Gene therapy is a powerful approach in the treatment of a wide range of both inherited and acquired diseases. Nonviral delivery systems have been proposed as safer alternatives to viral vectors because they avoid the inherent immunogenicity and production problems that are seen when viral systems are used. Many cationic polymers, including high-molecular-weight polyethylenimine (PEI) have been widely studied as gene-delivery carriers, both, in vitro and in vivo. However, interest has recently developed in degradable polymeric systems. The advantage of degradable polymer is its low in-vivo cytotoxicity, which is a result of its easy elimination from the cells and body. Degradable polymer also enhances transfection of DNA or small interfering RNA (siRNA) for efficient gene expression or silencing, respectively. This review paper summarizes and discusses the recent advances with degradable PEIs, such as cross-linked and grafted PEIs for DNA and siRNA delivery.
Rationale: The low efficiency of conventional therapies in achieving long-term survival of patients with lung cancer calls for the development of novel therapeutic options. Recent advances in aerosol-mediated gene delivery have provided the possibility of an alternative for the safe and effective treatment of lung cancer. Objectives: To demonstrate the feasibility and emphasize the importance of noninvasive aerosol delivery of Akt1 small interfering RNA (siRNA) as an effective and selective option for lung cancer treatment. Methods: Nanosized poly(ester amine) polymer was synthesized and used as a gene carrier. An aerosol of poly(ester amine)/Akt1 siRNA complex was delivered into K-ras LA1 and urethane-induced lung cancer models through a nose-only inhalation system. The effects of Akt1 siRNA on lung cancer progression and Akt-related signals were evaluated. Measurements and Main Results: The aerosol-delivered Akt1 siRNA suppressed lung tumor progression significantly through inhibiting Akt-related signals and cell cycle. Conclusions: The use of poly(ester amine) serves as an effective carrier, and aerosol delivery of Akt1 siRNA may be a promising approach for lung cancer treatment and prevention.
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