” The dominant strategy for repairing a broken, injured, or damaged brain was to replace the lost neurotransmitters (for example, providing L-dopa for Parkinson’s disease [PD], which works pretty well for a while) or, more experimentally, to replace the missing or dead neurons (as in neural

transplantation for treating Inhibitors,research,lifescience,medical PD, Huntington’s disease [HD], Alzheimer’s disease, amyotrophic lateral sclerosis, or spinal cord injury). The replacement of dead cells by transplantation of externally derived cells continues both experimentally and clinically and, with the new hope provided by the Wortmannin order availability (albeit limited) of the pluripotent human embryonic stem cells, Inhibitors,research,lifescience,medical optimism for transplantation therapy has been renewed. The previously accepted dogma of adult neural stability is now being called into question. Pioneering studies by Raisman,3

Bjorklund;’ and Aguayo5 and their colleagues in the 1960s and 1970s revealed that damaged axons could grow under some extraordinary circumstances. These studies have led to a recent stampede of very promising work that could lead to the regeneration of cut or damaged axons due to spinal cord injury.6 A deeper blow to the dogma of adult neural stability has been the recent acceptance of the ability Inhibitors,research,lifescience,medical of certain areas of the adult brain to generate new neurons throughout life, known as adult Inhibitors,research,lifescience,medical neurogenesis. Early evidence of this ability was generated by Altman and colleagues in the 1960s and 1970s,7 and was beautifully extended to birds by Goldman and Nottebohm in the 1980s,8 and later to nonhuman primates and humans in the 1990s.9 During this same period, it was discovered that adult neurogenesis itself was not stable and

predictable, but was, in fact, highly regulated by experience, with stress and aging decreasing neurogenesis and environmental enrichment and Inhibitors,research,lifescience,medical exercise increasing neurogenesis. Stem cells in the adult brain The surprising observation that neurogenesis continues in the adult nervous system has led to the discovery that there are stem cells in the adult brain that generate the new neurons. A stem cell is an uncommitted cell that, when it divides, can give rise to itself (self-renewal) and can also Oxalosuccinic acid give rise to any or all of the three main cell lineages of the brain: neurons, astrocytes, and oligodendrocytes. Using a variety of methods, it is now possible to isolate these stem cells from the adult brain and use specific growth factors, like fibroblast growth factor (FGF) and epidermal growth factor (EGF), to induce them to divide indefinitely in culture dishes in the laboratory. .Most of the studies that have determined that the cells from the brain are stem cells have done so by studying the cells in vitro; the demonstration of “sternness” in vivo in the adult brain is difficult.