Figure 3

Proposed models for the role of stem cells in development of inflammation. A) Production of inflammatory mediators during inflammation can increase the number of committed progenitor cells. B) Chemotactic mediators released during inflammation can provoke the recruitment of stem cells from the circulation to the site of inflammation where they undergo a rapid proliferation phase, followed by terminal differentiation into inflammatory cells (mast cells, dendritic cells, eosinophils, neutrophils, etc) at the site of the inflammatory reaction, contributing to development and chronicity of disease. C) Inflammatory mediators provoke the release of proteases (MMPs) by granulocytes or stem cells within the bone marrow, which cleave the molecular anchors of stem cells and increase their release in the circulation.