DIRECT GENE-TRANSFER INTO HUMAN EPILEPTOGENIC HIPPOCAMPAL TISSUE WITHAN ADENOASSOCIATED VIRUS VECTOR - IMPLICATIONS FOR A GENE-THERAPY APPROACH TO EPILEPSY

Purpose: Virus vectors capable of transferring genetic information int o human cells provide hope for improved therapy in several neurologica l diseases, including epilepsy. We evaluated the ability of an adeno-a ssociated Virus (AAV) vector to transfer and cause expression of a lac Z marker gene in brain slices obtained from patients undergoing tempor al lobectomy for control of medically intractable seizures. Methods: H uman brain slices were injected with an AAV vector (AAVlacZ) encoding Escherichia coli beta-galactosidase and incubated for as long as 24 h. The presence of lacZ mRNA. beta-galactosidase protein and enzymatic a ctivity were assayed by reverse transcriptase polymerase chain reactio n (rtPCR), immunocytochemistry, and the X-GaI technique, respectively. Results: AAVlacZ directed the expression in human epileptogenic brain of E. coli beta-galactosidase that had functional activity. Expressio n was observed in less than or equal to 5 h and was sustained for as l ong as the slices were viable. Morphological analysis indicated that n eurons were preferentially transfected, and there was no evidence of c ytotoxicity. Conclusions: Our results confirm the feasibility of using AAV vectors to transfer genes into the human CNS and in particular, i nto neurons. Replacement of the lacZ gene with a functional gene modul ating hippocampal neuronal physiology, might allow a localized genetic intervention for focal seizures based on the stereotaxic or endovascu lar delivery of such a vector system into the appropriate brain region .