Gene delivery to human sweat glands: a model for cystic fibrosis gene therapy

Gene therapy vectors are mostly studied in cultured cells, rodents, and sometimes in non-human primates, but it is useful to test them in human tissue prior to clinical trials. In this study, we investigated the possibility of using human sweat glands as a model for testing cystic fibrosis (CF) gene therapy vectors. Human sweat glands are relatively easy to obtain from skin biopsy, and can be tested for CFTR function. Using patients' sweat glands could provide a safe model to study the efficacy of CF gene therapy. As the first step to explore using sweat glands as a model for CF gene therapy, we examined various ex vivo gene delivery methods for a helper-dependent adenovirus (HD-Ad) vector. Gene delivery to sweat glands in skin organ culture was studied by topical application, intradermal injection or submerged culture. We found that transduction efficiency can be enhanced by pretreating isolated sweat glands with dispase, which suggests that the basement membrane is a critical barrier to gene delivery by adenoviral vectors. Using this approach, we showed that Cftr could be efficiently delivered to and expressed by the epithelial cells of sweat glands with our helper-dependent adenoviral vector containing cytokeratin 18 regulatory elements. Based on this study we propose that sweat glands might be used as an alternative model to study CF gene therapy in humans.