Transplantation of hematopoietic stem cells is an effective treatment for patients with malignant blood diseases. The composition and quality of the transplanted cells are crucial to the outcome. Researchers from Lund University, Sweden, have now developed a method to improve the quality of the transplanted cells using ultrasound for cell separation. For patients with blood cancer, a blood stem cell transplant is often the only treatment that can cure the disease. The quality of the transplanted blood stem cells and the choice and composition of the transplanted cells can be crucial.