Stem cells are unspecialized precursor cells characterized by two unique abilities. First, they are capable of reproducing themselves (self-renewal), thereby sustaining a stem cell pool. Second, they are able to develop into other cell types (differentiation) carrying out particular tissue functions. Thus, stem cells are essential for the development, turnover and repair of tissues. Because of their capacities, stem cells are ideal candidates for the treatment of diseases and regenerative medicine restoring lost or damaged cells or tissues.