Submitted by InZerSchtinker t3_10bo6os in askscience
saganmypants t1_j4bbnde wrote
Cancer cells are grown in vitro and then injected into the animal at the desired location of the tumor. For most reliable model systems the parameters for what cell subtype to use and how many cells to inject are known and published
theythembian t1_j4bqyra wrote
Amongst that scientific community, is this considered ethical or a necessary evil?
saganmypants t1_j4brme8 wrote
I think it depends on who you ask, but most likely the people engaging in this work would believe that it is necessary at the moment to move medicine forward. There are panels that oversee the experimental design of any such study and I can assure you that they take their job very seriously. My PI in grad school was roasted by them during a meeting because he had not adequately outlined a pain management protocol for the mice in our study that were getting an experimental cancer drug. Everything in these studies is done with ethics at heart
tourniquette2 t1_j4cu2v1 wrote
Ok, the pain management protocol for mice gave me the warm fuzzies. At least they’re not just being tormented. I always considered animal testing only borderline ethical at the best of times, but it’s at least reassuring that their pain is managed and they’re kind of cared for.
[deleted] t1_j4fiam8 wrote
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theythembian t1_j4btykt wrote
How interesting! Wow have they always cared to conduct studies while being ethical? Or is this a recent change that scientists intentionally approach these experiments with ethics/compassion in mind?
itakestressnaps t1_j4ccqe8 wrote
It’s been around for decades now, but i believe they’ve gotten stricter and stricter in the 21st century.
Usually, at least in the US, the institution has an internal committee, which also answers to higher ups outside the university. These internal committees usually have vets, bioethicists, other scientists who can validate that the science is clear and justified, etc. EVERYTHING has to be outlined in detail, prior to procedures, and no deviations can occur. There’s quite literally a strict rule for everything and anything you could think of. And of course, all personnel has to undergo ethics and technical trainings, online and in-person, and get certified and approved to work each protocol.
Any modifications to protocols have to written in detail, with justifications, and has to be approved prior to implementation. At my institution, there are also surprise visits where they drop in and watch you to make sure you’re following everything down to a T. And we have 24 hour animal techs and vets on call.
Animal work is not my favorite, even though I do it for certain things. And there are definitely a lot of people that prefer not to do it themselves, but the biomedical community in general does believe it is necessary. After all, medicine is where it is now because of animal research. It’s saved countless lives and extended our life expectancy by a LOT in many countries.
_BlueFire_ t1_j4dr0k2 wrote
We're looking for alternatives, but until we'll be able to replicate an entire system in vitro the results won't be as reliable. That would lead to less reliable drugs or a much slower progress, as we would need human testing for more possible drugs.
There are those who see one way or the other as the better, it really depends on your "ethical priorities"
wakka55 t1_j4clgwr wrote
Can you inject any mouse off the street and give it the cancer? Or are these special genetically matching mice that don't reject the injection immediately as a foreign invader?
What if you inject a human with it? Do the researchers need hazmat suits to handle these mice?
saganmypants t1_j4craod wrote
You probably could do any old street mouse but there are companies who produce litter after litter of genetic cloned mice so that your results are consistent and not dependent upon genetic variation. There are different mouse models, but in many cases the mice have compromised or differently engineered immune systems to mitigate immune system interference.
Typical experiments use mouse cancer cell lines so if injected into a human it would be rejected by your immune system, but there are some models of mice with humanized immune systems which are capable of acquiring human cell tumors and those cells could theoretically be transplanted into people. Usually no hazmat suits AFAIK, just typical gloves and lab coat. I am merely a synthetic organic chemist so I don't know much more detail beyond that but have learned enough about it through colleagues who go on to test the things we make
research_guy17 t1_j4cvxlz wrote
You could attempt "any mouse off the street", but primarily tumor xenograph models are established in SCID mice, bred and cloned for the function. SCID means they are immune deficient, otherwise the immune system of the regular mouse would likely generate antibodies to the injected cells and either reject the attempt to grow the tumor or result in poor health or even death of the "regular" mouse.
captaincumsock69 t1_j4e5hrs wrote
They use mice that are either purchased or bred for the research. They might use genetic knockout mice or just wild type depends on the project. Presumably if you injected a juman with it a tumor would grow but this is not allowed in most countries
Tasty-Fox9030 t1_j4ffbog wrote
This sounds so cartoonishly evil that it's difficult to believe, but people have actually been deliberately injected with human cancer cells and they generally do NOT get established.
Horrible but true:
Tuskegee syphilis study not America's only medical scandal https://aquila.usm.edu/cgi/viewcontent.cgi?article=1242&context=ojhe
In general it's going to be ok because a healthy immune system is going to recognize the cells as foreign. The problem with getting cancer for the most part is that they ARE your cells. (Ideally your body recognizes your own cancer cells anyway but you get the idea.) If you're immunosuppressed for whatever reason it's possible.
ElkSkin t1_j4eh28w wrote
If injected cancer can take hold, why doesn’t skin or oral cancer spread person to person?
sciguy52 t1_j4eyihe wrote
It has to do with our immune systems. For example if you get a kidney transplant (and don't have an identical twin donor), the kidney will have cell markers on them that are used to recognize the tissue as "self". So the donor had a kidney with a certain set of proteins on the cells of all their tissues that their immune system can identify its own tissues as "self" and the immune cells will not attack them while in the donor's body (in a healthy person). The kidney recipient will have their own set of these proteins that do the same thing, however the donor and recipient have differences in these markers between them. Those differences cause the recipients immune system to recognize the donors kidney as not self but "foreign" so the immune system attacks. This is why we give immune suppressing drugs to transplant patients for life to stop the immune system from killing the organ. If you were lucky and had an identical twin, then these "self" markers would be identical too, and you could get a kidney from them and the immune system would not reject it and no immune suppressing drugs needed.
Instead of kidneys, lets say you injected tumor cells from the donor into a non identical twin recipient what happens? The vast majority of the times the immune system will recognize these as "not self but foreign" and immediately attack and kill them. This is why most of the time you can't exchange cancer cells with another person and give them cancer. Again, identical twins? Different situation. Their "self" markers are the same so cancer cells from one twin would not be attacked by the other twins immune system and could grow and give the recipient cancer. This simplified a bit gets the concept across.
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