Lee Hsuan-Shu, Crane Gracy G, Merok Joshua R, Tunstead James R, Hatch Nicole L, Panchalingam Krishnanchali, Powers Mark J, Griffith Linda G, Sherley James L
The Biological Engineering Division, Biotechnology Process Engineering Center, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Bldg. 16, Room 743b, Cambridge, MA 02139, USA.
Biotechnol Bioeng. 2003 Sep 30;83(7):760-71. doi: 10.1002/bit.10727.
Adult stem cells have potential use for several biomedical applications, including cell replacement therapy, gene therapy, and tissue engineering. However, such applications have been limited due to difficulties encountered in expanding functional adult stem cells. We have developed a new approach to the problem of adult stem cell expansion based on the suppression of asymmetric cell kinetics (SACK). We postulated that asymmetric cell kinetics, required for adult stem cell function, were a major barrier to their expansion in culture. As such, conversion of adult stem cells from asymmetric cell kinetics to symmetric cell kinetics would promote their exponential expansion and longterm propagation in culture. The purine nucleoside xanthosine (Xs), which promotes guanine ribonucleotide biosynthesis, can be used to reversibly convert cells from asymmetric cell kinetics to symmetric cell kinetics. We used Xs supplementation to derive clonal epithelial cell lines from adult rat liver that have properties of adult hepatic stem cells. The properties of two Xs-derived cell lines, Lig-8 and Lig-13, are described in detail and compared to properties of adult rat hepatic cell lines derived without Xs supplementation. The Xs-derived cell lines exhibit Xs-dependent asymmetric cell kinetics and Xs-dependent expression of mature hepatic differentiation markers. Interestingly, Lig-8 cells produce progeny with properties consistent with hepatocyte differentiation, while Lig-13 progeny cells have properties consistent with bile duct epithelium differentiation. A stable adult cholangiocyte stem cell line has not been previously described. Consistent with the principles of their derivation, the SACK-derived hepatic cell lines exhibit neither senescence nor tumorigenic properties, and their differentiation properties are stable after longterm culture. These characteristics of SACK-derived stem cell lines underscore asymmetric cell kinetics as an essential adult stem cell property with potential to be the basis for a general approach to expansion and propagation of diverse adult stem cells.
成体干细胞在多种生物医学应用中具有潜在用途，包括细胞替代疗法、基因治疗和组织工程。然而，由于在扩增功能性成体干细胞过程中遇到困难，此类应用受到了限制。我们基于抑制不对称细胞动力学（SACK）开发了一种解决成体干细胞扩增问题的新方法。我们推测，成体干细胞功能所需的不对称细胞动力学是其在培养中扩增的主要障碍。因此，将成体干细胞从不对称细胞动力学转变为对称细胞动力学将促进其在培养中的指数扩增和长期增殖。促进鸟嘌呤核糖核苷酸生物合成的嘌呤核苷黄嘌呤（Xs）可用于将细胞从不对称细胞动力学可逆地转变为对称细胞动力学。我们使用添加Xs的方法从成年大鼠肝脏中获得了具有成年肝干细胞特性的克隆上皮细胞系。详细描述了两个由Xs衍生的细胞系Lig - 8和Lig - 13的特性，并与未添加Xs衍生的成年大鼠肝细胞系的特性进行了比较。由Xs衍生的细胞系表现出依赖Xs的不对称细胞动力学和依赖Xs的成熟肝分化标志物表达。有趣的是，Lig - 8细胞产生的后代具有与肝细胞分化一致的特性，而Lig - 13后代细胞具有与胆管上皮分化一致的特性。此前尚未描述过稳定的成年胆管细胞干细胞系。与它们的衍生原理一致，由SACK衍生的肝细胞系既不表现出衰老也不具有致瘤特性，并且它们的分化特性在长期培养后是稳定的。SACK衍生的干细胞系的这些特征强调了不对称细胞动力学是成体干细胞的一种基本特性，有可能成为多种成体干细胞扩增和增殖通用方法的基础。
