Principles of Regenerative Biology – Bruce M. Carlson

Principles of Regenerative Biology

Regeneration is one of the most fascinating phenomena in biology, but it is also one of the most complex. Virtually all species, from protozoa to humans, have the capacity to regenerate, but the extent of their regenerative ability varies greatly. Planaria, starfish and some worms can regenerate most of their body, whereas many other species are able to regenerate only parts of specifi c tissues. Among the vertebrates, urodele amphibians are the best adapted for regeneration; they can regenerate limbs, tails, jaws, eyes and a variety of internal structures.
For much of the twentieth century, mammals, including humans, were considered to have a poor capacity for regeneration. This was particularly true up to the late 1950s, when I fi rst began to explore the literature on regeneration. A research visit to the Soviet Union during 1965–1966 exposed me to many new ways of looking at mammalian regeneration. Perhaps the most striking to me was the emphasis on uslovie (“conditions”) of regeneration that abounded in the Russian regeneration literature of the 1960s. The essence of this concept was that the success of regeneration often is a function of the environment in which the regenerative process is taking place. I was initially
inclined to attribute this emphasis to the waning infl uence of Lysenkoism, which still permeated the Russian biology of the time. This element was certainly present, but during my several decades of research on regeneration since that time, I have come to appreciate how important the environment is in supporting or failing to support regenerative processes in mammals.
With the explosion of knowledge from molecular biology and the burgeoning interest in generating or regenerating tissues or organs through various tissue engineering or stem cell approaches, many scientists and students have shown a renewed interest in the phenomenon of regeneration. Because relatively few have had the luxury of being able to approach the phenomenon of regeneration from a broad biologic perspective, I thought that it would be useful to write a short book that outlines some of the fundamental biologic principles of regeneration. As the book has evolved, the contents have focused principally on regeneration in vertebrate systems, but when certain points are best illustrated by examples taken from the very diverse universe of invertebrate regeneration, they are included, as well. In order to manipulate regenerative processes, it is important to understand the underlying principles of regeneration. Laying these out is what this book is all about.