Multipotential stem cells and 'side population' cells
Multipotential stem cells and 'side population' cells
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DOI：
10.1080/146532402761624638
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发表时间：
2002-10-01
期刊：
影响因子：
4.5
通讯作者：
Goodell, MA
中科院分区：
文献类型：
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作者：
Goodell, MA
在过去的两年中，我们看到了一系列令人眼花缭乱的关于潜在的新干细胞类型的报道，这些干细胞类型可以产生各种分化的间充质（和其他）细胞。这些干细胞来源于许多不同的组织来源，通常是BM[1]，但也有皮肤[2]和脑[3]。最近，Catherine Verfaillie的研究小组报道了一种看似稳定的、不朽的多能成体祖细胞（MAPC），它的行为有点像胚胎干细胞，在成人和胚胎中产生多种细胞类型。这些无数的干细胞类型之间是否存在某种关系？目前尚不清楚所有这些干细胞类型是否具有相似的广泛分化特征，也不知道它们是否最终都来源于一个干细胞，可能存在于骨髓中。有很多不同的分离方法，因为有出版物，没有人直接比较每个“干细胞”群体，这使得不可能确定是一个或多个干细胞群体被表征。我们研究了“侧群”或SP细胞，这是在有效的赫斯特染料流出的基础上鉴定的。我们最初通过筛选hoechst染色的小鼠BM细胞群来鉴定SP细胞，以寻找那些可以重建致命辐照受体[5]的细胞。SP细胞能有效地重组小鼠。比整个骨髓多1000倍，因此被定义为造血干细胞（HSC）。群体是高度均匀的，大约90%的SP细胞表达干细胞标记物Sca-1， c-Kit和造血Ag CD45。直到几年前，我们和该领域的大多数人都认为，一次造血干细胞，永远是造血干细胞，而且造血干细胞只产生血液的细胞成分。最近对组织限制性干细胞具有更广泛潜力的可能性的兴奋使我们和其他人考虑SP细胞可以制造其他组织的可能性。我们的研究小组[6]和R. Mulligan（与L. Kunkel和E. Gussoni合作，[7]）研究了SP细胞向特定间质组织的分化。在这些实验中，小鼠骨髓SP细胞产生非造血后代的天然能力通过稳定地将SP细胞移植到致命辐照受体的骨髓中，然后在目标组织中诱导急性损伤来评估（或者，在Gussoni等人的情况下，使用营养不良的mdx小鼠，它不断经历骨骼肌再生）。让SP细胞首先在造血系统中稳定地植入，可以让潜在的后代有时间产生并循环到损伤区域。这种实验设计与那些将干细胞群直接引入损伤组织b[8]的实验设计有本质上的不同，在这种情况下，干细胞必须能够迅速粘附在损伤组织上，不受损伤部位发生的正常重塑过程（如炎症细胞的进入和组织重塑）的影响，并分化为非造血细胞。当骨髓移植先于损伤时，HSC （SP细胞）有机会产生中间后代，这些后代可能更（或更少）适合循环、外渗、进入和分化到损伤组织。我们的实验室和Mulligan的实验室报告分化为骨骼肌[7]、心肌和内皮细胞[6]。然而，在这两份报告中，分化为这些非原生组织的频率非常低——通过供体标记（lacZ或y染色体）、心脏或骨骼肌Ags的存在以及造血Ags的缺乏来测量，损伤区域检测的细胞分化为非造血细胞的比例为0.1-0.01%。既不……
In the past 2 years we have seen a dizzying array of reports of potential new stem cell types that can generate a variety of differentiated mesenchymal (and other) cells. These stem cells are derived from many different tissue sources, frequently BM [1], but also skin [2] and brain [3]. Most recently, Catherine Verfaillie’s group has reported a seemingly stable, immortal multipotent adult progenitor cell (MAPC) from BM that behaves somewhat like a embryonal stem cell, generating many cell types in adults and embryos [4]. Is there a relationship between these myriad stem cell types? It is not known whether all these stem cell types have similar broad differentiation profiles, nor whether they are all ultimately derived from one stem cell, perhaps residing in the BM. There are as many different isolation procedures as there are publications, and no one has directly compared each ‘stem cell’population, which makes it impossible to determine if one or many stem cell populations are being characterized. We have studied ‘side population’or SP cells, which are identified on the basis of efficient Hoechst dye efflux. We originally identified SP cells by screening Hoechst-stained murine BM cell populations for those that would reconstitute lethally irradiated recipients [5]. SP cells reconstituted mice with an efficiency. 1000-fold over whole BM, and were therefore defined as hematopoietic stem cells (HSC). The population is highly homogeneous, with around 90% of SP cells expressing the stem cell markers Sca-1, c-Kit, and the hematopoietic Ag CD45. Until a few years ago we, along with most others in the field, considered that once an HSC, always an HSC, and that HSC exclusively produce the cellular components of blood. The recent excitement over the possibility that tissue-restricted stem cells had broader potential led us and others to consider the possibility that SP cells could make other tissues. Our group [6], and that of R. Mulligan (in collaboration with L. Kunkel and E. Gussoni,[7]) examined SP cell differentiation into specific mesenchymal tissues. In these experiments, the native ability of mouse BM SP cells to generate non-hematopoietic progeny was evaluated by stably engrafting the SP cells into the BM of lethally irradiated recipients, then inducing an acute injury in the tissue of interest (or, in the case of Gussoni et al., using the dytstrophic mdx mouse, which constantly undergoes skeletal muscle regeneration). Allowing the SP cells to first stably engraft in the hematopoietic system allows time for potential progeny to be generated and to circulate to the region (s) of injury. This experimental design is substantially different from those that introduce stem cell populations directly into injured tissue [8]—in this case stem cells must be able to rapidly adhere to the injured tissue, not be affected by the normal remodeling processes occurring at the site of injury (such as entry of inflammatory cells and tissue remodeling) and differentiate into non-hematopoietic cells. When BM engraftment precedes injury, the HSC (SP cells) have the opportunity to generate intermediate progeny, which may be more (or less) suited to circulation, extravasation, and entrance and differentiation into the injured tissue. Our lab, and that of Mulligan, reported differentiation into skeletal muscle [7], cardiac muscle, and endothelial cells [6]. However, in both reports, the frequency of differentiation into these non-autochthonous tissues was very low—in the order of 0.1–0.01% of cells examined in the region of injury had differentiated into non-hematopoietic cells, as measured by a donor marker (lacZ or Y-chromosome), presence of cardiac or skeletal muscle Ags, and lack of hematopoietic Ags. Neither …