In summary, the demonstration that cell dose is the most important factor influencing outcome has led university physicians to develop new approaches to expand the stem cell pool either by expansion in the laboratory prior to transplantation, expansion by mixing two UCB units, or by expansion in the patient by co-infusing healthy stroma from one of the parents. While none of these approaches has been proven, support by the Children's Cancer Research Fund has been instrumental in allowing the development of new treatments with the ultimate goal of improving the rate of cure in children and adults with life-threatening diseases.