AAV vector mediated gene delivery of endothelin converting enzyme-1 reduces β-amyloid deposits in transgenic APP + PS1 mice

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ABSTRACTS / Experimental Neurology 198 (2006) 558 – 597

robustly stimulated the elongation and arborization of dendrites in freshly differentiated neurons. Furthermore, TSA promoted the full functional maturation of these neurons by inducing the complete development of (voltage-sensitive) ion-channels resulting in their typical excitability and characteristic action potential firing patterns. Gene expression analysis revealed the TSA-dependent upregulation of GAP43 but unexpectedly could not demonstrate the involvement of REST-dependent neuronal genes. Our study shows that modification of HDAC activity is involved in the transcriptional regulation of various aspects of NSC differentiation including cell lineage specification and maturation. doi:10.1016/j.expneurol.2006.02.025

BrdU is not a reliable label for transplanted cells in the central nervous system T.C. Burns 1,2,3, X.R. Ortiz-Gonza´lez 2,3, M. Gutie´rrez Pe´rez 4, C.D. Keene 2,3, Z.L. Demorest 2, Y. Nakagawa 1,3,5, J.M. Garcia-Verdugo 6, F. Prosper 4, W.C. Low 1,2,3,5, C.M. Verfaillie 1,3 1 Stem Cell Institute, University of Minnesota, Minneapolis, USA 2 Department of Neurosurgery, University of Minnesota, Minneapolis, USA 3 Graduate Program in Neuroscience, University of Minnesota, Minneapolis, USA 4 Clı´nica Universitaria, Universidad de Navarra, Pamplona, Spain 5 Department of Neuroscience, University of Minnesota, Minneapolis, USA 6 Department of Cell Biology, University of Valencia, Valencia, Spain Thymidine analogs, including bromodeoxyuridine (BrdU), chlorodeoxyuridine (CldU), iododeoxyuridine (IdU) and tritiated thymidine (3H-T) label dividing cells by incorporating into DNA during S phase of cell division and are widely employed to identify cells transplanted into the central nervous system (CNS). However, the potential for transfer of thymidine analogs from grafted cells to dividing host cells has not been thoroughly tested. We here demonstrate that graft-derived thymidine analogs can become incorporated into host neural precursors and glia in the embryonic, neonatal and adult brain. Large numbers of labeled neurons and glia were found 3 –12 weeks after transplantation of thymidine analoglabeled live stem cells, suggesting differentiation of grafted cells. Labeled neurons were found in known neurogenic regions, and labeled glia were widely distributed around the graft site and in areas of astrocytosis after injury. Importantly, however, similar results were obtained after transplantation of dead cells or labeled fibroblasts. Transplantation of live or dead BrdU, IdU or tritiated thymidine-labeled cells derived from transgenic GFP or Rosa 26 mice resulted in labeled host neurons and glia that were negative by immunohistochemistry

and PCR for the graft transgene. Our findings reveal for the first time that thymidine analog labeling may not be a reliable means of identifying transplanted cells, particularly in highly proliferative environments such as the developing, neurogenic or injured brain. doi:10.1016/j.expneurol.2006.02.026

AAV vector mediated gene delivery of endothelin converting enzyme-1 reduces B-amyloid deposits in transgenic APP + PS1 mice N.C. Carty 1, V. Ronan 1, C. Meyers 2, K. Nash 2, N. Muzyckza 2, M. Gordon 1, D. Morgan 1 1 Department of Pharmacology and Molecular Therapeutics, University of South Florida, Alzheimer’s Research Laboratory, Tampa, USA 2 Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, Gainesville, USA The aberrant accumulation of h-amyloid peptides in the brain has been recognized as an essential factor in the pathology of Alzheimer’s disease. Consequently, targeting methods of reducing Abeta (Ah) deposition are a major area of therapeutic research. Recently, it has been argued that the concentrations of Ah in the brain can be modulated by several endogenous zinc metallopeptidases or h-amyloid degrading enzymes which include: neprilysin, endothelin converting enzymes, insulin degrading enzyme, and plasmin. In the current study, we investigate the effects of an intracranial administration of a recombinant adeno-associated viral vector (rAAV) containing either the secreted or neuronal form of the ECE-1 gene on amyloid deposition in APP + PS1 transgenic mice. Recombinant AAV vectors were injected unilaterally into the right anterior cortex and hippocampus of 6-month-old mice while the left untreated hemisphere served as an internal control. The control group was treated with saline. The animals were sacrificed after 6 weeks and histology was performed to measure ECE-1 expression and brain amyloid deposition. Immunohistochemistry for ECE-1 revealed strong expression in areas immediately surrounding the injection sites and a lesser degree of expression was seen in the contralateral hippocampus in mice receiving the gene for neuronal ECE-1 (ECE-n). Animals treated with the secreted ECE-1 (ECE-s) gene showed similar results but no expression was seen in the left untreated hemisphere. Control mice showed no expression. Immunohistochemistry for total Ah was significantly decreased in the anterior cortex of mice receiving ECE-s gene and also decreased in the hippocampus. Decreases in Ah were also seen in mice receiving ECE-n. These results indicate that increasing the expression of certain endogenous h-amyloid degrading enzymes through gene therapy is a promising therapeutic avenue through which to treat AD. (Supported by the Johnnie B Byrd Alzheimer’s Research Institute). doi:10.1016/j.expneurol.2006.02.027