Stem cells are responsible for tissue or organ formation during prenatal life, and also for further growth. They are also responsible for repairing and regeneration of internal body system. This internal replenishing system works continuously throughout our life span. These cells display important attributes, which distinguishes them from normal cells. The cell division of stem cell gives rise to new stem cell or turned into specialized cell with definite function such as a muscle cell, a red blood cell, or a brain cell. In vivo or in vitro stimuli activate these cells to acquire special functions by becoming part of tissue- or organ-specific cells. Stem cells in the gut and bone marrow are at continuous task to repair and replace injured or eroded tissues, and therefore they multiply regularly by a process of cell division. In the organs like the pancreas and the heart, they are generated under certain physiologic conditions (http://stemcells.nih.gov/info/basics/basics4.asp). The major breakthroughs in stem cell research will able to figure out clearly the development of an organism from a single cell. The most of the work is reported on two types of stem cells embryonic stem cells and non-embryonic stem cells. There is a recent introduction of genetically "reprogrammed" stem cell termed as induced pluripotent stem cells (iPSCs) in 2006. Stem cell therapy is administered through local delivery or systemic infusion, of autologous or allogeneic cells. This aids in restoring the viability or functioning of damaged and malfunctioned tissues (Lu, Zhang & Jin, 2009).
Non-embryonic stem cells are also called as ‘adult stem cells’. They are undifferentiated cells, found throughout the body of animals and humans in differentiated tissue or organ after the embryonic growth. They are also termed as somatic stem cells which are responsible for building different specialized cell types. These cells play pivotal