Gene Delivery To The Nervous System

National Institute Of Neurological Disorders And Stroke

Investigators

Linked publications, trials & patents

Abstract

1. The study on PGC1a expression in neural cells and its potential role in the regulation of cytoskeleton dynamics was temporarily put on hold. 2. For the study on the inhibition of Cdk5/p25 kinase hyperactivity during neurodegeneration, the following observations can be added: Cell supernatants from cells that express a transgene, which encodes a new chimeric, inhibitory peptide against Cdk5/p25 activity showed high peptide levels, clearly demonstrating efficient secretion of the peptide. In vitro assays using histone 1 phosphorylation confirmed that the peptide was functional, able to inhibit Cdk5/p25 kinase activity in vitro. As a control, cell supernatants containing a secreted, but scrambled peptide were only weakly inhibitory. Medium alone did not inhibit. Neural progenitor cells that were infected by a lentiviral vector, which encodes the inhibitory peptide, appeared unaffected by the expression, secretion and reuptake of this chimeric cell-penetrating peptide. Infected cells included neurons, glial cells and their precursor cells. These results confirmed the key functional properties of the vector-encoded peptide. Instead of infecting hematopoietic stem cells directly with the LV vector prior to transplantation into transgenic mouse models of neurodegenerative diseases such as the 5xFAD mouse (Alzheimers disease), we refined our experimental strategy to initially focus on the safety of the peptide and then on its therapeutic efficacy. Transgenic mice or other transgenic animal species will be created using high-titer LV vector co-expressing the peptide and EGFP. Normal development and behavior of these mice will indicate peptide safety. We anticipate that the peptide will be expressed, secreted, and it will penetrate many cell types. Potential inhibition of normal Cdk5/p35 activity during development could lead to perinatal lethality. Healthy transgenic mice will then be bred with mouse models of neurodegenerative diseases, with preference for the 5xFAD disease model, to demonstrate therapeutic efficacy of the peptide. If the peptide shows efficacy, EGFP and peptide expressing hematopoietic stem cells will be isolated from the initial transgenic mice and transplanted into ablated and conditioned 5xFAD mice to evaluate whether the transmigration of peptide-secreting monocytes to sites of injury and amyloid plaques is sufficient to ameliorate the disease. If successful, this delivery approach is scalable to human patients.