Major advances in Neurobiology have shown that the central nervous system can regenerate and repair itself in response to cell damage due to ischemia and trauma, yet these innate recovery mechanisms remain limited and poorly understood. Recently, endogenous cell proliferation has been recognized as a mechanism to replenish lost neurons following injury, and that this phenomenon is age-dependent being much more pronounced in juvenile and young animals than elderly. Traumatic brain injury (TBI) is the major cause of death and disability in persons under the age of 45. Over 5.3 million Americans currently live with disabilities due to TBI, ranging from cognitive impairment to vegatative state. Studies have shown that endogenous cells from the subventricular zone and the hippocampal subgranular zone constantly generate new neurons throughout life, and that this process is enhanced after injury. Moreover, we and others have shown that newly-generated hippocampal dentate granular neurons can integrate and form synaptic connections to the existing hippocampal circuitry. We have also shown that this injury-enhanced endogenous neurogenic response is associated with the expression levels of several trophic factors following TBI. We have further shown that administration of exogenous trophic factors can not only enhance neurogenesis but also greatly improve recovery of cognitive function in adult animals following injury. In this proposal, we will specifically investigate how the endogenous neurogenic capacity of the brain can be enhanced to repair damaged neuronal circuitry. We will first examine the extent to which the newly- generated neurons establish connections to their target and communicate with neighboring cells through synaptic connections;Secondly, to further explore the effect of trophic factors on neurogenesis and functional recovery, we plan to assess expression levels of a broad spectrum of growth factors in the hippocampus following TBI in juvenile, adult and aged animals using antibody array methods. Thirdly, we will then utilize this information to manipulate endogenous neurogenesis and test the extent to which cognitive recovery in the adult and elderly brain following TBI can be improved by administering trophic factors that promote neurogenesis. Collectively, these studies will provide the mechanistic underpinning for rational construction of clinical trials on trophic factor administatrion for severely head injured patients who have sustained hippocampal damage - one of the most common patterns of cognitive impairment in this common, and currently untreatable condition.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
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Clinical Neuroscience and Disease Study Section (CND)
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Owens, David F
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Virginia Commonwealth University
Schools of Medicine
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Sun, Dong (2016) Endogenous neurogenic cell response in the mature mammalian brain following traumatic injury. Exp Neurol 275 Pt 3:405-410
Patel, Kaushal; Sun, Dong (2016) Strategies targeting endogenous neurogenic cell response to improve recovery following traumatic brain injury. Brain Res 1640:104-113
Sun, Dong; Daniels, Teresa E; Rolfe, Andrew et al. (2015) Inhibition of injury-induced cell proliferation in the dentate gyrus of the hippocampus impairs spontaneous cognitive recovery after traumatic brain injury. J Neurotrauma 32:495-505
McGinn, Melissa J; Colello, Raymond J; Sun, Dong (2012) Age-related proteomic changes in the subventricular zone and their association with neural stem/progenitor cell proliferation. J Neurosci Res 90:1159-68
Sun, Dong; Gugliotta, Marinella; Rolfe, Andrew et al. (2011) Sustained survival and maturation of adult neural stem/progenitor cells after transplantation into the injured brain. J Neurotrauma 28:961-72
Richardson, R Mark; Singh, Amanpreet; Sun, Dong et al. (2010) Stem cell biology in traumatic brain injury: effects of injury and strategies for repair. J Neurosurg 112:1125-38
Sun, Dong; Bullock, M Ross; Altememi, Nabil et al. (2010) The effect of epidermal growth factor in the injured brain after trauma in rats. J Neurotrauma 27:923-38
Reid, Wendy Murdock; Rolfe, Andrew; Register, David et al. (2010) Strain-related differences after experimental traumatic brain injury in rats. J Neurotrauma 27:1243-53
Sun, Dong; Bullock, M Ross; McGinn, Melissa J et al. (2009) Basic fibroblast growth factor-enhanced neurogenesis contributes to cognitive recovery in rats following traumatic brain injury. Exp Neurol 216:56-65