Identification, Cellular Localization, and Participation of Chaperonins in Protein Folding

Risks, benefits and ethical, legal, and societal considerations for translation of prenatal gene therapy to human application

The still experimental nature of prenatal gene therapy carries a certain degree of risk, both for the pregnant mother as well as for the fetus. Some of the risks are procedural hazards already known from more conventional fetal medicine interventions. Others are more specific to gene therapy such as the potential for interference with normal fetal development, the possibility of inadvertent germ line gene transfer, and the danger of oncogenesis. This chapter reviews the potential risks in relation to the expected benefits of prenatal gene therapy. It discusses the scientific, ethical, legal, and social implications of this novel preventive approach to genetic disease and outlines preconditions to be met in preparation for a potential future clinical application.

Current Status of Gene Therapy for Cystic Fibrosis Pulmonary Disease

Cystic fibrosis (CF) is a common lethal genetic disorder that affects all ethnic populations; however, it is most prevalent in Caucasians. Intensive basic research over the last 20 years has resulted in a wealth of information regarding the CF gene, its protein product and the mutational basis of disease. This increased understanding has lead to the development of gene therapy for the treatment of CF pulmonary disease. Delivery of the CF gene to the airway requires direct in vivo transfer using vectors encoding for normal CF transmembrane regulator (CFTR) protein. Several vectors are currently available for CF gene transfer and include both viral (adenoviruses, adeno-associated viruses) and non-viral (liposomal) systems. Initial clinical trials with each of these vectors have demonstrated that gene transfer to the CF airway is possible. The efficiency of transfer and duration of expression, however, have been limited. The effects of gene transfer on correction of the basic ion transport defects have also been highly variable and inconsistent, irrespective of the vector. Currently, the risk of severe immunological reactions is the primary factor limiting the clinical advancement of gene therapy. Both the adenoviral and liposomal vectors are associated with significant acute inflammatory reactions. The adenoviruses and adeno-associated viruses also elicit humoral immune responses that significantly reduce the efficiency of transgene expression and increase the risk of readministration. Several strategies are under investigation to improve the efficiency of gene transfer to the CF airway. These include overcoming local barriers in the lung, circumventing the immune response and improving vector internalization and/or uptake. Application of gene transfer in the child and possibly the fetus are also potential future clinical applications of gene therapy. However, despite considerable research with gene therapy, there is little evidence to suggest that a well tolerated and effective gene transfer method is imminent and aggressive use of conventional pharmacological therapies currently offer the greatest promise in the treatment of patients with CF.