New Neurons in the Post-ischemic and Injured Brain: Migrating or Resident?

Abstract

The endogenous potential of adult neurogenesis is of particular interest for the development of new strategies for recovery after stroke and traumatic brain injury. These pathological conditions affect endogenous neurogenesis in two aspects. On the one hand, injury usually initiates the migration of neuronal precursors (NPCs) to the lesion area from the already existing, in physiological conditions, neurogenic niche – the ventricular-subventricular zone (V-SVZ) near the lateral ventricles. On the other hand, recent studies have convincingly demonstrated the local generation of new neurons near lesion areas in different brain locations. The striatum, cortex, and hippocampal CA1 region are considered to be locations of such new neurogenic zones in the damaged brain. This review focuses on the relative contribution of two types of NPCs of different origin, resident population in new neurogenic zones and cells migrating from the lateral ventricles, to post-stroke or post-traumatic enhancement of neurogenesis. The migratory pathways of NPCs have also been considered. In addition, the review highlights the advantages and limitations of different methodological approaches to the definition of NPC location and tracking of new neurons. In general, we suggest that despite the considerable number of studies, we still lack a comprehensive understanding of neurogenesis in the damaged brain. We believe that the advancement of methods for in vivo visualization and longitudinal observation of neurogenesis in the brain could fundamentally change the current situation in this field.

Pyridoxine Deficiency Exacerbates Neuronal Damage after Ischemia by Increasing Oxidative Stress and Reduces Proliferating Cells and Neuroblasts in the Gerbil Hippocampus

“…Interestingly, Nrf2 is one of the essential elements to regulate the hippocampal neurogenesis [ 51 ] and homocysteine reduced cell differentiation in chicken embryonic brain [ 52 ]. However, neurogenesis in the dentate gyrus is unlikely to be related to regeneration; rather, migrating neuroblasts from SVZ may contribute to regeneration [ 53 , 54 ]. Moreover, the initial increase in neurogenesis in the dentate gyrus may be accompanied by its significant decrease at a later stage after ischemia [ 7 ] due to the limited pool of stem cells in this region [ 55 ].…”

Differential roles of exogenous protein disulfide isomerase A3 on proliferating cell and neuroblast numbers in the normal and ischemic gerbils

“…There have been conflicting evidences about the source of new neurons in the CA1 region after ischemia and potentials to regenerate in the DG. A study demonstrates the source of new neurons in the hippocampal CA1 region comes from DG (Bendel et al, ), while other study shows limited information of their origins (Nemirovich‐Danchenko & Khodanovich, ) because of low ability for self‐renewal (Mignone, Peunova, & Enikolopov, ). In the SVZ of lateral ventricle, only 20%–30% cells are divided symmetrically and have self‐renewal activity in the niche for several months before generating neurons (Obernier et al, ), while asymmetric divisions are dominantly found in the progenitor cells of the DG (Encinas et al, ).…”

Glycyrrhizin Blocks the Detrimental Effects of HMGB1 on Cortical Neurogenesis after Traumatic Neuronal Injury

“…In contrast, increasing evidence demonstrates the existence of NSPCs at the site of cortical injury in in vivo animal models of TBI [ 13 , 47 , 48 ]). Whilst it is unclear whether these cells are resident or migrating, it raises the exciting prospect of neural repair in a condition as anatomically heterogeneous as TBI [ 49 ]. However, existing studies demonstrate that immature newborn neurons do not go on to survive in the injured brain [ 13 , 50 , 51 ].…”