Antisense oligonucleotide G3139 is designed for Bcl-2 downregulation and is known to induce toll-like receptor activation. Novel stabilized lipid-polycation-DNA (sLPD) nanoparticles were constructed and evaluated for the delivery of G3139 to human carcinoma KB cells and for bioactivity in vivo. Polyethylenimine (PEI) was incorporated as a DNA condensing agent. The lipid composition used was DOTAP/DDAB/Chol/TPGS/linoleic acid/hexadecenal at molar ratios of 30/30/34/1/5/0.2. The nanoparticles were stabilized by the formation of a reversible covalent bond between the aldehyde group on the cis-11-hexadecenal and amines on the PEI. When sLPDs were used to transfect KB cells, 90.4% Bcl-2 downregulation was observed, compared to no significant down-regulation by free G3139 and 54.6% down regulation by non-stabilized LPD-G3139. The sLPDs were then evaluated for therapeutic efficacy in mice bearing KB subcutaneous tumors and were found to trigger a strong antitumor response, inhibiting tumor growth and prolonging survival with 72% increase in lifespan (ILS). Consistent with previous reports on other G3139 nanoparticles, the increased anti-tumor activities of sLPDs in vivo were found to be associated with increased cytokine induction rather than Bcl-2 down-regulation, suggesting an immunological mechanism.
Nanoparticles; antisense oligonucleotide; reversible crosslinking; cancer; immunotherapy; drug delivery
We herein report the preparation along with the in vivo and in vitro MRI characterization of two generation four and five cystamine core dendrimers loaded with thirty and fifty-eight derivatized Gd-DOTA (G4SS30, G5SS58) respectively. Likewise the development and characterization of two half-dendrimers conjugated to the F(ab’)2 fragment of the monoclonal antibody (mAb) panitumumab functionalized with a maleimide conjugation functional group site (Ab-(G4S15)4, Ab-(G5S29)4) are also described. The in vitro molar relaxivity of the Ab-(G4S15)4 conjugate, measured at pH 7.4, 22°C, and 3T showed a moderate increase in relaxivity as compared to Magnevist (6.7 vs. 4.0 mM-1s-1) while the Ab-(G5S29)4 conjugate was two-fold higher (9.1 vs. 4.0 mM-1s-1). The data showed that only a high injection dose (0.050 mmol Gd3+/kg) produced a detectable contrast enhanced contrast for the Ab-(G4S15)4 conjugate while a lower dose (0.035 mmol Gd3+/kg) was sufficient for the Ab-(G5S29)4 conjugate. The antibody-SMCC conjugate was purified by a Sephadex G-100 column and the antibody-dendrimer-based agents were purified by spin filtration using a Centricon filter (50,000 MCO). The protein assay coupled with Cysteine and Ellman's assay indicated an antibody to dendrimer ratio of 1:4. The in vivo blood clearance half-lives of the four agents measured at the jugular vein were ~12-22 min.
CD105 (endoglin) is an independent prognostic marker for poor prognosis in > 10 solid tumor types, including breast cancer. The goal of this study was to develop a CD105-specific agent for both positron emission tomography (PET) and near-infrared fluorescence (NIRF) imaging, which can have potential clinical applications in diagnosis and imaged-guided surgery of breast cancer. TRC105, a chimeric anti-CD105 monoclonal antibody, was labeled with both a NIRF dye (i.e. 800CW) and 64Cu to yield 64Cu-NOTA-TRC105-800CW. Flow cytometry analysis revealed no difference in CD105 binding affinity/specificity between TRC105 and NOTA-TRC105-800CW. Serial PET imaging revealed that the 4T1 murine breast tumor uptake of 64Cu-NOTA-TRC105-800CW was 5.2 ± 2.7, 11.0 ± 1.4, and 13.0 ± 0.4 %ID/g at 4, 24, and 48 h post-injection respectively. Tumor uptake as measured by ex vivo NIRF imaging exhibited a good linear correlation with the %ID/g values obtained from PET (R = 0.74). Biodistribution data were consistent with the PET/NIRF findings. Blocking experiments, control studies with dual-labeled cetuximab (an isotype-matched control antibody), and histology confirmed the CD105 specificity of 64Cu-NOTA-TRC105-800CW. Successful PET/NIRF imaging of CD105 expression warrants further investigation and clinical translation of dual-labeled TRC105-based imaging agents.
CD105/endoglin; positron emission tomography (PET); near-infrared fluorescence (NIRF); tumor angiogenesis; TRC105; 64Cu; breast cancer
Premature recognition and clearance of nanoparticulate imaging and therapeutic agents by macrophages in the tissues can dramatically reduce both the nanoparticle half-life and delivery to the diseased tissue. Grafting nanoparticles with hydrogels prevents nanoparticulate recognition by liver and spleen macrophages and greatly prolongs circulation times in vivo. Understanding the mechanisms by which hydrogels achieve this “stealth” effect has implications for the design of long-circulating nanoparticles. Thus, the role of plasma protein absorption in the hydrogel effect is not yet understood. Short-circulating dextran-coated iron oxide nanoparticles could be converted into stealth hydrogel nanoparticles by crosslinking with 1-chloro-2,3-epoxypropane. We show that hydrogelation did not affect the size, shape and zeta potential, but completely prevented the recognition and clearance by liver macrophages in vivo. Hydrogelation decreased the number of hydroxyl groups on the nanoparticle surface and reduced the binding of the anti-dextran antibody. At the same time, hydrogelation did not reduce the absorption of cationic proteins on the nanoparticle surface. Specifically, there was no effect on the binding of kininogen, histidine-rich glycoprotein, and protamine sulfate to the anionic nanoparticle surface. In addition, hydrogelation did not prevent activation of plasma kallikrein on the metal oxide surface. These data suggest that: (a) a stealth hydrogel coating does not mask charge interactions with iron oxide surface and (b) the total blockade of plasma protein absorption is not required for maintaining iron oxide nanoparticles’ long-circulating stealth properties. These data illustrate a novel, clinically promising property of long-circulating stealth nanoparticles.
iron oxide; nanoworms; CLIO; SPIO; kininogen; clearance; plasma; stealth; liver
Controlling and preventing aggregation is critical to the development of safe and effective antibody drug products. The studies presented here test the hypothesis that Protein A and Protein G inhibit the agitation-induced aggregation of IgG. The hypothesis is motivated by the enhanced conformational stability of proteins upon ligand binding and the specific binding affinity of Protein A and Protein G to the Fc region of IgG. The aggregation of mixed human IgG from pooled human plasma was induced by agitation alone or in the presence of: (i) Protein A, (ii) Protein G or (iii) a library of 24 peptides derived from the IgG-binding domain of Protein A. Aggregation was assessed by UV spectroscopy, SDS-PAGE, high performance size-exclusion chromatography (HP-SEC), dynamic light scattering (DLS) and fluorescence spectroscopy. Additional information on IgG-ligand interactions was obtained using differential scanning fluorimetry (DSF) and competitive binding studies. The results demonstrate that Protein A provides near-complete inhibition of agitation-induced aggregation, while Protein G and two peptides from the peptide library show partial inhibition. The findings indicate that the IgG Protein A binding site is involved in the agitation-induced aggregation of IgG, and suggest a dominant role of colloidal interactions.
protein formulation; biologics; IgG; aggregation; Protein A; Protein G; peptide library
The Biopharmaceutics Drug Disposition Classification System (BDDCS) was successfully employed for predicting drug-drug interactions (DDIs) with respect to drug metabolizing enzymes (DMEs), drug transporters and their interplay. The major assumption of BDDCS is that the extent of metabolism (EoM) predicts high versus low intestinal permeability rate, and vice versa, at least when uptake transporters or paracellular transport are not involved. We recently published a collection of over 900 marketed drugs classified for BDDCS. We suggest that a reliable model for predicting BDDCS class, integrated with in vitro assays, could anticipate disposition and potential DDIs of new molecular entities (NMEs). Here we describe a computational procedure for predicting BDDCS class from molecular structures. The model was trained on a set of 300 oral drugs, and validated on an external set of 379 oral drugs, using 17 descriptors calculated or derived from the VolSurf+ software. For each molecule, a probability of BDDCS class membership was given, based on predicted EoM, FDA solubility (FDAS) and their confidence scores. The accuracy in predicting FDAS was 78% in training and 77% in validation, while for EoM prediction the accuracy was 82% in training and 79% in external validation. The actual BDDCS class corresponded to the highest ranked calculated class for 55% of the validation molecules, and it was within the top two ranked more than 92% of the times. The unbalanced stratification of the dataset didn’t affect the prediction, which showed highest accuracy in predicting classes 2 and 3 with respect to the most populated class 1. For class 4 drugs a general lack of predictability was observed. A linear discriminant analysis (LDA) confirmed the degree of accuracy for the prediction of the different BDDCS classes is tied to the structure of the dataset. This model could routinely be used in early drug discovery to prioritize in vitro tests for NMEs (e.g., affinity to transporters, intestinal metabolism, intestinal absorption and plasma protein binding). We further applied the BDDCS prediction model on a large set of medicinal chemistry compounds (over 30,000 chemicals). Based on this application, we suggest that solubility, and not permeability, is the major difference between NMEs and drugs. We anticipate that the forecast of BDDCS categories in early drug discovery may lead to a significant R&D cost reduction.
BDDCS; ADMET; GRID; MIF; Drug Disposition; Drug-Drug Interactions; VolSurf+; FDA solubility; machine learning
The ATP-binding cassette transporters p-glycoprotein and breast cancer resistance protein have been shown to be critical determinants limiting drug transport across the BBB into the brain. Several therapeutic agents have been shown to be substrates for these two transporters, and as a result they have limited distribution to the brain. Recently, it has been shown that these two drug transporters cooperate at the BBB and brain penetration of dual substrates increase significantly only when both are absent, e.g., in the Mdr1a/1b-/-Bcrp1-/- mice. The present study uses the brain penetration of sorafenib to investigate these findings and attempts to explain the mechanistic basis of this cooperation with a simple theory based on affinity and capacity dependent carrier-mediated transport. The brain efflux index method, combined with the organotypic brain slices, were used to determine the net contribution of P-gp and BCRP to the total clearance of sorafenib out of the brain and show that its efflux at the BBB is mediated primarily by BCRP. Sorafenib clearance out of the brain decreased 2-fold in the Bcrp1-/- mice and 2.5-fold in the Mdr1a/1b-/-Bcrp1-/- mice. Clearance out of brain when P-gp was absent did not change significantly compared to wild-type. We also investigated the expression of P-gp and BCRP in the genetic knockout animals and saw no differences in either P-gp or BCRP in the transporter deficient mice compared to the wild-type mice. In conclusion, this study explains the cooperation of P-gp and BCRP by analysis of the efflux clearance of sorafenib and correlating it to the ‘mechanisms’ that determine the clearance, i.e., affinity and capacity.
Blood-brain barrier; P-glycoprotein; BCRP; Cooperation; Sorafenib; Efflux; Transporters
We have shown that the rat can quantitatively predict the verapamil-cyclopsorine A (CsA) drug-drug interaction (DDI) at the human blood-brain barrier (BBB). In addition, the potency (EC50) of CsA to inhibit rat BBB P-gp can be predicted from in vitro studies in MDRI-transfected cells. To assess if these excellent agreements extend to other substrates, we determined the magnitude of P-gp-based DDI at the rat BBB between loperamide (Lop) or its metabolite, N-desmethyl Lop (dLop), and escalating CsA blood concentrations. The percent increase in the brain:blood Lop concentration ratio was described by the Hill equation, Emax=2000%, EC50=7.1 μM and γ=3.7. The potency (EC50) of CsA to inhibit P-gp at the rat BBB was independent of the substrate used (verapamil, Lop, or dLop). Like the verapamil-CsA DDI, the potency (EC50) of CsA to inhibit rat BBB P-gp could be predicted from studies in MDRI-transfected cells. When 11C-Lop was co-administered with a 10 mg/kg i.v. infusion of CsA 1yielding ~5.6 uM CsA blood concentration) to healthy volunteers, the brain distribution of 11C-radioactivity was increased by 110% 1. When corrected for diffusible Lop metabolite(s), this translates into an increase in 11C-Lop brain distribution of 457%. Based on our rat data, we estimated a remarkably similar value at 5.6 μM blood CsA concentration, 588% increase in Lop brain distribution. These data support our conclusion that the rat is a promising model to predict P-gp based DDI at the human BBB.
P-glycoprotein; blood-brain-barrier; Cyclosporine A; Loperamide; N-desmethyl Loperamide; drug-drug interaction; in vitro to in vivo correlation
Tumor resistance to chemotherapy is the major obstacle to employ cisplatin, one of the broadly used chemotherapeutic drugs, for effective treatment of various tumors in the clinic. Most acknowledged mechanisms of cancer resistance to cisplatin focus on increased nuclear DNA repair or detoxicity of cisplatin. We previously demonstrated that there was a unique metabolic profile in cisplatinresistant (CP-r) human epidermoid adenocarcinoma KB-CP 20 and hepatoma BEL 7404-CP 20 cancer cells. In this study, we further defined hyperpolarized mitochondrial membrane potentials (Δψm) in CP-r KB-CP 20 and BEL 7404-CP 20 cells compared to the cisplatin-sensitive (CP-s) KB-3-1 and BEL 7404 cells. Based on the mitochondrial dysfunction, mitaplatin was designed with two mitochondrial-targeting moieties [dichloroacetate (DCA) units] to the axial positions of a six-coordinate Pt(IV) center to sensitize cisplatin resistance. It was found that mitaplatin induced more apoptosis in CP-r KB-CP 20 and BEL 7404-CP 20 cells than that of cisplatin, DCA and cisplatin/DCA compared on an equal molar basis. There was more platinum accumulation in mitaplatin-treated CP-r cells due to enhanced transmembrane permeability of lipophilicity, and mitaplatin also showed special targeting to mitochondria. Moreover, in the case of treatment with mitaplatin, the dramatic collapse of Δψm was shown in a dose-dependent manner, which was confirmed by FACS and confocal microscopic measurements. Reduced glucose utilization of CP-r cells was detected with specifically inhibited phosphorylation of pyruvate dehydrogenase (PDH) at Ser-232, Ser-293, and Ser-300 of the E1α subunit when treated with mitaplatin, which was indicated to modulate the abnormal glycolysis of resistant cells. The present study suggested novel mitochondrial mechanism of mitaplatin circumventing cisplatin resistance toward CP-r cells as a carrier across membrane to produce CP-like cytotoxicity and DCA-like mitochondria-dependent apoptosis. Therefore, mitochondria targeting compounds would be more vulnerable and selective to overcome cisplatin resistance due to the unique metabolic properties of CP-r cancer cells.
mitaplatin; cisplatin; cancer resistance; mitochondrial dysfunction
Transscleral retinal delivery of celecoxib, an anti-inflammatory and anti-VEGF agent is restricted by its poor solubility and binding to the melanin pigment in choroid-RPE. The purpose of this study was to develop soluble prodrugs of celecoxib with reduced pigment binding and enhanced retinal delivery.
Three hydrophilic amide prodrugs of celecoxib were synthesized and characterized for solubility and lipophilicity. In vitro melanin binding to natural melanin (Sepia Officinalis) was estimated for all three prodrugs. In vitro transport studies across isolated bovine sclera and sclera-choroid-RPE (SCRPE) were performed. Prodrug with the highest permeability across SCRPE was characterized for metabolism and cytotoxicity and its in vivo transscleral delivery in pigmented rats.
Celecoxib succinamidic acid (CSA), celecoxib maleamidic acid (CMA), and celecoxib acetamide (CAA) were synthesized and characterized. Aqueous solubilities of CSA, CMA, and CAA were 300-, 182-, and 76-fold higher, respectively, than celecoxib. Melanin binding affinity and capacity was significantly lower than celecoxib for all three prodrugs. Rank order for the % in vitro transport across bovine sclera and SCRPE was CSA > CMA ~ CAA ~ celecoxib, with the transport being 8-fold higher for CSA than celecoxib. CSA was further assessed for its metabolic stability and in vivo delivery. CSA showed optimum metabolic stability in all eye tissues with only 10–20 % conversion to parent celecoxib in 30 minutes. Metabolic enzymes responsible for bioconversion included amidases, esterase, and cytochrome P-450. In vivo delivery in pigmented BN rats showed that CSA had 4.7-, 1.4-, 3.3-, 6.0-, and 4.5- fold higher delivery to sclera, choroid-RPE, retina, vitreous, and lens than celecoxib. CSA has no cytotoxicity in ARPE-19 cells in the concentration range of 0.1 to 1000 μM.
Celecoxib succinamidic acid is a soluble prodrug of celecoxib with reduced melanin binding which enhances transscleral retinal delivery of celecoxib.
Celecoxib; prodrugs; transscleral; melanin binding; retinal delivery
Indocyanine green (ICG) is a conventional dye that can be used in clinicalnear-infrared (NIR) imaging and it is also an effective light absorber for laser-mediated photothermal therapy. However, applications of ICG were limited due to its fast degradation in aqueous media and quick clearance from the body. Herein, an ICG-containing nanostructure, ICG-PL-PEG, was developed for photothermal therapy, which was self-assembled by ICG and phospholipid-polyethylene glycol (PL-PEG). Our in vitro and in vivo experiments demonstrated that ICG-PL-PEG suspension was more efficient in producing a NIR-dependent temperature increase than ICG alone, due to the increase of ICG monomers from the addition of PL-PEG to match the central wavelength of the 808-nm laser. When conjugated with integrin αvβ3 monoclonal antibody (mAb), ICG-PL-PEG could be selectively internalized and retained in target tumor cells. Irradiation of an 808-nm laser after intravenous administration of ICG-PL-PEG-mAb resulted in tumor suppression in mice, while ICG alone only had limited effect. This is the first time an ICG-containing nanostructure has been used through systemic administration to achieve an efficient in vivo photothermal effect for cancer treatment. Therefore, ICG-PL-PEG could be used as a fluorescent marker as well as a light-absorber for imaging-guided photothermal therapy. All the components of ICG-PL-PEG have been approved for human use. Therefore, this unique ICG-containing nanostructure has great potential in clinical applications.
laser-mediated photothermal therapy; ICG-containing nanostructure; self-assembly; NIR-dependent temperature increase; photothermal tumor suppression
The aim of this study is to compare the cytotoxicity mechanisms of linear PEI to two analogous polymers synthesized by our group: a hydroxyl-containing poly(L-tartaramidoamine) (T4) and a version containing an alkyl chain spacer poly(adipamidopentaethylenetetramine) (A4) by studying the cellular responses to polymer transfection. We have also synthesized analogues of T4 with different molecular weights (degrees of polymerization of 6, 12, and 43) to examine the role of molecular weight on the cytotoxicity mechanisms. Several mechanisms of polymer-induced cytotoxicity are investigated, including plasma membrane permeabilization, the formation of potentially harmful polymer degradation products during transfection including reactive oxygen species, and nuclear membrane permeabilization. We hypothesized that since cationic polymers are capable of disrupting the plasma membrane, they may also be capable of disrupting the nuclear envelope, which could be a potential mechanism of how the pDNA is delivered into the nucleus (other than nuclear envelope breakdown during mitosis). Using flow cytometry and confocal microscopy, we show that the polycations with the highest amount of protein expression and toxicity, PEI and T443, are capable of inducing nuclear membrane permeability. This finding is important for the field of nucleic acid delivery in that not only could direct nucleus permeabilization be a mechanism for pDNA nuclear import but also a potential mechanism of cytotoxicity and cell death. We also show that the production of reactive oxygen species is not a main mechanism of cytotoxicity, and that the presence or absence of hydroxyl groups as well as polymer length plays a role in polyplex size and charge in addition to protein expression efficiency and toxicity.
Gene delivery polymers; toxicity; polyethylenimine; apoptosis; PGAAs; glycopolymer
Here we described a paclitaxel (PTX) nanocrystals formulation using D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) as the sole excipient for overcoming multidrug resistance (MDR), a key challenge in current cancer therapy. To the best of our knowledge, it is the first report on PTX nanocrystals which can reverse MDR. TPGS serves as a surfactant to stabilize the nanocrystals and a P-gp inhibitor to reverse MDR. The size and morphology of the nanocrystals were studied by transmission electron microscopy and the crystalline structure was determined by powder X-ray diffraction. In vitro drug release profile showed that the nanocrystals exhibited sustained release kinetics compared to Taxol which is the clinical paclitaxel formulation. The cytotoxicity and antitumor efficacy in xenograft models were also investigated. It is demonstrated that PTX/TPGS nanocrystals have significant advantages over Taxol in achieving better therapeutic effect in Taxol-resistant cancer cells both in vitro and in vivo, which was also confirmed by apoptosis assays. We envision that further development of this type of nanocrystals will provide a novel strategy for drug delivery and multidrug resistance treatment.
multidrug resistance; paclitaxel; nanocrystals; TPGS; cancer
Although the potent anti-tumor activity of nitric oxide (NO) supports its promise as an anti-neoplastic agent, effective and selective delivery and action on tumor and not normal cells remains a limiting factor. Nanoparticle-based delivery of NO has been considered as one approach to overcome these limitations. Therefore, we determined the utility of NO delivery using silica nanoparticles and evaluated their anti-tumor efficacy against human ovarian tumor and nontumor cells. The NO-releasing nanoparticles exhibited enhanced growth inhibition of ovarian tumor cells when compared to both control nanoparticles and a previously reported small molecule NO donor, PYRRO/NO. In addition, the NO-releasing nanoparticles showed greater inhibition of the anchorage-independent growth of tumor-derived and Ras-transformed ovarian cells. Confocal microscopy analysis revealed that fluorescently-labeled NO-releasing nanoparticles entered the cytosol of the cell and localized to late endosomes and lysosomes. Furthermore, we observed a nanoparticle size dependency on efficacy against normal versus transformed ovarian cells. Our study provides the first application of nanoparticle-derived NO as an antitumor therapy and supports the merit for future studies examining nanoparticle formulation for in vivo applications.
Nanoparticle; silica; nitric oxide; ovarian cancer; Ras
The plant virus, Cowpea mosaic virus (CPMV), is developed as a carrier of the chemotherapeutic drug doxorubicin (DOX). CPMV-DOX conjugate, in which eighty DOX molecules are covalently bound to external surface carboxylates of the viral nanoparticle (VNP), shows greater cytotoxicity than free DOX toward HeLa cells when administered at low dosage. At higher concentrations CPMV-DOX cytotoxicity is time-delayed. The CPMV-conjugate is targeted to the endolysosomal compartment of the cells, in which the proteinaceous drug carrier is degraded and the drug released. This study is the first demonstrating the utility of CPMV as a drug delivery vehicle.
Cowpea mosaic virus; doxorubicin, drug delivery; viral nanoparticle; cancer
Non-ionic surfactant vesicles, or SPANosomes (SPs), comprised of cationic lipid and sorbitan monooleate (Span 80) were synthesized and evaluated as siRNA vectors. The SPs had a mean diameter of less than 100 nm and exhibited excellent colloidal stability. The SP/siRNA complexes possessed a slightly positive zeta potential of 12 mV and demonstrated a high siRNA incorporation efficiency of greater than 80%. Cryogenic transmission electron microscopy (cryo-TEM) imaging of the SP/siRNA indicated a predominantly core-shell structure. The SP/siRNA complexes were shown to efficiently and specifically silence expression of both green fluorescent protein (GFP) (66% knockdown) and aromatase (77% knockdown) genes in breast cancer cell lines. In addition, the cellular trafficking pathway of the SP/siRNA was investigated by confocal microscopy using molecular beacons as probes for cytosolic delivery. The results showed efficient endosomal escape and cytosolic delivery of the siRNA cargo following internalization of the SP/siRNA complexes. In conclusion, Span 80 is a potent helper lipid and the SPs are promising vehicles for siRNA delivery.
Drug delivery; Nanoparticles; Surfactant vesicles; siRNA; Molecular beacon
Previously we have shown cationic lipid (R)-DOTAP as the immunologically active enantiomer of the DOTAP racemic mixture, initiating complete tumor regression in an exogenous antigen model (murine cervical cancer model). Here, we investigate the use of (R)-DOTAP as an efficacious adjuvant delivering an endogenous antigen in an aggressive murine solid tumor melanoma model. (R)-DOTAP/Trp2 peptide complexes showed decreasing size and charge with increasing peptide concentration, taking a rod-shape at highest concentrations. The particles were stable for at 2 weeks at 4°C. A dose of 75nmol Trp2 (formulated in (R)-DOTAP) was able to show statistically significant tumor growth delay compared to lower doses of 5 and 25nmol which were no different than untreated tumors. (R)-DOTAP/Trp2 (75nmol) treated mice also showed increased T cell IFN-γ secretion after restimulation with Trp2, as well as CTL activity in vivo. This vaccination group also showed the highest population of functionally active tumor-infiltrating lymphocytes, indicated by IFN-γ secretion after restimulation with Trp2. Thus, (R)-DOTAP has shown the ability to break tolerance as an adjuvant. Its activity to enhance immunogenicity of other tumor associated antigens should be studied further.
(R)-DOTAP; peptide vaccine; melanoma; immunotherapy
Cell penetrating peptides (CPPs) are short strands of arginine and/or lysine-rich peptides (<30 amino acids) that use their cationic nature for efficient intracellular accumulation. CPPs have been used for small interfering RNA (siRNA) delivery by direct complexation with the siRNA anionic phosphate backbone. During this process, however, part of the CPP cationic charges are neutralized, and the resultant loss of free positive charges may substantially compromise CPP’s internalization capabilities and eventually reduce siRNA delivery efficiency. The purpose of this study was to design a novel type of polyplex for siRNA delivery to overcome the CPP neutralization issue. This novel polyplex consists of three components: siRNA, 21mer oligolysine (K21) chemically modified to incorporate CPP conjugation sites (K21-PDP), and CPP delivery moiety. The siRNA was first neutralized by cationic charges of K21-PDP to form a polyplex. Then a cationic (hexa-arginine – R6) or an amphipathic (model amphipathic peptide – MAP) CPP was conjugated to the polyplex. Agarose gel shift assays indicated that the siRNA could be released from the polyplex after K21-PDP degradation or polyplex dilution. Furthermore, the total intracellular internalization of these two CPP-polyplexes was studied. Compared with R6-polyplex, MAP-polyplex exhibited 170 and 600-fold greater uptake of fluorescently-labeled siRNA at 1 and 6 h post-transfection, respectively. MAP-polyplex also exhibited comparable GFP silencing effects as Lipofectamine 2000 complex in Huh7.5 cells stably transfected to express GFP-LC3, whereas R6-polyplex did not demonstrate significant silencing activity. Further studies indicated that the K21-PDP/siRNA polyplex formation and conjugation of MAP to the polyplex were essential for siRNA polyplex uptake and gene silencing. MAP-polyplex was also shown to be unaffected by the presence of 10% FBS during transfection. In addition, MAP-polyplex uptake was dependent on vesicle formation and fusion due to 70 and 54% loss of uptake at 4 and 16°C, respectively, compared to incubation at 37°C. Therefore, the amphipathic CPP is a more suitable carrier moiety for delivery of siRNA polyplex.
Cell penetrating peptides; siRNA; siRNA delivery; oligoarginine; model amphipathic peptide; polyplex; membrane transduction peptides
Ghrelin, an enteric peptide hormone linked to the pathophysiology of obesity has been a therapeutic target of great interest over the past decade. Many research efforts have focused on the antagonism of ghrelin’s endogenous receptor GHSR1a, which is found along ascending vagal afferent fibers, as well as in the arcuate nucleus of the hypothalamus. Additionally, peptidic inhibitors against ghrelin O-acyltransferase, the enzyme responsible for the paracrine activation of ghrelin, have recently been studied. Our research has taken an alternative immunological approach, studying both active and passive vaccination as a means to sequester ghrelin in the periphery, with the original discovery in rat of decreased feed efficiency and adiposity, as well as increased metabolic activity. Using our previous hapten designs as a stepping-stone, three monoclonal antibodies (JG2, JG3, and JG4) were procured against ghrelin and tested in vivo. While mAb JG4 had the highest affinity for ghrelin, it failed to attenuate the orexigenic effects of food deprivation on energy metabolism or food intake in mice. However, animals that were administered a combination of JG3:JG4, (termed a doublet), or JG2:JG3:JG4, (termed a triplet), demonstrated higher heat dispersion and rate of respiration (higher CO2 emission and O2 consumption) during a 24-hr fast refeed. Mice administered the triplet cocktail of JG2:JG3:JG4 also demonstrated decreased food intake upon refeeding as compared to control animals. Recently, Lu and colleagues reported that a passive approach using a single, high affinity N-terminally directed monoclonal antibody did not abrogate the effects of endogenous ghrelin. Our current report corroborates this finding, yet, refutes that a monoclonal antibody approach cannot be efficacious. Rather, we find that a multiple monoclonal antibody (oligoclonal) approach can reproduce the underlying logic to previously reported efficacies using active vaccinations.
ghrelin; monoclonal antibodies; passive vaccination; active vaccination; metabolism; food intake
This study involves a promising approach to achieve sustained pulmonary drug delivery. Dry powder particulate carriers were engineered to allow simultaneous aerosol lung delivery, evasion of macrophage uptake, and sustained drug release through a controlled polymeric architecture. Chitosan grafted with PEG was synthesized and characterized (FTIR, EA, DSC and 2D-XRD). Then, a series of respirable amphiphilic hydrogel microparticles were developed via spray drying of curcumin-loaded PLGA nanoparticles with chitosan-grafted-PEG or chitosan. The nano and microparticles were fully characterized using an array of physicochemical analytical methods including particle size, surface morphology, dynamic swelling, density, moisture content and biodegradation rates. The PLGA nanoparticles and the hydrogel microspheres encapsulating the curcumin-loaded PLGA nanoparticles showed average size of (221-243 nm) and (3.1-3.9 μm), respectively. The developed carriers attained high swelling within a few minutes, showed low moisture content as dry powders (0.9-1.8%), desirable biodegradation rates, high drug loading (up to 97%), and good sustained release. An aerosolization study was conducted using a next generation impactor and promising aerosolization characteristics were shown. In vitro macrophage uptake studies, cytotoxicity and in-vitro TNF-α assays were performed for the investigated particles. These assays revealed promising bio-interactions for the respirable/swellable nano-micro particles developed in this study as potential carriers for sustained pulmonary drug delivery.
Nanoparticles; microspheres; PLGA; chitosan; PEG; curcumin; pulmonary; sustained; lung; drug delivery
We describe the use of Co(III) Schiff base-DNA conjugates, a versatile class of research tools that target C2H2 transcription factors, to inhibit the Hedgehog (Hh) pathway. In developing mammalian embryos, Hh signaling is critical for the formation and development of many tissues and organs. Inappropriate activation of the Hedgehog (Hh) pathway has been implicated in a variety of cancers including medulloblastomas and basal cell carcinomas. It is well known that Hh regulates the activity of the Gli family of C2H2 zinc finger transcription factors in mammals. In Drosophila the function of the Gli proteins is performed by a single transcription factor with an identical DNA binding consensus sequence, Cubitus Interruptus (Ci). We have demonstrated previously that conjugation of a specific 17 base-pair oligonucleotide to a Co(III) Schiff base complex results in a targeted inhibitor of the Snail family C2H2 zinc finger transcription factors. Modification of the oligonucleotide sequence in the Co(III) Schiff base-DNA conjugate to that of Ci’s consensus sequence (Co(III)-Ci) generates an equally selective inhibitor of Ci. Co(III)-Ci irreversibly binds the Ci zinc finger domain and prevents it from binding DNA in vitro. In a Ci responsive tissue culture reporter gene assay, Co(III)-Ci reduces the transcriptional activity of Ci in a concentration dependent manner. In addition, injection of wild-type Drosophila embryos with Co(III)-Ci phenocopies a Ci loss of function phenotype, demonstrating effectiveness in vivo. This study provides evidence that Co(III) Schiff base-DNA conjugates are a versatile class of specific and potent tools for studying zinc finger domain proteins and have potential applications as customizable anti-cancer therapeutics.
Basal Cell Carcinoma; Cobalt chelate/Schiff base; Development; Drosophila; Hedgehog Signaling; Cubitus interruptus; Transcription Factor; Zinc Fingers
Adjuvants modulate protective CD8+ T cell responses generated by cancer vaccines. We have previously shown that immunostimulatory CpG ODN significantly augments tumor protection in mice given adenovirus cancer vaccines. Here, we examined the impact of chitosan, another candidate vaccine adjuvant, on protection conferred by adenovirus cancer vaccines. Unexpectedly, immunization of mice with adenovirus cancer vaccines in combination with chitosan provided little protection against tumor challenge. This directly correlated with reduced detection of Ag-specific CD8+ T cells, IFN-γ production and cytotoxic T cell activity. We ruled out immunosuppressive regulatory T cells since frequency did not change regardless of whether chitosan was delivered. In mammalian cell lines, chitosan did not interfere with adenovirus transgene expression. However, infection of primary murine bone marrow-derived dendritic cells with adenovirus complexed with chitosan significantly reduced viability, transgene expression and upregulation of MHC class I and CD86. Our in vitro observations indicate that chitosan dramatically inhibits adenovirus-mediated transgene expression and antigen presenting cell activation, without which CD8+ T cell activation cannot occur in vivo. These surprising data demonstrate for the first time that chitosan vaccine formulations can negatively impact the induction of CD8+ T cell responses via its effect on dendritic cells, which is clinically important since consideration of chitosan as an adjuvant for vaccine formulations is growing.
Chitosan; CpG ODN; adenovirus; cancer vaccine; dendritic cell; CD8+ T cell
Delivery of short interfering RNA (siRNA) to cells in culture, and in vivo, is possible with combined use of a receptor-specific monoclonal antibody (MAb) and avidin-biotin technology. In the present studies, the luciferase gene is transiently expressed in human 293 epithelial cells. The siRNA delivery system is comprised of the siRNA, mono-biotinylated on the 3′-terminus of the sense strand, and a conjugate of streptavidin (SA) and a MAb to the human insulin receptor (HIR). Exposure of cells to 3′-biotinyl-siRNA bound to the HIRMAb/SA conjugate, but not to unconjugated SA, avidin, or the HIRMAb, causes a >90% reduction in luciferase gene expression. The receptor-targeted siRNA effect is maximal at 48 hours after delivery of the siRNA to the cells, and the effect is lost by 7 days after a single application of the targeted siRNA in culture. The KI of the receptor-targeted siRNA inhibition of gene expresssion is 30.5 ± 11.7 nM, and significant inhibition is observed with siRNA concentrations as low as 3 nM. In conclusion, the combination of a receptor-specific targeting ligand, such as the HIRMAb, and avidin-biotin technology, allows for high affinity capture of the mono-biotinylated siRNA by the targeting MAb. The siRNA is effectively delivered to the cytosol of cells and knockdown of gene expression with the HIRMAb/SA delivery system is comparable to RNA interference effects obtained with cationic polyplexes. Whereas the use of cationic polyplexes in vivo is problematic, the bond between the targeting MAb and the siRNA is stable with avidin-biotin technology, and RNAi effects at distant sites such as brain are observed in vivo following an intravenous administration of the targeted siRNA.
blood-brain barrier; insulin receptor; luciferase; RNAi; siRNA
Local intravaginal drug therapy is preferred for treatment of ascending genital infections during pregnancy. In the present study, in-situ forming biodegradable hydrogel for sustained release of amoxicillin in the cervicovaginal region is described. A generation 4 poly(amidoamine) [G4-(NH2)64] dendrimer with peripheral thiopyridyl terminations is crosslinked with 8-arm polyethylene glycol (PEG) bearing thiol terminations. The hydrogels were formulated and tested in-vivo in pregnant guinea pig model for volume, retention times, biodegradation, tolerability and transport across fetal membrane. The physicochemical characterization of the hydrogels was carried out using differential calorimetry, SEM, and confocal imaging. The hydrogels offer antibacterial activity arising from sustained release of amoxicillin from gels. The in-vivo studies in guinea pig showed that 100-200 μL of gel sufficiently covered the cervicovaginal region with a residence time of at least 72 h and gel was primarily retained in the maternal tissues without crossing the fetal membranes into the fetus. The dendrimer gels were stable upto 72 h and the in-vivo biodegradation of gel occurred after 72 h and this correlated well with the in-vitro degradation pattern. The pH of the vagina was not altered upon application of the gel and none of the animals aborted upto 72 h after application of gel. The histological evaluation of the cervical tissues showed absence of edema in epithelial cell layer, no sloughing of the epithelial or superficial mucous layer, absence of necrosis and infiltration of inflammatory cells in the submucosal layers confirmed that tissues were tolerant to the gel. The immunohistofluorescence images showed the localization of the gel components on the superficial mucified epithelial layer. The crosslinking density and swelling of hydrogels was impacted by the polymer content and the 10 % hydrogels exhibited highest crosslink density. The in-vitro drug release studies carried out using Franz diffusion cells showed that amoxicillin release from 6 and 10 % gels was sustained for 240 h as compared to 3 % gels. As the polymer concentration increased to 10 % the release pattern from gels approached diffusion controlled mechanism with diffusional exponent n = 0.49. In conclusion, the biodegradable in-situ forming hydrogels of present study offer a therapeutic option to provide sustained localized delivery of amoxicillin intracervically to the pregnant woman for the treatment of ascending genital infections.
Injectable hydrogels; biodegradable hydrogel; sustained release of amoxicillin; pregnant guinea pig model; pregnancy; treatment of genital infections; formulation; in-vitro and in-vivo evaluation
Polymeric micelles formed by the self-assembly of amphiphilic block copolymers can be used to encapsulate hydrophobic drugs for tumor-delivery applications. Filamentous carriers with high aspect ratios offer potential advantages over spherical carriers, including prolonged circulation times. In this work, mixed micelles comprised of poly (ethylene oxide)-poly-[(R)-3-hydroxybutyrate]-poly (ethylene oxide) (PEO-PHB-PEO) and Pluronic F-127 (PF-127) were used to encapsulate a near-infrared fluorophore. The micelle formulations were assessed for tumor accumulation after tail vein injection to xenograft tumor-bearing mice by non-invasive optical imaging. The mixed micelle formulation that facilitated the highest tumor accumulation was shown by cryo-electron microscopy to be filamentous in structure compared to spherical structures of pure PF-127 micelles. In addition, increased dye loading efficiency and dye stability was attained in this mixed micelle formulation compared to pure PEO-PHB-PEO micelles. Therefore, the optimized PEO-PHB-PEO/PF-127 mixed micelle formulation offers advantages for cancer delivery over micelles formed from the individual copolymer components.
Filamentous micelles; indocyanine green; tumor delivery; triblock copolymers