AstraZeneca and Sweden's Cellartis say they have signed an extension to their ongoing collaboration to develop improved safety screening systems based on human embryonic stem cell-derived liver and heart muscle cells. Terms of the collaboration were not disclosed.

This represents an extension of a two-year agreement signed by the companies in July 2006 to explore whether cells taken from established hESC lines could be differentiated into functioning human hepatocytes and myocyctes. The firms said that with "further improvements in differentiation technologies, scientists will be able to better predict drug metabolism and potential liver and cardiac adverse side effects in humans much earlier in the drug discovery process".

Cellartis chief executive Mats Lundwall said that the collaboration "now enters an exciting phase", adding that "we continue to validate our reputation as a leading player in the hESC arena through such deals". Jan Lundberg, executive vice president of discovery for AstraZeneca, said that "if we can successfully and reliably create a consistent supply of differentiated embryonic stem cells, we will be able to more accurately detect side effects for new drugs".

He added that "such a breakthrough could improve R&D productivity by reducing attrition rates and ultimately lead to safer medicines for patients. While significant scientific hurdles remain, we are making good progress and gaining valuable experience.”