Progress in gene and cell therapy for cystic fibrosis lung disease.

Although the development of gene therapy for cystic fibrosis (CF) was high priority for many groups in academia and industry in the first 10 to 15 years after cloning the gene, more recently active research into CF gene therapy is only being performed by a small number of committed, mainly academic, groups. However, despite the waning enthusiasm, which is largely due to the realisation that gene transfer into lungs is more difficult than originally thought and the fact that meaningful clinical trials are expensive and difficult to perform, gene therapy continues to hold promise for the treatment of CF lung disease. Problems related to repeat administration of adenovirus and adeno-associated virus-based vectors led to a focus on non-viral vectors in clinical trials. The UK CF Gene Therapy Consortium is currently running the only active gene therapy programme, aimed at assessing if repeated administration of a non-viral gene transfer agent can improve CF lung disease. However, the recent suggestion that lentiviral vectors may be able to evade the immune system and, thereby, allow for repeat administration and long lasting expression opens new doors for the use of viral vectors in the context of CF gene therapy. In addition, early pre-clinical studies have recently been initiated to address cell therapy-based approaches for CF. This involves systemic and topical administration of a variety of stem/progenitor cells, as well as first attempts as producing a tissue-engineered lung. Recent studies in viral and non-viral vector developments, as well as cell therapy will be discussed and an update on clinical gene therapy studies will be provided here.