3D Printing: The Future of Medicine

With the creation of 3D printing, a whole new field of science has been created. When one thinks about 3D printing, they probably think of 3D printed guns, tools, and other machinery. 3D printing excels at creating intricately detailed 3D structures, typically from inert materials like plastic or metal. However, in recent years, scientists have been able to manipulate 3D printing to “print” cells and other organic substances. Through this advancement, the creation of human organs is now becoming a reality via technology. No longer will donors have to give up their lives or organs in order to save another person. However, problems are arising with the creation of such technology. The organs in our body are incredibly complex, with millions of vessels and capillaries running through them and distributing nutrients to every cell of our body.

This biological “machinery” is incredibly intricate and even harder to recreate. To solve this problem, researchers at Harvard University have developed several ”bio-inks” – an ink with an unusual property of melting as it cools, rather than as it warms up, which allows scientists to create and mimic blood vessels. This discovery allowed the scientists to first print an “interconnected network of filaments, then melt them by chilling the material and suction the liquid out to create a network of hollow tubes, or vessels.” Consequently, they created the structure of blood vessels for the tissue, allowing for the distribution of nutrients required to sustain development. However, researchers at Wake Forest University have approached this problem in a different manner. Rather than having a main focus on the creation of blood vessels, they “[created] the [Integrated] Tissue and Organ Printing System (ITOP) over the past decade. The system involves a custom-designed 3D printer that utilizes a water-based ink optimized to promote the health and growth of encapsulated cells.” It also prints impermanent channels along which nutrients can be distributed to the cells, helping the tissues survive long enough to produce their own blood vessels.

The creation of blood vessels hasn’t been the only problem that scientists have faced with 3D printing. With organs that have different cells and several dissimilar layers of tissues, researchers have had to find a way to create a “heterogeneity of cells in 3 dimensions.” Different types of cells in the human body have different functions, and the environment in which they thrive is dependent on their location. In many cases, the lack of heterogeneity between cells in tissues has been closely linked to different diseases, as well as cancer. Ultimately, by capitalizing on the different sensitivities of certain tissues and hydrogels to light, “photo-liable reactions have been widely exploited to spatially soften or stiffen hydrogel structures in 2D structures.” However, in 3D structures, a new challenge arises, mainly due to the light scattering as a result of the homogeneity of the structures. Oxygen inhibition layers do show promise in preventing the problems that arise with light scattering, but it causes incomplete growth of tissues and uneven surfaces. Using “continuous liquid interface production, an oxygen-permeable layer can be created on the oxygen inhibited layer, allows for the printing of 3D structures with heterogeneity.”

Having discovered a solution to cell differentiation and the creation of blood vessels throughout an organ, researchers are now attempting to grow organs using actual tissue from humans. Researchers at Organovo, a San Diego-based company, has created the ability to print bio-inks of tissues recreated from the cells of humans. However, the implications for this research extend far beyond that of organ replacement. This new 3D printed tissue could serve as a way to test new drugs, rather than using animals or clinical trials which often carry risk to the recipients. Believing in the potential for this technology to combine with other areas of study, researchers are attempting to interface 3D printing with the liver’s regenerative ability to heal chronic liver conditions. A team at the MRC Centre for Regenerative Medicine at the University of Edinburgh is attempting to use macrophages (white blood cells) that are “very effective at stimulating regeneration in the liver by breaking down scar tissue that accumulates during liver disease.” By attempting to grow healthy macrophages in a laboratory setting, Professor Stuart Forbes, Director of the MRC Centre, hopes to insert these cells into the liver to induce self-regeneration. However, in cases where the liver is too damaged, researchers hope to replace parts of the liver with healthy tissue that can then provide an impetus for healing and regrowth.

Despite the many challenges that accompany 3D printing of organs, the technology displays a potential to exceed all expectations and prove useful in many facets of medicine through the application of organ replication, drug testing, as well as, interfacing with new areas of medicine.