3D Printed Organs: The Challenges to Overcome
In the medical industry, 3D printing technology is usually used in one of two ways: inorganic printing and bioprinting. Inorganic printing is used for creating models of body parts and implants, whereas bioprinting creates organic printing using cells. The most important goal for bioprinting is the future possibility to successfully print fully functioning organs which may be used for transplants and regenerative therapy. Being able to successfully print organs would have numerous benefits, such as reducing the waiting times for organ transplants, and bypassing adverse autoimmune reactions the body.
This breakthrough may result in a revolution for regenerative medicine and transplantation, but there are many challenges which must first be overcome in order to reach this goal. One key challenge for the printing of fully functional human organs is their complexity. Organs are made up of many variable cell types and parts such as various cell types, nerves, and tissues, which all must be correctly positioned with a high degree of precision in order to create functioning organs. The technology to accurately recreate these structures is not currently available but is an exciting prospect for the future of regenerative medicine and bioprinting.
Bioprinters are being used for various projects both in research and practical applications; however, they will require upgrades to speed, resolution and compatibilities with biomaterials in order to successfully print organs. Fortunately, significant developments are being made in bioprinting technology in order to more quickly print complex structures with various cells and biomaterials.
One of the most difficult challenges in the creation of 3D printed organs is that all organs need a flow of blood in order to provide nutrients and oxygen to the cells. This is necessary for the organs to function and survive; however, this is extremely difficult to recreate due to the limitations on bioprinter technology, as the nozzle diameter of the bioprinters is too wide to produce blood vessels small enough.
In addition to the bioprinters, the biomaterials used for the printing of organs must be considered. Biomaterials are either synthetic or non-synthetic, with each having their own properties and strengths. Natural biomaterials are well suited to cell attachment and differentiation. However, synthetic biomaterials are more adaptable, with the ability to more easily change viscosity, stiffness and shape. They also have the benefit of being more printable and stronger than animal-derived bioinks.
Non-animal derived bioinks often include peptide and protein molecules found in the natural extracellular matrix. These molecular recognition motifs enable cell-surface receptors to bind to the bioink, allowing cell-detection of matrix mechanics. These smart materials’ rheological properties and gelation kinetics can be controlled by varying their monomer concentration or supplementing with additives to reduce printing-related cell damage. These smart bioinks do not only have excellent printability and shape-fidelity, but some might enable more efficient application of mechanical stimulation to encapsulated cells to simulate external forces exerted in shearing, compressing, or stretching bioreactors. Thereby, these biomaterials might have a high potential to form truly functional organs.
In the last year, significant breakthroughs have been made in the journey to 3D printed organs which can be transplanted into human bodies. By using a combination of human cells and biomaterials, researchers at the University of Tel Aviv have successfully created a 3D printed heart complete with cells, chambers, ventricles, and blood vessels. The structure of a 3D printed heart has been completed before, but this is the first-time to cells and blood vessels have been implemented. Other breakthroughs include bioprinted corneas, which match the shape and size of the original cornea, and an organ which can mimic the properties of a lung.
There are many challenges which still stand in the way of successful 3D printed organs, but there are many opportunities and advancements in bioprinting which may make the dream of fully functional bioprinted organs a reality.