progenitor cells (EPCs) play a significant role in the formation of both
embryonic and adult blood vessels. Fibrogenesis & Tissue Repair has just
published a review in which the authors discuss the current literature
concerning postnatal vasculogenesis – the process by which EPCs contribute to
new blood vessel formation in adults.
vasculogenesis consists of four inter-related steps, with the success of each
step depending on the ability of the EPCs to respond accordingly to various
molecular cues. The review by Francisco Caiado and Sérgio Dias focuses
on the importance of integrins in the regulation of EPCs and their contribution
to each of the four stages of postnatal vasculogenesis.
of four principle stages of postnatal vasculogenesis involves EPCs responding
to chemoattractant signals and moving from a stem cell niche within the bone
marrow to the peripheral blood. The homing of EPCs to sites of neoangiogenesis
constitutes the second stage of the process and the third step involves the
EPCs migrating to their required location. The final step sees EPCs differentiating
into mature endothelial cells and/or the upregulation of existing endothelial cells.
express 13 integrin subunits, with specific subunits being upregulated and
activated at each of the four stages of postnatal vasculogenesis. Integrins
play a key role in the regulation of EPC function through their interaction
with components of the extracellular matrix and cell surface proteins.
The authors conclude that “although there has been some success in
using EPCs as therapeutic agents (as shown by recent clinical trials), we
suggest that targeted and tissue-specific manipulation of EPC-integrin
interactions may be crucial to further improve the usage of this cell
population as a relevant clinical agent”.