STEM CELLS

Stem Cells



Stem Cells

Introduction

Stem cells are unique cells capable of differentiating into specialized cell types when required. Stem cells aid in the healing process of injuries by regenerating the lost areas of the body. Broken bones, ripped muscles, cut or scratched skin and other possible damages get covered with stem cells of the body. They regenerate forming into the specialized cells (muscle cells, bone cells, blood cells, skin cells, etc.) to make up for the loss. Stem cells get further categorized in terms of their sources; embryonic stem cells and adult stem cells. Embryonic stem cells gets derived from a four to five days old human embryo, which further divide and specialize to form different parts organs and other body structures. Adult stem cells, or somatic stem cells, found within different types of tissues. These remain in a dormant state for years until stimulated by a disease or injury (Imura & Kornblum, 2003).

Stem Cells

The brain is a complex organ. Until the end of 20 e century, it got considered as stable, with no mechanism for neuronal regeneration, which would vitiate the theory that the brain must be stable to be stored memories and thoughts at throughout life. From the 1960s through the sophisticated biology techniques cellular and molecular, several observations have followed and helped highlight what was once considered a heresy born neurons in the adult brain throughout life in mammals. Some of the questions related to neuron stem cell are:

What are the areas where neurogenesis occurs in its infancy and adulthood?

What are the cellular and molecular mechanisms that underlie the neurogenesis; what is the epigenetic determinism?

How to use these mechanisms to generate cells when needed; what are the possible therapeutic applications?

Discovery of the Existence of Stem Cells

The view that the adult brain is considered stable based on the difference of plasticity between the brain of a fetus and a child with that of an adult. It has long been that the brain of an adolescent child will reorganized according to external stimuli; and can regenerate more easily than adult brain, in case of injury. Studies have to easily view areas of divisions in the embryonic brain, or during the postnatal period, but it is rare to observe in the adult brain. In addition, the cells in a division that could be observed were considered, on morphological criteria, such as precursors of glial cells and not as neuronal cells (Nakano & Imura, 2006).

In 1965, Joseph Altman published an article in which he indicated had discovered the phenomenon of neurogenesis in the adult mammalian brain (Autoradiography and Histological evidence of postnatal hippocampal neurogenesis in rats). At that time, only the regeneration of astrocytic glial cells got considered possible, as evidenced by glial scars observed after brain injury. J. Altman, however, characterized, on morphological criteria, new cells identified as neurons (larger and clearer with conventional stains that glial cells). However, this argument was not considered concluding in a stable theory governed by the brain (Garcia & Doan, ...