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

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