Characterization of cell subpopulations expressing progenitor cell markers in porcine cardiac valves

PLoS One. 2013 Jul 23;8(7):e69667. doi: 10.1371/journal.pone.0069667. Print 2013.


Valvular interstitial cells (VICs) are the main population of cells found in cardiac valves. These resident fibroblastic cells play important roles in maintaining proper valve function, and their dysregulation has been linked to disease progression in humans. Despite the critical functions of VICs, their cellular composition is still not well defined for humans and other mammals. Given the limited availability of healthy human valves and the similarity in valve structure and function between humans and pigs, we characterized porcine VICs (pVICs) based on expression of cell surface proteins and sorted a specific subpopulation of pVICs to study its functions. We found that small percentages of pVICs express the progenitor cell markers ABCG2 (~5%), NG2 (~5%) or SSEA-4 (~7%), whereas another subpopulation (~5%) expresses OB-CDH, a type of cadherin expressed by myofibroblasts or osteo-progenitors. pVICs isolated from either aortic or pulmonary valves express most of these protein markers at similar levels. Interestingly, OB-CDH, NG2 and SSEA-4 all label distinct valvular subpopulations relative to each other; however, NG2 and ABCG2 are co-expressed in the same cells. ABCG2(+) cells were further characterized and found to deposit more calcified matrix than ABCG2(-) cells upon osteogenic induction, suggesting that they may be involved in the development of osteogenic VICs during valve pathology. Cell profiling based on flow cytometry and functional studies with sorted primary cells provide not only new and quantitative information about the cellular composition of porcine cardiac valves, but also contribute to our understanding of how a subpopulation of valvular cells (ABCG2(+) cells) may participate in tissue repair and disease progression.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP-Binding Cassette Transporters / metabolism
  • Animals
  • Antigens / metabolism
  • Aortic Valve / cytology
  • Biomarkers / metabolism*
  • Cell Membrane / metabolism
  • Cell Separation
  • Cells, Cultured
  • Extracellular Matrix / metabolism
  • Heart Valves / cytology*
  • Humans
  • Lung / cytology
  • Membrane Proteins / metabolism
  • Models, Biological
  • Osteogenesis
  • Platelet Endothelial Cell Adhesion Molecule-1 / metabolism
  • Proteoglycans / metabolism
  • Stage-Specific Embryonic Antigens / metabolism
  • Staining and Labeling
  • Stem Cells / cytology*
  • Stem Cells / metabolism*
  • Sus scrofa / metabolism*


  • ATP-Binding Cassette Transporters
  • Antigens
  • Biomarkers
  • Membrane Proteins
  • Platelet Endothelial Cell Adhesion Molecule-1
  • Proteoglycans
  • Stage-Specific Embryonic Antigens
  • chondroitin sulfate proteoglycan 4
  • stage-specific embryonic antigen-4