Enhanced Photodynamic Therapy Efficacy through Solid Lipid Nanoparticle of Purpurin-18-N-Propylimide Methyl Ester for Cancer Treatment.

Photodynamic therapy (PDT) is an innovative cancer treatment that utilizes light. When light irradiates, purpurin-18-N-propylimide methyl ester (P18 N PI ME) generates reactive oxygen species that destroy cancer cells. The hydrophobic nature of P18 N PI ME presents challenges regarding its aggregation in the body, which can affect its effectiveness. This study aimed to enhance the bioavailability and effectiveness of cancer treatment by synthesizing P18 N PI ME and formulating P18 N PI ME-loaded solid lipid nanoparticles (SLNs). The efficacy of PDT was estimated using the 1,3-diphenylisobenzofuran (DPBF) assay and photocytotoxicity tests on the HeLa (human cervical carcinoma) and A549 (human lung carcinoma) cell lines. The P18 N PI ME-loaded SLNs demonstrated particle sizes in the range of 158.59 nm to 248.43 nm and zeta potentials in the range of -15.97 mV to -28.73 mV. These SLNs exhibited sustained release of P18 N PI ME. DPBF analysis revealed enhanced PDT effects with SLNs containing P18 N PI ME compared with standalone P18 N PI MEs. Photocytotoxicity assays indicated toxicity under light irradiation but no toxicity in the dark. Furthermore, the smallest-sized formulation exhibited the most effective photodynamic activity. These findings indicate the potential of P18 N PI ME-loaded SLNs as promising strategies for PDT in cancer therapy.

Design of smart chemotherapy of doxorubicin hydrochloride using nanostructured lipid carriers and solid lipid nanoparticles for improved anticancer efficacy.

Doxorubicin hydrochloride (DOX) is an anticancer agent used in cancer chemotherapy. The purpose of this study was to design nanostructured lipid carriers (NLCs) of DOX as smart chemotherapy to improve its photostability and anticancer efficacy. The characteristics of DOX and DOX-loaded NLCs were investigated using UV-Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, particle size, and zeta potential study. The cytotoxicity of DOX was evaluated against three cancer cell lines (HeLa, A549, and CT-26). The particle size and zeta potential were in the range 58.45-94.08 nm and -5.80 mV - -18.27 mV, respectively. The chemical interactions, particularly hydrogen bonding and van der Waals forces, between DOX and the main components of NLCs was confirmed by FTIR. NLCs showed the sustained release profile of DOX. The photostability results revealed that the NLC system improved the photostability of DOX. Cytotoxicity results using the three cell lines showed that all formulations improved the anticancer efficacy of free DOX, and the efficacy was dependent on cell type and particle size. These results suggest that DOX-loaded NLCs are promising chemotherapeutic agents for cancer treatment.

Long-Wavelength Absorbing Benzimidazolo-Chlorin for Enhanced Photodynamic Therapy.

In this study, we condensed methyl pyropheophorbide-a (2) with 1,2-phenylenediamine to synthesize benzimidazolo-chlorin (3a) as an effective near-infrared photosensitizer (PS) with an absorption maximum of 730 nm. The ability of 3a to generate singlet oxygen, as well as its photodynamic effect on A549 and HeLa cells, was investigated. PS exhibited strong phototoxicity and negligible dark toxicity. Its structure was examined by UV-visible spectroscopy, nuclear magnetic resonance, and high-resolution fast atom bombardment mass spectrometry.

pH-Responsive Nano-transferosomes of Purpurin-18 Sodium Salt and Doxorubicin for Enhanced Anticancer Efficiency by Photodynamic and Chemo Combination Therapy.

Cancer is a devastating disease and a major human health concern. Various combination treatments have been developed to combat cancer. To obtain superior cancer therapy, the objective of this study was to synthesize purpurin-18 sodium salt (P18Na) and design P18Na- and doxorubicin hydrochloride (DOX)-loaded nano-transferosomes as a combination of photodynamic therapy (PDT) and chemotherapy for cancer. The characteristics of P18Na- and DOX-loaded nano-transferosomes were assessed, and the pharmacological efficacy of P18Na and DOX was determined using the HeLa and A549 cell lines. The nanodrug delivery system characteristics of the product were found to range from 98.38 to 217.50 nm and -23.63 to -41.10 mV, respectively. Further, the release of P18Na and DOX from nano-transferosomes exhibited a sustained pH-responsive behavior and burst in physiological and acidic environments, respectively. Accordingly, the nano-transferosomes effectively delivered P18Na and DOX into cancer cells, with less leakage in the body, and exhibited pH-responsive release in cancer cells. A photo-cytotoxicity study to HeLa and A549 cell lines revealed a size-dependent anti-cancer effect. These results suggest that the combined nano-transferosomes of P18Na and DOX are effective in the combination of PDT and chemotherapy for cancer.

Improved anticancer efficacy of methyl pyropheophorbide-a-incorporated solid lipid nanoparticles in photodynamic therapy.

Photodynamic therapy (PDT) is a promising anticancer treatment because it is patient-friendly and non-invasive. Methyl pyropheophorbide-a (MPPa), one of the chlorin class photosensitizers, is a drug with poor aqueous solubility. The purpose of this study was to synthesize MPPa and develop MPPa-loaded solid lipid nanoparticles (SLNs) with improved solubility and PDT efficacy. The synthesized MPPa was confirmed 1H nuclear magnetic resonance (1H-NMR) spectroscopy and UV-Vis spectroscopy. MPPa was encapsulated in SLN via a hot homogenization with sonication. Particle characterization was performed using particle size and zeta potential measurements. The pharmacological effect of MPPa was evaluated using the 1,3-diphenylisobenzofuran (DPBF) assay and anti-cancer effect against HeLa and A549 cell lines. The particle size and zeta potential ranged from 231.37 to 424.07 nm and - 17.37 to - 24.20 mV, respectively. MPPa showed sustained release from MPPa-loaded SLNs. All formulations improved the photostability of MPPa. The DPBF assay showed that SLNs enhanced the 1O2 generation from MPPa. In the photocytotoxicity analysis, MPPa-loaded SLNs demonstrated cytotoxicity upon photoirradiation but not in the dark. The PDT efficacy of MPPa improved following its entrapment in SLNs. This observation suggests that MPPa-loaded SLNs are suitable for the enhanced permeability and retention effect. Together, these results demonstrate that the developed MPPa-loaded SLNs are promising candidates for cancer treatment using PDT.

Solid Lipid Nanoparticles of Curcumin Designed for Enhanced Bioavailability and Anticancer Efficiency.

Curcumin (Cur) has anticancer properties but exhibits poor aqueous solubility, permeability, and photostability. In this study, we aimed to develop a solid lipid nanoparticle (SLN) system to enhance Cur bioavailability. The characteristics of Cur-loaded SLNs prepared by sonication were evaluated using UV-vis and Fourier transform infrared spectroscopy. The mean particle size of the stearic acid-based, lauric acid-based, and palmitic acid-based SLNs was 14.70-149.30, 502.83, and 469.53 nm, respectively. The chemical interactions between Cur and lipids involved hydrogen bonding and van der Waals forces. The formulations with high van der Waals forces might produce a neat arrangement between Cur and lipids, leading to a decrease in particle size. The Cur formulations showed enhanced cytotoxicity in HeLa, A549, and CT-26 cells compared with pure Cur. Additionally, the anticancer effect is dependent on particle size and the type of cell line. Therefore, Cur-loaded SLNs have the potential for use in anticancer therapy.

Synthesis and Design of Purpurin-18-Loaded Solid Lipid Nanoparticles for Improved Anticancer Efficiency of Photodynamic Therapy.

Purpurin-18 (P18) is one of the essential photosensitizers used in photodynamic therapy (PDT), but its hydrophobicity causes easy coalescence and poor bioavailability. This study aimed to synthesize P18 and design P18-loaded solid lipid nanoparticles (SLNs) to improve its bioavailability. The characteristics of the synthesized P18 and SLNs were evaluated by particle characteristics and release studies. The effects of P18 were evaluated using the 1,3-diphenylisobenzofuran (DPBF) assay as a nonbiological assay and a phototoxicity assay against HeLa and A549 cell lines as a biological assay. The mean particle size and zeta potential of the SLNs were 164.70-762.53 nm and -16.77-25.54 mV, respectively. These results indicate that P18-loaded SLNs are suitable for an enhanced permeability and retention effect as a passive targeting anti-cancer strategy. The formulations exhibited a burst and sustained release based on their stability. The DPBF assay indicated that the PDT effect of P18 improved when it was entrapped in the SLNs. The photocytotoxicity assay indicated that P18-loaded SLNs possessed light cytotoxicity but no dark cytotoxicity. In addition, the PDT activity of the formulations was cell type- and size-dependent. These results suggest that the designed P18-loaded SLNs are a promising tool for anticancer treatment using PDT.

Synthesis and Characterization of a Conductive Polymer Blend Based on PEDOT:PSS and Its Electromagnetic Applications.

The purpose of this study is to prepare a resistive lossy material using conducting polymers for electromagnetic wave absorbers. This paper presents a conductive paste largely composed of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) with a polyurethane binder. The various secondary compounds are added in small amounts to an aqueous blended solution in order to enhance the electrical and mechanical properties of the conductive thin film. The synthesized conductive paste is characterized through electrical, chemical, and morphological analyses. The electrical conductivity of the thin film is measured using a four-point probe and surface profiler. The chemical and morphological changes are studied in various experiments using a Raman microscope, X-ray photoelectron spectroscopy, a scanning electron microscope, and an atomic force microscope. In order to verify the applicability of the synthesized conductive paste, which is composed of 70 wt% PEDOT:PSS, 30 wt% polyurethane, and secondary additives (DMAE 0.4 wt%, A-187 0.5 wt%, DMSO 7 wt%, Dynol 604 0.1 wt%, PUR 40 2.5 wt%), the Salisbury screen absorber is fabricated and evaluated in the X-band. According to the results, the absorber resonates at 9.7 GHz, the reflection loss is -38.6 dB, and the 90% absorption bandwidth is 3.4 GHz (8.2 to 11.6 GHz). Through this experiment, the applicability of the PEDOT:PSS-based conductive paste is sufficiently verified and it is found that excellent radar-absorbing performance can be realized.

Design and Characterisation of pH-Responsive Photosensitiser-Loaded Nano-Transfersomes for Enhanced Photodynamic Therapy.

Photodynamic therapy (PDT) is a non-invasive and tumour-specific therapy. Photosensitizers (PSs) (essential ingredients in PDT) aggregate easily owing to their lipophilic properties. The aim of this study was to synthesise a PS (methyl pheophorbide a, MPa) and design a biocompatible lipid-based nanocarrier to improve its bioavailability and pharmacological effects. MPa-loaded nano-transfersomes were fabricated by sonication. The characteristics of synthesised PS and nano-transfersomes were assessed. The effects of PDT were evaluated by 1,3-diphenylisobenzofuran assay and by measuring photo-cytotoxicity against HeLa and A549 cell lines. The mean particle size and zeta potential for nano-transfersomes ranged from 95.84 to 267.53 nm and -19.53 to -45.08 mV, respectively. Nano-transfersomes exhibited sustained drug release for 48 h in a physiological environment (as against burst release in an acidic environment), which enables its use as a pH-responsive drug release system in PDT with enhanced photodynamic activity and reduced side effects. The formulations showed light cytotoxicity, but no dark toxicity, which meant that light irradiation resulted in anti-cancer effects. Additionally, formulations with the smallest size exhibited photodynamic activity to a larger extent than those with the highest loading capacity or free MPa. These results suggest that our MPa-loaded nano-transfersome system is a promising anti-cancer strategy for PDT.

Origin and Distribution of Daytime Electron Density Irregularities in the Low-Latitude F Region.

Electron density irregularities on the dayside in the low-latitude F region are understood as remnants (or fossils) of nighttime plasma bubbles. We provide observational evidence of the connection of daytime irregularities to nighttime bubbles and the transport of the daytime irregularities by the vertical motion of the background ionosphere. The distributions of irregularities are derived using the measurements of the ion density by the first Republic of China satellite from March 1999 to June 2004. The seasonal and longitudinal distributions of daytime and nighttime irregularities in low latitudes show a close similarity. The high occurrence rate of daytime irregularities at the longitudes where strong irregularities occur frequently at night provides strong evidence of the association of daytime irregularities with nighttime bubbles. Nighttime irregularities are concentrated in the equatorial region, whereas daytime irregularities spread over broader latitudes. The seasonal and longitudinal variation of the latitudinal spread of daytime irregularities is consistent with the morphologies of plasma density and vertical plasma velocity. The zonal wave number 4 pattern, which corresponds to that in plasma density, is identified in the distribution of daytime irregularities. These observations lead to the conclusion that the morphology of daytime irregularities in the low-latitude F region is dominated by the morphology of bubbles at night and the ionospheric fountain process on the dayside.

Graphene Oxide Nanoparticles Having Long Wavelength Absorbing Chlorins for Highly-Enhanced Photodynamic Therapy with Reduced Dark Toxicity.

The long wavelength absorbing photosensitizer (PS) is important in allowing deeper penetration of near-infrared light into tumor tissue for photodynamic therapy (PDT). A suitable drug delivery vehicle is important to attain a sufficient concentration of PS at the tumor site. Presently, we developed graphene oxide (GO) nanoparticles containing long wavelength absorbing PS in the form of the chlorin derivative purpurin-18-N-ethylamine (maximum absorption wavelength [λmax] 707 nm). The GO-PS complexes comprised a delivery system in which PS was loaded by covalent and noncovalent bonding on the GO nanosheet. The two GO-PS complexes were fully characterized and compared concerning their synthesis, stability, cell viability, and dark toxicity. The GO-PS complexes produced significantly-enhanced PDT activity based on excellent drug delivery effect of GO compared with PS alone. In addition, the noncovalent GO-PS complex displayed higher photoactivity, corresponding with the pH-induced release of noncovalently-bound PS from the GO complex in the acidic environment of the cells. Furthermore, the noncovalently bound GO‒PS complex had no dark toxicity, as their highly organized structure prevented GO toxicity. We describe an excellent GO complex-based delivery system with significantly enhanced PDT with long wavelength absorbing PS, as well as reduced dark toxicity as a promising cancer treatment.

Tumor Size-Dependent Anticancer Efficacy of Chlorin Derivatives for Photodynamic Therapy.

Photodynamic therapy (PDT) with a suitable photosensitizer molecule is a promising anticancer treatment. We evaluated two chlorin molecules as potential photosensitizers, methyl pyropheophorbide a (MPPa) and N-methoxyl purpurinimide (NMPi), against A549 human lung adenocarcinoma cells in vitro as well as in A549 tumor-bearing mice in vivo. Cell viability, microscopy, and fluorescence-activated cell sorting (FACS) analyses were performed for the in vitro studies. MPPa and NMPi showed high phototoxicity in vitro, which was dependent on the concentration of the photosensitizers as well as the light irradiation time. In the animal study, tumor volume change, tumor surface alterations, and hematoxylin & eosin (H&E) and terminal deoxyribonucleotidyl transferse-mediated dUTP nick-end labelling (TUNEL) staining analyses were performed and compared between small (tumor volume of 50 mm³) size of initial tumors. MPPa and NMPi showed high anticancer efficacy against small-size tumors, indicating that early treatment with PDT is effective. Especially, repeated two times PDT with NMPi allowed almost complete eradication against small-size tumors. However, MPPa and NMPi were not effective against large-size tumors. In conclusion, the two chlorin derivatives, MPPa and NMPi, show good anticancer efficacy as promising photosensitizers for PDT in vitro and in vivo. Moreover, their activity in vivo was significantly dependent on the initial tumor size in mice, which confirms the importance of early cancer treatment.

Gold nanorod-photosensitizer complex obtained by layer-by-layer method for photodynamic/photothermal therapy in vitro.

Gold nanorod (GNR)-photosensitizer (PS) complex was prepared using anionic PS (sodium salt of purpurin-18) and cationic poly(allylamine hydrochloride) by layer-by-layer method, and was characterized by transmission electron microscopy, UV-vis spectroscopy, and zeta potential. The GNR-PS complex is a promising agent for synergistic (photothermal and photodynamic) therapy (PTT/PDT), in which PTT generates heat as well as operates the PS release which maximize the following PDT activity. The combined dual therapy, PTT followed by PDT, exhibits a significantly higher photocytotoxicity result based on synergistic effect of hyperthermia from PTT as well as singlet oxygen photogeneration from PDT.

Synthesis and characterization of novel purpurinimides as photosensitizers for photodynamic therapy.

A series of novel purpurinimides with long wavelength absorption were designed and synthesized to develop novel and potential photosensitizers. These compounds were investigated through reduction, oxidation, rearrangement reaction and amidation reactions of methyl pheophorbide a. They demonstrated a considerable bathochromic shift of the major absorption band in the red region of the optical spectrum (695-704 nm). Newly synthesized purpurinimides were screened for their antitumor activities, and showed higher photodynamic efficiency against A549 cell lines as compared to purpurin-18 methyl ester. The results revealed the novel purpurinimides could be potential photosensitizers.

Efficient photosensitization by a chlorin-polyoxometalate supramolecular complex.

The 4:1 supramolecular complexed ionic salt between pyridinium chlorin and polyanionic [α-SiMo12O40](4-) exhibits significantly enhanced photodynamic activity against A549 cell lines because of increased singlet oxygen photogeneration through high cellular penetration and localization of the chlorin molecules on the ionic salt into the cancer cell. Confocal laser scanning microscopy images clearly represent a higher uptake and photodynamic effect of this supramolecular complex corresponding to the lower IC50 value compared to the free chlorin.

Reservoir-type microcapsules prepared by the solvent exchange method: effect of formulation parameters on microencapsulation of lysozyme.

A new microencapsulation technique based on the solvent exchange method was implemented using an ultrasonic atomizer system to encapsulate a protein drug in mild conditions. The reservoir-type microcapsules encapsulating lysozyme as a model protein were prepared by inducing collisions between the aqueous droplets containing lysozyme and the droplets of organic solvent with dissolved poly(lactic acid-co-glycolic acid) (PLGA). The main focus of the study was to examine formulation variables on the size and the encapsulation efficiency of the formed microcapsules. The formulation variables examined were concentrations of mannose in the aqueous cores, NaCl in the aqueous collection medium, and PLGA in organic solvent. The mean diameter of the microcapsules ranged from 40 microm to 100 microm. Smaller microcapsules showed lower encapsulation efficiencies. The resulting microcapsules released native lysozyme in a sustained manner, and the release rate was dependent on the formulation conditions, such as the concentration and molecular weight of the polymer used. The solvent exchange method does not induce lysozyme aggregation and loss of its biological activity. The solvent exchange method, implemented by the ultrasonic atomizer system, provides an effective tool to prepare reservoir-type microcapsules for delivering proteins.

Paclitaxel-coated expanded polytetrafluoroethylene haemodialysis grafts inhibit neointimal hyperplasia in porcine model of graft stenosis.

BACKGROUND: The main pathology of haemodialysis graft stenosis is venous neointimal hyperplasia at graft-venous anastomoses. Neointimal hyperplasia is also observed in cases of coronary artery in-stent restenosis. Paclitaxel is a chemotherapeutic agent used to treat cancer, and has been proven to inhibit neointimal hyperplasia of coronary artery in-stent restenosis. In this study, we examined whether a paclitaxel-coated haemodialysis graft could inhibit neointimal hyperplasia and prevent stenosis. METHODS: We dip-coated paclitaxel on expanded polytetrafluoroethylene (ePTFE) grafts at a dose density of 0.59 microg/mm(2). In vitro release tests showed an initial paclitaxel burst followed by a long-term slow release. Using ePTFE grafts with (coated group, n = 8) or without a paclitaxel coating (control group, n = 11), we constructed arteriovenous (AV) grafts connecting the common carotid artery and the external jugular vein in Landrace pigs. RESULTS: After excluding seven pigs for technical failure, cross-sections of graft-venous anastomoses obtained 6 weeks after placing the AV grafts were analysed. Percentage luminal stenosis, ratios of intima to media in whole cross-sections, areas of intima in the peri-junctional areas (within 2 mm above and 2 mm below the graft-venous junction), and the mean thickness of intima within venous sides of cross-sections, were 60.5% (range, 41.5-60.7), 13.0 (range, 8.6-20.4), 23.7 mm(2) (range, 10.8-32.1) and 2.1 mm (range, 1.1-3.0), respectively, in the control group, whereas corresponding median values in the coated group were 10.4% (range, 1.0-17.8), 1.0 (range, 0.7-5.1), 1.6 mm(2) (range, 0.2-8.0) and 0.3 mm (range, 0.1-2.2). All parameters were significantly different between the two groups (P<0.05 by Mann-Whitney test). CONCLUSION: Paclitaxel-coated ePTFE grafts could prevent neointimal hyperplasia and the stenosis of AV haemodialysis grafts.

Preparation and characterization of biodegradable nanoparticles entrapping immunodominant peptide conjugated with PEG for oral tolerance induction.

PEG-conjugated immunodominant peptides for collagen-induced arthritis (CIA) were prepared for oral tolerance induction instead of whole Type II collagen (CII), because a small peptide can be converted to a macromolecule soluble in methylene chloride by the coupling of poly-ethylene glycol (PEG). PEG-pep1 was synthesized from a peptide and mPEG-NH2 (Mw approximately 5000) using SPDP as a linker, whereas PEG-pep2 was prepared by the direct disulfide coupling between PEG-OD (Mw approximately 10,000) and the peptide. PEG-pep1 and PEG-pep2 were purified by gel permeation chromatography (GPC), and the peak fractions of GPC were identified by GPC and MALDI-TOF mass spectroscopy. The peptide coupling gave much earlier retention times for PEG-pep1 (11.26 min) and PEG-pep2 (10.61 min) than for mPEG-SPDP (15.63 min) and mPEG-OD (14.58 min). The Mw's of mPEG-NH2, mPEG-SPDP, PEG-pep1, mPEG-OD and PEG-pep2 were 5451, 5588, 7035, 10,360 and 11,826, respectively, suggesting that PEG-pep1 and PEG-pep2 of high purity could be obtained. The nanoparticles entrapping PEG-pep1 and PEG-pep2 (NP/PEG-pep1 and NP/PEG-pep2) were prepared by the o/w solvent evaporation method, whereas the peptide-loaded nanoparticles (NP/pep) were prepared by the w/o/w double emulsion method. Although all the nanoparticles had a similar spherical morphology under scanning electron microscopy, NP/pep showed up as having a larger mean size than the others, which was confirmed by dynamic light scattering analysis (NP/pep, 499.7+/-27.2 nm; NP/PEG-pep1, 333.0+/-16.8 nm; NP/PEG-pep2, 342.4+/-15.1 nm). The lower encapsulation efficiency of NP/pep (21.0+/-1.6%) than NP/PEG-pep1 (66.5+/-5.0%) and NP/PEG-pep2 (73.8+/-5.5%) can also be attributed to the preparation method. In in vitro release studies, NP/PEG-pep1 and NP/PEG-pep2 displayed a similar release profile, close to a linear release pattern, whereas NP/pep displayed a tri-phasic release profile. From these results, it was demonstrated that nanoparticles entrapping a PEG-conjugated peptide could be an alternative delivery method for the induction of oral tolerance rather than CII and peptide.

Investigation of the factors influencing the release rates of cyclosporin A-loaded micro- and nanoparticles prepared by high-pressure homogenizer.

An oil-in-water solvent evaporation method was used to prepare cyclosporin A (CyA)-loaded particles varying in size (nanoparticles, 'small-sized' microparticles, 'large-sized' microparticles), polymer compositions [poly(D,L-lactide-co-glycolic acid) (PLGA) 50/50, PLGA 85/15, poly(D,L-lactic acid) (PLA)] and additive fatty acid ester (ethyl myristate; EM). The particles were characterized for drug loading and entrapment efficiency by high-performance liquid chromatography, particle size by dynamic light scattering and surface morphology by scanning electron microscopy (SEM). In vitro release kinetics were studied using a modified dialysis method. The results showed drug loadings ranging from 6.48 to 9.01% with high encapsulation efficiency (71.2-98.9%). SEM studies showed discrete and spherical particles with smooth surfaces, whereas rather gross surface defects resulted from the incorporation of EM as an additive. The release profiles of various formulations approximated zero-order release kinetics in the first 3 weeks with a negligible initial burst. In general, the smaller the particle size and the higher the glycolic acid content in the copolymer, the faster the release of CyA. The effect of EM on the release profile appeared to be rather complex since an increased release rate was observed from EM containing PLGA 50/50 particles, whereas the incorporation of EM into the PLGA 85/15 and PLA particles led to a decreased release rate. Further investigation needs to be performed to elucidate the reason why EM influences the CyA release differently depending on the particle size and polymer type.

Suppression of collagen-induced arthritis by single administration of poly(lactic-co-glycolic acid) nanoparticles entrapping type II collagen: a novel treatment strategy for induction of oral tolerance.

OBJECTIVE: Poly(lactic-co-glycolic acid) (PLGA), a biodegradable polymer, is a carrier for drug delivery systems. This study was undertaken to investigate the tolerogenic effect of single administration of PLGA entrapping type II collagen (CII) on the development of collagen-induced arthritis (CIA). METHODS: The biophysical properties of PLGA nanoparticles entrapping CII (PLGA-CII) were investigated by in vitro release testing of CII, immunohistochemistry analysis, and electron microscopy. PLGA-CII was fed singly to animals 14 days before immunization, and the effect on joint inflammation was assessed. Circulating IgG anti-CII antibodies and T cell responses to CII in draining lymph nodes were assayed by enzyme-linked immunosorbent assay and (3)H-thymidine incorporation assay, respectively. The expression of messenger RNA (mRNA) for transforming growth factor beta (TGFbeta) and tumor necrosis factor alpha (TNFalpha) was determined by reverse transcriptase-polymerase chain reaction. RESULTS: The in vitro release test showed that CII was slowly discharged from PLGA-CII over a period of a month. After single administration of PLGA-CII, numerous particles approximately 300 nm in size were detectable in Peyer's patches, by electron microscopy and immunohistochemical staining for CII, 14 days after the original feeding. Mice fed a single dose of PLGA containing 40 microg of CII had significantly reduced values for incidence and severity of arthritis, serum IgG anti-CII antibodies, and CII-specific T cell proliferation as compared with mice fed solvent alone, those fed 6 doses of 20 microg CII alone, and those fed a single dose of PLGA alone. PLGA-CII was also able to suppress CIA after disease onset. Moreover, PLGA-CII-fed mice showed a higher level of TGFbeta mRNA expression in Peyer's patches, but a lower level of TNFalpha mRNA expression in draining lymph nodes, compared with the other groups of mice. CONCLUSION: Our data show that PLGA may serve as a powerful vehicle to promote the tolerance effect of oral CII and that single administration of PLGA-CII may hold promise as a new treatment strategy in rheumatoid arthritis.