Once again, I am about a week behind the news—
Last week’s Nature included a report, covered in the general press, that researchers at UCLA had caused “stem cells derived from human skin” (i.e., induced pleuripotent stem cells, or “iPSCs”) to differentiate into clumps of brain-like tissue in the laboratory. Apparently, embryos need not be and were not created or destroyed to do this work. The immediate goal was to get a laboratory model of a disorder called “microcephaly,” a disorder in which brain growth and, consequently, cognition are severely impaired.
As with other iPSC work, stem cells were derived from the skin of people with and without microcephaly, then the iPSCs were treated in the lab with a mix of factors to get them to grow and differentiate into brain cells. One of these factors was a gel that mimics natural connective tissue in the human brain. (Our organs are built on these connective tissue “scaffolds,” creating a potentially fruitful path for engineering new, healthy tissues or even full organs to replace diseased ones. In another context, work is attempting to generate a human heart by taking a cadaver donor heart, stripping the heart cells off of the scaffold, and getting new heart cells to grow from iPSCs that would be derived from the skin of someone who needed a heart transplant. This is still a distant prospect, but a potentially interesting one.)
In the brain tissue experiment, pea-sized clumps of tissue were obtained that resemble—but only very loosely—brain tissues that interact with one another. The brain tissue clumps from the cells of the microcephalic person had abnormalities in development, compared to the clumps obtained from the cells of the non-effected person; these abnormalities were consistent with hypotheses about the cause of microcephaly. How compelling this result is, I don’t know, nor do I know whether it’s all just a case of confirmation bias—seeing what we want to see based on what we already think is true. But it sounds like great work, in any event.
This work appears clearly ethical, using ethically-derived stem cells to create what is truly a clump of cells, and not a new individual, in a way where no human/non-human hybrid is created, all done for an ethical goal. Even if the work proceeded to the point of brain tissue engineering and therapy—for example, to treat someone who had a stroke—that looks like an ethical research and development path, assuming that embryos are not created or destroyed to do it.
What gets the headlines, of course, is the notion of creating an artificial brain in the lab, in much the same way as the heart example described above. I’m not losing sleep over this one. To begin with, last week’s new reports will full of the sort of blithe statements that crop up even in good science writing like you see in Nature:
- “A fully-formed artificial brain might still be years away…” [might be?]
- The clumps formed had “no recognizable physiological structure”
- They also “lacked blood vessels,” limiting their growth, and
- “Normal brain maturation in an intact embryo is probably guided by growth signals from other parts of the body.”
These statements, especially the last one, speak to the organic development of living individuals and the limitations of any plans, or interpretation of the results, of organ engineering results along lines like those described here. First, even if one could “build a brain” (or a complex structure that was a candidate to be called an artificial brain) in the lab, it would be isolated neural tissue, not a new individual, I would argue. Now, one could counter, “Let’s do the experiment. Let’s see how this thing handles inputs, and measure the resulting outputs.” And I could imagine a descendant of Ray Kurzweil trying that. But it seems to me that the required peripheral apparatus—essentially, a brain and an environment—would be so cumbersome and unachievable that any results with the artificial brain would be so limited that the relevance would be called into question. Put another way, the more complex the phenomenon to model, the more dubious the model becomes. Put the artificial brain into a robot, you say? That would be some robot—trying to mimic the full range of human experience. Well, we already have lots of robots to do things—industrial robots, robot vacuum cleaners, “face robots” to take care of people—and they really all compromises to accomplish limited goals, with varying degrees of success.
As readers of this blog well know, if one wants to manufacture a person, the various ARTs and cloning are more direct approaches, and they seem more technically and ethically relevant—even in a highly optimistic read on synthetic biology’s prospects, I think—than building a person with a brain entirely from raw materials.
Put another way, the scarecrow will have to make do with his diploma.
What about an eventual brain transplant? Have a future Young Frankenstein insert an artificial brain from “Abby Normal?” Again, why? Download one’s experiences for “immortality?” Someone would want to try this dubious project. It seems like one could choose more durable hardware than neurons. Prolong life in the human body? A lot of other cybernetics would be needed—kind of like Robocop. And how would one get from here to there? I can’t conceive of anything that would look like an ethical experiment under the current understanding of experimentation on human subjects—even with an expansive view of autonomy. Space prevents an attempt to elaborate. I suppose that could be left for the comment section.