title: A co-culture assay of embryonic zebrafish hearts to assess migration of epicardial cells in vitro.
abstract: BACKGROUND
  The vertebrate heart consists of three cell layers: the innermost endothelium, the contractile myocardium and the outermost epicardium. The epicardium is vital for heart development and function, and forms from epicardial progenitor cells (EPCs), which migrate to the myocardium during early development. Disruptions in EPC migration and epicardium formation result in a number of cardiac malformations, many of which resemble congenital heart diseases in humans. Hence, it is important to understand the mechanisms that influence EPC migration and spreading in the developing heart. In vitro approaches heretofore have been limited to monolayer epicardial cell cultures, which may not fully capture the complex interactions that can occur between epicardial and myocardial cells in vivo.
  
  
  RESULTS
  Here we describe a novel in vitro co-culture assay for assessing epicardial cell migration using embryonic zebrafish hearts. We isolated donor hearts from embryonic zebrafish carrying an epicardial-specific fluorescent reporter after epicardial cells were present on the heart. These were co-cultured with recipient hearts expressing a myocardial-specific fluorescent reporter, isolated prior to EPC migration. Using this method, we can clearly visualize the movement of epicardial cells from the donor heart onto the myocardium of the recipient heart. We demonstrate the utility of this method by showing that epicardial cell migration is significantly delayed or absent when myocardial cells lack contractility and when myocardial cells are deficient in tbx5 expression.
  
  
  CONCLUSIONS
  We present a method to assess the migration of epicardial cells in an in vitro assay, wherein the migration of epicardial cells from a donor heart onto the myocardium of a recipient heart in co-culture is monitored and scored. The donor and recipient hearts can be independently manipulated, using either genetic tools or pharmacological agents. This allows flexibility in experimental design for determining the role that target genes/signaling pathways in specific cell types may have on epicardial cell migration.
authors.affiliation: Molecular and Environmental Toxicology Center, University of Wisconsin, 1300 University Avenue, Madison, WI, 53706, USA. msyue@wisc.edu.
authors.forename: Monica S
authors.initials: MS
authors.lastname: Yue
authors.affiliation: Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin, 777 Highland Avenue, Madison, WI, 53705, USA. plavicki@wisc.edu.
authors.forename: Jessica S
authors.initials: JS
authors.lastname: Plavicki
authors.affiliation: College of Life Science, Shaanxi Normal University, Xi'an, Shaanxi, 710062, China. lixinyi@snnu.edu.cn.
authors.forename: Xin-yi
authors.initials: XY
authors.lastname: Li
authors.affiliation: Molecular and Environmental Toxicology Center, University of Wisconsin, 1300 University Avenue, Madison, WI, 53706, USA. richard.peterson@wisc.edu.|Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin, 777 Highland Avenue, Madison, WI, 53705, USA. richard.peterson@wisc.edu.
authors.forename: Richard E
authors.initials: RE
authors.lastname: Peterson
authors.affiliation: Molecular and Environmental Toxicology Center, University of Wisconsin, 1300 University Avenue, Madison, WI, 53706, USA. wheidema@wisc.edu.|Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin, 777 Highland Avenue, Madison, WI, 53705, USA. wheidema@wisc.edu.
authors.forename: Warren
authors.initials: W
authors.lastname: Heideman
mesh_terms: D000818:Animals; D002465:Cell Movement / Q000502:physiology*; D049109:Cell Proliferation; D018920:Coculture Techniques; D004625:Embryo, Nonmammalian / Q000196:embryology; D006321:Heart / Q000196:embryology*; D006330:Heart Defects, Congenital / Q000196:embryology; D016027:Heart Transplantation / Q000379:methods; D009206:Myocardium / Q000378:metabolism; D009924:Organ Culture Techniques; D038081:Organogenesis / Q000502:physiology*; D010496:Pericardium / Q000166:cytology / Q000502:physiology*; D020825:T-Box Domain Proteins / Q000235:genetics; D015027:Zebrafish / Q000196:embryology*
chemical_list: D020825:T-Box Domain Proteins; C103172:T-box transcription factor 5