Hwiwon Lee

Target-Specific Gene Silencing of Layer-by-Layer Assembled Gold–Cysteamine/siRNA/PEI/HA Nanocomplex

Target-specific intracellular delivery of small interfering RNA (siRNA) is regarded as one of the most important technologies for the development of siRNA therapeutics. In this work, a cysteamine modified gold nanoparticles (AuCM)/siRNA/polyethyleneimine (PEI)/hyaluronic acid (HA) complex was successfully developed using a layer-by-layer method for target-specific intracellular delivery of siRNA by HA receptor mediated endocytosis. Atomic force microscopic and zeta potential analyses confirmed the formation of a AuCM/siRNA/PEI/HA complex having a particle size of ca. 37.3 nm and a negative surface charge of ca. -12 mV. With a negligible cytotoxicity, AuCM/siRNA/PEI/HA complex showed an excellent target-specific gene silencing efficiency of ca. 70% in the presence of 50 vol % serum, which was statistically much higher than that of siRNA/Lipofectamine 2000 complex. In the competitive binding tests with free HA, dark-field bioimaging and inductively coupled plasma-atomic emission spectroscopy confirmed the target-specific intracellular delivery of AuCM/siRNA/PEI/HA complex to B16F1 cells with HA receptors. Moreover, the systemic delivery of AuCM/siRNA/PEI/HA complex using apolipoprotein B (ApoB) siRNA as a model drug resulted in a significantly reduced ApoB mRNA level in the liver tissue. Taken together, AuCM/siRNA/PEI/HA complex was thought to be developed as target-specific siRNA therapeutics for the systemic treatment of various liver diseases.

Hyaluronate–Gold Nanoparticle/Tocilizumab Complex for the Treatment of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory immune disease causing the inflammation of synovial membrane and the articular cartilage destruction. In this work, hyaluronate-gold nanoparticle/Tocilizumab (HA-AuNP/TCZ) complex was prepared for the treatment of RA. AuNP was used as a drug carrier with antiangiogenic effect. TCZ is a humanized monoclonal antibody against the interleukin-6 (IL-6) receptor and used as an immunosuppressive drug by interfering IL-6 in the pathogenesis of RA. HA is known to have cartilage-protective and lubricant effects. HA was modified with cystamine via reductive amination, which was reduced with dithiothreitol (DTT) to prepare end-group thiolated HA (HA-SH). AuNP was chemically modified with HA-SH and physically modified with TCZ. The formation of HA-AuNP/TCZ complex was corroborated by UV-vis spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM). The therapeutic effect of HA-AuNP/TCZ complex on RA was confirmed in collagen-induced arthritis (CIA) model mice by ELISA, histological, and Western blot analyses.

Cationic solid lipid nanoparticles derived from apolipoprotein-free LDLs for target specific systemic treatment of liver fibrosis

Low density lipoprotein (LDL) plays an important role in transporting fat molecules including cholesterols in the body. In this work, cationic solid lipid nanoparticles (CSLNs), bioinspired and reconstituted from natural LDLs, were designed and applied to target specific systemic delivery of connective tissue growth factor siRNA (siCTGF) for the treatment of liver fibrosis. They could form a nuclease-resistant stable nano-complex with siRNA, which was efficiently internalized into cells achieving targeted gene silencing in the presence of serum with a remarkably low cytotoxicity. After intravenous injection, CSLN/siCTGF complex was target specifically delivered to the liver and resulted in a significant reduction in collagen content and pro-fibrogenic factors like tumor necrosis factor alpha (TNF-α), transforming growth factor beta (TGF-β), interleukin-6 (IL-6), and CTGF with the dramatic improvement of patho-physiological symptoms in liver fibrosis model rats. The bio-distribution study by fluorescence bioimaging and single-photon emission computed tomography (SPECT) confirmed the target specific delivery and accumulation of CSLN/siCTGF complexes to the liver tissues.

Reducible hyaluronic acid-siRNA conjugate for target specific gene silencing.

Despite wide applications of polymer-drug conjugates, there are only a few polymer-siRNA conjugates like poly(ethylene glycol) conjugated siRNA. In this work, reducible hyaluronic acid (HA)-siRNA conjugate was successfully developed for target specific systemic delivery of siRNA to the liver. The conjugation of siRNA to HA made it possible to form a compact nanocomplex of siRNA with relatively nontoxic linear polyethyleneimine (LPEI). After characterization of HA-siRNA conjugate by size exclusion chromatography (SEC) and gel electrophoresis, its complex formation with LPEI was investigated with a particle analyzer. The HA-siRNA/LPEI complex had a mean particle size of ca. 250 nm and a negative or neutral surface charge at physiological condition. The reducible HA-siRNA/LPEI complex showed a higher in vitro gene silencing efficiency than noncleavable HA-siRNA/LPEI complex. Furthermore, after systemic delivery, apolipoprotein B (ApoB) specific HA-siApoB/LPEI complex was target specifically delivered to the liver, which resulted in statistically significant reduction of ApoB mRNA expression in a dose dependent manner. The HA-siRNA conjugate can be effectively applied as a model system to the treatment of liver diseases using various siRNAs and relatively nontoxic polycations.

Anion Binding by Electron-Deficient Arenes Based on Complementary Geometry and Charge Distribution

Extended electron-deficient arenes are investigated as potential neutral receptors for polyanions. Anion binds via σ interaction with extended arenes, which are composed solely of C and N ring atoms and CN substituents. As a result, the positive charge on the aromatic C is enhanced, consequently maximizing binding strength. Selectivity is achieved because different charge distributions can be obtained for target anions of a particular geometry. The halides F(-) and Cl(-) form the most stable complex with 6, while the linear N3(-) interacts most favorably with 7. The trigonal NO3(-) and tetrahedral ClO4(-) fit the 3-fold rotational axis of 6 but do not form stable complexes with 5 and 7. The Y-shaped HCOO(-) forms complexes with 4, 5, and 7, with the latter being the most stable. Thus, the anion complexes exhibit strong binding and the best geometrical fit between guest and host, reminiscent of Lego blocks.

Hyaluronate-Death Receptor 5 Antibody Conjugates for Targeted Treatment of Liver Metastasis.

The liver is the most frequent site of metastasis with a 5-year survival rate of only 20-40%. In this work, hyaluronate (HA)-death receptor 5 antibody (DR5 Ab) conjugate was synthesized as a dual targeting therapeutic agent to treat liver metastasis. Dual targeting was achieved by DR5 Ab, a humanized agonistic monoclonal antibody binding to DR5 frequently overexpressed in many kinds of cancer cells, and by HA, a natural polysaccharide binding to HA receptors highly expressed in both the liver and cancer cells. Thiol end-modified HA was site-specifically conjugated to N-glycan on Fc region of oxidized DR5 Ab using a heterobifunctional linker of 3-(2-pyridyldithio)propionyl hydrazide (PDPH). The successful synthesis of HA-DR5 Ab conjugate was confirmed by (1)H NMR, purpald assay, dynamic light scattering (DLS), and high-performance liquid chromatography (HPLC). In vitro analysis of HA-DR5 Ab conjugate revealed that the conjugation of HA to DR5 Ab did not affect the binding affinity and anticancer efficacy of DR5 Ab. Remarkably, according to in vivo bioimaging study, HA-DR5 Ab conjugate appeared to be highly accumulated in the liver and dramatically effective in inhibiting the tumor growth in liver metastasis model mice.

Tocilizumab–Alendronate Conjugate for Treatment of Rheumatoid Arthritis

An autoimmune disease of rheumatoid arthritis (RA) causes severe inflammation on the synovial membrane, which results in the destruction of articular cartilage and bone. Here, Tocilizumab (TCZ)-Alendronate (ALD) conjugate is synthesized for the early intervention of RA. A humanized monoclonal antibody of TCZ shows an immunosuppressive effect, targeting interleukin-6 (IL-6) receptor in the RA pathogenesis. ALD is an anti-inflammatory bisphosphonate drug which can bind to the exposed bone surface. ALD is conjugated selectively to N-glycan on Fc region of TCZ using a chemical linker of 3-(2-pyridyldithio)propionyl hydrazide (PDPH)-poly(ethylene glycol)-N-hydroxysuccinimide (PDPH-PEG-NHS). The successful synthesis of TCZ-ALD conjugate is corroborated by 1H NMR, the purpald assay, mass spectrometry (MS), and high performance liquid chromatography (HPLC). In vitro binding affinity and cell viability tests confirmed the biological activity of TCZ-ALD conjugate. Furthermore, in vivo efficacy of TCZ-ALD conjugate is confirmed by microcomputed tomography (CT), histology, and Western blot analyses for the treatment of RA.