Stem cell biology is a relatively new field that explores the characteristics and possible clinical applications of the different types of pluripotential cells that serve as the progenitors of more differentiated cell types. In addition to potential therapeutic applications (Chap. 67), patient-derived stem cells can also provide disease models and a means to test drug effectiveness. Identification, Isolation, and Derivation of Stem Cells Resident Stem Cells The definition of stem cells remains elusive. Stem cells were originally postulated as unspecified or undifferentiated cells that provide a source of renewal of skin, intestine, and blood cells throughout the lifespan. .
