Stem cells

esearch into the role of stem cells in mammalian physiology has
burgeoned over the past 20 years. Indeed, in 2007 Martin Evans,
Mario Capecchi and Oliver Smithies were recognised for their
rpioneering contributions to stem-cell research by being award the
Nobel Prize for Medicine. It is therefore timely to present this Nature Reviews
collection on stem cells — a selection of recent Reviews and Perspectives speci
chosen to provide an introduction to diverse aspects of stem cell research.
It is now over half a century since bone-marrow reconstitution experiments,
first indicated the existence of the haematopoietic stem cell (HSC). Its discover
awakened the field of stem-cell biology. In a Review on page S5, Anne Wilson a
Andreas Trumpp describe the recent progress in understanding the HSC bone
marrow microenvironment, known as the HSC niche. Such understanding will
allow expansion of HSCs for therapeutic use.
An important question being addressed by the stem-cell community is how
do stem cells age and how does this contribute to mammalian ageing? On pag
S19, Norman Sharpless and Ron DePinho discuss how certain stem cells obta
decreased regenerative capacity with advancing age, and how this has a role i
human age-related conditions such as frailty, atherosclerosis and type II diabe
Another disease in which stem cells are hypothesised to have a key role, is
cancer. Cancer stem cells are thought to maintain the growth of the tumour,
and the role of stem cells in brain tumours is the focus of the Review by Angelo
Vescovi, Rossella Galli and Brent Reynolds on page S30. Understanding the
cellular and genetic mechanisms that control adult neurogenesis and brain
tumorigenesis should enable the development of new therapeutic strategies.
Finally, in a Perspective article on page S42 Shin-Ichi Nishikawa, Lars Marti
Jakt and Takumi Era discuss the technical challenge of studying early processe
mammalian embryogenesis — an essential area of study for further elucidatio
of the molecular mechanisms that govern stem-cell fate and the identification
specific stem-cell markers.