Regenerative medicine: Stem cell research turns to the spleen.

Extract: Though conventional medical wisdom has long considered the spleen a dispensable organ, it appears to be more than it seems. Newly identified stem cell populations have been found in the spleen of adult mice, challenging conventional wisdom and providing a potential source of stem cells for treating disease. These stem cells are relevant to future cellular therapies for diabetes and other diseases. At the interface of the circulatory and immune systems, the spleen normally has dual roles in maintenance and adaptation to stress or disease. The red pulp of the spleen holds macrophages (a type of white blood cell) that normally filter and remove cellular debris and bacteria from the circulation. The white pulp of the spleen -- its lymphoid compartment -- is crucial for immune surveillance and response. It creates antibodies against invading pathogens (infectious agents) and releases platelets and neutrophils (another type of white blood cell) in response to bleeding or infection. The spleen also has a lesser known but well-documented function. It has long been established that the spleen contains a reserve population of hematopoietic, or blood-forming, stem cells that is tapped when the bone marrow cannot fully meet the body's demand in times of stress and disease.