The derivation of two additional human embryonic stem cell lines from day 3 embryos with low morphological scores

BACKGROUND: Immune rejection can lead to the failure of human embryonic stem cell (hES cell) transplantation. One approach to address the problem is to establish hES cell line banks. Due to the limited source of human embryos and to ethical reasons, the hES cell lines are not readily available. This study was undertaken to determine whether discarded day 3 embryos with low morphological scores could develop into blastocysts and produce hES cell lines. METHODS: A total of 130 day 3 embryos with low morphological scores were cultured to blastocyst stage, and inner cell masses (ICM) were isolated by immunosurgery. Colonies derived from the ICM were passaged every 4–7 days and evaluated for cell surface markers, differentiation potentials and karyotypes. RESULTS: A total of 19 blastocysts were obtained from 130 embryos (quality score