The aim of the research is to identify and characterize genes that regulate the growth of blood stem cells. It is the blood stem cells that are responsible for the regeneration of the blood system during bone marrow transplantation. This is a life-saving treatment for thousands of blood cancer patients every year. Unfortunately, a large number of patients are still unable to receive this treatment due to insufficient stem cells. It is therefore essential to find ways to make stem cells multiply before transplantation. A large number of research groups around the world have been working on this for a long time without much success and we currently know very little about the mechanisms that regulate the growth of blood stem cells. We have developed a genetic screening method based on so-called RNA interference (RNAi) that makes it possible to systematically inhibit the function of thousands of genes in hematopoietic stem cells and then study how this affects the growth of the stem cells. In our experiments with this method, we have succeeded in identifying several genes that can be inhibited to increase stem cell growth. In parallel with new screening experiments, we are now studying some of these genes in detail to understand how they affect stem cell function and whether they can be exploited to propagate blood stem cells outside the body under clinically relevant conditions.