New Developments in Stem Cell Biotechnology

The subject of stem cells has attracted a great deal of interest in the public during the last twelve years. Indeed it brings about the hope of a novel medicine through which cells in the adult organism that are deficient or subjected to massive death could be replaced by healthy ones. With the increase in longevity in industrialized countries, such instances, resulting from degenerative diseases, are more and more common. This regenerative medicine would complement therapeutics relying on surgery, chemistry and antibodies, which are one of the most important legacies of the 20th century. During the last four decades it has been recognized that stem cells are present in virtually all tissues in adult vertebrates and are a source of youth, since their role is to replace cells which regularly die during the lifetime of the individual. Moreover, vertebrate embryos are entirely made up of stem cells at the early stages of their development. This pluripotent state of embryonic cells is transitory, but can be captured thanks to the spectacular advances in the biotechnologies during the last decades. It is now possible to maintain this particular stemness state in culture, thus generating permanent cell lines, endowed with the properties of this pivotal and intriguing type of cells. The term stem cell can be found in the scientific literature of the first half of the 20th century. However, its definition was not clear until it was based on rigorous experimental criteria. This was achieved in the 1960s thanks to a series of studies that demonstrated the mechanisms through which the replacement of blood cells, whose normal lifespan is short, takes place. In this article I will review the seminal work that has led to the scientific definition of a stem cell and then go through the successive breakthroughs that have stood out as landmarks in the field over the years and have led to the state of the art of today.