachment of fMLF residues increased the t(1/2) of PEG(5K) by threefold but decreased the t(1/2) of PEG(20K) by 40%. Attachment of fMLF increased accumulation of nanocarriers into macrophages of liver, kidneys and spleen. However, on a molar basis, penetration was equivalent suggesting nanocarrier size and targeting moieties are important determinants.

CONCLUSIONS

These results demonstrate the feasibility for targeting macrophages, a primary HIV reservoir site. However, these studies also suggest that balancing peripheral tissue penetration (a size-dependent phenomenon) versus target cell uptake specificity remains a challenge to overcome.

Targeted Proapoptotic Anticancer Drug Delivery System

A novel targeted proapoptotic anticancer drug delivery system (DDS) was developed and evaluated both in vitro and in vivo. The system contains poly(ethylene glycol) polymer (PEG) as a carrier, camptothecin (CPT) as an anticancer drug/cell death inducer, a synthetic analogue of luteinizing hormone-releasing hormone (LHRH) peptide as a targeting moiety/penetration enhancer, and a synthetic analogue of BCL2 homology 3 domain (BH3) peptide as a suppressor of cellular antiapoptotic defense. The design of the multicomponent DDS allowed for a conjugation of one or two copies of each active ingredient (CPT, LHRH, and BH3) to one molecule of PEG carrier. The complex structure of the PEG conjugates was visualized at nanometer resolution using atomic force microscopy. We found that the ligand-targeted DDS for cancer cells preferentially accumulated in the tumor and allowed the delivery of active ingredients into the cellular cytoplasm and nuclei of cancer cells. Simultaneous apoptosis induction through the caspase-dependent signaling pathway and inhibition of cellular antiapoptotic defense by the suppression of BCL2 protein enhanced cytotoxicity and antitumor activity of the entire DDS to a level which could not be achieved by individual components applied separately. The DDS containing two copies of each active component (CPT, LHRH, and BH3) per molecule of PEG polymer had the highest anticancer efficiency in vitro and in vivo.

Immuno-targeting of nonionic surfactant vesicles to inflammation

Niosomes composed of sorbitan monostearate (Span 60), polyoxyethylene sorbitan monostearate (Tween 61), cholesterol, and dicetyl phosphate were conjugated with a purified monoclonal antibody to CD44 (IM7) through a cyanuric chloride (CC) linkage on the polyoxyethylene group of the Tween 61 molecule. Inclusion of small amounts of Tween 61 within the surfactant component of niosomes formed using thin film hydration techniques and sonication did not hamper vesicle stability as compared to Span 60 niosomes. Conjugation was verified by UV absorbance of fluorescently tagged IM7 in non-fluorescing niosomes and fluorescent micrographs. The immuno-niosomes were incubated with synovial lining cells expressing CD44. Attachment of niosomes was evident and showed selectivity and specificity compared to controls. These findings suggest that the resulting immuno-niosomes may provide an effective method for targeted drug delivery.

Enhanced cytotoxicity of monoclonal anticancer antibody 2C5-modified doxorubicin-loaded PEGylated liposomes against various tumor cell lines

Doxorubicin-loaded long-circulating liposomes (Doxil, ALZA Corp.) were additionally modified with the nucleosome-specific monoclonal antibody 2C5 (mAb 2C5) recognizing a broad variety of tumor cells via the tumor cell surface-bound nucleosomes. These mAb 2C5-modified PEGylated liposomes demonstrated 3-8-fold increase in the in vitro binding and internalization by multiple cancer cell lines of diverse origins (murine LLC, 4T1, C26 and human BT-20, MCF-7, and PC3), as shown by flow cytometry (FACS) and epi and confocal microscopy. As a result, mAb 2C5-modified Doxil demonstrated significantly higher cytotoxicity towards various cancer cells, including those resistant to doxorubicin, than all control preparations. The specific internalization of the mAb 2C5-Doxil into cytosol, along with the nuclear localization of their drug load, inside the target cancer cells were mainly responsible the superior anticancer activity. The IC50 values of mAb 2C5-Doxil with various murine and human cancer cells were 5-8-fold lower than those of control doxorubicin-loaded liposomes, Doxil or Doxil modified with a nonspecific IgG.

Preparation, characterization, and optimization of pancreas-targeted 5-Fu loaded magnetic bovine serum albumin microspheres

The magnetic bovine serum albumin (BSA) microspheres (MS) were prepared by emulsification/solidification method. In this experiment, two kinds of magnetic MS, e.g. BSA MS and PEG-incorporated BSA microspheres (PMS) were prepared. The obtained MS were characterized by Malvern laser particle sizer and scanning electron microscopy (SEM). The obtained MS were spherical and about 1.3 microm in size. The magnetic responsivity and in vitro release behavior of these MS were studied in detail. The in vivo distribution and targeting delivery of 5-fluorouracil (5-Fu) magnetic MS after artery administration were studied in rat. The results showed that PMS could efficiently delivery 5-Fu to the targeted site compared with BSA MS without PEG MS and free drug.

Mitochondrial medicine: pharmacological targeting of mitochondria in disease

Mitochondria play a central role in cell life and death and are known to be important in a wide range of diseases including the cancer, diabetes, cardiovascular disease, and the age-related neurodegenerative diseases. The unique structural and functional characteristics of mitochondria enable the selective targeting of drugs designed to modulate the function of this organelle for therapeutic gain. This review discusses mitochondrial drug targeting strategies and a variety of novel mitochondrial drug targets including the electron transport chain, mitochondrial permeability transition, Bcl-2 family proteins and mitochondrial DNA. Mitochondrial drug-targeting strategies will open up avenues for manipulating mitochondrial functions and allow for selective protection or eradication of cells for therapeutic gain in a variety of diseases.

Targeting cancer cells using PLGA nanoparticles surface modified with monoclonal antibody

Targeting drugs to their sites of action is still a major challenge in pharmaceutical research. In this study, polylactic-co-glycolic acid (PLGA) immuno-nanoparticles were prepared for targeting invasive epithelial breast tumour cells. Monoclonal antibody (mAb) was used as a homing ligand and was attached to the nanoparticle surface either covalently or non-covalently. The presence of mAb on the nanoparticle surface, its stability and recognition properties were tested. Protein assay, surface plasmon resonance, flow cytometry and fluorescence-immunostaining confirmed the presence of mAb on nanoparticles in both cases. However, a binding assay using cell lysate revealed that the recognition properties were preserved only for nanoparticles with adsorbed mAb. These nanoparticles were more likely to be bound to the targeted cells than non-coated nanoparticles. Both types of nanoparticles entered the target MCF-10A neoT cells in mono-culture. In co-culture of MCF-10A neoT and Caco-2 cells immuno-nanoparticles were localized solely to MCF-10A neoT cells, whereas non-coated nanoparticles were distributed randomly. Immuno-nanoparticles entered only MCF-10A neoT cells, while non-coated nanoparticles were taken up by both cell types, indicating specific targeting of the immuno-nanoparticles. In conclusion, we demonstrate a method by which mAbs can be bound to nanoparticles without detriment to their targeting ability. Furthermore, the results show the effectiveness of the new carrier system for targeted delivery of small or large active substances into cells or tissues of interest.

Microparticle adhesive dynamics and rolling mediated by selectin-specific antibodies under flow

In vitro studies were performed to characterize the relative performance of candidate receptors to target microparticles to inflammatory markers on vascular endothelium. To model the interactions of drug-bearing microparticles or imaging contrast agents with the vasculature, 6 micron polystyrene particles bearing antibodies, peptides, or carbohydrates were perfused over immobilized E- or P-selectin in a flow chamber. Microparticles conjugated with HuEP5C7.g2 (HuEP), a monoclonal antibody (mAb) specific to E- and P-selectin, supported leukocyte-like rolling and transient adhesion at venular shear rates. In contrast, microparticles conjugated with a higher affinity mAb specific for P-selectin (G1) were unable to form bonds at venular flow rates. When both HuEP and G1 were conjugated to the microparticle, HuEP supported binding to P-selectin in flow which allowed G1 to form bonds leading to stable adhesion. While the microparticle attachment and rolling performance was not as stable as that mediated by the natural ligands P-selectin Glycoprotein Ligand-1 or sialyl Lewis(x), HuEP performed significantly better than any previously characterized mAb in terms of mediating microparticle binding under flow conditions. HuEP may be a viable alternative to natural ligands to selectins for targeting particles to inflamed endothelium.

New method for delivering a hydrophobic drug for photodynamic therapy using pure nanocrystal form of the drug

A carrier-free method for delivery of a hydrophobic drug in its pure form, using nanocrystals (nanosized crystals), is proposed. To demonstrate this technique, nanocrystals of a hydrophobic photosensitizing anticancer drug, 2-devinyl-2-(1-hexyloxyethyl)pyropheophorbide (HPPH), have been synthesized using the reprecipitation method. The resulting drug nanocrystals were monodispersed and stable in aqueous dispersion, without the necessity of an additional stabilizer (surfactant). As shown by confocal microscopy, these pure drug nanocrystals were taken up by the cancer cells with high avidity. Though the fluorescence and photodynamic activity of the drug were substantially quenched in the form of nanocrystals in aqueous suspension, both these characteristics were recovered under in vitro and in vivo conditions. This recovery of drug activity and fluorescence is possibly due to the interaction of nanocrystals with serum albumin, resulting in conversion of the drug nanocrystals into the molecular form. This was confirmed by demonstrating similar recovery in presence of fetal bovine serum (FBS) or bovine serum albumin (BSA). Under similar treatment conditions, the HPPH in nanocrystal form or in 1% Tween-80/water formulation showed comparable in vitro and in vivo efficacy.

Panning and identification of a colon tumor binding peptide from a phage display peptide library

Tumor-targeting therapy can be an efficacious way to cure a malignant tumor in clinical trials. Phage display is a molecular diversity technology that allows the presentation of a large number of peptides or proteins on the surface of filamentous phage for various applications. In this study, we report on using phage display to generate peptide libraries that bind to colon cancer tissues. To accomplish this, we developed a screening protocol that contained 3 rounds of in vitro positive panning on colon cancer cells (SW480) and 2 rounds of subtractive screening in vitro on normal human intestinal epithelial cells with a phage display-7 peptide library. After several rounds of panning, both phage titer and recovery efficiency were significantly improved. Through a cell-based enzyme-linked immunosorbent assay, immunofluorescence, in vivo binding assay, immunocytochemical staining, and immunohistochemical staining, peptide CP15 (VHLGYAT) was demonstrated to be the most effective peptide in targeting tumor cells (SW480 and HT29 cells) and tumor tissues but not the normal human intestinal epithelial cells and control colon tissue. These studies suggest that peptide CP15 may be a promising lead candidate in the development of a useful colon tumor diagnostic and targeted drug delivery agent.

Synthesis and characterizations of amphiphilic poly(l-lactide)-grafted chondroitin sulfate copolymer and its application as drug carrier

In this investigation, new biodegradable brush-like amphiphilic copolymers were synthesized by ring opening polymerization. Poly(L-lactide) (PLLA) was grafted onto chondroitin sulfate (CS), which is one of the physiologically significant specific glycosaminoglycans (GAGs), using a tin octanoate [Sn(Oct)2] catalyst in DMSO. The hydroxyl groups of the chondroitin sulfate were used as initiating groups. These functional groups enable specific mucoadhesion or receptor recognition. The degree of substitution (DS), the degree of polymerization (DP) and the chondroitin sulfate content (from 1.1 to 15.4%) were analyzed by 1H NMR. The characteristics of these grafted copolymers, including the structure, the thermal properties and biodegradability, etc., were examined with respect to CS content. Meanwhile, the amphiphilic core (PLLA)-corona (CS) nanoparticles, with size smaller than 200 nm, was examined by dynamic light scattering (DLS). Zeta potential analysis exhibited the value in the range -18.3 to -49.4 mV. The morphologies of the nanoparticles were observed by field-emission scanning electron microscopy (FE-SEM). The nanoparticles with lower cytotoxicity were examined by MTT assay. Furthermore, the in vitro BSA release kinetics of those CSn-PLLA nanoparticles was also determined in this study.

Preparation of PEG-conjugated fullerene containing Gd3+ ions for photodynamic therapy

A novel photosensitizer with magnetic resonance imaging (MRI) activity was designed from fullerene (C(60)) for efficient photodynamic therapy (PDT) of tumor. After chemical conjugation of polyethylene glycol (PEG) to C(60) (C(60)-PEG), diethylenetriaminepentaacetic acid (DTPA) was subsequently introduced to the terminal group of PEG to prepare PEG-conjugated C(60) (C(60)-PEG-DTPA). The C(60)-PEG-DTPA was mixed with gadolinium acetate solution to obtain Gd(3+)-chelated C(60)-PEG (C(60)-PEG-Gd). Following intravenous injection of C(60)-PEG-Gd into tumor-bearing mice, the PDT anti-tumor effect and the MRI tumor imaging were evaluated. The similar O(2)(*-)generation was observed with or without Gd(3+) chelation upon light irradiation. Both of the C(60)-PEG-Gd and Magnevist(R) aqueous solutions exhibited a similar MRI activity. When intravenously injected into tumor-bearing mice, the C(60)-PEG-Gd maintained an enhanced MRI signal at the tumor tissue for a longer time period than Magnevist(R). Injection of C(60)-PEG-Gd plus light irradiation showed significant tumor PDT effect although the effect depended on the timing of light irradiation. The PDT efficacy of C(60)-PEG-Gd was observed at the time when the tumor accumulation was detected by the enhanced intensity of MRI signal. This therapeutic and diagnostic hybrid system is a promising tool to enhance the PDT efficacy for tumor.

Effect of an oscillating magnetic field on the release properties of magnetic collagen gels

The paper describes the effect of an oscillating magnetic field (OMF) on the morphology and release properties of collagen gels containing magnetic nanoparticles and microparticles and fluorescent drug analogues. Collagen gels were prepared through fibrillogenesis of collagen in the presence of iron oxide magnetic particles averaging 10 nm or 3 mum in diameter and rhodamine-labeled dextran (Dex-R) of molecular weights between 3000-70 000 g/mol. Dextran molecules effectively simulate protein-based drugs, since they have similar molecular weights and dimensions. The paper discusses the effect of an OMF on the release properties of the gels and proposes an empirical model to predict the release rate. It also demonstrates the self-repair capability of collagen gels following the structural damage caused by an OMF.

Novel amphiphilic macromolecules and their in vitro characterization as stabilized micellar drug delivery systems

A series of amphiphilic macromolecules, amphiphilic scorpion-like macromolecules (AScMs) and amphiphilic star-like macromolecules (ASMs), were evaluated as potential drug delivery systems for intravenous administration. AScMs aggregate to form polymeric micelles; whereas the ASMs have a covalently bound core structure and behave as unimolecular micelles. Four structurally different AScMs and two ASMs were selected for further evaluation focusing on micellar stability and biocompatibility. AScMs were determined to have extremely low cmc values, indicating excellent thermodynamic stability compared to other polymeric micelle systems. Particle sizes of the AScM polymeric micelles and ASM unimolecular micelles were between 10 and 20 nm, and remained constant for up to 3 weeks storages as aqueous solutions at room temperature (approximately 23 degrees C) and 37 degrees C. The dissociation kinetics of the AScM polymeric micelles were slowed relative to small molecule surfactant micelles, again indicating enhanced kinetic stability. With respect to hemolytic activity, AScMs with longer acyl chains were hemolytic; whereas the ASMs had minimal hemolytic activity due to the covalently bound structure. Both ASM unimolecular micelles and AScM polymeric micelles have excellent micellar stability, but the ASMs are more suitable as injectable drug delivery systems due to their low hemolytic activity.