Viruses have evolved to be highly effective vehicles for delivering genes into cells. Seeking to take advantage of these traits, scientists can reprogram viruses to function as vectors, capable of carrying their genetic cargo of choice into the nuclei of cells in the body. Such vectors have become critical tools for delivering genes to treat disease or to label neurons and their connective fibers with fluorescent colors to map out their locations. Because viral vectors have been stripped of their own genes and, thereby, of their ability to replicate, they are no longer infectious. Therefore, achieving widespread gene delivery with the vectors is challenging. This is especially true for gene delivery to hard to reach organs like the brain, where viral vectors have to make their way past the so-called blood-brain barrier, or to the peripheral nervous system, where neurons are dispersed across the body.
Now, to enable widespread gene delivery throughout the central and peripheral nervous systems, Caltech researchers have developed two new variants of a vector based on an adeno-associated virus (AAV): one that can efficiently ferry genetic cargo past the blood-brain barrier; and another that is efficiently picked up by peripheral neurons residing outside the brain and spinal cord, such as those that sense pain and regulate heart rate, respiration, and digestion. Both vectors are able to reach their targets following a simple injection into the bloodstream. The vectors are customizable and could potentially be used as part of a gene therapy to treat neurodegenerative disorders that affect the entire central nervous system, such as Huntington’s disease, or to help map or modulate neuronal circuits and understand how they change during disease.
The work was done in the laboratory of Viviana Gradinaru, assistant professor of biology and biological engineering, Heritage Medical Research Institute Investigator, director of the Center for Molecular and Cellular Neuroscience in the Tianqiao and Chrissy Chen Institute for Neuroscience at Caltech, and principal investigator of the Beckman Institute’s CLOVER (CLARITY, Optogenetics, and Vector Engineering Research) Center.
A paper describing the research appears online in the June 26 issue of Nature Neuroscience.
“We have now developed a new collection of viruses and tools to study the central and peripheral nervous systems,” says Gradinaru. “We are now able to get highly efficient brain-wide delivery with just a low-dose systemic injection, access neurons in difficult-to-reach regions, and precisely label…