Derivation, Characterization, and In Vitro Differentiation of Canine Embryonic Stem Cells.

Embryonic stem (ES) cells have created considerable excitement in the last few years due to their unlimited potential to produce cells for tissue repair and replacement. However, a large animal pre-clinical model is necessary to establish the safety and efficacy of ES cell-derived tissue replacement therapy. The canine model has long been used in medical research, has been well established to study adult stem cell transplantation and has been highly predictive of clinical outcomes in humans, more so than rodent models. Given the documented record for extrapolating from dog to man, we hypothesize that the dog would serve as an ideal pre-clinical in vivo model for studying the clinical applications of ESC derived tissue. Eleven putative ES cell lines were initiated from canine blastocysts harvested from natural matings. One line described here, FHDO-7, has been maintained through 34 passages and has many characteristics of ES cells from other species. FHDO-7 cells are alkaline phosphatase positive and express both message and protein for the Oct4 transcription factor. They also express message for Nanog and do not express message for Cdx2 which is associated with trophectoderm. Furthermore, they express a cluster of pluripotency-associated microRNAs (miR-302b, miR-302c and miR-367) that have been found to be characteristic of human and mouse ES cells. The FHDO-7 cells grow on feeder layers of modified mouse embryonic fibroblasts (MEF) as flat colonies that resemble ES cells from mink, a close phylogenetic relative of dog. When cultured in nonadherent plates without feeders the cells form embryoid bodies (EB). Under various culture conditions the EBs give rise to ectoderm-derived neuronal cells expressing β3-tubulin, mesoderm-derived osteocytes producing bone, and endoderm-derived cells expressing alpha feto protein or Clara cell specific protein. These results indicate that FHDO-7 is a pluripotent embryonic stem cell line.