Platelet derived growth factor (PDGF) is part of the PDGF/VEGR family. As the name suggests it is produced by platelets, and by several other cell types including endothelial cells, fibroblasts, vascular smooth muscle cells, osteoblasts, glia and neurons.4 In platelets, PDGF is stored in α-granules, and released in response to platelet activation, leading to stimulation of epithelial cells.
PDGFs are dimers of PDGF-A, -B, -C or -D polypeptide chains, arranged in homodimers (eg PDGF-AA and PDGF-BB) or heterodimers (eg PDGF-AB). There are two receptors for PDGFs, PDGFR-α and PDGFR-β. PDGFR-α is a receptor for all PDGF dimers apart from PDGF-DD, while PDGFR-β is a receptor for PDGF-BB and PDGF-DD.5 Activation of these receptors by PDGF leads to activation of downstream signalling pathways including PI3K, MAPK and STAT3 pathways.6 PDGF plays an important role in embryonic development, cell proliferation, cell migration and angiogenesis. PDGF is a potent mitogen for cells of mesenchymal origin such as fibroblasts, glial cells and vascular smooth muscle cells.