All of the lines were derived from individual embryos. A significant difference was found among the lines. As microRNAs have been proved to play a key role in the maintenance of pluripotency and the cell cycle regulation of stem cells miRNA microarray analysis was performed to characterize differential expression. MiRNAs were found to express differently in PGC lines with high proliferation rate, compared to PGC lines with low proliferation rate and gga-miR-2127 expressed differently in female and male cell lines. The microarray analysis also revealed high expression level of the gga-miR-302b-3p strand (member of miR-302/367 cluster) in slowly proliferating PGC lines compared to gga-miR-302b-5p strand. We confirmed that the inhibition of miR-302b-5p significantly increases the doubling time of the examined PGC lines.
In conclusion, the researchers found that gga-miR-181-5p, gga-miR-2127 and members of the ggamiR-302/367 cluster have a dominant role in the regulation of avian primordial germ cell proliferation.