Isolation of embryonic stem-like cells from equine blastocysts and their differentiation in vitro.

Embryonic stem (ES) cells are pluripotent cells with the potential capacity to generate any type of cell. We describe here the isolation of pluripotent ES-like cells from equine blastocysts that have been frozen and thawed. Our two lines of ES-like cells (E-1 and E-2) appear to maintain a normal diploid karyotype indefinitely in culture in vitro and to express markers that are characteristic of ES cells from mice, namely, alkaline phosphatase, stage-specific embryonic antigen-1, STAT-3 and Oct 4. After culture of equine ES-like cells in vitro for more than 17 passages, some ES-like cells differentiated to neural precursor cells in the presence of basic fibroblast growth factor (bFGF), epidermal growth factor and platelet-derived growth factor. We also developed a protocol that resulted in the differentiation of ES-like cells in vitro to hematopoietic and endothelial cell lineages in response to bFGF, stem cell factor and oncostatin M. Our observations set the stage for future developments that may allow the use of equine ES-like cells for the treatment of neurological and hematopoietic disorders.