94. Targeting Endothelial Cells in Mice with Adeno-Associated Virus Serotype 1 Vector

Top of pageAbstract Adeno-associate virus (AAV) has a broad spectrum of tissue tropism, with different AAV serotypes displaying tissue affinities consistent with the presence of their receptor molecules. While the cellular receptor molecule(s) for AAV serotype 1 (AAV-1) is not known, we have found that endothelial cells of mice are a primary target of AAV-1. Self-complementary AAV vectors expressing green fluorescent protein (GFP) from a CMV promoter were delivered into adult mice by intravenous (IV) or intracisternal (IC) injection, 10 minutes after an IV infusion of mannitol. Multiple tissues, including brain, spinal cord, liver, spleen, kidney, heart and skeletal muscle, were examined for transgene expression by GFP immunofluorescence assay at 1 and 3 months postinjection. IV delivery of 1 1011 AAV-1 vector particles resulted in GFP expression in hepatocytes (>50%), cardiac myocytes (30%), skeletal muscle cells (50%), and a global distribution of GFP-positive neuronal and non-neuronal cells in brain and spinal cord. After IC injection (2 1010 particles), a broad dispersion of GFP expression was observed in neuronal and non-neuronal cells in cerebellum, brain stem, cerebral cortex, hippocampus, thalamus, olfactory and spinal cord, as well as in hepactocytes (5% with and 2–3% without mannitol pretreatment). Surprisingly, GFP was readily detected in endothelial cells of blood vessels in all tissues analyzed after IV delivery, and in brain and liver blood vessels after IC injection. The identity of endothelial cells was confirmed by immunofluorescence using an antibody against Von Willibrand factor. Transduction of endothelial cells was not observed using the same vector genome in an AAV-2 capsid. These results demonstrated that AAV-1 is very efficiently taken up by endothelial cells after IV or IC administration of vector. Our data also demonstrates that AAV vector when delivered into the cerebral spinal fluid enters the systematic circulation and can infect endothelial cells as well as other cells types in peripheral tissues. We speculate that AAV-1 vector may provide a valuable tool in therapeutic gene delivery for many diseases directly or indirectly involving endothelial cells.