By: Hamza Alsamraee
On average, 20 Americans die every day due to challenges surrounding organ availability. Even more frustrating, particularly in developing countries, is the existence of a black market for organs posing dangerous avenues of organ procurement. However, science may come to the rescue again! Spanning the frontiers of scientific possibility is 3D bioprinting. Bioprinting started in the late 80’s with modified normal printers. These printers were filled with “bioink”- a liquid mixture of cells and nutrients- instead of traditional ink. Bioprinting soon gained 3D capabilities and is rapidly progressing from experimentation to application.
How does 3D bioprinting work: A cooking guide
Just as a chef makes a world class dish tailored to customer needs, a physician must cater a “bio-recipe” to each individual patient.
What better way to do that other than scanning the patient’s own organs/tissues? Typically, medical imaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) visualize the model. In CT, an X-ray source rotates around an object where a sensor measures the beam intensity to draw a picture of the object. MRIs utilize strong magnetic fields changing the energy states of atoms within tissues, which characterize that shape. These initial bio-recipes are computer-assisted designs (CAD).
Just as a chef tweaks a recipe, a physician often needs to tweak these files, making them suitable for 3D printing. After the CAD file is adjusted, it is converted into a format the bioprinter can understand, making the bio-recipe ready for execution.
Onto the cooking! 3D bioprinting works via a process called additive manufacturing. This methodology adds thin layers to a base until an object is created, like making a layered cake. Since this procedure is “additive,” it is economical and eco-friendly since no waste is produced.
Now, for the final touches. After printing, both mechanical and chemical stimulations are required to mature tissues and maintain the structural integrity, just as a world class chef must perfect the structure and design of a dish.
Design issues & potential solutions: Moving toward mass production
Sometimes, a direct copy of the patient’s organs may not be desirable due to injury or disease, thereby requiring supplements to the design. Moreover, since physicians often need to manually manipulate these scans, medical imaging alone is not a feasible approach for mass production of bio-objects. A promising alternative method is biomodeling. This method uses mathematical modeling techniques to either supplement or entirely replace medical imaging.
Current MRI and CT technologies are limited in their abilities to accurately print at the cellular level, resulting in potential mechanical and structural issues in the tissue. Utilizing biomodeling techniques significantly aids overcoming this barrier by producing high-definition bio-recipes suitable for bioprinters. Kucukgul et al. (2015) tackled this challenge of printing hollow structures using biomodeling to print an aorta. Remarkably, biomodeling aided in designing the aorta, resulting in a self-supporting structure, not requiring a scaffold to maintain mechanical integrity. After obtaining a 3D image of an aorta using traditional MRI and CT techniques, Kucukgul et al. (2015) converted non-smooth scans into smooth surfaces suitable for 3D printing using a simple algorithm.
Ethical considerations and future directions
3D bioprinting is still in its infancy, and regulations are sparse in this field. For example, the malfunctioning of these objects needs to be regulated. However, it is not so easy to determine who is liable. “The complication is that there are many actors involved, from scientists, to companies, to doctors and health care system, patient, insurance etc., so there is no straightforward way to determine responsibility,'' remarked Dr. Niki Vermeulen of the University of Edinburgh.
Moreover, the categorization of bio-objects is a tricky issue, as they blur the line between non-life and life. To change this, Dr. Vermeulen co-founded the network of researchers “Bio-objects and their Boundaries.” This network developed the concept of a bio-object where they are working to develop a legal framework for bio-objects.
More research is needed before using 3D bioprinting in precision medicine, specifically for organ transplants. The long-term behavior of bio-objects is still a mystery, but animal models may provide the key. Just as drug therapies are tested in animals before human consumption, so should bio-objects be. However, the personalized nature of bio-objects “means that the normal safety/regulation paradigms do not work, and the patient treated with the first 3D bioprinted organ transplant would be the proof person,” remarked Dr. Vermeulen. Regardless, 3D bioprinting carries immense promise for biomedical advancement. 3D bioprinting can potentially address the organ shortages and save countless lives.
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