Targeting of the prostacyclin specific IP1 receptor in lungs with molecular conjugates comprising prostaglandin I2 analogues.
ABSTRACT Molecular conjugates comprising targeting ligands hold great promise for site-specific gene delivery to distant tumors and individual organs including the lung. Here we show that prostaglandin I2 analogues can be used to improve gene transfer efficiency of polyethylenimine (PEI) gene vectors on bronchial and alveolar epithelial cells in vitro and lungs of mice in vivo. Prostacyclin (IP1) receptor expression was confirmed in pulmonary epithelial cell lines by western blot. Iloprost (ILO) and treprostinil (TRP), two prostaglandin I2 analogues, were conjugated to fluorescein-labeled BSA (FLUO-BSA) and compared for IP1 receptor binding/uptake in different lung cell lines. Binding of FLUO-BSA-ILO was 2-4-fold higher than for FLUO-BSA-TRP and could be specifically inhibited by free ILO and IP1 receptor antagonist CAY10449. Internalization of FLUO-BSA-ILO was confirmed by confocal microscopy. Molecular conjugates of PEI and ILO (PEI-g-ILO) were synthesized with increasing coupling degree (F(ILO) (ILO:PEI) = 2, 5, 8, 16) and analyzed for DNA binding, particle formation and transfection efficiency. At optimized conditions (N/P 4, F(ILO) = 5), gene expression using PEI-g-ILO was significantly up to 46-fold higher than for PEI gene vectors and specifically inhibited by CAY10449. Gene expression in the lungs of mice after aerosol delivery was 14-fold higher with PEI-g-ILO F(ILO) = 5 than for PEI. We suggest that targeting of IP1 receptor using ILO represents a promising approach to improve pulmonary gene transfer.
Article: Invading target cells: multifunctional polymer conjugates as therapeutic nucleic acid carriers[show abstract] [hide abstract]
ABSTRACT: Polymer-based conjugates are an interesting option and challenge for the design of nano-sized drug-delivery systems, as they require advanced conjugation chemistry and precise engineering. In the case of nucleic acid therapy, non-viral carriers face several biological barriers during the delivery process, namely 1) protection of the cargo from extracellular degradation, 2) avoidance of non-specific interactions with non-targeted tissues, 3) efficient entry into the target cells, 4) intracellular trafficking to the site of action and 5) cargo release. To take on these obstacles, multifunctional conjugates can act as “smart polymers” with microenvironment-sensing dynamics to facilitate the separate delivery steps. Synthesis of defined polymer architectures with precise functionalization enables structure-activity relationships to be investigated and the integration of key functions for efficient delivery. Thus bioresponsive polymer conjugates, which are equipped with molecular devices responding to the certain microenvironments within the delivery pathway (e. g. pH, redox potential, enzymes) can be assembled. This review focuses on the modular engineering and conjugation of multifunctional polymeric structures for the utilization as “tailor-made” nucleic acid carriers. Keywordsconjugate–DNA–gene transfer–polymer–RNA–targeting04/2012; 5(3):275-286.