Recombinant adeno-associated virus vector expressing glial cell line-derived neurotrophic factor reduces ischemia-induced damage

To explore the potential of using the recombinant adeno-associated viral (r AAV) vector, expressing glial cell line-derived neurotrophic factor (GDNF) as the gene therapy for stroke, we injected rAAV vectors expressing GDNF (r AAV-GDNF) into the cortex of rats which had been experiencing transient bil ateral common carotid artery ligation and right middle cerebral artery liga tion for 90 min. GDNF levels in cortical tissues of rAAV-GDNF injected anim als were significantly higher than in the control animals injected with rAA V-expressing lacZ (rAAV-lacZ), indicating that rAAV can deliver and express the GDNF gene in cortical tissues. Triphenyltetrazolium chloride tissue st ain analysis revealed that the rAAV-delivered GDNF gene could rescue the br ain tissues from ischemia-induced injury. Cortical tissues which received r AAV-GDNF injections had both significantly smaller total volumes of infarct ion and smaller areas of infarction on each brain slice than those which we re injected with rAAV-lacZ. An in situ labeling analysis demonstrated signi ficantly less apoptotic cells in cortical tissues rescued by rAAV-GDNF, ind icating prevention of apoptosis as the mechanism of cortical cell protectio n. Moreover, immunohistochemistry staining of Neu-N indicated that the resc ued brain tissues contained the same number of Neu-N-positive neuronal cell s as contralateral undamaged brain tissues. This provides strong evidence t hat cortical neuronal cells can be rescued by GDNF gene therapy. Indeed, th ese findings show that the rAAV is a potential delivery vector of GDNF gene for the therapy of stroke. (C) 2000 Academic Press.