DIRECT ASTROCYTE TO NEURON REPROGRAMMING FOR FUNCTIONAL REPAIR IN INTRACRANIAL HEMORRHAGE MOUSE MODEL

Open Access
Author:
Huang, Pengqian
Area of Honors:
Biology
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Gong Chen, Thesis Supervisor
  • Bernhard Luscher, Honors Advisor
Keywords:
  • ICH
  • collagenase
  • stroke
  • neuronal loss
  • direct conversion
  • NeuroD1
  • Hippocampus
  • Striatum
  • astrocytes
  • neuronal recovery
Abstract:
According to the American Stroke Association, hemorrhagic stroke accounts for about fifteen percent of all strokes and causes more than thirty percent of mortality of all stroke incidents. In an ongoing experiment in our lab, expressing a specific transcription factor, NeuroD1, in the region of the brain affected by stroke has been shown to create new neurons and decrease astrocytic reactivity in an intracerebral ischemic injury mouse mode. Therefore, a similar approach was attempted in an intracerebral hemorrhage (ICH) mouse model to convert reactive astrocytes to functional neurons and to repair the damaged neuronal circuit. In this investigation, a focal ICH mouse model was established by injecting bacterial collagenase IV into the hippocampus and striatum area of the mouse’s brain. Following the injury, a viral vector encoding a single transcription factor, NeuroD1 (ND1) was injected at the injury core, using an adeno-associated virus carrier. We found that collagenase injection can cause a focal hemorrhage in mouse brain and the initial hemorrhage leads to severe secondary injuries including massive tissue and neuronal loss. Additionally, we also found that following ND1 injection new neurons were present around the injury core 17 days post-viral injection (dpi) in hippocampus and striatum. Additionally, signals for the immunoreactivity markers GFAP and Iba1 representative of activated astrocytes and microglia, respectively, and the brain infarct volume/glial scar were reduced in the treatment group compared to the control group. Our experiments show that NeuroD1 is able to rescue neuronal loss in the hippocampus and the striatum and improve the brain environment after induced ICH using Collagenase IV.