When you’re heart is broken, you’ll do anything to fix it. Even replace it with a pig heart. Scientists at the University of Minnesota have been working on stripping down hearts, removing much of the muscular and vascular tissue. What you get is a semi-translucent “decellularised” heart. Add some stem cells, and a new heart can be grown on this scaffold. A new heart that your body won’t reject, at least in theory. When Singularity Hub first brought you this story last year, researchers at UM were using the technique on rat hearts. Now, they’ve moved on to pig hearts and we’ve got a hold of some cool new pics and a short video from New Scientist. Check them out before and after the break.

At top, a rat's heart is decellularised until it becomes a scaffold. Stem cells from mice are then applied to the heart, and it is recellularised at bottom. Photo courtesy of University of Minnesota.

It's alive! This rat heart is being pumped in an artificial structure, allowing stem cells to grow into a new version of the organ. Photo courtesy of the University of Minnesota

The biggest problem is making sure that each heart grown is fully functioning and able to be transplanted. After being decellularised, each heart has to be recellularised by applying a coating of stem cells and having blood pumped through the heart scaffolding. Along with chemical signals from the scaffold cells, the blood allows the stem cells to specialize into the various needed tissues. Looking at the rat hearts in the pumping machine, it’s hard to believe that you are looking at a living, autonomous organ outside a body. Check out the video from New Scientist:

The ultimate goal, as you would guess, is to radically increase the availability of hearts for transplant in humans. While pig hearts provide a good scaffold, we may see human hearts (from cadavers) as the finalized product. Similar techniques are being used for livers, kidneys, and lungs. Using a patient’s stem cells, and either pig or cadaver scaffolding, doctors may be able to “grow” organs for transplant. Organs where most of the cells share the same DNA as the patient. It’s the ideal situation.

But we are years away from that case at the very least. The University of Minnesota first released information on their research on rat hears back in January 2008. Eighteen months later, and we’re just now seeing pig hearts in various stages of decellularisation. If and when recellularized pig hearts can be transplanted into pigs and keep them alive (the test already passed with rat hearts) we may hear talk about starting human trials. Judging by the slow but steady progress so far, this may be three to five years away. Fortunately, heart transplant patients have some experience with waiting and hoping.

From left to right: A normal pig heart, a pig heart after being decellularised, the pig heart prepared for recellularisation. Photos courtesy of the University of Minnesota.

Printing blood vessels one plane at a time

Well, not quite. Although the website’s generic mission statement alludes to being able to print whole organs, like hearts or kidneys, that technology is quite a long way off. The research published by this federally funded project founded by Dr. Gabor Forgacs, a researcher at the University of Missouri, indicates that the company is first working on printing fully functioning blood vessels and arteries.

Organovo claims that printing blood vessels from the patient’s own cells will enable a transplant, like a bypass surgery, to work better. There is little to no chance of the patient rejecting the cells, as they are autologous. Another advantage of the bioprinting system is that there is no need for plastic scaffolding, which is said to cause inflammation and reduce the effectiveness of the transplant.

The idea behind the printing system is that the organ is printed layer by layer. A printer, using cell globules as ink, places them down onto a bio-degradable sheet of paper, where the cells naturally fuse together to create a small piece of the organ. A piece of bio-paper is put between each layer of the organ and, after all of the cells in the same layer are fused, the paper disintegrates and allows the different layers to fuse to each other. Eventually, after many layers, the blood vessel will materialize and be fully functional. Take a look at the video for a better explanation and some pretty 3-D computer model rendering:

There is a lot to be said about hyping a product. Much like the law of inverse excellence haunts the cinema industry (the more trailers you see on the television, the worse it will be), the more people make a big deal out of this technology, the less likely we are to be impressed with it. Even the founder of the company in the above video admits that growing entire organs is more of a dream that could be achieved within our lifetimes, not an imminent technological breakthrough. That should not detract, however, from the capabilities of this technology that may be just over the horizon. Okay, so a few blood vessels are not as cool as a new lung, but such a technology could make medical practices that are already established even safer. To not have to worry over tissue rejection would be cause for celebration among most surgeons.

So, is this technology something to be excited about? Well, yes. We are now capable of regenerating parts of our own bodies. Regardless of which parts, that is still a neat proposition. Come on, most men can’t even regenerate their own hair, no less new blood vessels. But Organovo will be a company to watch for a long time coming. They have set forth a difficult goal to achieve, one day reproducing entire organs, and it is wholly possible that they may accomplish this many decades down the road. For now, though, we will simply avoid the hype and look forward to not having to worry about tissue rejection if the Tarot cards forecast a bypass surgery.

Organs grown from a person’s own cells are the holy grail of medicine and human longevity. These organs are not rejected by the body’s immune system as foreign invaders because they actually originate from the patient. Here at singularity hub we will be following this field intensely as it may be one of the most revolutionary and game changing developments ever to beset mankind. Is your heart getting too old sir? No problem…lets just grow you a new one! The implications are stunning!

Below is a video from recent CBS coverage on regenerative medicine that is a must see if you are out of the loop on this amazing development:

Regeneration of cells – CBS Cutting Edge