Gene therapy for the lysosomal storage disorders

The lysosomal storage disorders (LSD) are monogenic inborn errors of metabolism with heterogeneous pathophysiology and clinical manifestations. In recent decades, these disorders have been models for the development of molecular and cellular therapies for inherited metabolic diseases. Studies in preclinical in vitro systems and animal models have established proof-of-concept for the development of bone marrow transplantation (BMT) and enzyme-replacement therapy (ERT) as therapeutic options for several LSDs. BMT is limited by poor donor availability and high morbidity and mortality, and although ERT is a good treatment, it is not a life-long cure. Its high cost remains an impediment for developing countries. While substrate synthesis inhibition therapy is an important idea, its clinical use is far from certain. The neuropathology present in many LSDs has responded poorly to BMT or ERT, which makes gene therapy an attractive therapeutic alternative. Oncoretroviral vectors, and more recently adeno-associated and lentiviral vectors have been tested with some success. This review summarizes the main gene therapy strategies which have been employed or are under development for both non-neurological and neuronopathic LSDs. Some of the in vitro and in vivo preclinical studies presented herein have provided the rationale for gene therapy clinical trials for Gaucher disease Type 1.