Neuroregeneration: Regulation in Neurodegenerative Diseases and Aging.

It had been commonly believed for a long time, that once established, degeneration of the central nervous system (CNS) is irreparable, and that adult person merely cannot restore dead or injured neurons. The existence of stem cells (SCs) in the mature brain, an organ with minimal regenerative ability, had been ignored for many years. Currently accepted that specific structures of the adult brain contain neural SCs (NSCs) that can self-renew and generate terminally differentiated brain cells, including neurons and glia. However, their contribution to the regulation of brain activity and brain regeneration in natural aging and pathology is still a subject of ongoing studies. Since the 1970s, when Fuad Lechin suggested the existence of repair mechanisms in the brain, new exhilarating data from scientists around the world have expanded our knowledge on the mechanisms implicated in the generation of various cell phenotypes supporting the brain, regulation of brain activity by these newly generated cells, and participation of SCs in brain homeostasis and regeneration. The prospects of the SC research are truthfully infinite and hitherto challenging to forecast. Once researchers resolve the issues regarding SC expansion and maintenance, the implementation of the SC-based platform could help to treat tissues and organs impaired or damaged in many devastating human diseases. Over the past 10 years, the number of studies on SCs has increased exponentially, and we have already become witnesses of crucial discoveries in SC biology. Comprehension of the mechanisms of neurogenesis regulation is essential for the development of new therapeutic approaches for currently incurable neurodegenerative diseases and neuroblastomas. In this review, we present the latest achievements in this fast-moving field and discuss essential aspects of NSC biology, including SC regulation by hormones, neurotransmitters, and transcription factors, along with the achievements of genetic and chemical reprogramming for the safe use of SCs in vitro and in vivo.