Man, I should have posted this on valentine’s day. Totally missed an opportunity there.
A friend of mine turned me on to this really cool article about using stem cells to help make heart transplants more viable. (Thanks Sarah!) This is definitely some super cool technology that we’re talking about here, and it represents a pretty amazing breakthrough in transplant technology.
However, this article’s headline and first few lines are crazy misleading. What we are absolutely NOT talking about here is doing away with the need for donor hearts. Maybe, MAYBE, this is a small step in that direction. Maybe. Or maybe not.
What this IS is a way to completely eliminate the risk of rejection of a transplanted organ, and allow transplant recipients to live without the need of immunosuppressant drugs. Which is HUGE. Please don’t think I’m being a humbug here; this is really, really cool research that when perfected will make a huge difference in the lives of many, many people. What this research is really doing is totally cool enough on its own, we don’t need to pretend that it’s doing something that it’s not.
So what is it doing, you may ask. Fair question. Let’s break it down, and take this one crazy-cool, pretty-much-miraculous innovation at a time.
To begin with, we will need a donor heart. Check. Okay, what do we do next?
Well, next we strip away all the cells, leaving only the extra-cellular material.
Okay, I don’t know about you, but this is the part where I start to realize that my entire understanding of the human body that I developed in high school biology was WRONG.
::shakes metaphorical fist at high school biology teacher, who was sort of a jerk anyway, so can be unfairly burdened with the blame that should actually be mounded on the tyranny of an outdated, curriculum-enslaved system of education::
Right, so my high school biology class taught me that the human body is made up entirely of cells. If you took the cells away, there would be nothing left. They didn’t mention this whole “extracellular material” thing. Turns out that we have a whole framework of structures running throughout our bodies that provide support, both structural and biochemical, and actually do a lot to define the different parts of our bodies.
I could keep talking about this forever, but maybe you should just go read the Wikipedia article and save us all some time.
Anyway, back to that donor heart we started with. After you strip away all the cellular material (again, how you do that is a very interesting question, but in the name of saving time I’ll just link you to the Wikipedia article), you are left with a genetically neutral framework for a heart. Because it’s the cells and not the extracellular material that contain the immunogenic antibodies that our bodies recognize as foreign material in a transplant situation, this framework by itself poses no threat of rejection. Of course, it’s also the cells that actually make it a heart, doing all those incidental things like, you know, CONTRACTING in order to move blood. The framework by itself is useless. So…what do we do to make this a functional heart again?
We introduce induced pluripotent stem cells, of course!
What’s that, you ask? I’M SO GLAD YOU ASKED! This is where things start to get really cool.
A pluripotent stem cell is just a cell that has the capacity to become any type of cell in the human body. They occur naturally in embryos, as part of the miracle of life that allows a single cell to grow into an enter human being. An induced pluripotent stem cell is a regular, adult, single-purpose cell that has been converted into a pluripotent cell through the introduction of specific proteins.
Yes, we can do that. Shinya Yamanaka won a Nobel Prize in 2012 for figuring out how to do it.
SCIENCE IS SO COOL GUYS!
So basically, scientists are taking some skin cells from an adult person, changing them into pluripotent cardiac cells, and introducing them into this neutral extracellular structure that they got from stripping all the cells out of a human heart. The new cells use the extracellular structure as a sort of scaffold and grow new heart tissue into the existing framework, in a process that is (I kid you not) called “recellularization.” That’s the word of the week, guys. Recellularization.
It’s a pretty cool idea, right? Growing a new heart that is a perfect genetic match for a transplant recipient. But does it work?
Well…sort of. Probably. We’re getting close.
There are still problems. It’s hard to create enough of the induced pluripotent cells to grow a whole heart, for one thing. And it’s really hard to replicate the interior conditions of a human body to allow for natural growth, for another. Researchers are also trying to figure out a way to make the whole process go more quickly.
But still, they did it. The hearts they produced were essentially immature, but they WORKED. The researchers were able to get the artificially grown hearts to beat. And that’s amazing.
So, in conclusion: science is cool. Yeah. Also, bodies are cool. And medical research is cool.
Or, if you want a more profound conclusion, consider this: the first successful human heart transplant took place in 1967. The patient survived for 18 days. That was only 49 years ago.
In a span of time that could easily contain a single adult human’s working career, we have gone from barely understanding the complexities of immunologic rejection to finding ways to subvert it entirely. I don’t think there is any field of science which is leaping ahead with the rapidity that medical research has show in the last few decades. Speaking as a relatively young person in my early 30’s, there is no way to know what could be possible in terms of medical treatments in my lifetime. Because of that, there is no way to predict what my generation’s average lifespan might be. We have broken the curve, and everything from here on out is unknown territory. Heart disease is still the leading cause of death in the US today. But tomorrow…who knows?