title: Telmisartan induces proliferation of human endothelial progenitor cells via PPARgamma-dependent PI3K/Akt pathway.
abstract: OBJECTIVE
  Although recent clinical trials have suggested that angiotensin II type 1 receptor blockers (ARBs) reduced cardiovascular events, the precise mechanisms involved are still unknown. Telmisartan, an ARB, has recently been identified as a ligand of peroxisome proliferator-activated receptor-gamma (PPARgamma). On the other hand, since endothelial progenitor cells (EPCs) are thought to play a critical role in ischemic diseases, we investigated effects of telmisartan on proliferation of EPCs.
  
  
  RESULTS
  Human peripheral blood mononuclear cells were isolated from healthy volunteers, and cultured on fibronectin-coated dishes in the presence or absence of telmisartan. Four days after starting culture, adherent cells were collected, and equal numbers of cells were reseeded into methylcellulose medium with or without telmisartan. In the presence of telmisartan, numbers of colonies increased in a dose-dependent manner. DiI-AcLDL uptake and lectin and CD31, CD34 staining revealed that these colonies were EPCs. Increase in colony number by treatment with telmisartan was absolutely inhibited when cultured with a specific inhibitor of PPARgamma. In addition, we observed that specific inhibitors of phosphoinositide-3 kinase (PI3K) abolished telmisartan-stimulated increase of monocytic EPC-like cells and telmisartan induced phosphorylation of Akt. Furthermore, mRNA expression of p21 was downregulated in a dose dependent manner, suggesting that growth inductive effects of telmisartan might be regulated by the PI3K/Akt and p21 signaling pathway.
  
  
  CONCLUSIONS
  These findings suggest that telmisartan might contribute to endothelial integrity and vasculogenesis in ischemic regions by increasing numbers of EPCs.
authors.affiliation: Department of Cardiology, Tokyo Women's Medical University, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Honda
authors.forename: Katsuhisa
authors.initials: K
authors.lastname: Matsuura
authors.forename: Noritoshi
authors.initials: N
authors.lastname: Fukushima
authors.forename: Yukio
authors.initials: Y
authors.lastname: Tsurumi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kasanuki
authors.forename: Nobuhisa
authors.initials: N
authors.lastname: Hagiwara
mesh_terms: D000328:Adult; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology*; D001562:Benzimidazoles / Q000494:pharmacology*; D001565:Benzoates / Q000494:pharmacology*; D049109:Cell Proliferation; D016922:Cellular Senescence; D042783:Endothelial Cells / Q000166:cytology*; D006801:Humans; D007511:Ischemia / Q000473:pathology; D007963:Leukocytes, Mononuclear / Q000166:cytology; D008024:Ligands; D008297:Male; D047495:PPAR gamma / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D013234:Stem Cells / Q000166:cytology*; D000077333:Telmisartan
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D001562:Benzimidazoles; D001565:Benzoates; D008024:Ligands; D047495:PPAR gamma; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D000077333:Telmisartan