Disruption of apical-basal polarity of human embryonic stem cells enhances hematoendothelial differentiation.

During murine development, the formation of tight junctions and acquisition of polarity are associated with allocation of the blastomeres on the outer surface of the embryo to the trophoblast lineage, whereas the absence of polarization directs cells to the inner cell mass. Here, we report the results of ultrastructural analyses that suggest a similar link between polarization and cell fate in human embryos. In contrast, the five human embryonic stem cell (hESC) lines displayed apical-basal, epithelial-type polarity with electron-dense tight junctions, apical microvilli, and asymmetric distribution of organelles.

Serum-free derivation of human embryonic stem cell lines on human placental fibroblast feeders.

Objective: To derive new human embryonic stem cell (hESC) lines on pathogen-free human placental fibroblast feeders under serum-free conditions. Because the embryo develops in close contact with extraembryonic membranes, we hypothesized that placental mesenchyme might replicate the stem cell niche in situ.

Design: We isolated and characterized human placental fibroblast lines from individual donors and tested their ability to support growth of federally registered hESC lines.