3D Printing and Your Liver

Take a moment and imagine this scenario: a terrible accident happens to your close friend and his liver is severely damaged. He'll need a new one but the waiting list for a liver donation is so long that it's unlikely he'll get one in time.

What to do?

Tissue engineering to the rescue. Recent research has blended synthetic biology, 3D printing, and a spoonful of sugar to build you a new liver from scratch.

 

Organ Transplantation

Historically, there has been no other solution to replace a damaged organ than to take a fully developed organ from someone who recently died (or someone very generous) and replace the damaged one. For the most part, that's still the case. However, a brief glimpse into the future of tissue engineering will probably blow your mind with the awesomeness of it all. But before we go there, why is this research so new? What's so hard about building a new organ?

The problems are too many to count, but a big one is blood flow. Suppose, for a sec, that you can take some liver cells (or kidney, or heart, or lung, or skin ... take your pick) and grow them in the right shape (the kidney would look like a kidney bean, right?). Even if those cells were from the person that needed the new organ, as soon as they were implanted, the cells would die. Dead. Kaput. Why is that? Because those cells need oxygen and nutrients to survive, and those things come from blood.

 

 

Capillary Action

Organs are filled with blood vessels.

"Well", you respond, "aren't they surrounded by blood if they've been implanted?". Yes, it's true. But look at it this way. Have you ever tried to cook dry rice or beans in boiling water? What happens if they don't soak and cook long enough? They're nasty and hard and nobody wants to eat them. The idea here is that it takes time for the beans/rice to soak up the water. The same thing happens with organs. They need time to soak up the oxygen and nutrients. If the organ is in one big lump, the cells on the outside will get oxygen and nutrients, but it will take so long to "soak up" to the inner core of the organ that the cells buried down there will die before it gets to them.

That's why our organs are filled with blood vessels of all sizes (called "vasculature"). They carry blood to every nook and cranny so that oxygen and nutrients don't take long at all to "soak in". BUT, It's really hard to get blood vessels to grow in the right pattern in an artificial organ. So, tissue engineers have been limited to building really thin or really small things ... until now.

Tissue Engineering - 3D Printing and Jello

To solve this "soaking  problem," a bioengineering team from UPenn and MIT developed a new technology that uses 3D printing to first make all the necessary blood vessels out of sugar. Yes, sugar. Why? Because it can hold it's shape when it's hard (think candy canes) AND it will dissolve in water.

The basic strategy is this:

1. 3D print the blood vessel structure you need for your artificial organ, using sugar.
2. Submerge the sugar-blood vessels in a gel (kind of like jello) that also contains the cells (liver, kidney, etc.)
3. Once the gel has solidified (doesn't take very long), dissolve the sugar blood vessels and start pumping blood through the newly opened channels. 
4. Save a life.

Now, don't go damaging your liver just so you can get one of these implanted in you ... they're not on the market yet. But do geek out about how bio-awesome it is. 

Some extra interesting tidbits:

1. The team uses an open-source 3D printer called "RepRap" to print the blood vessel network out of sugar. In theory, you could build a 3D printer of your own, then start building organs for your pet fish ...  
2. Another open-source 3D printing platform is called "MakerBot".