5 ms·

It would be interesting to know how the scaling-up procedure works? Is it similar to scaling up and productionizing a software system? Anyways, I guess the onl

by xiphias 10y ago

It would be interesting to know how the scaling-up procedure works? Is it similar to scaling up and productionizing a software system? Anyways, I guess the only question is how much time it will take to have mass-scale gene editing on people.

nonbel 10y ago
If you are imagining having something injected into you and your cells being "edited" in situ, I doubt it can happen with this tech. The process is very toxic to cells in every paper that reports that aspect. You will only see them remove the cells, "edit" them in a dish, then inject them back in. I even suspect a major portion of the "editing" is not editing at all, but rather selecting for the small number of pre-existing cells that are mutants at any site. This works because the mutants are "immune" due to lacking the recognition sequence. Then again, I haven't read a paper on it in awhile now (and the ones posted here seem to be mostly editorials nowadays), so maybe they figured something out.
- deleted 10y ago
  [deleted]
- dekhn 10y ago
  "The process is very toxic to cells...." you mean like chemotherapy?
  - nonbel 10y ago
    Yes, the way CRISPR/Cas9 works, the DNA must be damaged. However, chemotherapy is not very selective about which cells it damages. Here, the DNA is much more difficult to damage if it is already missing the exact sequence being targeted for "editing", so the targeted cells will die while the mutants divide to take their place. If I thought specific somatic mutations were good drug targets for cancer, I would be more enthusiastic about CRISPR/Cas9 as a less toxic chemotherapy than a gene-editing therapy.
entee 10y ago
Sounds like they would need to know how to grow massive amounts of these cells in culture for this to be viable. As others have noted here, only about 20% of the cells get the desired fix and many cells die in the process of getting the fix. Cell culture of human and stem cells is non-trivial and rarely gets done on a large scale. Most of the time you have to grow cells in a petri-dish which in practice means you get very low cell density (number of cells per volume of space it takes to culture the cell i.e. the stacking of the petri dish, the 2D surface they occupy in that dish, how dense the cells like to get within that dish before dying etc.). Ideally you want to grow things to high density in a medium where the cells can out-compete all contaminants. One example is yeast fermentation, the yeast outcompetes everything. Another is e-coli in the lab, where the coli grows faster than most anything in the culture. All of these are liquid suspensions, not on dishes. In this case, we're talking about a blood disease, so you may be able to grow the cells in liquid culture. You also have easy access to a lot of them (blood is pretty easy to get, in contrast to say, brain). This is where CRISPR is most likely to show results in the clinic in the near future, but there are still lots of hurdles to overcome.
mjfl 10y ago
Absolutely not. Scaling is the whole problem with gene therapy. If we could scale it we would have had it in 1999. In that year, a man was injected with lentivirally carried genetic therapy to cause his liver cells to break down ammonia (they weren't before and he couldn't eat certain foods, lived an uncomfortable but livable life). He died due to the immune response. His name was [Jesse Gelsinger](https://en.wikipedia.org/wiki/Jesse_Gelsinger https://en.wikipedia.org/wiki/Jesse_Gelsinger). It froze gene therapy funding for 10 years. Siddharta Mukerjee has a really good discussion on it in his book, The Gene. Scaling gene therapy is THE problem of gene therapy. Not editing genes themselves.
- dekhn 10y ago
  (I know the answer, but) Why would the death of a single person from a clinical trial freeze an entire category of funding? Surely, many people die in clinical trials of other types of medicine (caused by the treatment) and that doesn't cause the trials to be shut down. Immunotherapy of cancer wouldn't be a viable treatment if subjected to the same level of regulation as gene therapy.

by xiphias 10y ago

nonbel 10y ago

If you are imagining having something injected into you and your cells being "edited" in situ, I doubt it can happen with this tech. The process is very toxic to cells in every paper that reports that aspect. You will only see them remove the cells, "edit" them in a dish, then inject them back in. I even suspect a major portion of the "editing" is not editing at all, but rather selecting for the small number of pre-existing cells that are mutants at any site. This works because the mutants are "immune" due to lacking the recognition sequence. Then again, I haven't read a paper on it in awhile now (and the ones posted here seem to be mostly editorials nowadays), so maybe they figured something out.

deleted 10y ago
[deleted]
dekhn 10y ago
"The process is very toxic to cells...." you mean like chemotherapy?
- nonbel 10y ago
  Yes, the way CRISPR/Cas9 works, the DNA must be damaged. However, chemotherapy is not very selective about which cells it damages. Here, the DNA is much more difficult to damage if it is already missing the exact sequence being targeted for "editing", so the targeted cells will die while the mutants divide to take their place. If I thought specific somatic mutations were good drug targets for cancer, I would be more enthusiastic about CRISPR/Cas9 as a less toxic chemotherapy than a gene-editing therapy.

entee 10y ago

Sounds like they would need to know how to grow massive amounts of these cells in culture for this to be viable. As others have noted here, only about 20% of the cells get the desired fix and many cells die in the process of getting the fix. Cell culture of human and stem cells is non-trivial and rarely gets done on a large scale. Most of the time you have to grow cells in a petri-dish which in practice means you get very low cell density (number of cells per volume of space it takes to culture the cell i.e. the stacking of the petri dish, the 2D surface they occupy in that dish, how dense the cells like to get within that dish before dying etc.). Ideally you want to grow things to high density in a medium where the cells can out-compete all contaminants. One example is yeast fermentation, the yeast outcompetes everything. Another is e-coli in the lab, where the coli grows faster than most anything in the culture. All of these are liquid suspensions, not on dishes. In this case, we're talking about a blood disease, so you may be able to grow the cells in liquid culture. You also have easy access to a lot of them (blood is pretty easy to get, in contrast to say, brain). This is where CRISPR is most likely to show results in the clinic in the near future, but there are still lots of hurdles to overcome.

mjfl 10y ago

Absolutely not. Scaling is the whole problem with gene therapy. If we could scale it we would have had it in 1999. In that year, a man was injected with lentivirally carried genetic therapy to cause his liver cells to break down ammonia (they weren't before and he couldn't eat certain foods, lived an uncomfortable but livable life). He died due to the immune response. His name was [Jesse Gelsinger](https://en.wikipedia.org/wiki/Jesse_Gelsinger https://en.wikipedia.org/wiki/Jesse_Gelsinger). It froze gene therapy funding for 10 years. Siddharta Mukerjee has a really good discussion on it in his book, The Gene. Scaling gene therapy is THE problem of gene therapy. Not editing genes themselves.

dekhn 10y ago
(I know the answer, but) Why would the death of a single person from a clinical trial freeze an entire category of funding? Surely, many people die in clinical trials of other types of medicine (caused by the treatment) and that doesn't cause the trials to be shut down. Immunotherapy of cancer wouldn't be a viable treatment if subjected to the same level of regulation as gene therapy.