The usage of novel chemicals and medications requires reliable data on the potential toxic effects on individuals. directed to the potential application of embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) for the assessment of developmental toxicology as well as cardio- and hepatotoxicology. With respect to embryotoxicology recent achievements of the embryonic stem cell test (EST) are described and current limitations as well as prospects of embryotoxicity studies using pluripotent stem cells are discussed. Furthermore recent efforts to establish hPSC-based cell models for testing cardio- and hepatotoxicity are presented. In this context methods for differentiation and selection of cardiac and hepatic AST-1306 cells from hPSCs are summarized requirements and implications with respect to the use of these cells in safety pharmacology and toxicology are presented and future AST-1306 challenges and perspectives of using hPSCs are discussed. (Evans and Kaufman 1981; Martin 1981). ESCs have been cultured on MEF-FL cells and after the identification of the differentiation-inhibiting activity AST-1306 (DIA) that represented the leukaemia-inhibitory factor (LIF; Smith et al. 1988; Williams et al. 1988) different murine (m) ESC lines were established which were able to proliferate and differentiate into cell types of all three primary germ layers. The cells formed in vitro functional cells of the heart skeletal muscle nerve system blood vascular liver pancreas and other tissues thereby recapitulating early developmental processes (reviewed in Wobus and Boheler 2005). Later on ESCs had been also induced to differentiate into feminine (Hübner et al. 2003) and male (Toyooka et al. 2003) germ-like cells. The real pluripotency of mESCs was demonstrated by shot into blastocysts (Bradley et al. 1984) a method that was later on improved by aggregating ESCs and blastomeres known as the “sandwich technique” (Nagy et al. 1993) or “tetraploid embryo complementation” (Eggan et al. 2001). These procedures allowed the generation of offspring that comes from ESCs completely. Furthermore approaches for the hereditary manipulation of ESCs by presenting genes (gain-of-function) or selectively turning off genes (loss-of-function) had been established (evaluated in Wobus and Boheler 2005). In gene-targeting (loss-of-function) tests ESCs offered as automobile for the selective inactivation of genes by homologous recombination (Thomas and Capecchi 1987) which up to now led to the creation greater than thousand “knock-out mice” with particular hereditary defects. At that ideal period just a few organizations analysed the in vitro differentiation of mESCs. This transformed in 1998 when Wayne Thompson been successful in the establishment from the 1st human being (h) ESC lines through the internal cell mass (ICM) of human being blastocysts (Thomson et al. 1998). hESCs display indefinite proliferation on FL cells a standard karyotype and high developmental capability in vitro (Reubinoff et al. 2000; evaluated in Stojkovic et al. 2004; Boheler and Wobus 2005; Cdx2 Murry and Keller 2008). The pluripotency of hESCs is tested by teratoma formation after transplantation into immunodeficient mice usually. The era of specific cell types from hESCs opened up the perspective of producing functional human being cells for regenerative therapies. At a comparable period as the 1st hESC derivation human being were founded from 5- to 7-week-old aborted human being foetuses (Shamblott et al. 1998). Human being EG cells demonstrated multi-lineage differentiation potential but limited proliferation and may be propagated just as EB derivatives. That is as opposed to murine EG cells that AST-1306 have been currently generated in 1992 by in vitro tradition of primordial germ cells from 9.5 to 11.5 d p.c. mouse embryos (Matsui et al. 1992; Resnick et al. 1992; Labosky et al. 1994). Murine EG cells demonstrated properties just like those of mESCs and could actually re-enter the germ range (Labosky et al. 1994; Stewart et al. 1994 discover Desk?1). When human being EG cell-differentiated neural derivatives had been transplanted into an pet model for neurorepair they showed some regenerative potential (Kerr et al. 2003) suggesting that hEG cells might possibly be an alternative to hESCs for therapeutic use. However the difficult isolation from human foetuses and the limited proliferative capacity restrict the applicability of hEG cells. Table?1 Properties of mouse and human pluripotent cell populations grown in vitro.