title: Human pulmonary valve progenitor cells exhibit endothelial/mesenchymal plasticity in response to vascular endothelial growth factor-A and transforming growth factor-beta2.
abstract: In situ analysis of fetal semilunar valve leaflets has revealed cells coexpressing endothelial and mesenchymal markers along the endothelium, with diminished frequency seen in adult valves. To determine whether such cells are progenitor cells, we isolated clonal populations from human pulmonary valves. The clones expressed endothelial markers but showed potential to further differentiate into endothelium in response to vascular endothelial growth factor (VEGF)-A. When exposed to transforming growth factor (TGF)-beta2, individual clones adopted a mesenchymal phenotype to varying degrees and expressed markers of endothelial to mesenchymal transformation (EMT). Both VEGF- and TGFbeta2-induced phenotypic changes were partially reversible, indicating the plasticity of these cells. When challenged with VEGF or TGFbeta2, a hierarchy of endothelial/mesenchymal potential could be seen among the clonal populations: cells initially closer to an endothelial phenotype showed a strong response to TGFbeta2 that could be inhibited by VEGF, whereas cells closer to a mesenchymal phenotype responded to TGFbeta2 but were resistant to endothelial-inducing effects of VEGF. These findings suggest the presence of bipotential valve progenitor cells with ability to differentiate into either endothelial or interstitial cells of the valve leaflet. Understanding the differentiation potential and function of these cells may be important for understanding heart valve disease and may also be applied to current paradigms for creating tissue-engineered heart valves.
authors.affiliation: Department of Surgery, Children's Hospital Boston, 300 Longwood Ave, Boston, MA 02115, USA.
authors.forename: Sailaja
authors.initials: S
authors.lastname: Paruchuri
authors.forename: Jeong-Hee
authors.initials: JH
authors.lastname: Yang
authors.forename: Elena
authors.initials: E
authors.lastname: Aikawa
authors.forename: Juan M
authors.initials: JM
authors.lastname: Melero-Martin
authors.forename: Zia A
authors.initials: ZA
authors.lastname: Khan
authors.forename: Stavros
authors.initials: S
authors.lastname: Loukogeorgakis
authors.forename: Frederick J
authors.initials: FJ
authors.lastname: Schoen
authors.forename: Joyce
authors.initials: J
authors.lastname: Bischoff
mesh_terms: D015415:Biomarkers / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects*; D002469:Cell Separation; D002999:Clone Cells / Q000166:cytology / Q000502:physiology; D042783:Endothelial Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D005260:Female; D005333:Fetus; D006351:Heart Valves / Q000196:embryology*; D006801:Humans; D008648:Mesoderm / Q000166:cytology* / Q000502:physiology; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000378:metabolism; D010641:Phenotype; D011664:Pulmonary Valve / Q000166:cytology*; D013234:Stem Cells / Q000166:cytology*; D014158:Transcription, Genetic / Q000187:drug effects; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D053781:Transforming Growth Factor beta2; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*
chemical_list: D015415:Biomarkers; C509041:TGFB2 protein, human; D016212:Transforming Growth Factor beta; D053781:Transforming Growth Factor beta2; D042461:Vascular Endothelial Growth Factor A