title: Functional Definition of Progenitors Versus Mature Endothelial Cells Reveals Key SoxF-Dependent Differentiation Process.
abstract: During adult life, blood vessel formation is thought to occur via angiogenic processes involving branching from existing vessels. An alternate proposal suggests that neovessels form from endothelial progenitors able to assemble the intimal layers. We here aimed to define vessel-resident endothelial progenitors in vivo in a variety of tissues in physiological and pathological situations such as normal aorta, lungs, and wound healing, tumors, and placenta, as well.
  
  
  
  Based on protein expression levels of common endothelial markers using flow cytometry, 3 subpopulations of endothelial cells could be identified among VE-Cadherin+ and CD45- cells.
  
  
  
  Lineage tracing by usingCdh5creERt2/Rosa-YFPreporter strategy demonstrated that the CD31-/loVEGFR2lo/intracellular endothelial population was indeed an endovascular progenitor (EVP) of an intermediate CD31intVEGFR2lo/intracellular transit amplifying (TA) and a definitive differentiated (D) CD31hiVEGFR2hi/extracellular population. EVP cells arose from vascular-resident beds that could not be transferred by bone marrow transplantation. Furthermore, EVP displayed progenitor-like status with a high proportion of cells in a quiescent cell cycle phase as assessed in wounds, tumors, and aorta. Only EVP cells and not TA and D cells had self-renewal capacity as demonstrated by colony-forming capacity in limiting dilution and by transplantation in Matrigel plugs in recipient mice. RNA sequencing revealed prominent gene expression differences between EVP and D cells. In particular, EVP cells highly expressed genes related to progenitor function includingSox9,Il33,Egfr, andPdfgrα.Conversely, D cells highly expressed genes related to differentiated endothelium includingEts1&2,Gata2,Cd31,Vwf, andNotch. The RNA sequencing also pointed to an essential role of theSox18transcription factor. The role of SOX18 in the differentiation process was validated by using lineage-tracing experiments based on Sox18CreERt2/Rosa-YFPmice. Besides, in the absence of functional SOX18/SOXF, EVP progenitors were still present, but TA and D populations were significantly reduced.
  
  
  
  Our findings support an entirely novel endothelial hierarchy, from EVP to TA to D, as defined by self-renewal, differentiation, and molecular profiling of an endothelial progenitor. This paradigm shift in our understanding of vascular-resident endothelial progenitors in tissue regeneration opens new avenues for better understanding of cardiovascular biology.
authors.affiliation: From The University of Queensland, UQ Centre for Clinical Research, Experimental Dermatology Group, Brisbane, QLD, Australia (J.P., E.J.S., M.P.R., H.Y.W., N.M.F., K.K.); The University of Queensland, UQ Diamantina Institute, Translational Research Institute, Woolloongabba, QLD, Australia (P.D., K.K.); The University of Queensland, School of Mathematics and Physics, Brisbane, QLD, Australia (Z.N.); and The University of Queensland, Institute of Molecular Biosciences, Brisbane, QLD, Australia (M.F.).
authors.forename: Jatin
authors.initials: J
authors.lastname: Patel
authors.affiliation: From The University of Queensland, UQ Centre for Clinical Research, Experimental Dermatology Group, Brisbane, QLD, Australia (J.P., E.J.S., M.P.R., H.Y.W., N.M.F., K.K.); The University of Queensland, UQ Diamantina Institute, Translational Research Institute, Woolloongabba, QLD, Australia (P.D., K.K.); The University of Queensland, School of Mathematics and Physics, Brisbane, QLD, Australia (Z.N.); and The University of Queensland, Institute of Molecular Biosciences, Brisbane, QLD, Australia (M.F.).
authors.forename: Elke J
authors.initials: EJ
authors.lastname: Seppanen
authors.affiliation: From The University of Queensland, UQ Centre for Clinical Research, Experimental Dermatology Group, Brisbane, QLD, Australia (J.P., E.J.S., M.P.R., H.Y.W., N.M.F., K.K.); The University of Queensland, UQ Diamantina Institute, Translational Research Institute, Woolloongabba, QLD, Australia (P.D., K.K.); The University of Queensland, School of Mathematics and Physics, Brisbane, QLD, Australia (Z.N.); and The University of Queensland, Institute of Molecular Biosciences, Brisbane, QLD, Australia (M.F.).
authors.forename: Mathieu P
authors.initials: MP
authors.lastname: Rodero
authors.affiliation: From The University of Queensland, UQ Centre for Clinical Research, Experimental Dermatology Group, Brisbane, QLD, Australia (J.P., E.J.S., M.P.R., H.Y.W., N.M.F., K.K.); The University of Queensland, UQ Diamantina Institute, Translational Research Institute, Woolloongabba, QLD, Australia (P.D., K.K.); The University of Queensland, School of Mathematics and Physics, Brisbane, QLD, Australia (Z.N.); and The University of Queensland, Institute of Molecular Biosciences, Brisbane, QLD, Australia (M.F.).
authors.forename: Ho Yi
authors.initials: HY
authors.lastname: Wong
authors.affiliation: From The University of Queensland, UQ Centre for Clinical Research, Experimental Dermatology Group, Brisbane, QLD, Australia (J.P., E.J.S., M.P.R., H.Y.W., N.M.F., K.K.); The University of Queensland, UQ Diamantina Institute, Translational Research Institute, Woolloongabba, QLD, Australia (P.D., K.K.); The University of Queensland, School of Mathematics and Physics, Brisbane, QLD, Australia (Z.N.); and The University of Queensland, Institute of Molecular Biosciences, Brisbane, QLD, Australia (M.F.).
authors.forename: Prudence
authors.initials: P
authors.lastname: Donovan
authors.affiliation: From The University of Queensland, UQ Centre for Clinical Research, Experimental Dermatology Group, Brisbane, QLD, Australia (J.P., E.J.S., M.P.R., H.Y.W., N.M.F., K.K.); The University of Queensland, UQ Diamantina Institute, Translational Research Institute, Woolloongabba, QLD, Australia (P.D., K.K.); The University of Queensland, School of Mathematics and Physics, Brisbane, QLD, Australia (Z.N.); and The University of Queensland, Institute of Molecular Biosciences, Brisbane, QLD, Australia (M.F.).
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Neufeld
authors.affiliation: From The University of Queensland, UQ Centre for Clinical Research, Experimental Dermatology Group, Brisbane, QLD, Australia (J.P., E.J.S., M.P.R., H.Y.W., N.M.F., K.K.); The University of Queensland, UQ Diamantina Institute, Translational Research Institute, Woolloongabba, QLD, Australia (P.D., K.K.); The University of Queensland, School of Mathematics and Physics, Brisbane, QLD, Australia (Z.N.); and The University of Queensland, Institute of Molecular Biosciences, Brisbane, QLD, Australia (M.F.).
authors.forename: Nicholas M
authors.initials: NM
authors.lastname: Fisk
authors.affiliation: From The University of Queensland, UQ Centre for Clinical Research, Experimental Dermatology Group, Brisbane, QLD, Australia (J.P., E.J.S., M.P.R., H.Y.W., N.M.F., K.K.); The University of Queensland, UQ Diamantina Institute, Translational Research Institute, Woolloongabba, QLD, Australia (P.D., K.K.); The University of Queensland, School of Mathematics and Physics, Brisbane, QLD, Australia (Z.N.); and The University of Queensland, Institute of Molecular Biosciences, Brisbane, QLD, Australia (M.F.).
authors.forename: Mathias
authors.initials: M
authors.lastname: Francois
authors.affiliation: From The University of Queensland, UQ Centre for Clinical Research, Experimental Dermatology Group, Brisbane, QLD, Australia (J.P., E.J.S., M.P.R., H.Y.W., N.M.F., K.K.); The University of Queensland, UQ Diamantina Institute, Translational Research Institute, Woolloongabba, QLD, Australia (P.D., K.K.); The University of Queensland, School of Mathematics and Physics, Brisbane, QLD, Australia (Z.N.); and The University of Queensland, Institute of Molecular Biosciences, Brisbane, QLD, Australia (M.F.). k.khosrotehrani@uq.edu.au.
authors.forename: Kiarash
authors.initials: K
authors.lastname: Khosrotehrani
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D001011:Aorta / Q000378:metabolism / Q000473:pathology; D016026:Bone Marrow Transplantation; D015820:Cadherins / Q000378:metabolism; D002454:Cell Differentiation; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology; D005260:Female; D017493:Leukocyte Common Antigens / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018919:Neovascularization, Physiologic; D010920:Placenta / Q000378:metabolism / Q000473:pathology; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D011247:Pregnancy; D055760:SOXF Transcription Factors / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism; D014947:Wounds and Injuries / Q000473:pathology / Q000628:therapy; D000099152:Cadherin 5
chemical_list: D015703:Antigens, CD; D015820:Cadherins; D017493:Leukocyte Common Antigens; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D055760:SOXF Transcription Factors; D040301:Vascular Endothelial Growth Factor Receptor-2; D000099152:Cadherin 5; C000592875:Kdr protein, mouse
keywords: angiogenesis inducing agents; endothelial cells; endothelial progenitor cells; neovascularization