ABSTRACT: The HH16/17 chicken proepicardium (PE) gives rise to the embryonic epicardium (Epi) which significantly contributes formation of the coronary vasculature during cardiac development. In contrast to explanted Epi cells, explanted PE cells can undergo differentiation into a cardiac myocyte phenotype. In order to assess which genes are associated with PE differentiation into distinc cellular lineages, two interconnented microarray gene-expression series were performed. 1: Gene-expression profiles at 12, 24, 36, 48, 60, 72 and 120 hours during cardiac myocyte differentiation from including the HH16/17 PE (t0h) were determined by hybridizing Cy3 and Cy5 labelled amplified RNA to the ArkGen 20K oligo arrays in a 2-color looped experiment design, i.e., hybridization of successive time-points per array, including dye swaps, resulting in four technical replicates for each time point. 2: Gene expression changes during normal embryonic Epi maturation were assess by hybridizing Epi from stages HH25, HH29, HH32 and HH37 in all possible pair-wise combinations, including dye-swaps, leading to 6 replicates per time point. To allow for valid comparisons between the Epi and untreated PE differentiation, these two array series were connected via hybridization of both Epi stage HH25 and HH29 with the PE explant at 48 hours in culture, with dye swaps. Keywords: time course, cardiac myocyte differentiation, embryonic coronary vessel formation, cell type comparison, mRNA expression Proepicardium to cardiac myocyte differentiation: 16 arrays for 8 time points [t0h,t12h,t24h,t36h,t48h,t60h,t72h,t120h]; successive time points hybridized per array in a loop design with dye swaps + Embryonic epicardium dfferentiation: 12 arrays for 4 time points [HH25,HH29,HH32,HH37]; all possible sample combination were hybridized with dye swaps + Epicardium to Proepicardium data connection: 4 arrays; comparing HH25 and HH29 Epicardium to t48h Proepicardium with dye swaps.
