Primary adult human astrocytes as an ex vivo vehicle for beta-glucuronidase delivery in the brain

Astrocytes are a good candidate cell type for brain transplantation: They a re endogenous to the CNS, they have efficient secretory machinery, and they play a major role in neuronal support. We assessed the potential of geneti cally modified primary adult human astrocytes as vehicles for the delivery of secreted molecules in the mammalian CNS. We report that such cells can b e efficiently transduced by a recombinant adenoviral vector carrying the hu man beta -glucuronidase cDNA (Ad/ CMV*beta -glu) and that the transduced as trocytes produce large amounts of the enzyme. Released beta -glucuronidase could be captured, in vitro, by primary neurons and astrocytes and by a neu roblastoma cell line and beta -glucuronidase-deficient fibroblasts. Followi ng grafting into the mouse striatum, adult human astrocytes survived and ex pressed the transgene for at least 8 weeks. Moreover, the dosage of beta -g lucuronidase activity within the grafted brains revealed high enzymatic lev els at a long distance from the graft. These experiments document the graft ing of engineered primary adult human astrocytes, allowing the release of a secreted therapeutic factor throughout the brain.