For the first time, two research teams independently created unique stem cells after cloning an embryo from adult cells. In the future, this technology can be used to create patient-specific spare tissues for degenerative diseases, for example, for replacing entire pancreatic tissues in patients with type 1 diabetes mellitus.
The first stem cell lines from cloned human embryos were registered in May 2013 by a team led by reproductive biology expert Shoukhrat Mitalipov at Oregon Health and Science University in Beaverton. Their cells were carriers of genomes taken from embryonic cells or from cells of eight-month-old babies. It was not clear then whether the technology would work if samples of cultures were taken from adult patients.
Now two groups of scientists have answered this question in the affirmative with their successful experiments. The first team, led by Young Gie Chung and Dong Ryul Lee of Seoul University, reported on April 17, 2014, that they had cloned embryonic stem cells (ESCs) using cell nuclei from two healthy men aged 35 and 75 years old.
Another team led by regenerative medicine specialist Dieter Egli of the New York Foundation for Stem Cell Research has published an article in Nature describing their experiment. They talk about ESCs obtained from a cloned embryo containing DNA from a 32-year-old woman with type 1 diabetes.
To obtain cloned embryos, all three groups used a modified version of a laboratory technique called therapeutic cloning (SCNT), in which a patient’s cell nucleus is placed in an unfertilized human egg, previously devoid of its own nucleus. Thus, the cell is reprogrammed into an embryonic state.
Recall that it was with the use of this technique that the first mammal, Dolly the sheep, was cloned from an adult cell in 1996.
The creators of the new technique note that ESCs produced by cloning are much safer and more reliable than the currently popular induced pluripotent cells. The latter are produced by adding genes to the cells of an adult patient, due to which they are reprogrammed back to an embryonic state. But even a small genetic mismatch can cause the body to reject the new tissue.
In addition to its main applications, the new embryo cloning technique will also help improve methods for reprogramming adult cells and study unique embryonic cell cultures and their development. Nevertheless, the authors are almost sure that things will not go further than a couple of experiments: the technique is expensive, technically difficult to execute, and will certainly entail ethical disagreements. Plus, getting an egg from a healthy donor is not easy and not cheap at all.
Considering induced pluripotent cells and ESCs from cloned embryos, scientists are inclined to believe that the first technique will be optimal for drug screening, but ESCs are still more suitable for practical medical purposes.
Dr. Mitalipov says that studies comparing IPCs and ESCs from the same donors are already in full swing. However, in the United States, this situation is complicated by a federal ban on the use of public funds for research and production of stem cells. Scientists hope that their work will attract the attention of colleagues who are interested in these experiments, which in turn will lead to a relaxation of government bans.