1. ¹Wolfson Centre for Gene Therapy of Childhood Disease, University College London Institute of Child Health, London,UK
2. ²Centre for Respiratory Research, University College London, London, UK
3. ³Department of Chemistry, University College London, London, UK
4. ⁴Division of Paediatrics, Department of Infection, Immunity and Inflammation, University of Leicester, Leicester Royal Infirmary, Leicester, UK
5. ⁵Portex Respiratory Medicine Group, University College London Institute of Child Health, London, UK

Correspondence: Stephen L. Hart, Wolfson Centre for Gene Therapy of Childhood Disease, University College London Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK. E-mail: shart@ich.ucl.ac.uk

Received 28 March 2007; Accepted 13 February 2008; Published online 25 March 2008.

Abstract

Synthetic vectors for cystic fibrosis (CF) gene therapy are required that efficiently and safely transfect airway epithelial cells, rather than alveolar epithelial cells or macrophages, and that are nonimmunogenic, thus allowing for repeated delivery. We have compared several vector systems against these criteria including GL67, polyethylenimine (PEI) 22 and 25 kd and two new, synthetic vector formulations, comprising a cationic, receptor-targeting peptide K₁₆GACSERSMNFCG (E), and the cationic liposomes (L) DHDTMA/DOPE or DOSEP3/DOPE. The lipid and peptide formulations self assemble into receptor-targeted nanocomplexes (RTNs) LED-1 and LED-2, respectively, on mixing with plasmid (D). LED-1 transfected airway epithelium efficiently, while LED-2 and GL67 preferentially transfected alveolar cells. PEI transfected airway epithelial cells with high efficiency, but was more toxic to the mice than the other formulations. On repeat dosing, LED-1 was equally as effective as the single dose, while GL67 was 30% less effective and PEI 22 kd displayed a 90% reduction of efficiency on repeated delivery. LED-1 thus was the only formulation that fulfilled the criteria for a CF gene therapy vector while GL67 and LED-2 may be appropriate for other respiratory diseases. Opportunities for PEI depend on a solution to its toxicity problems. LED-1 formulations were stable to nebulization, the most appropriate delivery method for CF.