3D printed organ transplants have been in the cards for a while, but deep tissue printing has proved problematic. Now a team of scientists in Korea think they have cracked the code for producing functional liver tissue by printing functional mouse liver cells.
Simply put, we need more livers than we currently have as hepatitis, cirrhosis and liver cancer are increasingly prevalent. The donor system, meanwhile, is inherently flawed.
Patients face agonising treatment while they wait for a suitable liver. There is simply no guarantee they will get a matching organ in time and even if they do, there can be serious complications with the recipient’s immune system rejecting the new organ.
Organs and thick tissue come with serious problems
3D printing promised an end to these problems, but it really isn’t as simple as bioprinting a new liver. Vascularized tissue is immensely complex and most bioprinted organs have failed shortly after their construction.
Now the team in Korea, led by Sungho Jang, has taken hepatocytes from a mouse and used them to create a 3D hepatic structure. That is the essential building block of a new liver.
The cells survived more than 30 days in vitro, where they were kept in an alginate solution. Other cells that had been produced between sandwiched layers of collagen or simple 2D printed cells showed morphological changes that suggested those routes were a dead end.
With the 3D printer, though, the cells maintained their integrity, there were no serious morphological changes and the hepatic marker genes were still expressed after the one-month period.
There’s potential, but we’re not there yet
So these hepatic cells have the potential to produce a working 3D printed liver. But we shouldn’t get too excited yet.
Keeping cells going under lab conditions and creating a fully functional liver that works as an actual transplant are two wholly different things. We have seen encouraging results like this before, but the problems tend to creep in with thick, vascularized tissue as the capillaries and blood vessels are immensely complicated structures and we simply haven’t managed to build anything close to the tools that nature gives us.
Executive and scientific director of the Cardiovascular Innovation Institute, Stuart Williams, reckons we’lll be printing hearts within a decade, although it could come much sooner. He says that we have already produced the smallest capillaries in isolation, but creating the whole organ is more complex than simply throwing together an STL file containing the parts.
Building an organ is a hugely complex task as there are so many variants. Even producing connective tissue, the glue that holds the layers together, is supremely complicated and the printing process itself is often the issue as the materials must be viscous enough to print and yet take their shape and form immediately.
Stem cells could have the answer
Some of the most encouraging results in recent times have come from stem cells, where scientists have used 3D printing to place them in a scaffold and effectively grow new tissue that can then be implanted into a patient.
The Korean researchers have gone a different way, however, and it will be interesting to see if they can turn this into a viable treatment. Whatever happens, though, it’s progress.