Earilier this month, reports came out regarding how a team of Wake Forest School of Medicine researchers devised a way to 3-D print human-scale bone, muscle and cartilage that survives when transplanted into animals.
Using clinical imaging data and an integrated tissue-organ printer, the researchers were able to create skull and jawbone, ear cartilage and muscle. The tissues, implanted in mice and rats, showed normal growth and function at five months.
Being able to bioprint reliable human tissues could further the field of personalized medicine by allowing surgeons to bioengineer body parts from the patient’s own tissues.
Anthony Atala, one of the Wake Forest researchers, discussed the research and what the next steps are for 3-D printing tissue in an exclusive interview with Healthcare Dive.
Can you discuss how you constructed the system?
Anthony Atala: 3-D printing has been around for a few years in terms of printing plastic and metal part. When you’re printing cells it’s a little bit tougher because cells are alive and the printing process could destroy the cells.
There’s been a lot of work where you can print cells so the challenge is printing tissues that would be large enough being implanted into humans because in nature there’s a maximum distance in which tissue will survive without blood vessels and that maximum distance is 0.2 millimeters. That’s the maximum distance a tissue will survive without nutrition, or blood vessel supply.
So we’ve been able to print most structures for a few years that don’t require vascularity but the challenge is “Can you print larger structures that can be implanted into patients.” With a bioprinter, we were able to create a system where one could actually print human scale constructs and allow the vascularity to occur. That’s basically what we worked on for 10 years.
When you’re working with living material and a fair amount time, how did the study’s approach or materials evolve?
Atala: To print these structures — complex tissue structures instead of just cells — part of the challenge was “how you get the tissues through these very fine nozzles” because nozzles we used are very small nozzles. They can print about 1/80th the diameter of a human hair. To do that, you can actually damage cells.
So one challenge was making sure the cells could go through these smaller nozzles and survive. A second challenge was making sure as you printed it, it would retain the structural integrity necessary to be implanted surgically. The third challenge was once you could implant [the tissue] surgically — these were [larger] human scale constructs; these were not 0.2 millimeters constructs — to make sure they survive inside the body.
Was this a proof-of-concept study? Or this technology ready to be used?
Atala: This was all proof-of-concept to show it can be done.
What are the next steps?
Atala: What we’re doing right now is the longterm testing required for safety so we can start putting [the tissues] into patients.
What does that entail?
Atala: [We’re] creating the same constructs that we’re creating now but we’re making sure that the materials will not be toxic when you enter them into the patients.
Are there sterility issues to think about when conducting this longterm testing?
Atala: We’re making [the tissues] with the patients’ own cells so there’s no rejection. The concept is you would take a very small piece of tissue from the patient’s organs, about half the size of a postage stamp.
We would take those cells and use those cells to print the structure. After we finish the next phase of the testing to make sure it’s safe, then we will test these structures in humans.
What is the future when it comes to 3-D bioprinting?
Atala: With this printing technology we showed we were able to print a whole range of tissues in terms of strength. We were able to show we were able to print soft tissue, such as muscle.
We were able to {print] medium strength tissues such as cartilage and harder, strong structures such as bone, jawbones or skull bones. All of this in hopes to start implanting such tissues in patients in the future.
Could 3-D printing help drive down costs of such implants?
Atala: That’s one of the reasons why we are working with a printer because a printer is a scale-up tool.
Instead of creating these things by hand, you can automate the process so you can create many of these structures at the same time, thus decreasing the costs.