Establishment and chimera analysis of 129/SvEv- and C57BL/6-derived mouse embryonic stem cell lines

Hundreds of new mutant mouse lines are being produced annually using gene targeting and gene trap approaches in embryonic stem (ES) cells, and the number is expected to continue to grow as the human and mouse genome projects progress. The availability of robust ES cell lines and a simple technology for making chimeras is more attractive now than over before. We established several new ES cell lines from 129/SvEv and C57BL/6 mice and tested their ability to contribute to the germline following blastocyst injections and/or the less expensive and easier method of morula-ES cell aggregation. Using morula aggregation to produce chimeras, mice newly derived 129/SvEx and two C57BL/6 ES cell lines tested at early passages were found to contribute extensively to chimeras and produce germline-transmitting male chimeras. Furthermore, the two 129/vEv ES cell lines that were tested and one of the C57BL/6 ES cell lines were able to maintain these characterisatics after many passages in vitro. Our results indicate that the ability of ES cells to contribute strongly to chimeras following aggregation with outbred embryos is a general property of early passage ES cells and can be maintained for many passages. C56BL/6-derived ES cell lines, however, have a greater tendancy than 129-derived ES cell lines to lose their ability to colonize the germline.

每年利用胚胎干细胞（ES）中的基因打靶和基因捕获方法会产生数百种新的突变小鼠品系，并且随着人类和小鼠基因组计划的推进，这个数量预计还会继续增加。现在，稳定的ES细胞系的可获得性以及制造嵌合体的简单技术比以往更具吸引力。我们从129/SvEv和C57BL/6小鼠中建立了几种新的ES细胞系，并测试了它们在囊胚注射和/或更便宜且更容易的桑椹胚 - ES细胞聚合法之后对生殖系的贡献能力。利用桑椹胚聚合法制造嵌合体，发现新获得的129/SvEx小鼠以及在早期传代时测试的两种C57BL/6 ES细胞系对嵌合体有广泛贡献，并能产生可传递生殖系的雄性嵌合体。此外，测试的两种129/vEv ES细胞系以及其中一种C57BL/6 ES细胞系在体外多次传代后仍能保持这些特性。我们的结果表明，ES细胞在与远交胚胎聚集后对嵌合体有强大贡献的能力是早期传代ES细胞的一种普遍特性，并且可以维持许多代。然而，C57BL/6来源的ES细胞系比129来源的ES细胞系更容易失去其在生殖系中定植的能力。