Canine Embryo‐Derived Stem Cells—Toward Clinically Relevant Animal Models for Evaluating Efficacy and Safety of Cell Therapies

Abstract

Pluripotent embryonic stem (ES) cells, which are available in mouse [1,2] and human [3], are permanent cell lines that can differentiate into cell types of all three germ layers. Therefore, ES cells have a remarkable potential for both basic research and clinical applications toward replacement of degenerated or malignant cells. From the perspective of hematology, where stem cell therapies are most advanced, ES cells have a number of advantages over conventional sources of transplantable material. They can be expanded indefinitely in vitro, and, more importantly, they can be obtained from a bank representing major haplotype combinations [4] or may even be derived by reprogramming somatic cells from individual patients. Proof of principle for this "therapeutic cloning" concept has been provided in the mouse [5]; however, translation of ES cell-based therapeutic strategies to clinical application requires larger animal models for predictive efficacy and safety studies.The dog has been used for preclinical studies of stem cell transplantation, and many techniques have been derived from canine studies [6]. Furthermore, techniques applicable to canine cells and dogs can be applied to man, taking into account known biologic properties of the dog [7]. Since the dog is the ideal preclinical model for testing new therapies for many human diseases, the availability of canine embryo-derived stem cells for in vitro differentiation studies will be of great value for the development of new therapies, especially in hematology. Moreover, nuclear transfer from canine somatic cells is possible [8], providing the opportunity to evaluate the concept of "therapeutic cloning" in a clinically relevant animal model.In a recent report, Hatoya and colleagues [9] describe the isolation of two ES-like cell lines from canine blastocysts. The cell lines were shown to exhibit characteristic ES-like morphology and expression of pluripotency markers. Importantly, the cells formed embryoid bodies in suspension culture, which differentiated upon adhesive culture into various cell types, including neuron-like, epithelium-like, fibroblast-like, melanocyte-like, and myocardium-like cells, demonstrating that these cells are indeed pluripotent. Unfortunately, it was not possible to maintain the undifferentiated phenotype of the cell lines beyond passage 8.We have performed similar studies that confirm the possibility of establishing canine embryo-derived cell lines and, more importantly, demonstrate for the first time that these cells can be

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

“…In the case of antibodies specific for SSEA-1, also known as CD15, which is expressed on human granulocytes as well as human ES cells, there was no specific labeling of dog granulocytes or ES cells (data not shown). This differed from the two previous reports on dog ES cells [15,16]; however, in the first study, no specificity controls for staining were included, and in the second, the data were not shown and the methods were not discussed.…”

“…Given our experience with the canine model and the extensive canine resource already established at our institute, we have focused on the dog for a preclinical ES cell model. To date, there have been two reports of cell lines derived from canine blastocysts: one in which the canine ES cells were lost after eight passages [15], and a second, more recent report in which passage 12 cells were shown to differentiate into mesoderm only [16]. Stable canine ES cells that give rise to cells representing all three germ layers have not been described.…”

Axolotl Nanog activity in mouse embryonic stem cells demonstrates that ground state pluripotency is conserved from urodele amphibians to mammals

“…In vitro, cell proliferation promoted by the WR domain is integral to the isolation of self-renewing pluripotent stem cells from early eutherian embryos (Alberio et al, 2010;Brons et al, 2007;Buehr et al, 2008;Evans and Kaufman, 1981;Honda et al, 2009;Schneider et al, 2007;Tesar et al, 2007;Thomson et al, 1998).…”

Characterization of Canine Embryonic Stem Cell Lines Derived From Different Niche Microenvironments

“…Embryo-derived cell lines have been obtained from nonlaboratory animals such as horses, cows, pigs, rabbits, and dogs [22][23][24][25][26]. The previous ESC-like lines from domestic species exhibit many, but not all, characteristics of established mouse and primate ESC lines.…”