Hyun-Jong Cho

Self-assembled nanoparticles based on hyaluronic acid-ceramide (HA-CE) and Pluronic® for tumor-targeted delivery of docetaxel

Hyaluronic acid-ceramide (HA-CE)-based self-assembled nanoparticles were developed for intravenous docetaxel (DCT) delivery. In this study, physicochemical properties, cellular uptake efficiency, and in vivo targeting capability of the nanoparticles developed were investigated. DCT-loaded nanoparticles composed of HA-CE and Pluronic 85 (P85) with a mean diameter of 110-140 nm were prepared and their morphological shapes were assessed using transmission electron microscopy (TEM). DCT release from nanoparticle was enhanced with increasing P85 concentrations in our in vitro model. Blank nanoparticles exhibited low cytotoxicity in U87-MG, MCF-7 and MCF-7/ADR cell lines. From cellular uptake studies, the nanoparticles developed enhanced the intracellular DCT uptake in the CD44-overexpressing cell line (MCF-7). The nanoparticles were shown to be taken up by the HA-CD44 interaction according to DCT and coumarin 6 (C6) cellular uptake studies. The multidrug resistance (MDR)-overcoming effects of DCT-loaded HA-CE/P85-based nanoparticles were also observed in cytotoxicity tests in MCF-7/ADR cells. Following the intravenous injection of DCT-loaded cyanine 5.5 (Cy5.5)-conjugated nanoparticles in MCF-7/ADR tumor-bearing mice, its in vivo targeting for CD44-overexpressing tumors was identified by non-invasive near-infrared (NIR) fluorescence imaging. These results indicate that the HA-CE-based nanoparticles prepared may be a promising anti-cancer drug delivery system through passive and active tumor targeting.

Proliferation and chondrogenic differentiation of human adipose-derived mesenchymal stem cells in porous hyaluronic acid scaffold

Human adipose-derived mesenchymal stem cells (AD-MSCs) attracted much interest as a promising alternative to autologous chondrocytes and bone marrow-derived mesenchymal stem cells for cartilage regeneration. Developing a suitable culture technique to direct AD-MSCs into the chondrogenic lineage could be a crucial prerequisite for the cartilage defect repair application of AD-MSCs. Herein, we prepared the PEGDG-crosslinked porous three-dimensional (3D) hyaluronic acid (HA) scaffold and evaluated for its feasibility to induce proliferation and chondrogenic differentiation of the AD-MSCs. In addition, the effect of bone-morphogenetic protein-2 (BMP-2) and platelet-derived growth factor (PDGF) on chondrogenic differentiation was further investigated. Proliferation and chondrogenic differentiation were evaluated by cell morphology, DNA contents, s-GAG contents, and level of mRNA expression of relevant marker genes. When cultured with reference chondrogenic medium (RCM; serum-free DMEM-HG supplemented with 10 ng/mL of transforming growth factor-β1 (TGF-β1), 50 nM ascorbate, 100 nM dexamethasone, and 5 μg/mL of ITS), better proliferation and chondrogenic differentiation of AD-MSCs were obtained in the 3D HA scaffold culture as compared to the micromass culture, a standard 3D culture system. Moreover, the level of chondrogenic differentiation of AD-MSCs in the HA scaffold-RCM culture system was further increased by BMP-2, and decreased by PDGF. These results suggested that the HA scaffold with RCM was a promising chondrogenic culture system of AD-MSCs, and that BMP-2 could potentially serve as a chondrogenic supplement for AD-MSCs. However, PDGF was determined to be an inappropriate supplement based on its inhibition of the chondrogenic differentiation of AD-MSCs.

Surface-modified solid lipid nanoparticles for oral delivery of docetaxel: enhanced intestinal absorption and lymphatic uptake

Docetaxel is a potent anticancer drug, but development of an oral formulation has been hindered mainly due to its poor oral bioavailability. In this study, solid lipid nanoparticles (SLNs) surface-modified by Tween 80 or D-alpha-tocopheryl poly(ethylene glycol 1000) succinate (TPGS 1000) were prepared and evaluated in terms of their feasibility as oral delivery systems for docetaxel. Tween 80-emulsified and TPGS 1000-emulsified tristearin-based lipidic nanoparticles were prepared by a solvent-diffusion method, and their particle size distribution, zeta potential, drug loading, and particle morphology were characterized. An in vitro release study showed a sustained-release profile of docetaxel from the SLNs compared with an intravenous docetaxel formulation (Taxotere®). Tween 80-emulsified SLNs showed enhanced intestinal absorption, lymphatic uptake, and relative oral bioavailability of docetaxel compared with Taxotere in rats. These results may be attributable to the absorption-enhancing effects of the tristearin nanoparticle. Moreover, compared with Tween 80-emulsified SLNs, the intestinal absorption and relative oral bioavailability of docetaxel in rats were further improved in TPGS 1000-emulsified SLNs, probably due to better inhibition of drug efflux by TPGS 1000, along with intestinal lymphatic uptake. Taken together, it is worth noting that these surface-modified SLNs may serve as efficient oral delivery systems for docetaxel.

Poloxamer/Cyclodextrin/Chitosan-Based Thermoreversible Gel for Intranasal Delivery of Fexofenadine Hydrochloride

To enhance permeation and solubility of an intranasal delivery system of fexofenadine hydrochloride (FXD HCl), a new formulation using poloxamer 407 (P407)/hydroxypropyl-β-cyclodextrin (HP-β-CD)-based thermoreversible gels with chitosan, was developed. Prepared gels were characterized by gelation temperature, viscosity, viscoelasticity, and drug release profile. The in vitro permeation study was performed in primary human nasal epithelial cell monolayers cultured by air-liquid interface method. The addition of chitosan caused the slight elevation of gelation temperature and viscosity-enhancing effect. Viscosity enhancement by the incorporation of chitosan caused the retardation of drug release from P407 gels in in vitro release test. The in vitro permeation profile showed that the increase in chitosan content (0.1% and 0.3%, w/v) significantly enhanced the permeation of FXD HCl. After intranasal administration of P407/HP-β-CD-based thermoreversible gels containing 0.1% and 0.3% of chitosan in rabbits at 0.5 mg/kg dose, plasma concentrations of FXD HCl were significantly higher than those of nasal solutions (p < 0.05). In particular, the bioavailability of the optimized thermoreversible gel containing 0.3% chitosan was about 18-fold higher than that of the solution type. These results suggested the feasibility that thermosensitive gels could be used as an effective dosage form to enhance the nasal absorption of FXD HCl.

Preparation and evaluation of spray-dried hyaluronic acid microspheres for intranasal delivery of fexofenadine hydrochloride.

Hyaluronic acid (HA)-based microspheres containing PEG 6000 and/or sodium taurocholate (NaTC) were prepared by the spray-drying method for nasal delivery of fexofenadine hydrochloride (HCl). Their physicochemical properties including particle size and drug contents were determined, while their morphology examined by a scanning electron microscope (SEM). The effects of the solubilizer (PEG 6000) and the permeation enhancer (NaTC) on the in vitro release characteristics of fexofenadine x HCl were observed. Moreover, the in vitro permeation of fexofenadine x HCl was determined using the human nasal cell (HNE) monolayers cultured on Transwell inserts. After nasal administration, fexofenadine x HCl in rabbit plasma was determined by the LC-MS/MS system. Fexofenadine x HCl-loaded microspheres were of spherical shape with 20-30 microm mean diameter. The loading efficiency was about 95%. In vitro release of fexofenadine x HCl from the microspheres was significantly increased with the addition of PEG 6000. Although NaTC did not alter the in vitro release of drug from the microspheres, its addition further increased the in vitro permeation of fexofenadine x HCl across the HNE cell monolayers. Moreover, the bioavailability of fexofenadine x HCl after nasal administration of the microsphere formulation to rabbits was increased up to about 48% while that of the control solution was only about 3%. These results indicated that the HA microsphere formulation could further be developed into a clinically useful nasal delivery system of fexofenadine x HCl.

The limited intestinal absorption via paracellular pathway is responsible for the low oral bioavailability of doxorubicin.

Abstract 1. Doxorubicin exhibited dose-independent pharmacokinetics after intravenous (5–20 mg/kg) and oral (20–100 mg/kg) administration to rats. Nearly all (82.1–99.7%) of the orally administered doxorubicin remained unabsorbed, and the hepatic first-pass extraction ratio and oral bioavailability of doxorubicin were approximately 0.5% and 1%, respectively. Based on these results, it is likely that the primary factor responsible for the low oral bioavailability of doxorubicin is the limited intestinal absorption, rather than the CYP3A4-mediated first-pass metabolism. 2. Moreover, the in vitro transport and cellular uptake studies using Caco-2 cell monolayers have revealed that doxorubicin crosses the intestinal epithelium primarily via the paracellular pathway (accounting for 85.6% of the overall absorptive transport) probably due to its physicochemical properties (hydrophilic cation; pKa = 9.67, log P = −0.5). These results suggest that P-glycoprotein (P-gp)-mediated efflux activity does not play a significant role in limiting the intestinal absorption of doxorubicin, attenuating the absorptive transport by only 5.56–13.2%. 3. Taken together, the present study demonstrated that the limited and paracellular intestinal absorption of doxorubicin was a major factor responsible for its low oral bioavailability, restricting the role of CYP3A4-mediated first-pass metabolism and P-gp-mediated efflux.

Development of udenafil-loaded microemulsions for intranasal delivery: In vitro and in vivo evaluations

To achieve rapid onset of action and improved bioavailability of udenafil, a microemulsion system was developed for its intranasal delivery. Phase behavior, particle size, transmission electron microscope (TEM) images, and the drug solubilization capacity of the microemulsion were investigated. A single isotropic region was found in pseudo-ternary phase diagrams developed at various ratios with CapMul MCM L8 as an oil, Labrasol as a surfactant, and Transcutol or its mixture with ethanol (1:0.25, v/v) as a cosurfactant. Optimized microemulsion formulations with a mean diameter of 120-154 nm achieved enhanced solubility of udenafil (>10mg/ml) compared with its aqueous solubility (0.02 mg/ml). An in vitro permeation study was performed in human nasal epithelial (HNE) cell monolayers cultured by the air-liquid interface (ALI) method, and the permeated amounts of udenafil increased up to 3.41-fold versus that of pure udenafil. According to the results of an in vivo pharmacokinetic study in rats, intranasal administration of udenafil-loaded microemulsion had a shorter T(max) value (1 min) compared with oral administration and improved bioavailability (85.71%) compared with oral and intranasal (solution) administration. The microemulsion system developed for intranasal administration may be a promising delivery system of udenafil, with a rapid onset of action and improved bioavailability.

Characterization and in vitro evaluation of freeze-dried microparticles composed of granisetron–cyclodextrin complex and carboxymethylcellulose for intranasal delivery

The aim of this study was to prepare microparticles (MPs) of granisetron (GRN) in combination with hydroxypropyl-β-cyclodextrin (HP-β-CD) and sodium carboxymethylcellulose (CMC-Na) by the simple freeze-drying method for intranasal delivery. The composition of MPs was determined from the phase-solubility study of GRN in various CDs. Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD) analysis and differential scanning calorimetry (DSC) studies were performed to evaluate possible interactions between GRN and excipients. The results indicated the formation of inclusion complex between GRN and CD, and the conversion of drug into amorphous state. The in vitro release of GRN from MPs was determined in phosphate buffered saline (pH 6.4) at 37°C. Cytotoxicity of the MPs and in vitro permeation study were conducted by using primary human nasal epithelial (HNE) cells and their monolayer system cultured by air-liquid interface (ALI) method, respectively. The MPs showed significantly higher GRN release profile compared to pure GRN. Moreover, the prepared MPs showed significantly lower cytotoxicity and higher permeation profile than that of GRN powder (p<0.05). These results suggested that the MPs composed of GRN, HP-β-CD and CMC-Na represent a simple and new GRN intranasal delivery system as an alternative to the oral and intravenous administration of GRN.

Preparation and characterization of MRI-active gadolinium nanocomposite particles for neutron capture therapy

We demonstrate the synthesis and characteristics of MRI-active Gd2O3 core/SiO2 shell/poly(2-methacryloyloxyethyl phosphorylcholine) corona composite nanoparticles (Gd2O3@SiO2@PMPC NPs). The prepared NPs have a number of attractive features in cancer diagnosis and neutron capture therapy (NCT): biocompatibility, colloidal stability, low cytotoxicity, nucleus affinity, passive targeting, etc. Monodisperse and highly crystalline Gd2O3 NPs were prepared using a polyol protocol to control the average particle size and surface properties. The Gd2O3 NPs were then functionalized with SiO2 and a biomimetic layer of PMPC, to achieve reduced toxicity and enhanced nucleus affinity, for use as an MRI-active Gd-NCT agent. The size of the NPs was tailored to be from 50 to 100 nm for passive accumulation in tumor tissue through loosened capillary vessels. The morphologies and structures of Gd2O3, Gd2O3@SiO2–Br, and Gd2O3@SiO2@PMPC NPs were studied by FT-IR, XRD, HR-TEM, and TGA. In vitro cytotoxicity was investigated with three kinds of normal and cancer cells, and in vitro and in vivo MRI analyses were performed to confirm the contrast ability, accumulation, and sustentation of NPs in tumor tissues.

Pharmacokinetic Interactions of Herbs with Cytochrome P450 and P-Glycoprotein

The concurrent use of drugs and herbal products is becoming increasingly prevalent over the last decade. Several herbal products have been known to modulate cytochrome P450 (CYP) enzymes and P-glycoprotein (P-gp) which are recognized as representative drug metabolizing enzymes and drug transporter, respectively. Thus, a summary of knowledge on the modulation of CYP and P-gp by commonly used herbs can provide robust fundamentals for optimizing CYP and/or P-gp substrate drug-based therapy. Herein, we review ten popular medicinal and/or dietary herbs as perpetrators of CYP- and P-gp-mediated pharmacokinetic herb-drug interactions. The main focus is placed on previous works on the ability of herbal extracts and their phytochemicals to modulate the expression and function of CYP and P-gp in several in vitro and in vivo animal and human systems.