106. Novel Subventricular Zone Early Progenitor Cell Specific Adenovirus for In Situ Brain Stem Cell Bioengineering Unveils Cellular Heterogeneity

Neural stem/progenitor cells (NSPC) have the potential to self-renew and to generate all neural lineages as well as to repopulate damaged areas in the brain. Our recent endeavors in the generation of Ad vectors that specifically target SPC in situ have focused on linking selective peptides to viral particles that direct the vector to yet unknown receptors on the surface of stem cells. Using an Ad-PEGylation approach, we demonstrated that a short artificial peptide, which specifically binds neural precursor cells established from the hippocampal area of adult mice or rats, was highly effective in targeting NSPC after vector administration into the brain. These studies also revealed that long-term transgene expression was restricted to precursor cells located in dentate gyrus, and was not detected in other brain regions such as the SVZ and the ependyma of the lateral ventricle. This new indirect evidence for precursor cell heterogeneity in different brain regions that warrants the development of NSPC-specific delivery vehicles was further investigated. Here, we demonstrate a target-specific adenoviral vector system for in vivo manipulation of stem cells in the subventricular zone of the adult mouse brain. For this purpose, we identified a series of peptide ligands via phage display. The peptide with the highest affinity was expressed in conjunction with a bispecific adaptor molecule. In order to verify the targeting potential of the specific peptide, green fluorescent protein-expressing Ad vectors were coupled with the adaptor molecule and injected into the subventricular region of adult mice by stereotaxic surgery. An efficient and selective transduction of NSPC in the SVZ was achieved, whereas hippocampal NSPC were negative. Our results offer an expeditious and simple tool to produce target-specific viral vectors for selective and direct bioengineering of stem cells in situ. This powerful technique provides an excellent opportunity to gain new insight into the fundamental mechanisms that control stem cell fate and to develop innovative strategies for a successfull treatment of brain disorders.This work was supported by the German Research Foundation (DFG) grant PU 188/8-1, WR 20/2-1 and Research funding provided by the Medical Faculty of Rostock University (FORUN program).