The Future of Organ Transplants: Bioprinting, Stem Cells and More
In the United States alone, over 100,000 people are on the organ transplant list. Around 17 of these people will die per day without having received the transplant. It’s clear that organs from human donors will never be adequate for everyone looking for a transplant. Thus, scientists have been researching alternatives, such as using organs made from repurposed stem cells, animal organs, and bioprinted (3D-printed) organs.
In this article, we explore the future of organ transplants. The article attempts to answer frequently asked questions about technologies, such as human organ 3D bioprinting, how close humanity is to bioprinting internal human organs, and if humans have successfully 3D-printed organ transplants yet.
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Improving Technology to Deliver Healthcare
In an article published by The NIH’s National Library of Medicine, Marilia Cascalho, Brenda M. Ogle, and Jeffrey L. Platt conclude that “the need for organ replacement not only exceeds by far the supply of organs available for transplantation, but the need is also likely to increase dramatically.”
Conscious of the reality presented by Ogle and others, scientists are turning to technology for new and innovative ways to deliver therapy and organs faster to those who need them.
Writing for the technology website ZDNet.com, Jo Best cites the principal investigator at Penn State University, Dr. Ibrahim Ozbolat, who says, “ Bioprinting has great promise -it has a lot of advantages and capabilities. Of course, it’s not really perfect yet, but despite that, we have all these good things going on in the field.”
Although the technology is not perfect yet, 3D printing looks like it is the future of medical technology. From 3D-printed drugs to 3D-printed organs, a technology that has its roots in manufacturing is rapidly branching into the medical field. The use cases of bioprinting are extensive. Scientists have bioprinted drugs, external human body parts, and even human internal organs.
Central to scientists’ technologies to deliver better healthcare through technologies like 3D bioprinting is the need to develop environmentally-friendly and biodegradable ways to deliver drugs and health services.
What is Human Organ Printing?
Bioprinting (also known as 3D bioprinting) is the combined use of biomaterials like cells and growth factors (naturally occurring substances that can stimulate cells’ production) to create structures that resemble body tissues. Bioprinting is an additive manufacturing process, implying that material is added to create something instead of starting with a block of material from which you need to remove parts to create an item.
The first step in bioprinting is the creation of a digital model of the tissue to be printed. This is followed by a layer-by-layer printing of the target tissue. The organs created through bioprinting are called engineered organs.
In a 2017 article published by the peer-reviewed literature repository, ScienceDirect.com, Elliot S Bishop, and several other authors note that there are generally three core perspectives to bioprinting. These are biomimicry, autonomous self-assembly, and the microtissue-based method. While none of these three approaches is exclusive to bioprinting, they can be applied, at different levels, based on parameters like target tissue type, user experience, and printing method.
Let’s take a closer look at the three bioprinting core perspectives in greater detail:
Biomimicry involves the conceptual reduction of tissue to its simplest parts to make the building up process easier. According to the Biomimicry Institute, “Biomimicry offers an empathetic, interconnected understanding of how life works and, ultimately, where we fit in.” It adds, “We can use biomimicry to not only learn from nature’s wisdom but also heal ourselves — and this planet — in the process.”
The first step involves selecting an appropriate scaffold material that most resembles the target tissue in structural and mechanical properties.
The second and final step in biomimicry is the use of bioreactors. These simulate an environment similar to that of the target tissue. Bioreactors are often used after tissue printing, during the period where the tissue is allowed to mature.
Autonomous self-assembly mimics a cell’s creation through an autonomous organization that involves no external intervention. Autonomic self-assembly does not rely on scaffolding.
In an article published by the NIH’s National Library of Medicine, Karoly Jakab and a group of other authors say that the autonomous self-assembly principle is based on the assumption that “living organisms, particularly the developing embryo, are quintessential self-organizing systems.”
The main advantage of autonomous self-assembly is that it produces organs with high cellular density, better cellular interactions, faster growth, and better long-term function.
Bishop and others note that “the concept of a microtissue approach to bioprinting relies on the fact that a typical complex in vivo tissue is composed of many simpler units whose combined structure and function contribute to the overall whole.” This bioprinting method also involves creating the organ without the need for a scaffold.
According to Bishop and others, the main advantage of using the microtissue approach is that it results in “accelerated rates of ECM [extracellular matrix] production, maturation, and differentiation of vascular tissue.”
What are the Benefits of 3D Organ Printing?
The main advantage of bioprinting is that it could accelerate human organ production so that people who need organs do not have to wait too long before they can access them. Even though human donors will still play an essential part in providing organs, the 3D organ printing technologies will be much-needed alternatives to ensure that no-one dies in the future waiting for organ transplants.
Writing for the NIH Director’s Blog, Dr. Francis Collins states that one of the main advantages of 3D organ printing is that it relies on the host person’s cells as the foundation for the new organ.
In an article produced for NBCNews.com, Sony Salzman proposes that, as the 3D organ printing technology gets better, it will become less likely that the host’s body will reject any organs produced for transplants.
As a general concept, bioprinting could result in humans gaining a better understanding of how nature works. This could result in human beings coming up with better ways to repair the damage caused by some of our environmentally-unfriendly actions. It makes it possible to consider ways of sustainable healthcare services and drug delivery.
How Close are we to Bioprinting Internal Organs?
A group of researchers from the Singapore University of Technology and Design (SUTD), Nanyang Technological University (NTU), and Asia University published a paper entitled, Print me an organ: Why are we not there yet? According to Professor Chua Chee Kai, a researcher at SUTD and lead author of the paper, “While 3D bioprinting is still in its early stages, the remarkable leap it has made in recent years points to the eventual reality of lab-grown, functional organs.” This suggests that a future where bioprinted internal organs are commonplace is inevitable.
Even though the use of transplantable fully-functional human internal organs is not yet common, Emma Yasinski, a science and medical journalist, is optimistic. She believes that “scientists are getting closer, making pieces of tissue that can be used to test drugs, and designing methods to overcome the challenges of recreating the body’s complex biology.”
Researchers have come as far as producing an organ similar to a human lung. Bioengineers achieved this at the University of Washington and Rice University. The technology used is called stereolithography apparatus for tissue engineering (SLATE). It is an open-source bioprinting technology used to create an organ that could sustain normal blood pressure and mimic breathing movements.
What Body Parts Can be 3D-Printed?
According to a website that brings together manufacturers of medical devices, MedicalDevice-Network.com, bones, corneas, cartilage, hearts, and skin have all been 3D-printed to varying degrees of success.
The Times of Israel reports that researchers from the University of Israel unveiled a 3D-printed heart made from human tissue in April 2019. The same paper reports this was the first artificial heart to have blood vessels, cells, chambers, and ventricles. It took between three to four hours to print the heart.
The world’s largest international online media platform on 3D printing and its applications, 3Dnatives.com, reports that the Director of the Wake Forest Institute for Regenerative Medicine, Professor Anthony Atala, unveiled a bioprinted kidney in 2011. The kidney was designed from stem cells in seven hours but could not live for very long.
3Dnatives also reports that ovaries, a mini liver, an ear, and a pancreas have also been bioprinted recently. This shows that even though there may still be issues with 3D bioprinted organs, the possibility of printing even the most intricate human organ is becoming a given.
Researchers in Groningen in the Netherlands have successfully bioprinted an antibacterial tooth. The tooth’s antibacterial abilities were tested against Streptococcus mutans (a bacteria commonly found in humans’ oral cavity) in a saliva solution. Ninety-nine percent of the bacteria were killed.
What Was the First 3D-Printed Organ?
Dr. Gabor Forgacs pioneered the research that led to the first successful 3D-printed organ. He started by observing cell behavior and discovered that the cells could fuse into entirely novel, spatial structures. Perhaps all of this would not have been made possible without the work of Charles W. Hull (Chuck) in 1984. Hull was the researcher who developed a stereolithography method (a 3D printing process that creates concept models and prototypes).
Have There Been Successful 3D-Printed Organ Transplants?
Most of the 3D-printed human organs have not been fully functional, but there have been a few successful transplants. As mentioned earlier, the scientists at the Wake Forest Institute for Regenerative Medicine printed and transplanted an artificial scaffold for a human bladder.
Currently, there are about ten people who have transplanted bladders made from their own cells. According to EBioMedicine, a publication of TheLancet.com, patients living with microtia has also had transplants done successfully. Microtia is a condition that causes the deformation of an individual’s external ear.
In China, five children living with microtia underwent successful bioprinted ear transplants. The artificial ears were made using cells from the patients’ bodies. The five children were observed for two and a half years, and the results were encouraging. Although two of the five patients had some issues with their new ears, the rest did not report any issues.
In 2016, a two-year-old girl from Queensland, Maia Van Mulligan, was born with only one ear and was put on a list for an ear transplant. On December 20, 2018, she had her missing ear successfully reconstructed thanks to 3D printing.
Using Animal Organs
Apart from 3D bioprinting, there are ongoing efforts in gene-editing technology to make it possible to transplant animal organs into human beings. Writing for the British publication, TheGuardian.com, Karen Weintraub says that it is no longer a question of if, but rather when this could happen.
In 2019, Weintraub reported that “researchers in South Korea are expected to transplant pig corneas into humans within a year.” She adds, “A handful of groups across the U.S. are also working toward pig organ clinical trials in the next few years, including a group at Massachusetts General Hospital in Boston that is starting a six-person clinical trial using “blankets” of pigskin to temporarily protect the skin of burn victims.”
While Marlon F. Levy, a medical doctor working at the Baylor University Medical Center, Dallas, Texas, accepts that there has been much progress in getting closer to animal-to-human transplants, he accepts that the clinical application process still needs to consider several issues within the field of genetics.