Professor Ian Wilmut, Centre for Reproductive Biology, University of Edinburgh, said:
“This is a very interesting paper that adds considerably to previous observations on the use of cell fusion. In some reports attention has been drawn to potential clinical use of this approach because this is a means of producing cells with some characteristics of embryo stem cells without use of an embryo. However, these cells have twice the desired number of chromosomes and cannot be considered as true embryo stem cells. There is no known means of removing those chromosomes that are not required.
“The important use of this approach is to study the mechanisms that cause a cell to change from one type to another, the process that involves “nuclear reprogramming”.
“The authors use excellent molecular techniques to show very carefully that the fused cells contained the chromosomes of both cell types and that there were changes in the functioning of the chromosomes of the fibroblast so that they became like those from the embryonic stem cell. The fused cells had the abilities of embryo stem cells in that they grew for very long periods in the laboratory and retained the ability to form all of the different tissues. This confirms that there had been accurate nuclear reprogramming. This system could be used to look for the unknown factors in cells that bring about “nuclear reprogramming”. Once these are identified they can be used to bring about “nuclear reprogramming”.
“In the mean time let us not waste time. There are methods of deriving embryo stem cells from cloned embryos that could be used to study and in time to treat human disease. Lets get on with this, for the sake of thousands of patients.”
Dr Petra Hajkova, Gurdon Institute, University of Cambridge, said:
“Reprogramming in this sense it a somatic cell regaining the capacity to create any cell type in the body.
“This capacity for reprogramming has been shown before on mouse stem cells, so this isn’t very surprising. However, it is the first time it has been shown to work in human cells, it seems that human cells have the same potential as mouse cells (or mouse equivalents). The fact the fused cells has double the number of chromosomes would cause problems which would prevent these cells being used for therapies. Furthermore, work from mice shows that if you remove the stem cells nucleus before fusion, reprogramming can’t occur.”
Professor Miodrag Stojkovic, Deputy Director, Centre for Stem Cell Biology and Developmental Genetics, University of Newcastle, said:
“This is interesting research which will help us understand how the nuclei of adult cells can reprogram. However, these cells would not be useful for stem cell treatments, because they are abnormal. These cells have 92 chromosomes rather than the normal 46. So nuclear transfer still remains the only procedure to derive patient-specific stem cells with a normal set of chromosomes.”
Notes to Editors: *Published in this weeks issue of Science: “Nuclear Reprogramming of Somatic Cells After Fusion with Human Embryonic Stem Cells,” by C.A. Cowan, J. Atienza, D.A. Melton and K. Eggan at Howard Hughes Medical Institute in Cambridge, MA and at Harvard University in Cambridge, MA.