Reprogramming and Stem Cell Laboratory, Centre for Reproduction and Development, Monash Institute of Medical Research, Monash University, 27-31 Wright St., Clayton, VIC, 3168, Australia.
Adv Exp Med Biol. 2013;786:5-25. doi: 10.1007/978-94-007-6621-1_2.
The molecular and phenotypic irreversibility of mammalian cell differentiation was a fundamental principle of developmental biology at least until the 1980s, despite numerous reports dating back to the 1950s of the induction of pluripotency in amphibian cells by nuclear transfer (NT). Landmark reports in the 1980s and 1990s in sheep progressively challenged this dogmatic assumption; firstly, embryonic development of reconstructed embryos comprising whole (donor) blastomeres fused to enucleated oocytes, and famously, the cloning of Dolly from a terminally differentiated cell. Thus, the intrinsic ability of oocyte-derived factors to reverse the differentiated phenotype was confirmed. The concomitant elucidation of methods for human embryonic stem cell isolation and cultivation presented opportunities for therapeutic cell replacement strategies, particularly through NT of patient nuclei to enucleated oocytes for subsequent isolation of patient-specific (autologous), pluripotent cells from the resulting blastocysts. Associated logistical limitations of working with human oocytes, in addition to ethical and moral objections prompted exploration of alternative approaches to generate autologous stem cells for therapy, utilizing the full repertoire of factors characteristic of pluripotency, primarily through cell fusion and use of pluripotent cell extracts. Stunningly, in 2006, Japanese scientists described somatic cell reprogramming through delivery of four key factors (identified through a deductive approach from 24 candidate genes). Although less efficient than previous approaches, much of current stem cell research adopts this focused approach to cell reprogramming and (autologous) cell therapy. This chapter is a quasi-historical commentary of the various aforementioned approaches for the induction of pluripotency in lineage-committed cells, and introduces transcriptional and epigenetic changes occurring during reprogramming.
哺乳动物细胞分化的分子和表型不可逆性至少是在 20 世纪 80 年代之前一直是发育生物学的基本原则，尽管早在 20 世纪 50 年代就有许多关于通过核移植（NT）诱导两栖动物细胞多能性的报告。20 世纪 80 年代和 90 年代的里程碑式报告逐步挑战了这一教条式假设；首先，包含整个（供体）卵裂球融合去核卵母细胞的重构胚胎的胚胎发育，以及从终末分化细胞克隆多莉（Dolly）。因此，证实了卵母细胞来源的因子内在逆转分化表型的能力。同时阐明了分离和培养人类胚胎干细胞的方法，为治疗性细胞替代策略提供了机会，特别是通过将患者核移植到去核卵母细胞中，随后从由此产生的囊胚中分离出患者特异性（自体）、多能细胞。与使用人类卵母细胞相关的后勤限制，除了伦理道德方面的反对意见，促使人们探索替代方法来生成用于治疗的自体干细胞，利用多能性的特征性全套因子，主要通过细胞融合和使用多能细胞提取物。令人震惊的是，2006 年，日本科学家通过递送四个关键因子（通过从 24 个候选基因中进行演绎法确定）描述了体细胞重编程。尽管不如以前的方法有效，但当前的大部分干细胞研究都采用这种集中方法来进行细胞重编程和（自体）细胞治疗。本章是对上述各种诱导谱系特异性细胞多能性的方法的准历史性评论，并介绍了重编程过程中发生的转录和表观遗传变化。
