Zipori Dov
Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, 76100, Israel.
Stem Cells. 2005 Jun-Jul;23(6):719-26. doi: 10.1634/stemcells.2005-0030.
The prevailing stem cell concept is derived from the large body of evidence available on the structure of the blood-generating system. Hemopoiesis is organized such that a multipotent stem cell, endowed with self-renewal capacity, is viewed as being positioned at the origin of a hierarchical tree of branching specificities, increasing maturity and decreasing self-renewal ability. Data accumulated in recent years on various stem cell systems often contradict this traditional view of stem cells and are reviewed herein. It is suggested that other options should be considered and put to experimental scrutiny; it is argued that the organization of the hemopoietic system may not represent a general structure of stem cell systems. The basic trait of the stem state is proposed to be plasticity. Self-renewal is not a specific stem cell trait; rather, it is exhibited by some mature cell types, whereas other particular stem cells are endowed with relatively poor renewal ability. Hierarchical structuring is also proposed to be an optional stem cell trait and may exist only in specific tissues where it serves the need for rapid expansion. The stem state is therefore defined by the highest degree of plasticity of a cell, within the repertoire of cell types present in the organism.
当前的干细胞概念源自关于造血系统结构的大量现有证据。造血过程的组织方式是，具有自我更新能力的多能干细胞被视为位于一个具有分支特异性、成熟度增加和自我更新能力下降的层次树的起源位置。近年来在各种干细胞系统中积累的数据常常与这种传统的干细胞观点相矛盾，本文对此进行综述。建议应考虑其他选项并进行实验检验；有人认为造血系统的组织方式可能并不代表干细胞系统的一般结构。干细胞状态的基本特征被认为是可塑性。自我更新并非特定的干细胞特征；相反，一些成熟细胞类型也表现出自我更新能力，而其他特定的干细胞自我更新能力相对较差。层次结构也被认为是一种可选的干细胞特征，可能仅存在于特定组织中，以满足快速增殖的需求。因此，干细胞状态是由细胞在生物体中存在的细胞类型库内的最高可塑性程度来定义的。
