Adult neurogenesis and cellular brain repair with neural progenitors, precursors and stem cells

Abstract

Recent work in neuroscience has shown that the adult central nervous system (CNS) contains neural progenitors, precursors and stem cells that are capable of generating new neurons, astrocytes and oligodendrocytes. While challenging the previous dogma that no new neurons are born in the adult mammalian CNS, these findings bring with them the future possibilities for development of novel neural repair strategies. The purpose of this review is to present the current knowledge about constitutively occurring adult mammalian neurogenesis, highlight the critical differences between 'neurogenic' and 'non-neurogenic' regions in the adult brain, and describe the cardinal features of two well-described neurogenic regions-the subventricular zone/olfactory bulb system and the dentate gyrus of the hippocampus. We also provide an overview of presently used models for studying neural precursors in vitro, mention some precursor transplantation models and emphasize that, in this rapidly growing field of neuroscience, one must be cautious with respect to a variety of methodological considerations for studying neural precursor cells both in vitro and in vivo. The possibility of repairing neural circuitry by manipulating neurogenesis is an intriguing one, and, therefore, we also review recent efforts to understand the conditions under which neurogenesis can be induced in non-neurogenic regions of the adult CNS. This work aims towards molecular and cellular manipulation of endogenous neural precursors in situ, without transplantation. We conclude this review with a discussion of what might be the function of newly generated neurons in the adult brain, and provide a summary of present thinking about the consequences of disturbed adult neurogenesis and the reaction of neurogenic regions to disease.

Neural stem cells: involvement in adult neurogenesis and CNS repair

“…activation of the endogenous regenerative capacity, is tightly associated with a phenomenon called 'adult neurogenesis' (reviewed by Sohur et al 2006). There is increasing evidence that neuronal cells are continuously produced in the adult mammalian brain under physiologic conditions, in the so-called adult neurogenic regions.…”

Introduction. The regenerating brain

“…In a complementary article, Sohur et al (2006) review neurogenesis in both the normal adult brain and also following injury. As they discuss, neurogenesis occurs normally in the adult brain, where it is well documented in the subventricular zone/olfactory bulb system and in the dentate gyrus of the hippocampus, and influenced by a number of physiological signals, but it is less clear whether significant neurogenesis occurs outside these two 'neurogenic' regions.…”

Human Embryo Neuronal Culture <i>in Vitro</i>: A Model to Study Cellular Physiology, Receptors, Power and Toxicity of Cytostatic Drugs for Human Use

“…The aim of the above mentioned researches was to obtain neural progenitors fit to integrate in vivo into a host tissue in order to replace damaged or absent neurons [3][4][5][6].…”