Transgenic rat models with either deleted or inserted genes could be on the horizon following a scientific breakthrough announced by Stem Cell Sciences (SCS).

The Cambridge, UK-based company said two independent laboratories in the UK and the US had achieved germ-line transmission from embryonic stem cells in rats using technology licensed exclusively to SCS by Edinburgh University in Scotland.

The technology’s main advantage, SCS noted, is that it allows the generation of both ‘knock-in’ and ‘knock-out’ rat models. ‘Knock-out’ models, which researchers use to study the effects of gene removal, can help to assess drug safety and efficacy, for example. ‘Knock-in’ models, which involve the insertion of genes such as those implicated in drug metabolism through the human liver, can provide information on human safety and pharmacokinetics.

Transgenic mice models are already created for drug discovery purposes in a very similar manner, SCS pointed out. However, rats are considered more predictable human models than mice for a number of psychiatric, neurological and cardiovascular drug targets. Moreover, the company added, the ability to ‘knock in’ human genes should enable drug metabolism studies to be performed with better predictability in rats than was previously available.

“We believe this opens the way to new and more effective drug discovery,” said SCS chief executive officer Dr Alastair Riddell. Under its agreement with Edinburgh University, the company has global exclusive rights to commercialise the rat ES cells, the specific culture medium used to generate and grow them, and any rats derived from the cells.

SCS has exclusively licensed two key patents for the technology from Edinburgh university and “now plans to engage in confidential discussions with interested parties seeking a sub-licence to use rat ES cells in their commercial drug discovery programmes”, it said.

According to the company, this is believed to be the first time germ-line transmission from rat ES cells has been demonstrated. Full scientific reports on the breakthrough, which has been independently verified, have been submitted to a major scientific journal for publication, it added.