3D bioprinting utilizes 3D printing technologies to develop cell patterns and, ultimately, a fully-functioning tissue out of a special biomaterial known as Bio-ink. Similar to traditional 3D printing, 3D bioprinting creates the object by depositing the Bio-ink layer by layer with cell function preservation in mind. The technology began with printing animal organs to human skin grafts. Regeneration of joints and ligament is also possible by bioprinting via “scaffolds” which act as a foundation for the said organic parts.
History of the Technology
3D bioprinting can be traced back to 1983, the year when stereolithography was invented. The technology, invented by Charles Hull, solidifies polymers from a nozzle using a laser. The nozzle was controlled by a program that read the design created by computer-aided design software. The end products were 3D objects that could be used for parts for larger machines very much like the 3D printers of today.
The first Stereolithography products were limited to products with less durability and life spans. By 1986, Hull’s company moved from polymer – which did not last long enough – to nanocomposites. This mixture of plastic and metals is much stronger and more durable than polymer and can be used to create more objects. This paved the way for products beyond automobile and industrial parts.
Around the late 90’s, scientists were already researching for materials to be used for creating fully-functioning human organs using 3D printing. In 1999, a synthetic scaffold to be used for the creating a fully-functioning human bladder was created by Wake Forest Institute scientists. Three years later, an animal kidney that secreted urine and filtered blood were created. Now, they are working on creating a human heart — a vital body organ that is thought to be less complicated in construction to others like the kidney, liver, etc.
3D bioprinting is very much like common 3D printing but instead of creating shapes out of layering, cell patterns are formed. The material used (Bio-ink) can be derived from alginate, gelatin or decellularized extracellular matrix (ECM). Alginate is extracted from brown algae, gelatin from cartilaginous meat or bone cuts and ECM from any mammalian tissue. Each material, with the right preparation, can effectively mimic the structure of human tissue.
The 3D bioprinting process is normally divided into pre-bioprinting, bioprinting and post-bioprinting sub-processes. In pre-bioprinting, the organ to be recreated is modeled and scanned to a computer. The scanning process can be common medical procedures like CT scan or MRI. Once the model is prepared, the actual bioprinting process can commence. In post-bioprinting, stimulations known as bioreactors are performed so that the host body accumulates the 3D printed organ as if it his or her own. The last subprocess is very much like the procedure done after organ transplants.
The impact of fully-functional 3D bioprinters impact on the medical world is astonishing. With it, essential human organs like the heart, liver, and kidneys can be reproduced. In the UK, a patient must wait almost three years for a kidney transplant. In the US, a million deaths could have been prevented if organ transplants were not delayed. 3D bioprinting can only take days.
However, creating fully functional human organs still need a couple of years before they can be reliably used in organic surgeries. The hindrance thus far is due to the unresolved issues in mimicking human capillaries which are too small to reproduce with the current level of technology used in 3D bioprinters. As of now, the technology is used to test the effect of drugs on synthesized tissues in the lieu of animal trials.
As mentioned earlier, the common current use of 3D bioprinting is focused on the production of cells and organs for testing drugs and pills. This was a result of the efforts on preventing the use of animals for such tests. However, scientists are looking forward to creating more significant applications of the technology.
Researchers at Wake Forest University have successfully printed a cartilage, a piece of a jawbone and a muscle to be used by a mouse. The difference of their end product with others is that theirs can receive oxygen and other cell nutrients. Similarly, Northwestern University stalwarts managed to 3D print an ovary to a mouse which became pregnant and gave birth.
Earlier researchers have managed to print out kidneys and blood vessels as well but as with the others, all are for animal tests. The only human application thus far is printing artificial skin for skin grafts and prosthetic limbs. But then again the lack of blood supply inhibits the tissues for self-repair and thus more patients still opt for synthetic implants and prosthetics. The disadvantage of synthetic materials is mechanical degradation over time.
Graphene as material for 3D bioprinting is also now possible. The advantage of using graphene is its strength which is a primary requirement for prosthetics. A technique called micropipette is used to create nanostructures for the object that can be customized to fit the patient. This results in a much more comfortable and naturally-fitted prosthetic.
Researchers from Case Western Reserve University have managed to mix graphene with thermoplastics to create a biomaterial that is flexible, strong and transparent and, best of all, compatible with biological cells. The possible application for this material is 3D printing ball joint sockets where flexibility is required.
3D bioprinting for human organs is not far away. The current challenge is creating capillaries which are too small for the current 3D bioprinters to create. Capillaries allow blood and other essential nutrients to flow into the organs, thereby keeping them alive. To boost morale on this research agenda, NASA is awarding $500,000 for creating a 3D bioprinted human tissue with a fully-functioning circulatory system that can survive for 30 days. With the overwhelming support of this technology, a 3D printed heart could be possible in six years.
With the commercialization of 3D bioprinting, we can expect the appearance of more companies that use the technology. This will lead to more people doing research on this topic, independently or codependent. This, in turn, could boost improvements on this promising technology.