Yunseong Jeong

Evaluation of generations 2, 3 and 4 arginine modified PAMAM dendrimers for gene delivery

It is a matter of concern to develop and design synthetic non-viral gene carriers with high transfection efficiency and low cytotoxicity in gene therapy. Recently, various arginine conjugated dendrimers showed better performance in transfection and greater viability than polyethyleneimine (PEI). In this study, we synthesized and investigated e-PAM-R G2, 3 and 4 which are biodegradable polyamidoamine (PAMAM) dendrimers modified with arginine and compared that with PAMAM-R series containing amide bonds for gene carriers. For plasmid DNA delivery, the transfection efficiency of e-PAM-R G4 was higher than G3 and G2 and similar to PAMAM-R G4 with favorable cell viability. Moreover, they indicated significantly higher suppression of TEL/AML1 protein, maybe due to rapid olidonucleotide (ODNs) release through biodegradability of e-PAM-R. These results suggest that biodegradable and non-toxic e-PAM-R may be useful carriers for the gene including plasmid DNA, antisense ODNs and si-RNA.

Ion pairs of risedronate for transdermal delivery and enhanced permeation rate on hairless mouse skin

Ion-paired solutions of risedronate (RIS) with L-arginine (ARG), L-lysine (LYS), and diethylenetriamine (DETA) were tested in vitro for their potential to enhance the penetration of RIS across the skin of hairless mouse. The xylene solubilities of RIS paired with ARG, LYS, and DETA in molar ratios of 1:2, 1:2, and 1:1 were 8.9%, 12.0%, and 2.1%, respectively, in comparison with the solubility in deionized water, but non-ion-paired RIS was not detected in xylene. In vitro permeation tests were performed on the skin of hairless mice, and the results indicated that ion-paired RIS could penetrate mice skin about 36 times more effectively than RIS alone. The cumulative amount of ion paired RIS after 24 h resulted in 475.18±94.19 μg/cm(2) and 511.21±106.52 μg/cm(2) at molar ratio of 1:2 and 1:1. The cumulative amount of RIS alone was as low as 14.13±5.49 μg/cm(2) in 24h. The hairless mice showed no skin irritation after a single administration of RIS alone and ion-paired RIS (1:2 molar ratio with ARG, and 1:1 molar ratio with DETA). In this study, we found that RIS can be delivered transdermally, and the ion-paired system in an aqueous solution showed an enhanced flux through the skin barrier.

The Natural Product NI-07, Is Effective Against Breast Cancer Cells While Showing No Cytotoxicity to Normal Cells

With the exception of a few anticancer agents, most breast cancer chemotherapeutics currently used have devastating effects on normal cells. We investigated the effectiveness of the natural product NI-07, derived from Arctium lappa,� to determine its killing potential on breast cancer cells and its cytotoxic effects in breast normal cells. The breast cancer cell lines HCC1419, MCF7, MDA-MB-231, MDA-MB-468, SKBR3, the normal mammary epithelial cell line HME 50 HT and the normal mammary fibroblast cell line CCD-1074sk were analyzed in concurrently treated cultures of NI-07, Taxol™ or Untreated. NI-07- treated and Taxol™ -treated cells were cultured for two weeks to assess cell resistance/recovery. Cell viability was determined by cell counts, Trypan Blue exclusion and microscopy. Additionally, cell viability and cytotoxicity were measured by XTT. Statistical significance (p � 0.05) of NI-07 to Untreated or Taxol™ was first determined using Two-Way ANOVA. Identified significant differences were further analyzed by One-Way ANOVA and Tukeys test for honestly significant differences. The effect size of NI-07 compared to untreated or Taxol™ was determined using Cohens d. Our results showed significant declines in cell viability occurring in NI-07- treated cancer cells after 48 hours of treatment in contrast to the more rapid effect of Taxol™ (<24h). Additionally, cancer cell recovery was less effective in NI-07 versus Taxol™. Furthermore, NI-07 showed no cytotoxicity in normal cells. This lack of cytotoxicity, coupled with its killing efficiency in cancer cells, suggests that NI-07 could potentially make a strong anti-cancer compound or neo-adjuvant to current chemotherapy-based treatments.

Effect of deoxycholate conjugation on stability of pDNA/polyamidoamine-diethylentriamine (PAM-DET) polyplex against ionic strength

Polyplexes formed from cationic polymer/pDNA have been known to be vulnerable to external ionic strength. To improve polyplex stability against ionic strength, we attempted the chemical conjugation of the hydrophobic deoxycholate (DC) moiety to the polyamidoamine-diethylenetriamine (PAM-DET) dendrimer. Dynamic light scattering studies showed that the tolerance of the resulting PAM-DET-DC against ionic strength is higher than that of PAM-DET. In addition, we confirmed that the stability of polyplex has a strong relationship with the degree of conjugation of the DC moiety to the PAM-DET dendrimer and the charge ratio of PAM-DET-DC. Furthermore, the transfection efficiency of the PAM-DET-DC polyplex is higher than that of PAM-DET but its cytotoxicity remains the same. Therefore, the chemical conjugation of DC is a safe and effective method for increasing the stability of supramolecules formed from electrostatic interaction.