title: Adipose stromal cells differentiate along a smooth muscle lineage pathway upon endothelial cell contact via induction of activin A.
abstract: BACKGROUND
  Adipose stromal cells (ASC) are therapeutically potent progenitor cells that possess properties of pericytes. In vivo, ASC in combination with endothelial cells (EC) establish functional multilayer vessels, in which ASC form the outer vessel layer and differentiate into mural cells.
  
  
  OBJECTIVE
  To identify factors responsible for ASC differentiation toward the smooth muscle cell phenotype via interaction with EC.
  
  
  RESULTS
  An in vitro model of EC cocultivation with ASC was used, in which EC organized into vascular cords, accompanied by ASC migration toward EC and upregulation of α-smooth muscle actin, SM22α, and calponin expression. Conditioned media from EC-ASC, but not from EC cultures, induced smooth muscle cell protein expression in ASC monocultures. EC-ASC cocultivation induced marked accumulation of activin A but not transforming growth factor-β1 in conditioned media. This was attributed to induction of activin A expression in ASC on contact with EC. Although transforming growth factor-β and activin A were individually sufficient to initiate expression of smooth muscle cell antigens in ASC, only activin A IgG blocked the effect of EC-ASC conditioned media. Although transforming growth factor-β was able to induce activin A expression in ASC, in cocultures this induction was transforming growth factor-β independent. In EC-ASC cocultures, activin A IgG or ALK4/5/7 receptor inhibitors blocked expression of α-smooth muscle actin in ASC in the absence of direct EC-cord contact, but this inhibition was circumvented in ASC by direct EC contact.
  
  
  CONCLUSIONS
  EC initiate a smooth muscle cell differentiation program in adjacent ASC and propagate this differentiation in distant ASC by induction of activin A expression.
authors.affiliation: From Indiana Center for Vascular Biology and Medicine, Department of Medicine (S.M.-C., I.P.L., H.L., D.F., P.C.-C., K.L.M., D.O.T.) and Department of Cellular and Integrative Physiology (K.L.M.) at Indiana University School of Medicine, Indianapolis; and VA Center for Regenerative Medicine, Department of Research and Development at R.L. Roudebush VA Medical Center, Indianapolis, IN (S.M.-C., I.P.L., H.L., D.F., P.C.-C., K.L.M., D.O.T.).
authors.forename: Stephanie
authors.initials: S
authors.lastname: Merfeld-Clauss
authors.affiliation: From Indiana Center for Vascular Biology and Medicine, Department of Medicine (S.M.-C., I.P.L., H.L., D.F., P.C.-C., K.L.M., D.O.T.) and Department of Cellular and Integrative Physiology (K.L.M.) at Indiana University School of Medicine, Indianapolis; and VA Center for Regenerative Medicine, Department of Research and Development at R.L. Roudebush VA Medical Center, Indianapolis, IN (S.M.-C., I.P.L., H.L., D.F., P.C.-C., K.L.M., D.O.T.).
authors.forename: Ivan P
authors.initials: IP
authors.lastname: Lupov
authors.affiliation: From Indiana Center for Vascular Biology and Medicine, Department of Medicine (S.M.-C., I.P.L., H.L., D.F., P.C.-C., K.L.M., D.O.T.) and Department of Cellular and Integrative Physiology (K.L.M.) at Indiana University School of Medicine, Indianapolis; and VA Center for Regenerative Medicine, Department of Research and Development at R.L. Roudebush VA Medical Center, Indianapolis, IN (S.M.-C., I.P.L., H.L., D.F., P.C.-C., K.L.M., D.O.T.).
authors.forename: Hongyan
authors.initials: H
authors.lastname: Lu
authors.affiliation: From Indiana Center for Vascular Biology and Medicine, Department of Medicine (S.M.-C., I.P.L., H.L., D.F., P.C.-C., K.L.M., D.O.T.) and Department of Cellular and Integrative Physiology (K.L.M.) at Indiana University School of Medicine, Indianapolis; and VA Center for Regenerative Medicine, Department of Research and Development at R.L. Roudebush VA Medical Center, Indianapolis, IN (S.M.-C., I.P.L., H.L., D.F., P.C.-C., K.L.M., D.O.T.).
authors.forename: Dongni
authors.initials: D
authors.lastname: Feng
authors.affiliation: From Indiana Center for Vascular Biology and Medicine, Department of Medicine (S.M.-C., I.P.L., H.L., D.F., P.C.-C., K.L.M., D.O.T.) and Department of Cellular and Integrative Physiology (K.L.M.) at Indiana University School of Medicine, Indianapolis; and VA Center for Regenerative Medicine, Department of Research and Development at R.L. Roudebush VA Medical Center, Indianapolis, IN (S.M.-C., I.P.L., H.L., D.F., P.C.-C., K.L.M., D.O.T.).
authors.forename: Peter
authors.initials: P
authors.lastname: Compton-Craig
authors.affiliation: From Indiana Center for Vascular Biology and Medicine, Department of Medicine (S.M.-C., I.P.L., H.L., D.F., P.C.-C., K.L.M., D.O.T.) and Department of Cellular and Integrative Physiology (K.L.M.) at Indiana University School of Medicine, Indianapolis; and VA Center for Regenerative Medicine, Department of Research and Development at R.L. Roudebush VA Medical Center, Indianapolis, IN (S.M.-C., I.P.L., H.L., D.F., P.C.-C., K.L.M., D.O.T.).
authors.forename: Keith L
authors.initials: KL
authors.lastname: March
authors.affiliation: From Indiana Center for Vascular Biology and Medicine, Department of Medicine (S.M.-C., I.P.L., H.L., D.F., P.C.-C., K.L.M., D.O.T.) and Department of Cellular and Integrative Physiology (K.L.M.) at Indiana University School of Medicine, Indianapolis; and VA Center for Regenerative Medicine, Department of Research and Development at R.L. Roudebush VA Medical Center, Indianapolis, IN (S.M.-C., I.P.L., H.L., D.F., P.C.-C., K.L.M., D.O.T.). tdmitry@iu.edu.
authors.forename: Dmitry O
authors.initials: DO
authors.lastname: Traktuev
mesh_terms: D000199:Actins / Q000378:metabolism; D030201:Activin Receptors, Type I / Q000378:metabolism; D028341:Activins / Q000378:metabolism*; D000273:Adipose Tissue / Q000166:cytology / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002450:Cell Communication; D002454:Cell Differentiation; D019070:Cell Lineage; D002465:Cell Movement; D002478:Cells, Cultured; D018920:Coculture Techniques; D042783:Endothelial Cells / Q000378:metabolism*; D038681:Follistatin / Q000378:metabolism; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000378:metabolism*; D008840:Microfilament Proteins / Q000378:metabolism; D009124:Muscle Proteins / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D018919:Neovascularization, Physiologic; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism; D015398:Signal Transduction; D051899:Smad2 Protein / Q000378:metabolism; D013997:Time Factors; D053773:Transforming Growth Factor beta1 / Q000378:metabolism; D015854:Up-Regulation; D000096985:Calponins
chemical_list: D000199:Actins; D030201:Activin Receptors, Type I; D028341:Activins; D002135:Calcium-Binding Proteins; D038681:Follistatin; D008840:Microfilament Proteins; D009124:Muscle Proteins; D017346:Protein Serine-Threonine Kinases; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta; D051899:Smad2 Protein; D053773:Transforming Growth Factor beta1; D000096985:Calponins; C541116:ACTA2 protein, human; C503233:FST protein, human; C497782:SMAD2 protein, human; C508960:TGFB1 protein, human; C422405:activin A; C051615:transgelin; C498932:ACVR1B protein, human; C424205:ACVR1C protein, human
keywords: activin A; adipose tissue; coculture techniques; endothelial cells; mesenchymal stem cells; neovascularization; smooth muscle