Ho Yub Yoon

Docetaxel-loaded RIPL peptide (IPLVVPLRRRRRRRRC)-conjugated liposomes: Drug release, cytotoxicity, and antitumor efficacy

We previously synthesized the RIPL peptide (IPLVVPLRRRRRRRRC) to facilitate selective delivery into hepsin-expressing cancer cells and showed that RIPL peptide-conjugated liposomes (RIPL-L) enhanced the intracellular delivery of fluorescent probes in vitro. In this study, docetaxel-loaded RIPL-L (DTX-RIPL-L) were prepared and evaluated for in vitro drug release, cytotoxicity, and in vivo antitumor efficacy. DTX was successfully encapsulated by pre-loading, with an average encapsulation efficiency and drug loading capacity of 32.4% and 21.39±2.05 (μg/mg), respectively. A DTX release study using dialysis showed a biphasic release pattern, i.e., rapid release for 6h, followed by sustained release up to 72h. The first-order equation provided the best fit for drug release (r2=0.9349). In vitro cytotoxicity was dose-dependent, resulting in IC50 values of 36.10 (SK-OV-3) and 48.62ng/mL (MCF-7) for hepsin-positive, and 61.12 (DU145) and 53.04ng/mL (PC-3) for hepsin-negative cell lines. Live/dead cell imaging was carried out to visualize the proportion of viable and nonviable SK-OV-3 cells. Compared to DTX solution, DTX-RIPL-L significantly inhibited tumor growth and prolonged survival time in BALB/c nude mice with SK-OV-3 cell tumors. We suggest that DTX-RIPL-L is a good candidate for efficient drug targeting to hepsin-expressing cancer cells.

Enhanced topical delivery of tacrolimus by a carbomer hydrogel formulation with Transcutol P

Abstract Tacrolimus (TAC), a non-steroidal anti-inflammatory and immunosuppressive agent, is used for the treatment of atopic dermatitis (AD) and skin immune diseases. TAC-loaded topical hydrogel formulations composed of carbomer, carnosine, transcutol P (diethylene glycol monoethyl ether) and humectant were prepared. For comparison, TAC-loaded topical cream-type formulations were also prepared and commercially available TAC ointment was used as a reference. A drug release study in vitro revealed that the total amount of TAC released from hydrogels over 24 h was approximately 30 times greater than that for the reference formulation. Compared to the reference ointment and creams, carbomer gel formulations showed higher skin permeation and retention of TAC (significantly different at p < 0.05), especially those with more than 10% of transcutol P. Therefore, carbomer gel formulations with sufficient levels of transcutol P are good candidates for skin delivery of TAC and have potential as therapeutic agents for the treatment of AD or immune skin disorders.

Development of a chitosan based double layer-coated tablet as a platform for colon-specific drug delivery.

A double layer-coated colon-specific drug delivery system (DL-CDDS) was developed, which consisted of chitosan (CTN) based polymeric subcoating of the core tablet containing citric acid for microclimate acidification, followed by an enteric coating. The polymeric composition ratio of Eudragit E100 and ethyl cellulose and amount of subcoating were optimized using a two-level factorial design method. Drug-release characteristics in terms of dissolution efficiency and controlled-release duration were evaluated in various dissolution media, such as simulated colonic fluid in the presence or absence of CTNase. Microflora activation and a stepwise mechanism for drug release were postulated. Consequently, the optimized DL-CDDS showed drug release in a controlled manner by inhibiting drug release in the stomach and intestine, but releasing the drug gradually in the colon (approximately 40% at 10 hours and 92% at 24 hours in CTNase-supplemented simulated colonic fluid), indicating its feasibility as a novel platform for CDD.

RIPL peptide-conjugated nanostructured lipid carriers for enhanced intracellular drug delivery to hepsin-expressing cancer cells

Background To facilitate selective and enhanced drug delivery to hepsin (Hpn)-expressing cancer cells, RIPL peptide (IPLVVPLRRRRRRRRC, 16-mer)-conjugated nanostructured lipid carriers (RIPL-NLCs) were developed. Methods NLCs were prepared using a solvent emulsification-evaporation method and the RIPL peptide was conjugated to the maleimide-derivatized NLCs via the thiol-maleimide reaction. Employing a fluorescent probe (DiI), in vitro target-selective intracellular uptake behaviors were observed using fluorescence microscopy and flow cytometry. Separately, docetaxel (DTX) was encapsulated by pre-loading technique, then cytotoxicity and drug release were evaluated. In vivo antitumor efficacy was investigated in BALB/c nude mice with SKOV3 cell tumors after intratumoral injections of different DTX formulations at a dose equivalent to 10 mg/kg DTX. Results RIPL-NLCs showed positively charged nanodispersion, whereas NLCs were negatively charged. DTX was successfully encapsulated with an encapsulation efficiency and drug loading capacity of 95–98% and 44-46 µg/mg, respectively. DTX release was diffusion-controlled, revealing the best fit to the Higuchi equation. Cellular uptake of DiI-loaded RIPL-NLCs was 8.3- and 6.2-fold higher than that of DiI-loaded NLCs, in Hpn(+) SKOV3 and LNCaP cells, respectively. The translocation of RIPL-NLCs into SKOV3 cells was time-dependent with internalization within 1 h and distribution throughout the cytoplasm after 2 h. DTX-loaded RIPL-NLCs (DTX-RIPL-NLCs) revealed dose-dependent in vitro cytotoxicity, while drug-free formulations were non-cytotoxic. In SKOV3-bearing xenograft mouse model, DTX-RIPL-NLCs significantly inhibited tumor growth: the inhibition ratios of the DTX solution-treated and DTX-RIPL-NLC-treated groups were 61.4% and 91.2%, respectively, compared to those of the saline-treated group (control). Conclusion RIPL-NLCs are good candidates for Hpn-selective drug targeting with a high loading capacity of hydrophobic drug molecules.

pH-sensitive PEGylation of RIPL peptide-conjugated nanostructured lipid carriers: design and in vitro evaluation

Background RIPL peptide (IPLVVPLRRRRRRRRC)-conjugated nanostructured lipid carriers (RIPL-NLCs) can facilitate selective drug delivery to hepsin (Hpn)-expressing cancer cells, but they exhibit low stability in the blood. Generally, biocompatible and nontoxic poly(ethylene glycol) surface modification (PEGylation) can enhance NLC stability, although this may impair drug delivery and NLC clearance. To attain RIPL-NLC steric stabilization without impairing function, pH-sensitive cleavable PEG (cPEG) was grafted onto RIPL-NLCs (cPEG-RIPL-NLCs). Methods Various types of NLC formulations including RIPL-NLCs, PEG-RIPL-NLCs, and cPEG-RIPL-NLCs were prepared using the solvent emulsification–evaporation method and characterized for particle size, zeta potential (ZP), and cytotoxicity. The steric stabilization effect was evaluated by plasma protein adsorption and phagocytosis inhibition studies. pH-sensitive cleavage was investigated using the dialysis method under different pH conditions. Employing a fluorescent probe (1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate [DiI]), in vitro drug delivery capacity of the cPEG-RIPL-NLCs under different pH conditions was also performed on Hpn-expressing SKOV3 cells and 3D-tumor spheroids. Results All prepared NLCs showed homogenous dispersion (<220 nm in size) with a negative ZP (−18 to −22 mV), except for positively charged RIPL-NLCs (~10 mV), revealing no significant cytotoxicity in either SKOV3 or RAW 264.7 cell lines. cPEG-RIPL-NLC protein adsorption was 1.75-fold less than that of RIPL-NLCs, and PEGylation significantly reduced the macrophage uptake. PEG detachment from the cPEG-RIPL-NLCs was pH-sensitive and time dependent. At 2 hours incubation, cPEG-RIPL-NLCs and PEG-RIPL-NLCs exhibited comparable cellular uptake at pH 7.4, whereas cPEG-RIPL-NLC uptake was increased over 2-fold at pH 6.5. 3D-spheroid penetration also demonstrated pH-sensitivity: at pH 7.4, cPEG-RIPL-NLCs could not penetrate deep into the spheroid core region during 2 hours, whereas at pH 6.5, high fluorescence intensity in the core region was observed for both cPEG-RIPL-NLC-and RIPL-NLC-treated groups. Conclusion cPEG-RIPL-NLCs are good candidates for Hpn-selective drug targeting in conjunction with pH-responsive PEG cleavage.