Altered Hippocampal Neurogenesis during the First 7 Days after a Fluid Percussion Traumatic Brain Injury

Traumatic brain injury (TBI) is a devastating disorder causing negative outcomes in millions of people each year. Despite the alarming number of brain injuries and the long-term detrimental outcomes that can be associated with TBI, treatment options are lacking. Extensive investigation is underway, in hopes of identifying effective treatment strategies. Among the most state-of-the-art strategies is cell replacement therapy. TBI is a seemingly good candidate for cell replacement studies because there is often loss of neurons. However, translation of this therapy has not yet been successful. It is possible that a better understanding of endogenous neurogenic mechanisms after TBI could lead to more efficacious study designs using exogenous cell replacement strategies. Therefore, this study was designed to examine the number and migration of immature neurons at 1 and 7 d after a fluid percussion TBI. The results show that the number of immature neurons increases from 7 d after a fluid percussion injury (FPI), and there is ectopic migration of doublecortin (DCX+) immature neurons into the hilar region of the dentate gyrus. These results add important data to the current understanding of the endogenous neurogenic niche after TBI. Follow-up studies are needed to better understand the functional significance of elevated neurogenesis and aberrant migration into the hilus.