Morula-derived human embryonic stem cells.

Human embryonic stem (ES) cells are known to derive from the inner cell mass of blastocyst. Although the embryos of other developmental stages have also been used as a source for ES cells in animal models, the feasibility of obtaining ES cell lines from human morula is not known, despite being an obvious source available through assisted reproduction and preimplantation genetic diagnosis programmes. This study describes an original technique for derivation of ES cells from human morula, which enabled the establishment of eight morula-derived ES cell lines. These ES cell lines were shown to have no morphological differences from the ES cells derived from blastocysts, and expressed the same ES cell specific markers, including Oct-4, tumour-resistance antigens TRA-2-39, stage-specific embryonic antigens SSEA-3 and SSEA-4, and high molecular weight glycoproteins TRA-1-60 and TRA-1-81, detected in the same colony of morula-derived ES cells showing specific alkaline phosphatase expression. No differences were observed in these marker expressions in the morula-derived ES cells cultured in the feeder layer free medium. Similar to ES cell originating from blastocyst, the morula-derived ES cells were shown to spontaneously differentiate in vitro into a variety of cell types, including the neuron-like and contracting primitive cardiocyte-like cells.