A Stem Cell Molecular Signature: Are There Hallmark Properties That are Shared by all Stem Cells?

摘要

Stem cells have long been regarded as a pool of undifferentiated cells that have the potential to proliferate, self-renew, and produce a variety of differentiated progeny, which gives them the capacity to regenerate several types of tissue. The classical paradigm describes undirectional, hierarchical lineage proceedings, which follow step-wise differentiation of totipotent or pluripotent stem cells through intermediate, more restricted progenitor cells, and finally to differentiated cells. A long-accepted tenet of stem cell biology proposed a model in which only embryonic stem cells (ESC) are pluripotent and able to differentiate into several lineages of progeny, whereas adult stem cells are restricted in their differentiate potential to the tissue in which they reside. However, a recent series of studies has challenged these fundamental concepts by suggesting that stem cells derived from adult tissues can differentiate outside their tissue of origin. Thus stem cells from the blood system, termed hematopoietic stem cells (HSC), were suggested to be capable of producing mature liver cells, muscle tissue, or even neurons.