title: TLR2-deficiency of cKit+ bone marrow cells is associated with augmented potency to stimulate angiogenic processes.
abstract: OBJECTIVE
  Toll-like receptor 2 (TLR2)-deficiency is associated with the preservation of vascular function and TLR2-deficient (TLR2(-/-)) mice exhibit increased neovascularization following induction of hindlimb ischemia. Hematopoietic stem cells play an important role in ischemia-induced angiogenesis and we now investigated whether the effects observed in TLR2(-/-) mice may be attributed to TLR2 deficiency on bone marrow-derived stem cells.
  
  
  RESULTS
  cKit-positive (cKit(+)) bone marrow cells (BMC) were isolated from wild type (WT) and TLR2(-/-) mice employing MACS-bead technology. Co-incubation of TLR2(-/-)cKit(+) BMC with mature endothelial cells (ECs) resulted in increased tube formation of ECs on matrigel, augmented sprouting in a 3D-collagen matrix and increased migratory capacity compared to co-incubation with WT cKit(+) BMC. In an in vivo matrigel plug assay, TLR2(-/-)cKit(+) BMC exhibited enhanced formation of capillary-like networks. In a murine model of hindlimb ischemia, administration of TLR2(-/-) cKit(+) BMC to WT mice augmented capillary density and reperfusion of ischemic M. gastrocnemius muscle tissue to the level of TLR2(-/-) mice. Western Blot analysis revealed comparable expression of CXCR4 on TLR2(-/-)cKit(+) BMC but increased activation of the PI3K downstream signaling molecule protein kinase B (PKB/AKT) compared to WT cKit(+) cells.
  
  
  CONCLUSIONS
  The absence of TLR2 on cKit(+) BMC is associated with augmented potency to support angiogenic processes in vitro and in vivo. Functional inhibition of TLR2 may therefore provide a novel tool to enhance stem cell function for the treatment of vascular diseases.
authors.affiliation: Clinic for Anesthesiology and Critical Care Medicine, University Hospital Rostock Rostock, Germany.
authors.forename: Nana-Maria
authors.initials: NM
authors.lastname: Wagner
authors.forename: Laura
authors.initials: L
authors.lastname: Bierhansl
authors.forename: Antje
authors.initials: A
authors.lastname: Butschkau
authors.forename: Gabriele
authors.initials: G
authors.lastname: Noeldge-Schomburg
authors.forename: Jan Patrick
authors.initials: JP
authors.lastname: Roesner
authors.forename: Brigitte
authors.initials: B
authors.lastname: Vollmar
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000378:metabolism*; D016026:Bone Marrow Transplantation; D002196:Capillaries / Q000378:metabolism / Q000503:physiopathology; D002478:Cells, Cultured; D018920:Coculture Techniques; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000378:metabolism*; D006614:Hindlimb; D061307:Human Umbilical Vein Endothelial Cells / Q000378:metabolism; D006801:Humans; D007511:Ischemia / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology / Q000601:surgery*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018482:Muscle, Skeletal / Q000098:blood supply*; D018919:Neovascularization, Physiologic; D058539:Phosphatidylinositol 3-Kinase / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism*; D019718:Receptors, CXCR4 / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D051195:Toll-Like Receptor 2 / Q000235:genetics / Q000378:metabolism*
chemical_list: C514936:CXCR4 protein, mouse; D019718:Receptors, CXCR4; C493486:Tlr2 protein, mouse; D051195:Toll-Like Receptor 2; D058539:Phosphatidylinositol 3-Kinase; D019009:Proto-Oncogene Proteins c-kit; D051057:Proto-Oncogene Proteins c-akt
keywords: TLR2; angiogenesis; cKit; hematopoietic stem cells; ischemia