For the first few millions years of our existence we got our chemicals directly from other organisms or the ground. People managed to come up with a lot of clever ways to extract, purify and modify these chemicals over the years since to make useful stuff: leather, beer, bronze, paper, vulcanized rubber, and the plastics of the great synthetic chemistry boon of the first half of the last century. It's been even more incredible what ingenuity people have demonstrated in identifying chemicals with medicinal properties in the organisms around them - and improving them. The significance of penicillin was not lost on the scientists who noticed it clearing colonies around the little ascomycete that produces it, but it didn't start saving soldiers until an ambitious germplasm collection and breeding project resulted in an isolate that produced prodigious quantities of the antibiotic, and synthetic chemistry altered its chemical nature to protect it from stomach acid. It's a testament to this triumph that those of us born since have such a cavalier attitude toward "infection." Lacerations are rarely fatal in the developed world these days.
Scientific medicine has begun to turn on the fulcrum of molecular/personalized medicine. Enormous investments have been made to determine the chemical signals that make the difference between a well-behaved, healthy cell and cancerous or infected ones. Increasingly, chemicals have been identified that radically affect the procession of disease, but they are often too complex to be synthesized economically by traditional synthetic organic chemistry.
As there's nothing new under the sun, we're back to looking at plants for our medicines. Organisms make chemicals. It's what they do. Chemicals that would be exceedingly expensive to produce in a test tube are routinely produced in our own bodies. So what happens when a chemical in our body is found, under certain conditions, to cure?
Bioreactors are (largely still hypothetical) organisms that has been genetically engineered to produce chemicals we value - medicines, industrial feedstocks, foods, and fibers. Medicine leads the way since we pay the most for it. Several systems have been successfully used/proposed to produce these engineered chemicals. These include transgenic animals, liquid culture of mammal cells, liquid culture of bacterial or fungal cells, or plants. Each has pros and cons. Plants for example can be grown (in agricultural settings) far cheaper than any other bioreactor, but present a high containment risk (i.e. if you have a transgene that you REALLY don't want to escape into the natural world, you're better off in a BSL-4 factory than some field out in Iowa).
And here's what I really am here to write about: An article I came across the other day that suggests that moss may be the ideal bioreactor*. I hadn't realized it was in the running. In a few decades, when you're being kept alive with cutting edge drugs that used to cost millions of dollars a gram, you may have that green stuff to thank.
Many of the advantages of moss also exist in "true" plants, but there are additional ones.
- Plants (like mammals) can produce complex, multi-part, and highly modified chemicals. Bacteria and fungi generally produce simpler and generally less 'animal-like' chemicals.
- In contained cell culture, plants can be grown much cheaper than animal or microbe cells
- Plant bioreactors won't be accidentialy contaminated with human pathogens
* Current Opinion in Plant Biology 2004 7:166-170
