At the moment, variations of the CRISPR-CAS system can only edit the genome of individual cells in vitro with varying efficiency. This is assuming you can culture the cells to begin with. For example, I work with human embryonic stem cells, which are particularly finicky. They won't tolerate much roughness and will even up and die on you if the growth conditions are just a bit off. This is very hard to achieve reliably as some culturing reagents (coating matrix, for example) are "undefined" products with variations in composition from batch to batch.
To go to a chop shop and treat your issue at the genetic level requires an in vivo way to introduce a CRISPR-enabled vector into your cells. This is not easy to do with today's technology, but it may not necessarily be a deal breaker. In the example you gave, a food allergy can probably be addressed by treating only the GI tract and the immune system that comes into contact with the offending allergen. As such, there is no need to target every living cell in your body in this case. However, if you are treating an illness involving a more fundamental life process, that is not the case. For example, a mitochondrial disease where basic cellular metabolism is defective would probably be best tackled when an individual is still a developing embryo or at least very, very young. Otherwise, tissues and organs that are not convenient to access will still retain the genetic defect and present problems for the host organism.
Another question is where in the genome you want to edit. So far, one of our experiments involving the targeted insertion (non-CRISPR method) of a construct into our hESCs have been a bust. Our best guess is that the intended site of transfection (sub-telemeric regions of chromosomes) is critical for cell survival and too much fiddling in the area is fatal. CRISPR-CAS was a compelling solution for us because of how ideally targeted it is supposed to be. We are not aware of anyone else who've used CRISPR with hESCs in the way that we are doing, but what has been reported so far with other experiments using notoriously difficult subjects has been encouraging. So far, the experiment shows clear evidence of true integration into the genome as opposed to a transient transfection. In about a week, a Southern blot verification will tell us if the integration was random or indeed targeted.
As rosy as I can paint a picture about what is possible, however, strong caution follows the introduction of any new technology. Anonymous Coward may be an asshole, but (s)he isn't wrong for being a cynic about the commercial deployment of this as a consumer product. Considering how complex human biology is, the chance of an unintended edit with unanticipated consequences is more than likely. Many genes are linked in very convoluted ways. Even with the human genome project having ostensibly mapped everything, we are still looking at just the tip of the iceberg. Having a complete manuscript, is very different from understanding all the nuances of the story. To get back to the spirit of your question, I would imagine that the scenario probably is more similar to dental service, where you go back periodically to check on the integrity of any major service, with tweaks along the way as necessary.
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Are there any useful avenues for tracking down forgotten developers? Should I go ahead if I can't find them? Have you ever had a situation where you needed something you knew was out there, but could no longer find?"
According to Falk, Shakespeare’s characters were connected to the cosmos in a way that seems quite foreign to the modern reader. Whether crying for joy or shedding tears of anguish, they look to the heavens for confirmation, calling out to “Jupiter” or “the gods” or “the heavens” as they struggle to make sense of their lives. "[Shakespeare] lived in an age of belief, yet a streak of skepticism runs through his work, especially toward the end of his career; in King Lear it reaches an almost euphoric nihilism. His characters often call upon the gods to help them, but their desperate pleas are rarely answered. Was Shakespeare a closet atheist, like his colleague Christopher Marlowe?"
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However the issue with embryonic stem cells are that they come from aborted human fetuses.
This is right-wing propaganda at its worst. embryonic stem cells DO NOT COME FROM ABORTED HUMAN FETUSES. They come from left over embryos that those seeking fertility treatment no longer need. They were never aborted because they were never implanted in the first place. Because they were never implanted, they never had the chance to develop into anything near resemblance to a fetus. Please get your facts straight, no matter which side of the debate you are on.
I work with human embryonic stem cells (hESC). I'm going to hazard a guess that you've bought into certain propaganda efforts attempting to mislead the public into believing ESC research "destroys" embryos. That is not at all the case. First a primer in cell biology: At a certain stage in their life cycle, most normal "somatic" cells enter a stage called "senescence" where they may continue to live but no longer divide and will eventually die. Stem cells, on the other hand, have the unique ability to continue dividing indefinitely without becoming "old". This "self-renewal" property makes a stem cell culture very much like the "mother dough" a baker would use to perpetuate starter cultures for years or decades.
Our lab uses uses cells that originated from fertility treatment at my institution's OB/GYN clinic. Individuals who have achieved a successful pregnancy would consent to allow fertilized but unimplanted embryos to be used for research purposes. (If we didn't ask for them, they would have been destroyed as medical waste.) During the early stages of growth, all the cells in the embryo have stem cell qualities and are all "self-renewing". Under artificial growth conditions, these cells are coaxed into remaining stem cells without developing further into a fetus with all different types of tissues and organs. As such, they remain masses of stem cells that could be split/divided and given to research groups as necessary.
So you see, a single embryo can establish a "cell line" that (depending on culture methods and/or skill/technique of cell-culturist) can be maintained indefinitely by researchers. At the moment, the "economics" of this has more to do with the resources needed to grow them rather than obtain them. Cell culture growth media is incredibly expensive right now because it is hard to keep these delicate, finicky guys happy in lab conditions. (Stem cells like growing in an organic environment - not in a dish.) So far, embryonic stem cells are only being used for research as a way to study some fundamental things that are still poorly understood. (Like for example how to grow cells intended for tissue/organ transplant in artificial conditions cheaply and reliably. Expect cost to come down as we make progress on this front.) My lab, for example, only grows enough of them to support a few experiments at a time on DNA damage/repair. Now, the anticipated therapeutic use of stem cells are different. But you would not necessarily need millions of them as one would as in the case of drug manufacturing to produce useful proteins. Because stem cells are "self-renewing", conceivably you only need enough of them to keep itself going in, say, replacing a failed organ or tissue.
At the moment, it is too early to concretely say what the future might look like where stem cells are commercially used for therapies. A couple of possible guesses for how they can be obtained: 1) a person donates his/her own by having parents who made the smart decision to bank "cord blood" saved from the umbilical cord when the baby was born. 2) the small minute number of stem cells that circulate in the blood or exist elsewhere in the body can be extracted. 3) Cells from other parts of your body that have already specialized into certain cell types can be treated to return them to a "stem-cell-like-state". This last thing is what people are talking about when they mention "induced pluri-potent stem cells" (iPSC). In any case, I find it hard to come up with a scenario where stem cells take on the qualities of a commodity to be produced for mass consumption. I suppose anything is possible, but other problems need to be solved along the way, like how to prevent organ rejection when your immune system recognize that your implant doesn't belong to you.