Stem cells in perspective

Abstract

The essence of a stem cell is that it is an unspecialized cell and therefore has the unique properties of retaining the ability to renew itself as well as being able to undergo multilineage differentiation. The transition between a stem cell and its progeny involves a number of steps with several intermediate cells known as transit amplifier cells which have a lesser ability to undergo self-renewal but are more likely to differentiate. Stem cells all give rise to differentiated cells. However, their degree of potency varies. In this study, an overview of the different types of cells is given, ranging from unipotent tototipotent cells. Each of the three main properties of stem cells is discussed in detail as are the different types of stem cells, namely embryonic, umbilical cord and adult stem cells. The new concept that adult stem cells are not lineage restricted is introduced, leading to adult stem cell plasticity. Finally, the stem cell niche has also been discussed.