Stem Cells, Definition, Classification and Sources

The human body is made up of about 220 different kinds of specialized cells such as nerve cells, muscle cells, fat cells and skin cells. All specialized cells originate from stem cells. Stem cells are not specialized and the process of their specialization is called differentiation. Depending on the source, stem cells can be classified into two broad categories i.e. embryonic stem cells that are derived from embryos and non-embryonic stem cells that are derived from adult and fetal tissues. Induced pluripotent stem cells, another types of pluripotent stem cells derived from any tissue by reprogramming and are the homologous source of stem cells. Stem cells are emerging as an important source of material for diseases in regenerative medicine. The non-embryonic stem cells like adult stem cells are in clinical use for many years and embryonic stem cells are now emerging as an alternative source for the same purpose with huge potentials in drug discovery and toxicological studies. The study of biology of stem cells is the hallmark of the recent emerging field of regenerative medicine and medical biotechnology.

Keywords: Embryonic stem cells, adult stem cells, feeder fibroblast, differentiation, pluripotency, induced pluripotent stem cells.