New experimental observations often require fresh concepts for their
interpretation, and at times even changes of paradigms. This is the
situation with the recent realization that circulating endothelial
progenitor cells may have an important contribution to the maintenance
and formation of new endothelium in adult organisms, in a surprisingly
wide variety of situations. The classical paradigm of angiogenesis,
centered on the notion of "sprouting" can hardly accommodate them. It
was previously realized that it needs to be "stretched out" to include
alternative mechanisms of microvascular development, such as
intussusception and capillary fusion. However, a major debate where to
reconsider the sprouting mechanism, and to promote alternative views,
did not take place yet. The number of publications in this field
increased exponentially in the last years. Nevertheless, the concepts
and notions so much needed to describe and to explain the new
observations are still scarce, and heterogeneous. Within the larger
community dedicated to the study of angiogenesis, the researchers
involved in investigation of circulating precursor endothelial cells
biology represent a subgroup with specific preoccupations and opinions.
Many of them did not meet each other so far, and no major scientific
events have been dedicated before exclusively to their interests. For
the above reasons, the idea to organize a symposium addressing the new
developments in angiogenesis research was received with enthusiasm by
all those involved in its preparation.