Thursday, March 20, 2008

Why medical experiments matter

A couple of days ago, Orac wrote a long post about animal testing - Bad scientific arguments in the service of "animal rights" activism.

Personally, I dislike furs and am against unnecessary animal testing ("unnecessary" of course being the hard-to-define keyword). Necessary testing, such as medical testing, on the other hand, I'm all for, and Orac gives many good arguments for why I should continue endorsing it.

One of the good examples that Orac mentions Dr. Judah Folkman, who did some critical cancer research on mice.

Folkman found a mouse tumor model that mimicked this behavior and in the early 1990s did a series of pioneering experiments. In a strain Lewis lung carcinoma cells of low metastatic potential (LLC-LM), when cells are injected into C57BL/6 mice and allowed to grow subcutaneously, if the tumor is left alone, mice develop only microscopic lung metastases. These metastases do not grow and kill the mouse. If, however, the primary cancer is removed, then many large lung metastases grow rapidly. The results of the experiment above strongly implied that the primary tumor is secreting something that suppresses the growth of microscopic metastases. After this, the Folkman group did what we like to call "brute force" science, collecting mouse urine and analyzing it for tumor suppressive activity until they were able to purify a single 38 kDa peptide, which they designated angiostatin. This involved analyzing literally gallons of mouse urine. (Who said science isn't glamorous?) Once Folkman's group had a bunch of angiostatin on hand, it peformed the following experiment. Two groups of mice were injected with LLC-LM and the tumors allowed to grow to a certain size, after which they were surgically removed. One group was treated with angiostatin, and the control group with saline. The result was that the control group developed massive lung metastases and died, while the group treated with angiostatin had microsocopic lung metastases that never grew beyond a ball of cells. Dr. Folkman then demonstrated that it was the inhibition of angiogenesis by the angiostatin that kept these tumors in check. Ultimately, he used a similar method to discover endostatin, and later he demonstrated that endostatin could induced tumor dormancy in mice. I trust that the reader can see how these seminal preclinical observations about angiogenesis would have been virtually impossible without animal models, given that angiogenesis requires the interaction between tumor cells, cells in blood vessels, and the surrounding tissue stroma to occur.


Of course, after this was done, Folkman could move on to testing on humans, but the animal testing was vital.

Just to put Orac's example into perspective, the very next day the NY Times, had an article about one of the humans involved in the tests - A Daring Treatment, a Little Girl’s Survival. The treatment is still being researched, and the data is so far anecdotal, but it seems promising. This means that it looks like Folman's experiments on mice will end up saving the lives of many humans, including the small girl mentioned in the NY Times article.

I'm sorry, but if I have to choose between humans and laboratory breed mice, I'll go for the humans.

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2 Comments:

Blogger The Evolved Rationalist said...

The people who are opposed to animal testing should offer themselves as lab rats instead. That would solve the problems, no?

March 21, 2008 6:12 PM  
Blogger Efrique said...

I'm greatly concerned about suffering we visit on animals (whether in labs, on farms, in slaughterhouses, in homes, or just in the wild, and I think we should do what we can to minimize animal suffering. (And I doubt many scientists would say much different.)

That said, I think one thing that we need to remember is that it's not just humans who benefit from the understanding that animal experiments gives us - animals, too, benefit.

April 15, 2008 5:27 AM  

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