For the first time in the world, Swedes have grown human embryonic stem cells in chemically controlled conditions without the use of animal substances, which is a prerequisite for clinical use in the future. The method has been developed by researchers at Karolinska Institute in Stockholm and were published in Nature Biotechnology.

Embryonic stem cells can develop into any other cell types in the body and have potential uses in treatments that entail replacement of diseased cells. But in this complicated procedure, contamination is a persistent problem facing cultivation and development of human embryonic stem cells.

The alternative solution has been to grow them in other human cells, but these support cells can produce thousands of uncontrolled proteins and, therefore, cause unreliable research findings. This is the reason that the team at Karolinska Institutet has endeavored - and now succeeded - in cultivating human stem cells without using other cells or substances of animal origin.

"For the first time, we can now grow human embryonic stem cells in large quantities in an environment that is fully defined chemically. This opens up new opportunities to develop different types of cells that can then be tested for treating diseases," said Professor Karl Tryggvason, which has led the research.

Only a single human protein, called laminin-511, is needed for a carpet upon which the growth is conducted. Up until now, various types of laminins have not been available for research. During the past two decades, Tryggvason's group has cloned genes for most human laminin varieties, studied their biological function and, most recently by using genetic technologies, succeeded in producing plentiful laminin variations.

Together with American researchers at the Harvard Stem Cell Institute, the Swedes have also demonstrated growing reprogrammed stem cells that develop retrogressively from connective tissue cells to stem cells.