Slanted Science

If you arrived here after an internet search for ‘nude mice‘, then you’re either in need of psychiatric care, or else you’d like some more information on a very important laboratory animal. Or both.

Either way: welcome!

Our recent story, describing the significance  of the naked mole rat in cancer research, reminded us of another example of nudity in this field. And so we give to you the nude mouse: over 40 years at the forefront of the race to develop new treatments for cancer and other diseases.

Background
Take a look at the picture above. The white, furry fellow on the left is a standard laboratory strain of mouse. The odd-looking, furless guy on the right is a strain of lab mouse called a ‘nude‘.

A quick note here: strain is in no way the same thing as species.

You probably know that mice and dogs are members of different species: they cannot produce fertile offspring (and it makes us chuckle to imagine them even trying). You probably also know that there are types of dog, such as Golden Retriever, Pug, and Rottweiler. Aother names for these doggy types is strains, and in the same way, there are strains of laboratory mice.

An individual strain of mice has some key genetic characteristics which identify it from other strains. When scientists breed one strain with itself repeatedly, it is said to be an inbred strain, and has very pure genetics. Breeding two or more different strains with each other produces an outbred line of mice, which partly retain the genetics of each of their parents, but in a mix-and-match kind of way. They are no longer a pure strain.

Hope that helps, but if you’d like some further assistance, please feel free to email us with specific questions at this address: Questions@SlantedScience.com. We’ll do our best to help you directly, or at least point you in the right direction for more in-depth research.

Discovery
In 1962, a Dr Grist – working at the Ruchill Hospital in Glasgow, Scotland – noticed an unusual trait appearing amongst his collection of breeding mice: apparent hairlessness.

As a previously-unseen phenotype (that means the physical manifestation of any particular gene), this was of interest to the doctor, and he continued to breed these particular mice.

Over the next couple of years, Dr Grist and others made some interesting discoveries about their apparently bald friends. Firstly: they weren’t truly hairless. They had just as many hair follicles as any other mouse, but the hairs these produced just curled around under the skin, never erupting into the outside world. Secondly: they had no thymus.

The Effects Of Being Athymic
Being without a thymus – in scientific terms they are athymic – means that nude mice cannot make a type of white blood cell called T-cells. A full description of T-cells is beyond our scope, but here is a link to their page on Wikipedia.

All that’s important for us here is that being without T-cells massively reduces the immunological defense system in nude mice.This means that they cannot fight infections very effectively or – most crucially – reject organ transplants.

Nude Mice As Tumor Recipients
This is where we see the true importance of nude mice in scientific research.

When scientists were looking at the effectiveness of new anti-cancer drugs, they previously had two choices: a) Test the drug’s efficacy using cancer cells grown in a Petri dish; or b) Give the drug to patients, and accept that it might be toxic or ineffective.

But some enterprising researchers realized that the nude mouse might allow them the best of both worlds: using human tumor cells, growing in a real living body, but with no risk to human patients.

How? Well, scientists could take a tiny piece from a human tumor – whether it’s in the brain, lung, pancreas, or anywhere else – and implant it under the skin of a nude mouse. It would then grow, just as though it was still inside the patient. After some time, it could be removed, split up into smaller pieces, and then put back under the skin of several more mice.

Grown in this way, one fragment of a human tumor could be propagated forever in as many mice as required, and this allowed scientists the ability to test their drugs in groups of mice, all growing the same tumor.

In this way, the nude mouse has been an absolute minstay in cancer drug discovery for the last several decades.

So, be thankful to this little creature, and his love of public nudity. He is saving lives every day.