Researchers discover important tool in understanding differentiation in human embryonic stem cells
Researchers at the University of Minnesota’s Stem Cell Institute have described how an existing genetic tool can be used to study how human embryonic stem cells differentiate. The research appears in the November 2007 issue of Experimental Biology and Medicine.
Researchers know very little about how human embryonic stem cells (hESC) self-renew. To fully understand these cells’ self renewal capacity and pluripotency, and their regulation, it is necessary to efficiently generate genetically modified cells and analyze the consequences of elevated and reduced expression of genes.
The research team, led by the University of Minnesota’s Meri Firpo, Ph.D., included gene therapy researchers at Los Angeles Children’s Hospital, and developmental biologists at the University of Michigan.
The researchers used “knockdown” technology to reduce the expression of oct4, a gene known to be necessary for self renewal of mouse and human embryonic stem cells. As seen in work done with mouse cells by knockdown and other genetic means, they showed that reducing the amount of oct4 in human ES cells induced differentiation.
The researchers then used a plasmid vector to transiently increase levels of oct4 in hESC. This also resulted in differentiation as expected, but with differentiation patterns similar to those seen with the knockdown. This was an unexpected result, because when expression of oct4 is up-regulated in mouse ES cells, they differentiate into a different type of cell than if the expression of oct4 is down-regulated.
Source: Society for Experimental Biology and Medicine
The researchers used “knockdown” technology to reduce the expression of oct4, a gene known to be necessary for self renewal of mouse and human embryonic stem cells. As seen in work done with mouse cells by knockdown and other genetic means, they showed that reducing the amount of oct4 in human ES cells induced differentiation.
The researchers then used a plasmid vector to transiently increase levels of oct4 in hESC. This also resulted in differentiation as expected, but with differentiation patterns similar to those seen with the knockdown. This was an unexpected result, because when expression of oct4 is up-regulated in mouse ES cells, they differentiate into a different type of cell than if the expression of oct4 is down-regulated.
Source: Society for Experimental Biology and Medicine
来自明尼苏达大学干细胞研究所的科学家最近描述了如何将一种基因工具应用于分析人类胚胎干细胞的分化过程。研究结果发表在11月份的《实验生物学和医学》（Experimental Biology and Medicine）上。
科学家对于人类胚胎干细胞（hESC）如何实现自我更新并不清楚。为了全面了解这些细胞的自我更新能力、多能性和调节过程，研究小组需要得到经过充分的基因改造的细胞，并分析对这些基因表达进行增强或是减弱之后的结果。
由明尼苏达大学的Meri Firpo博士领导的研究小组和洛杉矶儿童医院的基因治疗学家以及密歇根大学的发展生物学家进行了合作。科学家们利用基因抑制技术（knockdown）来降低oct4基因的表达，这是一种对老鼠和人类中胚胎干细胞进行自我更新非常关键的基因。通过观察经过基因抑制和其它基因手段处理后的老鼠细胞，科学家发现降低人类胚胎干细胞中oct4的含量可以诱导分化的发生。
科学家接着使用质粒载体来增加hESC中的oct4含量。它同样也会造成预期中的细胞分化，并且分化的模式和基因抑制中观察到的类似。这出乎科学家的预料，因为当在老鼠的胚胎干细胞中提高oct4的表达时，其分化成的细胞类型和oct4表达被抑制时并不一样。（刘乐译自physorg）
