Non-invasive 3D Bioprinting
Written by Sophia Desai
3D printing technology has become so prominent and accessible that anyone is able to purchase a machine and create products. Therefore, it was inevitable that this concept would make its way into the biotech field. 3D bioprinting is a novel way of 3D printing that uses biocompatible materials, like cells, as the “ink” in order to create biomedical components that can imitate body parts. This technology has emerged as an innovative way to address regenerative medicine, tissue engineering, and more, as it can create functional living tissues. 3D bioprinting has the ability to reduce the need for transplants, which could have major implications for public health given the long wait for transplants in the US.
Currently, to execute this technology, doctors need to expose the area where the printed tissue will be placed, whether implanting an already existing 3D bioprinted object or using in situ printing. In situ printing involves printing the object directly into the desired location while the site is open and accessible. However, a recent study from Sichuan University in China has found a possible method for noninvasive 3D bioprinting that could solve this problem. Researchers have discovered that near-infrared (NIR) wavelengths of light can be used for digital NIR photopolymerization (DNP). Photopolymerization uses light to join small molecules together into a larger one, and this helps fabricate structures for 3D printing. In this experiment, a micromirror device modulates the NIR to the desired pattern for whichever object or tissue is to be printed. A nano initiator molecule starts the polymerization of monomers. The desired bioink is injected subcutaneously, meaning just beneath the skin, and outside radiation from the NIR starts formation of a customized tissue.
This study could have major implications for public health across the globe. Ear birth defects are relatively common, especially in Asia where this study was done, and they require implantation of artificial tissue. This implantation often causes Iatrogenic, or surgery-related, injury. The researchers for this paper performed a test to see if an ear could be 3D printed noninvasively. To do this, an image of an ear was formulated by taking the mirror image of the opposite ear. Bioink made of cartilage cells called Chondrocytes was subcutaneously injected into mice with a nano initiator. Consequently, the mice were illuminated with the NIR wavelengths modulated for the personalized ear shape. 20 seconds later, an ear-shaped construct was noninvasively printed in vivo, meaning inside a living organism. The ear shape was maintained after 1 month of observation.
Overall, this research could mark a large step forward in medicine. Regarding the future utilization of 3D bioprinting, the 16 authors of the paper note that, “it is very important to customize 3D printing systems for the specific medical applications.” This means future tests should be done using different bioinks to print more tissues in order to see if the DNP method carries over to other uses. Eventually, clinical testing can be done so that this technology can be employed in regular medical practice.
Additional experiments should also be done to see if different wavelengths of light would be compatible. UV light is a common option, but it is likely to injure more cells than NIR light, so it is not viable for this method. On the other hand, NIR light could cause other complications to the body; for example, long exposure to infrared waves can increase the body temperature, which might lead to issues during medical procedures. NIR light has low energy photons, and the nano initiators have inadequate photon absorption, so different possible initiators should be looked into. There is some preliminary promise in natural ones such as Bacteriochlorophyll and dye borate.
This novel method of the already “disruptive technology” of 3D bioprinting is poised to grow and change noninvasive medicine. It may have the capability to reduce the need for transplants, saving the lives of thousands of people each year who wait for organs. This noninvasive 3D bioprinting could also cause less reliance on stem cells for regenerative medicine, which is very controversial. As the increase in funding pushes the growth of the industry, limitations are likely to be encountered. However, I believe that this breakthrough is the first step of many to employ noninvasive 3D bioprinting in a clinical use.
Works Cited:
Chen, Y., Zhang, J., Liu, X., Wang, S., Tao, J., Huang, Y., . . . Gou, M. (2020, June 01). Noninvasive in vivo 3d bioprinting. Retrieved February 25, 2021, from https://advances.sciencemag.org/content/6/23/eaba7406
Jennifer Whitlock, R. (2020, January 30). The use of in situ in surgery and cancer treatments. Retrieved February 25, 2021, from
https://www.verywellhealth.com/in-situ-explained-3157097
Murphy, S., & Atala, A. (2014, August 05). 3D bioprinting of tissues and organs.
Retrieved February 25, 2021, from https://www.nature.com/articles/nbt.2958
Organ donation Statistics. (2021, April 02). Retrieved April 12, 2021, from https://www.organdonor.gov/statistics-stories/statistics.html
Photopolymerization. (2020, December 16). Retrieved February 25, 2021, from https://www.whiteclouds.com/3DPedia/photopolymerization.html