Producing or growing tissues that could avoid the immune response of donor tissues sounds far-fetched, but in some limited applications has already been achieved. Tissues for drug development testing are already available. Replacement skin is expected to be available within 3 years and to take off quickly. While much progress has been made, there is still much to be done to achieve a scalable production process. The good news is there are two very distinct groups working from very different perspectives.
Biologists have had great success with using decellularized tissues to obtain an extracellular matrix (ECM) scaffold of the original tissue. By seeding an ECM scaffold with a patient’s own progenitor or adult stem cells, things like bladders and urine tubes have successfully been created and implanted at the Wake Forest Institute for Regenerative Medicine. The same process has potential to create hearts, livers, kidneys, and more on a very small scale.
Engineers over the last 25 years have developed additive manufacturing (AM/3D printing) to be able to print almost any shape with a wide range of materials including biomaterials that can be used as scaffolds and more. The medical industry has been a leader in the creation of end-use additively manufactured applications. The combination of 3D imaging technology (MRI, CT) to create patient-specific digital images and the ability to print from this data is compelling to an industry always looking for ways to improve and even change lives. In 2001, Siemens shared how they used stereolithography to manufacture cases for hearing aids, printed from scans of the ear canal. Within a few years, using the technology for this became standard for hearing aid manufacturers.
Bioprinting combines the biology and engineering approaches into what could be the answer to producing tissues. While there is great interest in bioprinting, (several companies having launched or are launching products, and many universities are leading developments) we are at the very beginning of the bioprinting product lifecycle. Biologists are beginning to work with bioprinting to create scaffolds and even print tissues. For engineers, biomedical applications, including bioprinting, has been identified as a growth sector for both additive and medical.
From the engineering perspective, the complexity grows as the technology gets closer to achieving production of tissues that can be used for burn victims, replacement of valves, joints, and organs.
Ken Church is both managing partner for Sciperio, a research and development think tank specializing in cross-disciplinary solutions; and research scientist for nScrypt, a developer of equipment for tissue engineering. Having worked in development of replacement tissues with some success and a few failures, provides some perspective on bioprinting:
“Bioprinting is not just the printing of organs which has received much hype...grow a heart, a bladder and other organs. How realistic is that and can we make that much of a leap from where we are today? Maybe we shouldn’t talk organs. That’s like talking about colonizing Mars. It is certainly interesting to talk about. The US government is putting some money in, but the rest of the world is working new rockets, space stations, the moon, studying Mars, and many hard problems that must be solved long before we colonize. What are the ‘new rockets’ for bioprinting?”
Some of these “rockets” may be no surprise.
Functional 3D bioreactors are needed. The most effective bioreactor is what nature has provided—the human body. This is a complex intertwined, optimized, biofeedback 3D system. 3D printed bioscaffolds are similar to having a skeleton and nothing else. 3D scaffolds need to be printed with feedback sensors, fluid flow, signal impulse, and functions. They also need to mimic natural function and shape. Thick tissue requires vascularization and a blood flow. If the tissue is too thick, it struggles to get oxygen and nutrients in and waste out. Few cells tolerate distances more than 200 µm from a blood vessel.
Logistics will be very different. Once the thick and complex tissues have overcome the technical hurdles, it will be important to transition the product. Moving product such as displays or smart phones is challenging, but trivial compared to moving and storing living products. New systems and possibly a completely different type of supply chain will need to be developed.
Acceptance will face challenges of the risk of the unfamiliar. Training will also be a challenge. Doctors today, have accepted and known practices they use. The new products will be much different. This is not a small task and when it is time for this to happen, it will take a serious focus and effort to be successful.
Possibly the biggest challenge though, may be communication. Biologists and engineers are both working toward the same goal, but they don’t speak the same language. Engineers’ experience in automation, controls, feedback, precision, speed, repeatability and extreme size scales will enable biology. However, engineers are not biologists. They do not know the relationships between cells and tissue, the complexity of cells, their diverse purposes, or how to divide or maintain these cells. Growing complex organs on a production scale will take both expert biologists and engineers. These disparate groups must learn to communicate effectively to reach the promised goals given by both sets of experts.
Some of the challenges of different languages are being addressed in the relatively new areas of tissue engineering and bioengineering. These areas hold great promise for the future. To take advantage of today’s knowledge, learning to understand and speak both biology and engineering may be the biggest rocket of all.
Colliding industries is not unusual, space and materials for example. Today, all space programs and applications have material experts that understand the specifics and challenges of that industry. Biology and engineering controls will become united. 3D bioprinting is a foundation that not only unites two disciplines, that unification will enable the hype and the hope of truly printing organs for implant. The future will unite bioprinting and endoscopic minimally invasive penetration to detect, strategically remove and strategically build parts of organs within the body.
For more on challenges to bioprinting: http://www.sme.org/MEMagazine/Article.aspx?id=84218&taxid=1417