Mechanism of efficient transfection of the nasal airway epithelium by hypotonic shock

The main barrier to gene transfer in the airway epithelium is the low rate of apical endocytosis limiting naked DNA uptake. Deionized water is known to stimulate the exocytosis of numerous intracellular vesicles during hypotonic cell swelling, in order to expand plasma membrane and prevent cell lysis. This is followed by the phase of regulatory volume decrease (RVD), during which the excess plasma membrane is retrieved by intensive endocytosis. Here we show that the more hypotonic the DNA solution, the higher the transfection of the nasal tissue. P2 receptors are known to be involved in RVD and we demonstrate that some P2 agonists and a P2 antagonist impair transfection in a time-dependent manner. Our study strongly suggests that the nasal airway epithelial cells take up plasmid DNA in deionized water during RVD, within approximately half an hour. Our simple gene delivery system may constitute a promising method for respiratory tract gene therapy.