For the first time in history, scientists have reprogrammed a whole batch of skin cells into a self-organizing, functioning network of brain cells, says a new study.
That’s right, y’all – Dr. Sheng Ding at UCSF is blowin’ up the stem cell research game once again – except this time, instead of just reprogramming individual cells at the genetic level, he’s flipped a molecular switch that tells a whole puddle of ‘em to morph into neurons, hook up with their neighbors, and consolidate into a working neural network.
Also, Prometheus came out this weekend. Coincidence? You decide.
[Quick Lil Note: this announcement is so brand-new that the actual paper hasn't even been released online yet - so I'm goin' off the official press release for right now. I'll keep my eye out for the paper, and post updates/corrections/etc. here as soon as Cell Press makes it available for viewing.]
Induced pluripotent stem cell research has really been booming over the past six years or so, ever since Shinya Yamakana demonstrated that adult somatic cells could be artificially induced to transform into stem cells – and those induced pluripotent stem cells (iPSCs) could, in turn, be told to develop into just about any other kind of cell in a mammalian body.
And just like that, the whole big Stem Cell Controversy became about as relevant as an 8-track player, while biologists got to work cookin’ up batches of iPSCs from skin cells and other tissue, and growing their new stem-cell zombie armies into things like very early-stage human embryos, and mice with two genetic fathers. Why? Because Science! That’s why! If ya scared, go to church.
Seriously, though – just picture this scenario: you’ve got a malignant tumor in your heart, and you’ve got two months to live. You’re not famous or wealthy, so your name isn’t at the top of any transplant recipient lists. But if your insurance will pay for it, a cutting-edge lab will grow new heart parts from your own cells – perfectly healthy, good-as-new, and 100 percent guaranteed to be biologically compatible. All that’s left is to remove the tumor, stick in the new bits, and let your body’s natural repair mechanisms take over from there.
Now imagine the same principle holds true for every organ and tissue in your body, and you can see why formidable stacks of cash are being thrown at this field right now.
Anyway, as you might expect from all this meddling with the fabric of life itself, the long-term results haven’t been perfect. For one thing, mice grown from iPSCs have a tendency to develop cancer. The rate is fairly low – around 20 percent – but that’s still enough to raise some yellow flags about using iPSCs to heal human tissue.
Another major hurdle for iPSCs right now is the frustratingly low rate at which ordinary cells can be successfully converted into iPSCs at all – the world’s top-tier teams are getting success rates in the .01-.1 percent range. For the less mathematically inclined, that’s a success rate of less than one percent. It’s improving, but only gradually.
One of the problems that really keeps stem cell researchers up at night, though, is how to create a sustainable batch of induced neural stem cells (iNSCs) – stem cells that can be trained to grow into all sorts of neurons.
A lot of teams have tried to work with iNSCs – a group led by Su-Chun Zhang at the University of Wisconsin-Madison School of Medicine and Public Health made a valiant attempt back in 2010 – but (and here I’m going to use some Official Scientific Jargon, so bear with me) “The cells always just kept doing a bunch of random shit.” In other words, the iNSCs failed to cooperate with the godlike masters who had endowed them with life.
That’s where Sheng Ding and his team at UCSF enter our tale, the journal Cell Stem Cell reports. Over the past couple years, Ding and his team have earned a reputation as world-class iPSC masters – mainly because of their (relatively) high success rates at reprogramming adult cells from humans and mice into iPSCs, and converting those iPSCs to all sorts of other cell types.
So when Dr. Ding heard all this whining about iNSCs, he just stepped right up and threw down, like, “Get on my level!”
Within days [our] skin cells transformed into early-stage brain stem cells, also called induced neural stem cells (iNSCs). These iNSCs began to self-renew, soon maturing into neurons capable of transmitting electrical signals. Within a month, the neurons had developed into neural networks.
How’d he manage to sustain viable iNSCs – not to mention make them cooperate? Wish I knew. I’m still waiting for the actual paper – I’ll post updates as soon as Cell Press releases it and I can read through the details.
Ding says he thinks iNSCs will prove to be beneficial not just for healing brain damage and studying diseases like Parkinsons, but also for growing complex neural networks to precise specifications – then testing and modifying at will.
Which makes me wonder…what if someday soon, we start growing neural networks designed to test, say, pain responses? How might we feel about causing them pain, if we knew this was their purpose? And even more intriguingly, if several teams have already bred viable mice from iPSCs, how long can it be until we’re growing humans from them?
…or just humanoid brains…?
How would you react if you saw the headline, “Working Human Brain Grown in Lab” on the front page of the New York Times one morning? What would it mean to you?