The complexing of cationic copolymer MPC30-DEA70 with TGF-ß1 antisense oligodeoxynucleotide and transfection into cardiomyocytes in vitro.

Although gene therapy is an attractive option for the treatment of cardiovascular diseases, the ideal gene delivery systems are still under investigation and must meet the following criteria: safety, adequate gene transfer efficiency, and stable expression of the transgene for a duration appropriate for treating the disease. In this study, we developed a cationic phosphorylcholine-containing diblock copolymer, namely MPC30-DEA70, as carrier systems to deliver a chemically synthesized transforming growth factor-beta 1(TGF-ß1) antisense oligonucleotide (AS-ODN) into cardiomyocytes (CMs) to observe the cell transfection efficiency of MPC30-DEA70 and the inhibition effect on the expression of TGF-ß1. MPC30-DEA70/TGF-ß1 AS-ODN complexes were formed through complexation between copolymer MPC30-DEA70 (N) and AS-ODN (P) at different N/P ratios and were characterized by DNA electrophoresis. Notably, the cytotoxicity and cell growth inhibition assay showed that the MPC30-DEA70 had low cytotoxicity to CMs within the effective transfection dosage range (<20 µL/mL). CLSM/TEM images displayed that most of the AS-ODN molecules engulfed by cells were located around the cell nuclei, and a few entered into the cell nuclei without harming the organelles in the cell. Transfection studies from CMs indicated a steady increase of transfection efficiency with increasing N/P ratios. The expression levels of TGF-ß1 mRNA and protein in CMs were significantly inhibited at high N/P ratios. This study shows that MPC30-DEA70 can function as an effective transgenic vector into CMs and that TGF-ß1 AS-ODN delivered by MPC30-DEA70 can silence the expression of the TGF-ß1 gene efficiently and specifically and thereafter antagonize TGF-ß1-mediated biological function in cardiomyocytes.

pH-Responsive and Biodegradable ZnO-Capped Mesoporous Silica Composite Nanoparticles for Drug Delivery.

As a drug delivery system (DDS), traditional mesoporous silica nanoparticles (MSNs) suffer from bioaccumulation in vivo and premature drug release in systemic circulation due to low degradation rate and lack of protective gatekeeper. Herein, we developed a safe and intelligent DDS with characteristics of pH-responsive biodegradation and controlled drug release based on mesoporous silica composite nanoparticles (MSCNs) capped with ZnO quantum dots (ZnO QDs). Acidic degradable MSCNs were successfully synthesized by doping Ca2+ and PO43- into the MSNs' framework. The in vitro doxorubicin hydrochloride (DOX) release was inhibited at neutral pH 7.4 but triggered significantly at pH 5.0 due to the dissociation of ZnO caps. The internalization behavior and cytotoxicity of 4T1 cells indicated MSCNs-ZnO could efficiently deliver DOX into the cells with significant antitumor activity. Such a DDS with pH-responsive biodegradation and controlled drug release has promising potential for cancer therapy.