In a breakthrough study, scientists at the University of Cambridge have been able to derive the so-called ‘naïve’ pluripotent stem cells from human embryos.
Naïve pluripotent stem cells are the most flexible types of stem cells that can develop into all tissues except the placenta. They are generally found and isolated from the blastocyst, which forms at day five after fertilization.
The ability to derive naïve stem cells from mouse embryos has been demonstrated about 30 years earlier by using a technique developed by Sir Martin Evans and Professor Matthew Kaufman during their time at Cambridge, but this is the first time this has been possible from human embryos.
In this work, scientists from the Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute managed to isolate the cells from the blastocyst at around day six after fertilization and grow them individually in culture.
The blastocyst also contain other cells including the cells that form the yolk sack and the placenta. By separating he naïve stem cells from the blastocyst, the researchers in effect stopped them ‘talking’ to each other, preventing them from being steered down a particular path of development.
“Until now it hasn’t been possible to isolate these naïve stem cells, even though we’ve had the technology to do it in mice for thirty years – leading some people to doubt it would be possible,” explains Ge Guo, the study’s first author, “but we’ve managed to extract the cells and grow them individually in culture. Naïve stem cells have many potential applications, from regenerative medicine to modelling human disorders.”
Naïve pluripotent stem cells can be programmed to differentiate to any type of tissue in the human body. Compared to pluripotent stem cells, that have already been ‘primed’ for differentiation into specific cell type whereas in the ‘Naïve’ cells all such instructions have been erased which may make it easier to direct them into any cell type of interest.
Therefore these cells are of enormous interest in the field of regenerative medicine and congential disorders.
Dr Jenny Nichols, joint senior author of the study, says that one of the most exciting applications of their new technique would be to study disorders that arise from cells that contain an abnormal number of chromosomes.
“Even in many ‘normal’ early-stage embryos, we find several cells with an abnormal number of chromosomes,” explains Dr Nichols. “Because we can separate the cells and culture them individually, we could potentially generate ‘healthy’ and ‘affected’ cell lines. This would allow us to generate and compare tissues of two models, one ‘healthy’ and one that is genetically-identical other than the surplus chromosome. This could provide new insights into conditions such as Down’s syndrome.”
The findings of the study were published in journal Stem Cell Reports.