Figure 2.

Roles of SDF/CXCR4 axis in regulating inflammation during wound repair. Inflammation is one of the major molecular and cellular events at the early stage of wound healing. CXCR4-expressing neutrophils can be first recruited in response to injury signals to the wound bed, followed by monocytes and Leukocytes to reinforce the inflammatory reaction. During inflammation, immune cells aggregated at the wound site, which can not only fight against invading microorganisms, but also produce various growth factors, such as FGF to direct re-epithelialization, fibroblast reconstruction and ECM remodeling. In the middle proliferative phase of wound healing, autologous or allogeneic stem cells are mobilized and migrate into the wound site, where they proliferate, secret cytokines, and participate in various cellular events in response to activation of SDF/CXCR4 signaling, including angiogenesis, muscle regeneration, and collagen synthesis. At the final stage of wound healing, immune cells progressively disappear. The fibroblasts deposit new extracellular matrix, which is gradually remodeled to form scar tissues. Blocking SDF/CXCR4 axis may result in a reduction in collagen production, thereby alleviating tissue fibrosis at the wound site. ADSCs, adipose tissue-derived stem cells; MSCs, mesenchymal stem cells. NK Cells; Natural Killer Cells. Blue arrows showing the migration/homing of cells induced by the SDF-1/CXCR4 axis.