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Seriously, why do we still use mice in labs?

I was planning on posting a new blog post on new CRISPR results, then I realised 2 keywords in the title: this has been successful in mice. Almost every piece of research that I have posted on this blog has been either tested in mice or its been successful in mice.

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This got me thinking, why do we still use mice to test everything on? So many new drugs and other therapies have proven to be successful in mice, but when applied to humans, they weren't successful at all. 

If you type into Google Scholar in mice, app 3,960,000 results come up. So clearly mice are incredibly important for scientific research if so much has been published on them.

The well-known reasons...

  1. Small size
  2. Easy to house and look after
  3. Adapt to new surroundings easily
  4. Have a short lifespan (2-3 years), therefore we can study generations of mice in a short period of time
  5. Inexpensive and can be bought in large quantities
  6. Can be bred specifically for research (medical trials require mice to be inbred so that they are almost genetically identical. 
  7. Easy for researchers to handle due to their calm and submissive nature (although this is not always the case for some mice and rat breeds)

The serious reasons...

It turns out that we share an estimated 97.5% of our genetic makeup with mice, this is also less than one percent between humans and chimps. Sharing most of our DNA with mice means that scientists can carry out most research on mice and come out with some genuine results which can most likely be suitable for humans.

Another reason is that the genetic, biological and behavioural characteristics of mice are very similar to those of humans, and a lot of symptoms that humans experience during certain conditions can be replicated in mice and rats.

So, testing on mice has provided us with a lot of advancement in the research and development of new drugs and treatments and they continue to help us predict what the reactions would be in humans without testing on humans. Testing on mice is a "better" solution than having to test everything directly on humans, for the time being till there is a replacement. 

But the problem is, is that more than often, things that work on mice just don't work on humans and other drugs that don't work on mice, just might work on humans. To the extent that big pharma companies have lost billions of pounds, working on a new drug, only to find out it doesn't work on humans, and scrapping the entire project in the end.

Yes, this isn't very ethical (the mice are made to have genetic defects, health issues and other things, just to be tested on them) and PETA will certainly have a few things to say about this, but mice are filling a gap, not very efficiently, but still filling it till there is a replacement to test our new medical drugs on.

There's another option?!

Don Ingber, a biologist at Harvard’s Wyss Institute for Biologically Inspired Engineering, has an idea for a replacement to mice and rats in the lab. And he's called it "organ-on-a-chip". It's small, about the size of a memory card. and is able to "emulate the microarchitecture and functions of living human organs, including the lung, intestine, kidney, skin, bone marrow and blood-brain barrier".  

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"Each individual organ-on-chip is composed of a clear flexible polymer about the size of a computer memory stick that contains hollow microfluidic channels lined by living human cells interfaced with a human endothelial cell-lined artificial vasculature, and mechanical forces can be applied to mimic the physical microenvironment of living organs, including breathing motions in lung and peristalsis-like deformations in the intestine. Because the microdevices are translucent, they provide a window into the inner workings of human organs."     Wyss Institute at Harvard 

Ingber, with his team at the Wyss Institute, eventually hope to be able to develop this technology so it is able to identify new therapeutics and help the development of research on many other health problems and to also share this with other researchers and pharmaceutical companies.

For the time being, science will still be reliant on mouse and rats for the experimentation of new therapeutics and until then, we hope that a more reliable solution will materialise, to save our valuable time and money. 

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  1. I spoke with a researcher developing a lab model based on human cells recently. She said that she would still do tests both in an animal model (she uses baby zebrafish as they're thought to experience less pain than mice) and on the new lab model in order to give as much reliable evidence as possible that the ideas she's working on are correct.

    1. That is really interesting and it's great to hear that the new lab model is being actively used and producing reliable results :)


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