The future of cell therapies includes regenerative treatments and tissue engineering, as well as many other possibilities, but it all depends on the development of highly efficient, low-cost ways to generate a ready supply of cells of any given type from a patient's own cells, such as a skin sample. The lower the cost the faster that research progresses today, and the establishment of low-cost methods of generating patient-specific cells is very much required to enable widespread use of affordable therapies tomorrow.
A little more than a decade ago it looked like the best way to create these cell supplies was to work on a technique called somatic cell nuclear transfer (SCNT), in which the nucleus from a patient's cell is introduced into an egg cell that has had its nucleus removed. The result recapitulates some of the early development of a blastocyst from which pluripotent cells can be harvested and developed into any type of human cell. Unfortunately this turned out to be more challenging than expected from a technical point of view, and as you may recall there was in addition a great deal of foolish political intervention that made it even harder to move forward. Then not so long afterwards the techniques for generating induced pluripotent stem (IPs) cells by direct reprogramming were discovered and the majority of the research community jumped ship for that much easier methodology.
Some researchers kept working on the roadblocks preventing implementation of SCNT in human cells, however, and have now finally achieved an initial success with adult human cells. This is the sort of result that can lead to the infrastructure necessary to generate patient-specific cells, but in this case it has more of the feel of the closing of a chapter. The leading edge of the research community now works with induced pluripotency and related forms of direct cell reprogramming, and is making rapid progress with those techniques. Success with SCNT is to be praised, but I think unlikely that it will gather much support in the present environment.
Last year, scientists in Oregon said they'd finally done it, using DNA taken from infants. Robert Lanza, chief scientific officer at Advanced Cell Technology, says that was an important step, but not ideal for medical purposes. "There are many diseases, whether it's diabetes, Alzheimer's or Parkinson's disease, that usually increase with age," Lanza says. So ideally scientists would like to be able to extract DNA from the cells of older people - not just cells from infants - to create therapies for adult diseases.
"What we show for the first time is that you can actually take skin cells, from a middle-aged 35-year-old male, but also from an elderly, 75-year-old male" and use the DNA from those cells in this cloning process, Lanza says. They injected it into 77 human egg cells, and from all those attempts, managed to create two viable cells that contained DNA from one or the other man. Each of those two cells is able to divide indefinitely, "so from a small vial of those cells we could grow up as many cells as we would ever want."
Lanza and his colleagues said their experiments revealed that some eggs were better at it than others. Researchers used 49 eggs from three women, though eggs from only two of them produced results. "The magic is in the egg," Lanza said.
Lanza said that most stem cell scientists have "jumped on the iPS bandwagon," but he argued that stem cells created by SCNT could still play a vital role in regenerative medicine. He envisions a day when multiple lines of stem cells are kept in banks and made available to patients based on their biological similarity, much the way blood and donor organs are now handled. "If we had these banks, we would have the raw material to do tissue engineering and grow up organs, or to grow up vessels, tendons or whatever you want."
Derivation of patient-specific human pluripotent stem cells via somatic cell nuclear transfer (SCNT) has the potential for applications in a range of therapeutic contexts. However, successful SCNT with human cells has proved challenging to achieve, and thus far has only been reported with fetal or infant somatic cells. In this study, we describe the application of a recently developed methodology for the generation of human embryonic stem cells via SCNT using dermal fibroblasts from 35- and 75-year-old males. Our study therefore demonstrates the applicability of SCNT for adult human cells and supports further investigation of SCNT as a strategy for regenerative medicine.