Adult stem cells are undifferentiated cells found throughout the body that divide to replenish dying cells and regenerate damaged tissues. Also known as somatic stem cells, they can be found in children, as well as adults.

A great deal of adult stem cell research has focused on clarifying their capacity to divide or self-renew indefinitely and their differentiation potential. Adult stem cells, like embryonic stem cells, have pluripotent potential and can differentiate into cells derived from all three germ layers. Pluripotent stem cells can be directly generated from adult fibroblast cultures.

While embryonic stem cell potential remains theoretical, adult stem cell treatments are already being used to successfully treat many diseases. The use of adult stem cell research and therapy is not as controversial as embryonic stem cells, because the production of adult stem cells does not require the destruction of an embryo. Adult stem cells also pose no medical dangers to the patient. Among the most stunning advancements in adult stem cell therapy are treatments for Parkinson's disease, juvenile diabetes, and spinal cord injuries.

In contrast with the embryonic stem cell research, more US government funding is being provided for adult stem cell research. Adult stem cells can be isolated from a tissue sample obtained from an adult (or cord blood, bone marrow, and other adult tissues). They have mainly been studied in humans and model organisms such as mice and rats.