Project Summary

Every year, traumatic brain injury, stroke and neurodegenerative disease collectively cost the Canadian medical system millions of dollars, and effective neural regenerative therapies remain elusive. Astrogliosis, a cellular response common to such neural insults, leads to the formation of a non-functional “glial scar” and an inhibitory cellular environment that impedes neural regeneration and further recovery. Our proposed project involves engineering microglia, the mobile immune cells of the brain, to package and deliver a therapeutic plasmid DNA construct specifically to the reactive astrocytes that comprise these glial scars. The plasmids will contain a reprogramming factor that converts reactive astrocytes into new neurons, helping to both restore the functional neuronal population and permit regrowth of damaged connections. Our specific objectives include:

1. Generate microglial cells that package plasmids into exosomes and secrete them at regions of neural damage.
2. Use these engineered microglia to target stable plasmid DNA copies of the reprogramming factor gene NeuroD1 to regions of astrogliosis in a cell culture model of Traumatic Brain Injury. NeuroD1 will be selectively expressed in reactive astrocytes, thereby directly converting obstructive glial scars to neurons (replacing at least some of those lost to damage or disease) and reducing the inhibitory environment produced by the reactive astrocytes.
3. Design a novel antibiotic-free plasmid selection system that will allow generation of the NeuroD1-carrying plasmids while avoiding the introduction of antibiotic-resistance coding genes into human cells. Our proposed system will also minimize the size of our plasmid for ease of exosomal packaging.

Altogether, this study provides a novel, tissue-specific, personalized, non-immunogenic, non-invasive neural rehabilitative therapy that has the potential to significantly improve current methods of stimulating functional recovery following brain injury or disease onset. The long-term objective of this proposal is to significantly improve current neural regeneration therapies in an effort to overcome the rehabilitative obstacles associated with CNS insults such as stroke, Alzheimer’s Disease, and traumatic brain injury in a non-invasive, cost-effective manner. Furthermore, with future discoveries of other novel tissue-specific tags coupled with targeted DNA transmission therapies such as that discussed in this study, this system can potentially be harnessed to combat other tissue-specific disorders.

Sponsors