A novel internally quaternized and surface-acetylated poly(amidoamine) generation four dendrimer (QPAMAM-NHAc) was synthesized and evaluated for intracellular delivery of siRNA. The proposed dendrimer as a nanocarrier possesses the following advantages: (1) modified neutral surface of the dendrimer for low cytotoxicity and enhanced cellular internalization; (2) existence of cationic charges inside the dendrimer (not on the outer surface) resulting in highly organized compact nanoparticles, which can potentially protect nucleic acids from degradation. The properties of this dendrimer were compared with PAMAM-NH 2 dendrimer, possessing surface charges, and with an internally quaternized charged and hydroxyl-terminated QPAMAM-OH dendrimer. Atomic force microscopy studies revealed that internally charged and surface neutral dendrimers, QPAMAM-OH and QPAMAM-NHAc, formed well-condensed, spherical particles (polyplexes) with siRNA, while PAMAM-NH 2 resulted in the formation of nanofibers. The modification of surface amine groups to amide significantly reduced cytotoxicity of dendrimers with QPAMAM-NHAc dendrimer showing the lowest toxicity. Confocal microscopy demonstrated enhanced cellular uptake and homogeneous intracellular distribution of siRNA delivered by the proposed QPAMAM-NHAc nanocarrier. The results clearly demonstrated distinct advantages of developed QPAMAM-NHAc/siRNA polyplexes over the existing nucleic acid dendrimeric carriers.

Purpose. To compare systemic intravenous and local intratracheal delivery of doxorubicin (DOX), antisense oligonucleotides (ASO) and small interfering RNA (siRNA). Methods. "Neutral" and cationic liposomes were used to deliver DOX, ASO, and siRNA. Liposomes were characterized by dynamic light scattering, zeta-potential, and atomic force microscopy. Cellular internalization of DOX, ASO and siRNA was studied by confocal microscopy on human lung carcinoma cells. In vivo experiments were carried out on nude mice with an orthotopic model of human lung cancer. Results. Liposomes provided for an efficient intracellular delivery of DOX, ASO, and siRNA in vitro. Intratracheal delivery of both types of liposomes in vivo led to higher peak concentrations and much longer retention of liposomes, DOX, ASO and siRNA in the lungs when compared with systemic administration. It was found that local intratracheal treatment of lung cancer with liposomal DOX was more efficient when compared with free and liposomal DOX delivered intravenously. Conclusions. The present study outlined the clear advantages of local intratracheal delivery of liposomal drugs for the treatment of lung cancer when compared with systemic administration of the same drug.

Many pathological conditions and environmental impacts lead to a decrease in tissue oxygen supply and severe cellular hypoxia. This secondary hypoxia can disturb cellular homeostasis, limiting the efficacy of the prescribed treatment for the primary lesion, eventually leading to cellular and organismal death. Jun N-terminal kinase 1 (JNK1) plays a major role in the hypoxic cellular damage. Therefore, we hypothesized that suppression of JNK1 activity will decrease cellular mortality under hypoxia and might increase the efficacy of traditional treatment of many pathological conditions. These investigations are aimed at studying the influence of the suppression of JNK1 activity on the development of cellular hypoxic damage. We used antisense oligonucleotides (ASO) and small interfering RNA (siRNA) targeted to JNK1 mRNA to inhibit the protein synthesis. Experiments were carried out on a cell culture under normoxia and hypoxic conditions that led to the death of approximately 50% of cells. ASO or siRNA was delivered by neutral or cationic liposomes. Intracellular localization of ASO and liposomes and mechanisms of apoptosis were studied. We found that the suppression of JNK1 activity by liposomal antisense oligonucleotides or siRNA limits the caspase-dependent apoptosis signaling pathway and decreases cellular mortality after severe hypoxia. JNK1 protein might be an attractive target for antihypoxic therapy in increasing resistance to many pathological conditions and diseases, leading to the oxygen deficit.

Many pathological conditions and environmental impacts lead to the development of severe tissue hypoxia that aggravates the primary disorder, provokes cell death, and limits the patient’s recovery. We hypothesized that suppression of Jun N-terminal kinase 1 (JNK1) will limit tissue damage induced by severe hypoxia. To test the hypothesis, antisense oligonucleotides (ASO) or small interfering RNA (siRNA) targeted to JNK1 mRNA were incorporated or complexed with neutral or cationic liposomes, respectively, and administered systemically to mice prior to hypoxia exposure. The animals were placed in a special chamber ventilated with room air (normoxia) or a gas mixture containing 6% O2 and 94% N2 (hypoxia). Liposomes, ASO, and siRNA were found to accumulate in the lungs, kidney, spleen, and heart. Only trace amounts of liposomes and their payloads (ASO and siRNA) were found in the brain. The down regulation of JNK1 protein limited activation of cell death signal, apoptotic, and necrotic tissue damage under hypoxic conditions. Consequently, we were able to verify our hypothesis and provide proof of concept of a unique approach to the prevention of cellular hypoxic damage by the suppression of JNK1 signaling pathways after the efficient delivery of ASO or siRNA.

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