Expansion of human embryonic stem cells in vitro

Abstract

This unit describes a protocol for the large-scale expansion of karyotypically normal human embryonic stem cells (hESCs). hESCs can be maintained indefinitely as dense colonies that are mechanically cut into pieces, which are subsequently transferred to fresh organ culture dishes seeded with primary mouse embryonic fibroblasts (MEFs). hESCs can also be enzymatically passaged (bulk culture); however, over time, this style of culturing may lead to the acquisition of chromosomal abnormalities. Nevertheless, enzymatic passaging can be used for short periods (up to 25 passages) without the appearance of cells with abnormal karyotypes.