Throughout life, blood cell production is dependent on a rare cell found in the bone marrow called the hematopoietic stem cell. This cell has the unique ability to divide and make identical copies of itself and also to generate progeny cells that can expand and acquire the specialized properties of mature circulating blood cells. Stem cells underpin a wide range of transplantation-based therapies for cancer, leukemia and genetic disorders. The use of these cells for therapeutic purposes requires genetic manipulation of hematopoietic stem cells, which involves inserting gene products directly into the cell’s genome. This procedure can also negatively affect chromosomes flanking the insertion site, causing variations in normal gene expression and malignant growth. Dr. Eric Yung is addressing these issues by developing methods to introduce new genes into stem cells without inserting them directly into the host genome. His strategy is to adapt and modify the ability of certain viruses to insert genetic material into cells. These methods may provide safer and more robust ways to achieve high level expression of genes. They may also aid understanding of the function of specific genes (for example genes that cause cancer) and the development of new methods to expand stem cells and develop new therapies for genetic disorders.