Intravenous Administration of Self-complementary AAV9 Enables Transgene Delivery to Adult Motor Neurons

Therapeutic gene delivery to the whole spinal cord is a major challenge for the treatment of motor neuron (MN) diseases. Systemic administration of viral gene vectors would provide an optimal means for the long-term delivery of therapeutic molecules from blood to the spinal cord but this approach is hindered by the presence of the blood-brain barrier (BBB). Here, we describe the first successful study of MN transduction in adult animals following intravenous (i.v.) delivery of self-complementary (sc) AAV9 vectors (up to 28% in mice). Intravenous MN transduction was achieved in adults without pharmacological disruption of the BBB and transgene expression lasted at least 5 months. Importantly, this finding was successfully translated to large animals, with the demonstration of an efficient systemic scAAV9 gene delivery to the neonate and adult cat spinal cord. This new and non-invasive procedure raises the hope of whole spinal cord correction of MN diseases and may lead to the development of new gene therapy protocols in patients.