In recent years it has been suggested that hematopoietic stem cells (HSCs) possess the ability to develop into different types of tissue in the body. Conceivably this phenomenon could one day facilitate treatment of a variety of degenerative diseases via harvesting a patient’s own HSCs, genetically modifying them, and then transplanting them back into the body. Unfortunately at present there is no effective way to maintain HSCs outside of the body, as the cells self-renew only in response to the unique combination of growth factors present within the specialized environment of the bone marrow. Michael Long is comparing how different environments affect the pathways by which HSCs receive chemical signals to renew. By studying HSC activity within bone marrow as well as an environment that does not promote HSC renewal such as the spleen he hopes to determine which signalling pathways are vital for HSC renewal. Ultimately, this information may allow researchers to identify how to recreate an environment outside the body that promotes HSC growth.