The neural stem and progenitor cells (NSCs and NPCs, respectively) found in the subventricular zone (SVZ) of the brain have the potential to replace damaged neuronal populations due to their ability to renew through cell division. These cells are therefore interesting targets for therapeutic manipulation in treatment of neurodegenerative diseases. Although the generation of new neurons from the SVZ occurs naturally, it is clear that in order to achieve therapeutically-relevant levels of neurogenesis, mechanisms such as localized delivery of growth factors to increase differentiation, migration and survival of new neurons from stem cell zones is required. The goal of this work is to develop a synthetic, biocompatible vector for efficient gene delivery to NPCs in the SVZ. The polymeric vector will incorporate multiple bioactive peptides to assist in NPC targeting and intracellular trafficking. Specifically, the peptide-functionalized polymer will include: (i) bioactive peptides for DNA condensation, cell targeting and endosomal escape, (ii) HPMA (N-(2- hydroxypropyl)methacrylamide) backbone for biocompatibility (iii) polyethylene glycol (PEG) for particle stabilization, and (iv) disulfide bonds for degradation after cellular internalization. The polymer composition will be optimized for high efficiency gene delivery to NPCs through in vitro transfection screening, and the mechanism of delivery investigated through flow cytometry, confocal microscopy and FRET analyses. In addition, the plasmid vector will be engineered for sustained transgene expression in NPCs that shuts down after the NPCs differentiate into mature neurons. The most promising vectors will be evaluated by intraventricular administration to mice in order to further optimize vectors for efficient in vivo delivery. The distribution of dual-labeled (plasmid and polymer) vectors after administration will be imaged by confocal microscopy of brain sections. In addition, the type of cells expressing the delivered transgene at various time points after transfection will be determined by fluorescent antibody staining of brain sections. Finally, the efficiency of in vivo gene transfer will be further enhanced by amplifying the number of dividing cells through localized growth factor delivery and by promoting neuron migration and survival by delivery of the BDNF (brain- derived neurotrophic factor) plasmid. If successful, the potential impact of this project is broad. The developed vectors could be used as vehicles to deliver therapeutic genes for treatment of neurogenerative CNS disorders.
Neurogenerative diseases of the brain, such as Alzheimer's Disease, Huntington's Disease, and Parkinson's Disease, affect over 20 million people worldwide, and most current treatments for these diseases are palliative rather than restorative. One promising treatment approach to neurodegenerative disorders is the manipulation of neural stem and progenitor cells in the adult human nervous system to restore lost neuronal populations. The goal of this work is to develop synthetic gene delivery vectors that can be used to specifically deliver growth factors to neural progenitor cells in the brain in order to stimulate neurogenesis. The proposed approach involves incorporating bioactive peptides in the polymeric vector to promote targeting to the neural progenitor cells and efficient intracellular delivery. The developed technology would have broad significance as vehicles to deliver therapeutic genes for CNS disorders.
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