Reprogrammed mouse fibroblasts can make a whole mouse
July 23, 2009In a paper publishing online July 23 in Cell Stem Cell, a Cell Press journal, Dr. Shaorong Gao and colleagues from the National Institute of Biological Sciences in Beijing, China, report an important advance in the characterization of reprogrammed induced pluripotent stem cells, or iPSCs.
Scientists working with iPSCs have been eager to find out if these cells are fully pluripotent, as this would tell us to what extent they have in fact been truly reprogrammed and resemble normal embryonic stem cells (ESCs).
The generally accepted "gold standard" for determining whether a mouse iPSC line has been fully reprogrammed is to show that when injected into an early embryo (or blastocyst), the iPSCs can contribute to many different tissues in the resulting chimeric mouse, including the germline. However, unlike bona fide mouse ESCs, until now mouse iPSCs have not been able to pass a more stringent test of true pluripotency termed "tetraploid complementation," which uses a hybrid embryo method to generate full-term mice entirely comprised of ESC-derived cells.
In their current report, Gao and his colleagues used established methods to reprogram mouse cells to isolate five new iPSC lines, and then found that, using one of these lines, they were able to make by tetraploid complementation embryos that survived until birth, and one embryo that also survived to adulthood.
The authors decided to test this specific iPSC line in the tetraploid complementation experiment because it gave an unusually high level of chimerism when injected into blastocysts and thus might have unique characteristics not found in many other iPSC lines. As emphasized by Gao, "Although these findings are an important proof of principle, it would be premature to make claims about whether iPSCs in general are functionally equivalent to normal ESCs." As the authors remark in their paper, it will be interesting to determine if there are specific reasons why this particular line succeeded where others have failed.
The demonstration that mouse iPSCs can, in fact, pass the most stringent test of pluripotency offers added hope that the process of reprogramming may indeed one day overcome the need for embryo destruction in order to derive pluripotent cells for research and potential therapies. However, it remains to be seen whether lessons obtained from these findings can be applied to human cells and thus whether human iPSCs will be a viable alternative to human ESCs in all circumstances.
Source: Cell Press
Aug 22, 2005 |
not rated yet |
0
The building blocks of life become the lego blocks of biologist and medical research corporations.
Personally, (very personally), I believe that we should be using such research to provide humans with the necessary capacities to exist on other planets and/or moons; but not to extend the life of small groups of eligible individuals here on Earth. The growing human population is (obviously) accelerating all of the environmental difficulties facing human (and all life forms) on Earth. Just as America released much of the population burden of Europe, Africa and Asia in the last five hundred years, we now need new territory for our population to extend into.
Extending human lives is very profitable, but the money will be a matter for archaeologists to study if we do not discover our new America soon.
In terms of preserving our species and life in general, (as we have no evidence of life "as we know it" anywhere else), we should at the very least be developing off-world colonies (with rapid development towards self-sufficiency) to ensure that life "as we know it" continues should an event like that on Jupiter a few days ago occur here on Earth. The simulations that will be created in coming months of what would have happened if that object had hit us, I predict, will paint a very bleak picture for human survival - or at least the survival of the technology and artificial infrastructures we currently enjoy ... including medical research.