Introduction

The term “stem cell” was originally used in the nineteenth century by embryologists to describe germ-line cells, that is, those that give rise to eggs and sperm. The first modern reference to stem cells came from scientists in the early 1960s when evidence was found of continuous cellular activity during neurogenesis in the brain. However, it was the hematologists Till and McCulloch who, in 1961, laid the foundations for future technological and conceptual advances in the field by demonstrating the presence of stem cells in the bone marrow [1]. Since then, and especially in the last 15 years, stem cell research has expanded exponentially.

Simply put, the driving force for the considerable interest in stem cells is the prospect that they represent a totally new approach to medicine in the twenty-first century. In particular, most excitement has been generated around the idea that stem cells can provide a limitless supply of tissue cell types for what is generally referred to as regenerative medicine, whether this be in the context of treatment of traumatic tissue damage or alleviation of the consequences of cellular loss brought about by disease or the result of ageing. However, there is more to the clinical application of stem cell biology knowledge than an off-the-shelf supply of large numbers of tissue cells. Hence, our ever-increasing understanding of stem cell biology is also likely to provide clues as to ways in which we might either influence the body’s own cellular replacement mechanisms for therapeutic benefit, for example, following severe ischemic damage in the brain or the heart, or overcome deficits in stem cell function that contribute partly or wholly to ageing in tissues such as muscle. Moreover, cancer has been shown to be underpinned by cells that have acquired aberrant stem cell-like properties, and it may prove possible to target these as a way of curtailing the development or progression of the disease.