哺乳动物多能干细胞:在创建疾病模型、发病机制、药物发现和个性化治疗中的作用

Mammalian pluripotent stem cells:effects on creating disease models,pathogenesis,drug discovery and personalized treatment

背景:多能干细胞的自我更新和多向分化的特征有可能彻底改变人们对生物学、医学、发育和疾病的理解。干细胞在胚胎发育的早期发挥着重要作用,研究干细胞可以深入理解生物体发育和组织器官形成的基本原理,探索各种疾病的潜在机制,研究受损组织和器官的修复和再生,以及推动药物发现和个性化治疗。目的:回顾多能干细胞的研究历程,并对多能干细胞的基本类别进行归纳总结,同时阐述常见哺乳动物中各类多能干细胞的建系情况。方法:应用计算机检索PubMed、Web of Science、中国知网和万方数据库,检索词为“多能干细胞,胚胎干细胞,诱导多能干细胞,扩展多能干细胞,家畜多能干细胞,Pluripotent stem cells,Embryonic stem cells,Induced pluripotent stem cells,Expanded potential stem cells,Livestock pluripotent stem cells等”,根据纳入标准和排除标准系统地筛选与哺乳动物多能干细胞相关的文献99篇进行综述分析。结果与结论:(1)小鼠胚胎干细胞经典理论认为,干细胞的多能态分为“初始”(na?ve)态和“始发”(primed)态两种,na?ve态对应于早期胚胎未植入子宫壁前的囊胚内细胞团;primed态对应于植入后的上胚层,二者在表观遗传特征、转录活性、外部信号依赖性和代谢表型等方面存在显著的特征差异;后来研究发现在初始态和始发态之间,还存在一个过渡状态——“形成态”(formative态);事实上,胚胎干细胞的多能性属于连续阶段的发展进程,而不是某种独立的细胞状态。(2)除了从囊胚内细胞团获得多能干细胞之外,还有多种多能干细胞获得方式和建系方法:如利用来源于小鼠胎儿原始生殖细胞所建立的胚胎生殖干细胞;利用Oct3/4,Sox2,c-Myc和Klf4因子诱导成年小鼠和人的成纤维细胞去分化所建立的诱导多能干细胞;体细胞核移植,孤雌激活,以及从新生或成体睾丸组织或卵巢组织中分离并进行类胚胎干细胞培养所建立的胚胎干细胞样细胞系;来源于多种成体组织的极小胚胎样干细胞和来源于前囊胚期的扩展多能干细胞,这些多能干细胞的共同特征为不断自我更新,表达核心多能因子,并具备原始三胚层分化能力。(3)目前,多能干细胞正在被用于疾病建模,以便研究不同疾病的机制并开发新的药物。同时,科学家正在尝试用多能干细胞培养各种组织和器官,为再生医学和移植提供新的可能性。然而,多能干细胞的临床应用面临着安全性挑战,包括细胞畸变和免疫排斥问题。不断改进多能干细胞的产生方法,将使其更安全、高效地适用于临床。(4)借鉴小鼠和人多能干细胞的获得方式和建系方法,研究者们已经在家畜中建立了各类多能干细胞,包括胚胎干细胞、诱导性多能干细胞、生殖细胞谱系的多能干细胞和扩展多能干细胞,这将为动物繁殖育种、基因工程、疾病模型、新药筛选和野生濒危动物保护提供新的途径。

BACKGROUND:The self-renewal and multi-directional differentiation of pluripotent stem cells possess the potential to revolutionize people's understanding of biology,medicine,development,and disease.Stem cells play an important role in the early stage of embryonic development,and the study of them could be beneficial to understanding of the basic principles of biological development and tissue or organ formation,exploring the potential mechanisms of various diseases,studying the repair and regeneration of damaged tissues or organs,and promoting drug discovery and personalized treatment.OBJECTIVE:To review the research progress of pluripotent stem cells,summarize and categorize the fundamental types of pluripotent stem cells,and elucidate the lineage situations of various types of pluripotent stem cells in common mammals.METHODS:PubMed,Web of Science,CNKI,and WanFang databases were searched systematically,with the keywords“pluripotent stem cells;embryonic stem cells;induced pluripotent stem cells;expanded potential stem cells;livestock pluripotent stem cells”in English and Chinese.The 99 articles related to mammalian pluripotent stem cells were systematically screened according to inclusion and exclusion criteria,and then reviewed.RESULTS AND CONCLUSION:(1)According to classical theory in mouse embryonic stem cell research,the pluripotent state of stem cells is divided into two forms:na?ve and primed.Na?ve state corresponds to the inner cell mass of pre-implantation embryos before attachment to the uterine wall,while primed state corresponds to the epiblast after implantation.These two states exhibit significant differences in epigenetic features,transcriptional activity,external signal dependency,and metabolic phenotype.It is later discovered that there is an intermediate state between na?ve and primed called formative pluripotency.Therefore,the pluripotency of pluripotent stem cells is a continuous developmental process rather than a unique cell state.(2)In addition to obtaining pluripotent stem cells from the inner cell mass,there are various methods and lineages for acquiring pluripotent stem cells,including embryonic germ cells established using primitive germ cells from mouse embryos,induced pluripotent stem cells created by the dedifferentiation of adult mouse and human fibroblasts with four factors—Oct3/4,Sox2,c-Myc,and Klf4;embryonic stem cell-like cell lines cultured from somatic cell nuclear transfer,parthenogenesis,neonatal or adult testicular or ovarian tissue,very small embryonic-like stem cells derived from various adult tissues and expanded pluripotent stem cells derived from pre-implantation stages.These pluripotent stem cells all share the common characteristics of continuous self-renewal,expressing core pluripotency factors and possessing the ability to differentiate into the three primary germ layers.(3)Currently,pluripotent stem cells are being used for disease modeling to study the mechanisms of various diseases and develop new drugs.Simultaneously,scientists are attempting to use pluripotent stem cells to cultivate various tissues and organs,offering new possibilities for regenerative medicine and transplantation.However,the clinical application of pluripotent stem cells faces safety challenges,including issues of cell mutations and immune rejection.Continual improvement in the methods of generating pluripotent stem cells will make them safer and more efficient for clinical applications.(4)Based on the methods of obtaining and lineage establishment of pluripotent stem cells in mice and humans,various types of pluripotent stem cells have been established in livestock,including embryonic stem cells,induced pluripotent stem cells,germ lineages of pluripotent stem cells,and expanded potential stem cells.Research on livestock pluripotent stem cells opens up new avenues for animal reproduction,breeding,genetic engineering,disease modeling,drug screening,and the conservation of endangered wildlife.