Epigenetic stability of single-cell clones of human amniotic fluid mesenchymal stem cell

Epigenetic regulation is critical for tissue differentiation. To further understand the epigenetic stability of a potentially useful cell source, we investigated the methylation characteristics of CpG islands of imprinted genes in human amniotic fluid mesenchymal stem cells (AFMSC), focusing on the differences among various single-cell clones and the effect of in vitro culture on the epigenetic changes of imprinted genes. Two amniotic fluid specimens were collected by amniocentesis, and a total of six single-cell clones AFMSC were derived using the in vitro cell culture method. We tested the differentially methylated regions (DMRs) of imprinted genes that are known to be important in cell biological functions or to be related to imprinting disorders, including H19, SNRPN, and KCNQ1OT1. DNA methylation statuses at DMRs of imprinted genes were analyzed by bisulfite genomic sequencing. Our results show that human AFMSC contain a unique epigenetic signature. The hypermethylation status of imprinting gene (H19 and KCNQ1OT1) in most single-cell clones of AFMSC was different from those of normal human blood cells. Nevertheless, H19 and KCNQ1OT1 possessed a substantial degree of epigenetic stability, despite differences in genetic background. Epigenetic instability of the imprinting gene (SNRPN) was observed during in vitro cell culture of human AFMSC. Our results urge further understanding of epigenetic status and epigenetic stability of AFMSC before it is applied in cell-replacement therapy. © 2011 Springer-Verlag Berlin Heidelberg.