Thursday, May 01, 2008 - Posts
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How do you feel about mass-producing and selling human tissue in machine form? I hope you like the idea. Because it's on the way.
A few days ago, the University of Michigan trumpeted a study validating the efficacy of its "bioartificial kidneys." In a clinical trial involving people with acute renal injury and failure, the kidney boosters cut the usual death rate (compared to patients using conventional "continuous renal replacement therapy") from two in three patients to one in three.
Pretty amazing. But just what is a "bioartificial" kidney? Here's U-M's description:
The bioartificial kidney includes a cartridge that filters the blood as in traditional kidney dialysis. That cartridge is connected to a renal tubule assist device [RAD], which is made of hollow fibers lined with a type of kidney cell called renal proximal tubule cells. These cells are intended to reclaim vital electrolytes, salt, glucose and water, as well as control production of immune system molecules called cytokines, which the body needs to fight infection. Conventional kidney dialysis machines remove these important components of blood plasma, along with toxic waste products, and cannot provide the immune regulation function of living cells. Initial testing in animals ... found the cells in the RAD perform the metabolic and hormonal functions lost in acute renal failure.
This is the point I've made in recent posts about biological pacemakers and limb regeneration. Prosthetics are nice, but flesh is better. That's why the U.S. Army is now funding tissue regeneration. Instead of trying to reengineer everything in biology, we're learning to borrow, cultivate, and replicate it. Let Mother Nature do the work: She already knows how to filter toxins while keeping what your body needs and regulating your systems.
David Humes, the professor behind the U-M study, is also the scientific founder of the company that's preparing to commercialize the RAD. He envisions the new paradigm this way:
[T]he nature of our new approach -- using living cells as therapeutic agents -- argues for the feasibility of developing whole classes of new cell-based and tissue engineered therapies. The ability to harness vital processes of cells, to target their living molecular machinery on restoring critical substances which have become disordered by disease, has vast implications for the future of medicine. The apparently successful use of living cells in this way validates our approach and should encourage others to investigate cell therapies for a range of disorders.
Technologically, this is a sensible and powerful idea. It will save lives. But as an inflection point in our thinking about human flesh, it's, well, pretty RAD. What we're getting into is not just the commercialization but the mass-production of body parts. It's a bit like PETA's campaign to commercialize lab-grown meat -- except that in this case, the meat will be human.
Where do we get the cells in the cartridge from? According to the American Society of Nephrology, they're "grown from donor kidneys." So we're starting with somebody's donated organ. Instead of transplanting it to one person, we're growing cells from it, which can then be farmed out to multiple patients. We're not just distributing the cells; we're incorporating them into what U-M calls a "living cell cartridge." It's bio -- it's artificial -- it's bio-artificial.
Like lab-grown meat, the living tissue in the cartridge may run into spoilage problems. U-M notes that its researchers are still working on the "challenges of mass producing, storing and shipping a living-cell device." But the goal, according to the nephrology society, is definitely "mass production." And the next step will be to repackage it as a "wearable kidney that performs natural functions unachievable through man-made technology alone." Real flesh, grown from somebody else, mass-produced, packaged into a cartridge, and worn on your body. Good luck sorting the bio from the artificial.
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I'm working on a post about bio-artificial organs for later this afternoon. In the meantime, I want to call your attention to a related item in this morning's news batch: a report in New Scientist about plastic red blood cells.
First of all, can I just say: I love New Scientist. It's one of the coolest things you could spend your time reading. They do just about the world's best job of keeping tabs on the latest far-flung developments in science. Believe me, I've been trying to do this for a month, and it's incredibly hard. It's not like politics, where everybody agrees on central characters and a narrative, like Hillary's latest photo op or what Obama ate for breakfast. You really have to scan the horizon and stay on your toes.
In this case, NS reporter Justin Mullins has flagged a patent application for plastic blood cells. If you get malaria or sickle-cell anemia, your red blood cells lose the agility to pass through small blood vessels. Wouldn't it be great if we could give you artificial blood cells to do the job? The patent application proposes exactly this: tiny "sacks" made of a chemical that's biologically harmless and binds easily so it can carry oxygen or carbon dioxide. Experiments in mice look OK so far.
The idea of having little plastic sacks pumped into your bloodstream sounds pretty freaky. We're talking about filling you with petroleum products in a way that challenges the meaning of "flesh and blood." For all I know, further animal or human testing may find unforeseen health risks from this kind of mixture, particularly at such a small scale and with such pervasion of the body. But if the technology turns out to be safe, it'll go a long way toward loosening our concept of ourselves as biological creatures.
So much for artificial technology replacing biology. Next, we'll talk about the reverse.
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