Delivery of acetylthevetin B, an antitumor cardiac glycoside, using polymeric micelles for enhanced therapeutic efficacy against lung cancer cells.

Acetylthevetin B (ATB), a cardiac glycoside from the seed of Thevetia peruviana (Pers) K Schum (yellow oleander), exhibits not only antitumor activity but also potential cardiac toxicity. In the present study, we attempted to enhance its antitumor action and decrease its adverse effects via chitosan-Pluronic P123 (CP) micelle encapsulation. Two ATB-loaded CP micelles (ATB-CP1, ATB-CP2) were prepared using an emulsion/solvent evaporation technique. They were spherical in shape with a particle size of 40-50 nm, showed a neutral zeta potential, and had acceptable encapsulation efficiency (>90%). Compared to the free ATB (IC50=2.94 µmol/L), ATB-loaded CP micelles exerted much stronger cytotoxicity against human lung cancer A549 cells with lower IC50 values (0.76 and 1.44 µmol/L for ATB-CP1 and ATB-CP2, respectively). After administration of a single dose in mice, the accumulation of ATB-loaded CP1 micelles in the tumor and lungs, respectively, was 15.31-fold and 9.49-fold as high as that of free ATB. A549 xenograft tumor mice treated with ATB-loaded CP1 micelles for 21 d showed the smallest tumor volume (one-fourth of that in the control group) and the highest inhibition rate (85.6%) among all the treatment groups. After 21-d treatment, no significant pathological changes were observed in hearts and other main tissues. In summary, ATB may serve as a promising antitumor chemotherapeutic agent for lung cancer, and its antitumor efficacy was significantly improved by CP micelles, with lower adverse effects.

[Therapeutic efficacy of pegylated polymyxin E in the treatment of infection induced by gramnegative bacteria and the effect of reducing nephrotoxicity].

Polymyxin E shows effective treatment of the infection induced by resistant gramnegative bacteria, but its nephrotoxicity severely limits the clinical application of this drug. In this work, methoxypolyethylene glycols 2000 (mPEG2K)-polymyxin E (PME) was synthesized via chemical grafting reaction and had been characterized. The antimicrobial activity and cytotoxicity of mPEG2K-PME in vitro were investigated on Escherichia coli and HK-2 cells, separately. Intra-abdominal infection model was further established in order to study the therapeutic effect and the toxic effect on kidney of mice. The results showed that mPEG2K-PME exhibited significant inhibitory effect on Escherichia coli and had a lower toxicity on HK-2 cells in vitro. At the same time, mPEG2K-PME had a good efficacy in the treatment of Escherichia coli infected mice in vivo. Moreover, nephrotoxicity caused by mPEG2K-PME was significantly reduced compared to free PME. mPEG2K-PME is promising in development of new preparations with high efficiency and low toxicity.

Chain-Length- and Saturation-Tuned Mechanics of Fluid Nanovesicles Direct Tumor Delivery.

Small unilamellar vesicles (SUVs), ubiquitous in organisms, play key and active roles in various biological processes. Although the physical properties of the constituent lipid molecules (i.e., the acyl chain length and saturation) are known to affect the mechanical properties of SUVs and consequently regulate their biological behaviors and functions, the underlying mechanism remains elusive. Here, we combined theoretical modeling and experimental investigation to probe the mechanical behaviors of SUVs with different lipid compositions. The membrane bending rigidity of SUVs increased with increasing chain length and saturation, resulting in differences in the vesicle rigidity and deformable capacity. Furthermore, we tested the tumor delivery capacity of liposomes with low, intermediate, and high rigidity as typical models for SUVs. Interestingly, liposomes with intermediate rigidity exhibited better tumor extracellular matrix diffusion and multicellular spheroid (MCS) penetration and retention than that of their stiffer or softer counterparts, contributing to improved tumor suppression. Stiff SUVs had superior cellular internalization capacity but intermediate tumor delivery efficacy. Stimulated emission depletion microscopy directly showed that the optimal formulation was able to transform to a rod-like shape in MCSs, which stimulated fast transport in tumor tissues. In contrast, stiff liposomes hardly deformed, whereas soft liposomes changed their shape irregularly, which slowed their MCS penetration. Our findings introduce special perspectives from which to map the detailed mechanical properties of SUVs with different compositions, provide clues for understanding the biological functions of SUVs, and suggest that liposome mechanics may be a design parameter for enhancing drug delivery.