The pivotal role of PDGF and its receptor isoforms in adipose-derived stem cells

Platelet-derived growth factor (PDGF) is one of the growth factors that reportedly regulates cell growth and division of mesenchymal cells. Although PDGF isoforms and their receptors reportedly play a pivotal role in mesenchymal stem cell regulation, there is a paucity of literature reviewing the role of PDGF in adipose-derived stem cells (ASCs). Therefore, we summarized previous reports on the expression and functional roles of PDGF and its receptor isoforms in this review. In addition, we examined findings pertaining to underlying molecular mechanisms and signaling pathways with special focus on PDGF-D/PDGFR beta. ASCs only express PDGF-A, -C, -D, PDGFR alpha, and PDGFR beta. PDGFRa expression decreases with adipocyte lineage, while PDGFR beta inhibits white adipocyte differentiation. In addition, PDGFR beta induces proliferation, migration, and angiogenesis and up-regulates the expression of paracrine factors in ASCs. Although PDGF-B and -D mediate their functions mainly by PDGFR beta and ROS generation, there are many differences between them in terms of regulating ASCs. PDGF-D is endogenous, generates ROS via the mitochondrial electron transport system, and regulates the autocrine loop of ASCs in vivo. Furthermore, PDGF-D has stronger mitogenic effects than PDGF-B.