Jung-Kyu Han1, Back-Kyung Kim2, Joo-Yun Won2, Youngchul Shin1, Saet-Byeol Choi1, Injoo Hwang1, Jeehoon Kang1, Ho-Jae Lee2, Seok-Jin Koh2, Jaewon Lee2, Jin Hur2, Hyun-Jai Cho1, In-Ho Chae1, Byung-Hee Oh1, Young-Bae Park1, Hyo-Soo Kim3. 1. National Research Laboratory for Cardiovascular Stem Cell Niche, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea. 2. National Research Laboratory for Cardiovascular Stem Cell Niche, Seoul National University College of Medicine, Seoul, Republic of Korea. 3. National Research Laboratory for Cardiovascular Stem Cell Niche, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea; Molecular Medicine & Biopharmaceutical Sciences, Seoul National University, Seoul, Republic of Korea. Electronic address: hyosoo@snu.ac.kr.
Abstract
BACKGROUND: Peroxisome proliferator-activated receptor (PPAR)-δ is a nuclear receptor regulating cell metabolism. The role of PPAR-δ in late endothelial progenitor cells (EPCs) has not been fully elucidated. We aim to understand the effects of PPAR-δ activation on late EPC and to reveal the underlying mechanism. METHODS AND RESULTS: Treatment with a highly selective PPAR-δ agonist (GW501516) induced proliferation of late EPCs and enhanced their vasculogenic potential. Search for the target molecule of PPAR-δ activation revealed endothelial differentiation gene (Edg)-2. Chromatin immunoprecipitation and promoter assays demonstrated that Edg-2 gene was specifically induced by PPAR-δ through direct transcriptional activation. Lysophosphatidic acid (LPA), an Edg ligand, mimicked the pro-vasculogenic effects of GW501516 in late EPCs whereas Edg antagonist (Ki16425) blocked these effects. Edg-2 is a membrane receptor for LPA which is a major growth factor from activated platelets. Thus, the interaction between platelets and late EPCs via the LPA-Edg-2 axis was assessed. Platelet supernatant boosted the pro-vasculogenic effects of GW501516, which was reversed by antagonist to PPAR-δ (GSK0660) or Edg (Ki16425). Both of in vivo Matrigel plug model and mouse skin punch-wound model demonstrated that the combination of platelets and PPAR-δ-activated late EPCs synergistically enhanced vascular regeneration. CONCLUSIONS: There exists a synergistic interaction between human platelets and late EPCs leading to vascular regeneration. This interaction consists of LPA from platelets and its receptor Edg-2 on the surface of EPCs and can be potentiated by PPAR-δ activation in EPCs. A PPAR-δ agonist is a good candidate to achieve vasculogenesis for ischemic vascular disease.
BACKGROUND: Peroxisome proliferator-activated receptor (PPAR)-δ is a nuclear receptor regulating cell metabolism. The role of PPAR-δ in late endothelial progenitor cells (EPCs) has not been fully elucidated. We aim to understand the effects of PPAR-δ activation on late EPC and to reveal the underlying mechanism. METHODS AND RESULTS: Treatment with a highly selective PPAR-δ agonist (GW501516) induced proliferation of late EPCs and enhanced their vasculogenic potential. Search for the target molecule of PPAR-δ activation revealed endothelial differentiation gene (Edg)-2. Chromatin immunoprecipitation and promoter assays demonstrated that Edg-2 gene was specifically induced by PPAR-δ through direct transcriptional activation. Lysophosphatidic acid (LPA), an Edg ligand, mimicked the pro-vasculogenic effects of GW501516 in late EPCs whereas Edg antagonist (Ki16425) blocked these effects. Edg-2 is a membrane receptor for LPA which is a major growth factor from activated platelets. Thus, the interaction between platelets and late EPCs via the LPA-Edg-2 axis was assessed. Platelet supernatant boosted the pro-vasculogenic effects of GW501516, which was reversed by antagonist to PPAR-δ (GSK0660) or Edg (Ki16425). Both of in vivo Matrigel plug model and mouse skin punch-wound model demonstrated that the combination of platelets and PPAR-δ-activated late EPCs synergistically enhanced vascular regeneration. CONCLUSIONS: There exists a synergistic interaction between human platelets and late EPCs leading to vascular regeneration. This interaction consists of LPA from platelets and its receptor Edg-2 on the surface of EPCs and can be potentiated by PPAR-δ activation in EPCs. A PPAR-δ agonist is a good candidate to achieve vasculogenesis for ischemic vascular disease.