Stem cells are undifferentiated basic units of life that have the potential either to differentiate into new cells with specialized functions or split to produce more stem cells. This is to say that a stem cell in its unspecialized form can be harvested to multiply into more stem cells or induced to become a specialized cell, such as the heart, the pancreas, etc. Kelly (2007) defined stem cells as “cells that have the capacity to self-renew as well as the ability to generate different cells.” He further stated in his book that stem cells can differentiate into many different types of cell that compose an organism, thus developing into mature cells that have different shapes and specialized functions such as heart, skin or nerve cells. Stem cells can divide and form many types of cells that compose an organism. The process of division and formation is referred to as ‘differentiation’.
Stem cells are known for several characteristics which are distinguished from other cells (specialized cells). First, stem cells have the ability to renew themselves through cell division or differentiation for a long period. Specialized cells such as muscle cells, blood cells and nerve cells can’t replicate themselves unlike stem cells that can proliferate into millions of cells over a long period. Secondly, stem cells can differentiate to form specialized cells such as tissue or specific organs in the body. Differentiation of cells occur in several stages of which may be triggered by signals inside and outside the cell. The internal signals are controlled by genes which spread across long strands of DNA and carry added instructions for all cellular structures and functions. While external signals include chemicals secreted by other cells, physical contact with other neighbouring cells and certain molecules called growth factor (Kelly, 2007). Finally, stem cells are unspecialized in the sense that it lacks tissue-specific structures that enable it perform specialized functions....