Stem cells from human embryos

One of the big aims in stem cell research has been to take DNA from adult into an egg cell to create a clone. Ever since the cloning of Dolly the sheep in 1996, researchers have been trying to recreate this experiment with other animals as well as humans. The results have been mixed over the years but in October a lab in the US published some results showing an extraction of reproducing stem cell from embryos, after injecting adult cells into egg cells  (Noggle, S. et al. Nature 478, 70-75 (2011)). 

Recently after the creation of induced pluripotent stem  (iPS) cells in  2006 it has been questioned whether it is still necessary to work on conventional stem cells. The advantage  of this approach is that it does not need egg cells and avoids most ethical issues associated with embryonic stem cells.

In conventional cloning techniques, the single set of chromosomes are removed from the egg cell, inject the two sets of chromosomes from the adult cells and try to get the introduced DNA to drive the egg towards embryonic development. These new cells normally are not like stem cells because they do not self replicate after a few divisions.

The current experiments were run on “… 270 eggs from 16 donors, isolating the three key events of conventional cloning techniques to see which was causing the problem. The culprit turned out to be removing the egg’s DNA.

Miodrag Stojkovic, a cloning expert at the University of Kragujevac in Serbia, echoes these concerns. “These are abnormal cells and therefore are a very limited tool to understand early human development,” …”

The problem with the current results are that the embryos are not true clones, because the DNA of the stem-cell line does not match that of the original adult cell but addresses some of the problem in this, still very open area of research.

The scientific community will pursue research in this exciting area which could potentially yield huge benefits.

Cloned human embryo makes working stem cells

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6 comments

  1. Azhaar sahib i thought honey was the future of neurodegenerative diseases? :) On the topic of stem cells, there is a great debate about the ethics and morality of human embryos. How do scientists go round this?
    I hope this doesn’t reveal too much of my complete ignorance of modern biology and medicine, but when a DNA from an adult cell is put into an egg, how do we hope to turn that into say a cloned heart or a cloned kidney? Because doing that would surely require the formation of a human embryo, and at what stage of the development is it unethical to extract stem cells and what stage is it okay? Furthermore, dilemma is if stem cells are extracted at a time when organs haven’t been formed, how do you know what you’re extracting will result in a heart or a liver etc? Hope my question makes sense.

    1. Apple seeds become apples, grape seeds become grapes. You shouldn’t however think of stem cells quite like that. It is not so much the seed that dictates the end product, but rather the soil it lands in.

      Take an extremely simplified example a brain stem cell. It does not have a fate as such from the beginning. Depending on where it goes, and what it is surrounded by, it can end up as many different things.

      As far as your question about extracting stem cells at the correct stage so as not to hinder development, know that the human body has a great ability to buffer itself. Stem cells have the ability to both divide into other stem cells, or to divide into their target cells. If you go in and take some out, they will just top themselves up. However it is worth noting that some people believe that stem cells are limited and once stocks run out they run out.

  2. My work is related to iPS cells, or rather the model I am working on could potentially help in understanding the development of iPS cells from differentiated adult cells.

    @Muddassar once you have an embryonic cell it is potentially possible to replicate the signal used in the normal development cycle to create any other type of cell. There is also a lot of research going on in understanding these signalling networks.

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