Fig. 1

Proposed endothelial progenitor cell (EPC) involvement after burn injury. Burn insult and resulting hypoxia/ischemia lead to the upregulation of HIF-1α which promotes VEGF and SDF-1α secretion as well as increased CXCR4 expression on EPCs. VEGF is primarily responsible for the proliferation of hematopoietic EPCs (local tissue environment/blood stream) and non-hematopoietic EPCs (bone marrow) while SDF-1α promotes transendothelial migration into the bloodstream and soft tissue as well as adhesion at the site of tissue injury. Hematopoietic EPCs contribute to burn injury through direct attachment, maturation to endothelial cells and the formation of new vascular tissue, while non-hematopoietic indirectly aid in this formation through the secretion of various cytokines