Gene delivery to hypoxic cells in vitro

Hypoxia in solid tumours has been correlated with poor prognosis and resist ance to radiation and chemotherapy. Hypoxia is also a strong stimulus for g ene expression. We previously proposed a gene therapy approach which exploi ts the presence of severe hypoxia in tumours for the induction of therapeut ic genes. Hypoxic cells are known to have a reduced metabolic rate, transcr iption and translation. These facts may prevent gene transfer and therefore warranted further investigation. In this paper the feasibility of gene del ivery in vitro under tumour conditions was demonstrated. DNA was delivered in vitro using a peptide-mediated non-viral system. Across a range of oxyge n tensions and mammalian cell lines (including human tumour and endothelial cells) it was shown that hypoxic cells could be transfected. Transfection efficiencies varied depending on the level of hypoxia, cell characteristics and gene promoters used. An in vitro model of hypoxia/reoxygenation, desig ned to mimic the variable nature of tumour hypoxia, showed that hypoxic pre conditioning and reoxygenation alone did not reduce transfection efficiency significantly; only chronic anoxia reduced transfection. The fact that nei ther intermediate hypoxia nor intermittent anoxia significantly reduced tra nsfection is promising for future hypoxia-targeted gene therapy strategies, (C) 2000 Cancer Research Campaign.