Blood Disease

Blood stem cells (also known as hematopoietic stem cells) were the first stem cells to be identified in humans. Their therapeutic potential was first recognized in the 1960s, and now, forty years later, they save tens of thousands of lives annually through transplantation.

The most common source of hematopoietic stem cells is bone marrow, but they can also be obtained from other sources including peripheral blood, umbilical cord blood, and embryonic stem cells. These stem cells are used to treat leukemias, lymphomas, multiple myeloma, aplastic anemia, and genetic diseases of the blood system; they are also used as an adjunct treatment in other types of cancers, as a way to repair the blood system after it has been damaged through chemotherapy. Genetically modified stem cells may also hold promise as a method for treating AIDS and many genetic disorders.

Research at HSCI is focused on increasing the scope and effectiveness of stem cell-based treatments. For example, HSCI co-director David Scadden is working to understand the normal bone environment in which blood stem cells develop, and to identify ways in which signals from the bone can be manipulated to increase the number of stem cells, an important determinant of success with clinical transplantation procedures. A discovery from this effort is now undergoing clinical testing in bone marrow transplantation centers at Harvard and elsewhere. There is also encouraging evidence that embryonic stem cells can be converted into bone marrow stem cells, and this allows us to envisage a new method of treating genetic diseases such as childhood leukemias. In this method, embryonic stem cells are generated through somatic cell nuclear transfer using a donor nucleus taken from a cell in the patient's skin. The resulting stem cells would then be engineered to repair the mutated gene. These cells, genetically identical to the original donor except for the repaired gene, could be grown in large quantities and converted into blood stem cells that could then be transplanted back into the original donor where they would repopulate the blood system with healthy rather than diseased cells. This is a technically demanding procedure, but it has already been demonstrated to work in mice by HSCI member George Daley. Dr Daley and others are now hoping to develop a similar procedure that can be tested in human clinical trials.