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Scientists Can Grow Stem Cells In a Petri Dish
rift321 writes "Scientists safely created induced pluripotent stem cells from human stem cells, and grew them in a petri dish. The previous methods for creating iPSC's involved the use of retroviruses, which rendered the stem cells unacceptable for human implantation due to an increased risk of cancer and mutations. The researchers used a safer, albeit slower process to modify the skin cells, using a cell-penetrating peptide to deliver the needed genes into the cell (PDF). I'd like to hear if anyone has some insight into exactly how close that brings us to everyday-use of stem cells for regenerative therapy, and exactly what obstacles remain before such therapies can be put to use."
You should see the stuff that grows on MY dishes!
And just what do you think you're going to do with it? TFA is a stupid, hype filled mess (as usual). The original article is here. The big deal is thus:
- Pluripotent stem cells MAY (big time maybe) be useful in a wide array of clinical applications.
- Embryonic stems cells are hard to obtain, have ethical issues to some folks.
- Fibroblasts (skin cells) are easy to obtain, not so ethically high strung and easy to grow.
- We've known for a couple of years that you can create what look to be stem cells by infecting fibroblasts using four (count'em only four) separate proteins. That's pretty amazing - the whole differentiation cascade is apparently controlled by a small number of discrete molecules.
- The problem is that to get those proteins inside the fibroblasts you have to use a (real) virus, which is interesting called a "Trojan" since it's "bringing in" foreigners. That is conceptually unappealing because the "stem cells" now have some viral garbage which may or may not interfere with experiments.
- The current research gets said proteins inside the cell using another clever "hack" - a small peptide (apparently derived from HIV infected cells) that allows the bigger proteins to sneak inside and do their magic.
- On first and second blush, the newly transformed stem cells look and act like Pleuripotent Embryonic Stem Cells (the real McCoy).
- But this remains to be seen, many a grant and paper are yet to come.
So don't get all wound up thinking you can inject this stuff into you and magically turn 16 again. Remember, you can only be young once.
But you can be immature forever.
Faster! Faster! Faster would be better!
I can manifest those mutant powers I've always wanted!
I'd be happy just to replace my missing teeth !
Smivs on the intertubes!
The innovation here is that they have a new approach to transform the cells into stem cells that may be safer than previous alternatives. For example, gene therapy commonly relies on viral vectors to insert genes to produce the proteins into the genome. However, because these insert randomly, they can inactivate genes involved in cell proliferation regulation etc. resulting in cancer. There are other approaches such as naked DNA transformation, but then the genes producing the proteins are generally not replicated or segregated evenly when the cell divides and are thus lost over successive divisions.
What these people have done, is to avoid all the usual problems by making the required proteins (already well known) for cell transformation in a bacterial system and adding a seqeuence to them that produces a cell penetrating end - similiar to that found in some viral proteins. This allows their proteins to penetrate the cells and activate pathways that inactivate/activate certain genes sets to make the cells pluripotent. These changes appear to be permanent and hold for over 35 passages.
As a side note, this is a burgeoning field of research. The efficiency and efficacy of certain protein products as above, and even genetic material, can be greatly enhanced by the addition of nuclear localisation sequences, certain histones and so on, without nasty side effects.
. . . now *that* will be cool!
. . . or, maybe not?
Schroedinger's Brexit: The UK is both in and out of the EU at the same time!
The whole idea is pretty simple: just delivering four key reprogramming proteins using shuttle of cell-penetrating peptide. Basing on experience of everyday life we may suppose that a simple solution is free of interference from large number of unknown factors, thus efficient. But that's not the case, the protocol developed by the authors leads to transformation of mere 0.001% of input cells, which is order of magnitude less than in protocols based on viral transfection, and perhaps orders of magnitude less than threshold for applications in medicine. Some improvement could be gained, however, if purified proteins were used. Moreover, this fibroblasts were used to some extent as "blackboxes" with transformation-inducing proteins provided and results checked out, but with no developed sense of what's going on inside, which constitute room another room for improvement.
There is more to this than it is published in the paper. You can use the same trick to push your newly obtained iPSC to differentiate into the cell type you need. For example introduction of MyoD can turn them into muscle cells for treatment of muscular dystrophy.
One potential problem is that they're using c-myc, an oncogene.
From the actual paper
Tumor cells are often found to have more c-myc protein than they should, and mice which have too much c-myc develop cancer much more frequently. By getting protein in rather than genes expressing the protein into cells, this is probably safer, as the cells aren't going to continue making c-myc presumably, but it is something that needs to be rigorously tested.
I think the chances of it being anything really dangerous are pretty low. You're going to be turning individual cells with this, growing a whole bunch, and differentiating the cells before putting it into a patient. The protein only needs to work on that first cell, and proteins are turned over pretty quickly, it's likely that by the time you got to making new tissues it would already be gone, and any left over would probably be very dilluted to where it won't have an effect.
Also, you can make these cells without it. C-myc was one of the initial four genes used to make plurpotent cells, but a short while later it was shown that c-myc only increases the efficiency. This current method is low-efficiency, and you'd expect the efficiency to drop even lower without c-myc. As the summary points out, they're already working on ways to increase the efficiency, dollars to doughnuts they're going to be trying it without c-myc in the near future.
As far as the question in the summary
I'd like to hear if anyone has some insight into exactly how close that brings us to everyday-use of stem cells for regenerative therapy, and exactly what obstacles remain before such therapies can be put to use."
It puts it a lot closer. Transgenic tissues are much more worrisome than protein-treated tissues. When you give the cell new instructions for how to make proteins that can cause cancer, that's dangerous. Supplying those proteins yourself, not as much.
There is still one major obstacle that's probably a bigger concern: we can deprogram these cells, but you want to be absolutely sure though they're reprogrammed before you put them into a patient. If you want to put new neurons into someone, you have to be sure you've turned all the iPSC into neurons. If you put undifferentiated cells into someone's brain, they tend to develop teratomas, which I think is one of the worst types of tumors to have. They're making strides on that, but I don't think they're to the point where they can say for sure that's not going to happen.
This current breakthrough is absolutely a great thing though, don't mean to diminish it, just that there are other steps.