Bone marrow–derived progenitor cells (BM-PC) bind directly to platelets (Plt) at sites of blood vessel injury.
Injured blood vessels are repaired in part by bone marrow (BM)-derived progenitor cells, which migrate to the afflicted vessel and differentiate into new vascular cells. The chemokine SDF-1 attracts these cells and is reportedly produced by dying smooth muscle cells (SMCs). But the timing didn't add up. Production of SDF-1 by SMCs requires at least six hours, whereas the recruitment of progenitor cells begins within minutes of vessel injury.
Massberg et al. now account for the short time lag by showing that platelets–not previously thought to release SDF-1–provide an early burst of the chemokine that helps reel in the first progenitor cells. In fact, although SMCs eventually produced...
