Research Studies in Organ Printing: The 3D-Printed Sugar Vascular System

Presently, 3D printing software is available on desktop computers for a relatively low cost, incorporating a variety of functions in different industries. In the past, 3D printing (also known as 3DP) was consistently applied to produce instant industrial prototypes, medical instruments, and in general design divisions. The software was industry-specific, costly, and open to a select few. 

Now, this technology is being widely adopted in the bioengineering industry. Using a step-by-step methodology and research study, a new generation of innovation is facilitating 3DP to construct a 3D version of a vascular system. Researchers at the University of Pennsylvania have used 3D printing to create a vascular system made out of sugar. The scientists have created a functional biomimetic that could decipher fundamental improvements for living tissues and propel bioengineering research into new and uncharted territory. Healthcare and bioengineering were the first two industry-adopters to utilize and leverage 3D printing technologies. Prosthetic medical models, surgical guides, hearing aids, implantable devices, and dental applications have all benefited in various ways from 3DP innovations.
(Link: http://www.upenn.edu/pennnews/news/penn-researchers-improve-living-tissues-3d-printed-vascular-networks-made-sugar)
    
However, one major barrier in utilizing 3DP innovation in bioengineering remains: the process of creating 3D layers composed of engineered living tissues. Researches are having a difficult time finding a way to prevent cells from suffocating. The studies have stalled in progress due to this complication; for example, one study involved substituting organs from the patients’ own cells. The structures of blood vessel networks are too sophisticated to be regenerated and studied in a lab.To get around this obstacle, bioengineering Postdoctoral Students Jordan Miller and Christopher Chen, along with the rest of their research team, have developed a new approach. The research team recreated a 3D filament network in the shape of a blood vessel system. This filament can be positioned inside a template. With the help of a RepRap, a 3D printer, and using the right materials, the students managed to provide a better simulation of vascular system. The team found an ideal combination of sucrose and glucose, with a small amount of dextran to maintain structure. (Link to: http://www.bodyworlds.com/en.html)

The 'Body Worlds' exhibit inspired Jordan Miller through its plethora of displays of plastic molds of organ systems, tendons, and muscular compositions within the human body. Miller decided to change direction and began focusing on printing the vasculature, rather than attempting to print out the actual tissue. This approach allowed the team to develop the shape of the vascular system composed of self-standing 3D filament networks; it also afforded them the opportunity to remove the mold and vascular system pattern after the engineering cells created a solid tissue enclosing the filament structure. (Link: http://www.robaid.com/tech/3d-printed-vascular-network-templates-made-from-sugar.htm)

After persistent trials, the team found a type of sugar to use that was firm enough to build the template. Sugar could be used for 3DP template development because it can be dissolved in water without causing any damage to the living cells and also provided a durable and protected shelter for cell development. The glucose and sucrose sugar formula was coated with a corn-based degradable polymer. The coating served two functions: the first was to stabilize the sugar after the 3DP process concluded, and the second was to allow the sugar to flow out of the water-based gel housing the cells via the channels they’ve forged. The sugar won’t constrain the gel solidification process or damage nearby developing cells.

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After being printed by the RepRap 3D printer, the cell cultures are placed around the vascular system made of sugar inside the template Once the sugar structure is removed, researchers will push fluid networks to deliver nutrients to the tissue.

A significant barrier to saturation in the vasculature market for this new invention is devising a system to mass-produce it. In an article on Robaid.com, Miller stated: “a RepRap 3D printer is only a tiny fraction of the cost of commercial 3D printers,” as well as offered to hold workshops to teach other researchers how to construct. 3D printing is still not feasible to mass-produce this delicate and complex invention. The RepRap 3D printer uses open-source software, however, the intricate nature of biotechnological inventions and the uniqueness involved with each case requires a large investment of time and energy. The researchers have no way to predict how scaling of their technology will play out in the marketplace. Researchers would have to produce a large amount of tissue, which would be costly and time-consuming for 3D printers to build the vascular channels layer-by-layer. Mass production will require standardization of Millet et al.’s product, an essential step stone towards industrial product certification.

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    The future trends for 3DP technology in bioengineering research include pursuing higher resolution for various materials used in inventions, lowering costs, and increasing printing speed. In the long-term, organ 3D printing will aid in developing simulations for surgical operations and organ transplants. Using a patient's own cells as proxy, eventually organs could be grown via 3DP in labs, solving organ shortages worldwide.