Stem Cell Sciences plc is pleased to announce that pioneering research describing a technique for creating authentic embryonic stem (ES) cells from rats has been published in the prestigious peer-reviewed journal, Cell (Ref. 1). This publication is believed to be the first in which germ-line transmission from rat ES cells has been definitively demonstrated. It uses technology licensed exclusively to SCS from the University of Edinburgh and developed by Professor Austin Smith and his team, now at Cambridge University. The technique is expected to allow the generation of consistently pure and stable rat ES cells, from which drug discovery assays as well as genetically modified animals can be created for academic, medical and pharmaceutical research.

The rat has been a hugely important organism in medical research and drug discovery over the past 100 years, during which time a large body of information on rat models of disease has been generated. Physiological processes and metabolic functions in the rat more closely mimic those of the human than do other model organisms such as the mouse and as a result the rat is regarded as the gold standard for studying the effects of drugs in the body. However, further studies such as defining drug action or the genetic basis of disease using rats have been hindered by the lack of sophisticated, precision genetic engineering, such as that achievable via ES cells in mice. Such barriers have now been overcome; by applying specific cell culture conditions, authentic rat ES cells can be made which can be precision engineered and then used to generate a completely novel range of rat models.

The main advantage afforded by this technology is that it allows the generation of both knock-out rat models, in which the effect of gene deletion is studied, as well as the generation of knock-in models, which involves the insertion of genes, perhaps human genes, in a precisely defined manner. For example, in the case of knock-out models, a lack of response or different response profile to drugs compared with non-engineered animals can provide information on drug efficacy. Alternatively, the insertion of genes such as those involved in drug metabolism in the human liver means that knock-in models can provide information on drug safety & metabolism. Under the terms of its agreement with Edinburgh University, SCS has global exclusive rights to commercialise pluripotent rat stem cells, the specific culture medium used to generate and grow the cells, and rats derived therefrom.

Dr Alastair Riddell, chief executive officer of Stem Cell Sciences, said "The impact of this new technique could be far-reaching in terms of opening the way to new and more effective drug discovery. Rat models are expected to be highly predictive of human responses to drugs, particularly for in psychiatric, neurological and cardiovascular areas. With this new technique allowing researchers to knock-in human genes it will be possible to conduct drug metabolism and toxicology studies with even higher predictability in rats than ever before. We expect there to be considerable commercial interest from companies wanting to access this exciting technology."