Bioprinting

Bioprinting

The bioprinting process is similar to fused deposition modeling (FDM). Instead of filament, bioink is deposited layer by layer at thicknesses of 0.5 mm (less than 1/100th of an inch) or less. As each layer is deposited, it solidifies to hold its shape. The process of blending and solidifying is called cross-linking and is sometimes aided by UV light, specific chemicals and heat via a UV light source.

Wake Forest Institute for Regenerative Medicine in Winston-Salem, N.C. built lab-grown organs by creating artificial scaffolds in the shape of the desired organ and then seeded the scaffolds with living cells. The lab-grown bladders were implanted into patients in 1999.

There are four levels of complexity that need to be considered as part of 3D bioprinting with living cells. First, flat structures (one living cell type) such as human skin. Second, tubular structures such as blood vessels (two major cell types). Third, hollow organs such as the stomach or bladder since they each have more complicated functions and work with other organs. Fourth, organs such as the heart, liver and kidneys that are among the most complex organs of the human body.

Another challenge in 3D bioprinting is figuring out how to seed the 3D-printed organs with both large and small blood vessels that can supply nutrient-rich blood to keep the living tissue healthy. So far, no lab has accomplished this but Organovo has built tissues containing tiny blood vessels about 50 microns or smaller (which is less than 2/1000 of an inch). Leading researchers of companies like Organovo and the Cardiovascular Innovation Institute agree that the solution involves harnessing the self-organization tendencies of living cells. Once researchers figure out how to print items tens of microns or hundreds of microns, then cells can undergo the biological developmental response in order to self-organize correctly.

Researchers at Tel Aviv University have 3D printed a rabbit-sized heart using a patient’s cells and are hopeful that one day they’ll be able to print a human-size heart for implant and replace the need for human donors. It can contract on its own, however, it is incapable of pumping at this stage. With future testing and innovation, they hope 3D printed hearts like this one can help treat patients who have cardiovascular disease. And most recently, Carnegie Mellon University reported they are now able to 3D bioprint functioning pieces of the heart, like a heart valve, using cells and collagen.

Bioprinting Today

What’s being bioprinted by whom

• Skull: University Medical Center Utrecht (Holland)
• Prosthetic Eyes: Fripp Design (England)
• Noses and Ears: Cornell University (USA)
• Synthetic Skin: Wake Forest (USA)
• Vaginas: Wake Forest (USA)
• Breasts: Queensland University of Technology (Australia)
• Kidneys: Hangzhou Dianzi University (China)
• Livers: Cleveland Liver Transplantation (USA)
• Bones & Limbs: Many Companies
• Heart components: Carnegie Mellon University (USA)