Due to the global shortage of organs and limited organ donors, thousands of patients with severe injuries, illnesses or genetic diseases want organs and tissues. Many of these patients die before transplants are available.
Tissue engineering is an emerging field manufacturing artificial tissue and organ substitutes as permanent solutions for replacing or repairing damage.
As biomedical researchers, we develop temporary 3D organ structures – so-called scaffolds – that can help regenerate damaged tissue and possibly lead to the creation of artificial organs. These tissues can also be used in various tissue engineering applications, including nerve repair in structures constructed from biomaterials.
Approximately 22.6 million patients worldwide require neurosurgical interventions annually to treat damage to the peripheral nervous system. This damage is mainly caused by traumatic events such as motor vehicle accidents, violence, workplace injuries or difficult births. The cost of repairing and regenerating nerves around the world is expected to reach more than $ 400 million by 2025.
Current surgical techniques allow surgeons to realign nerve endings and encourage nerve growth. However, the incidence of recovery in the injured nervous system is not guaranteed and the return of function is almost never complete.
Animal experiments on rats have shown that if more than two centimeters of nerves are damaged, the gap cannot be bridged properly and can lead to a loss of muscle function or muscle feeling. In this condition, it is important to use scaffolding to bridge two sides of the damaged nerve, especially with large nerve injuries.
For large nerve injuries (larger than 2 cm), a scaffold must act as a bridge to connect two sides of the injured nerve. Photo credit: Saman Naghieh, author provided
3D bioprinting prints 3D structures layer by layer, similar to 3D printers. Using this technique, our research team created a porous structure from the patient’s nerve cells and a biomaterial to bridge an injured nerve. We used alginate – made from seaweed – because the human body does not reject it.
Although this technique has not yet been tested in humans, once it has been refined it can help patients waiting for tissues and organs.
Alginate is a challenging material because it collapses easily when 3D printing. Our research focuses on developing new techniques to improve printability.
For nerve repair, alginate has beneficial properties for the growth and functions of living cells, but its poor 3D printability severely limits its manufacture. This means that alginate flows easily during the printing process, resulting in a collapsed structure. We developed a manufacturing method in which cells are contained in a porous alginate structure that is created with a 3D printer.
Previous research used molding techniques to create an alginate without a porous structure to improve nerve regeneration. The cells don’t like such a fixed environment. However, 3D printing a porous alginate structure is difficult and often impossible.
Our research addresses this problem by printing a porous structure of alginate layer by layer instead of a molded bulk algae. Such a structure has interconnected pores and provides a cell-friendly environment. Cells can easily communicate with each other and start regeneration, while the 3D printed alginate provides temporary support for them.
An artificial ear made by a 3D printer: from medical imaging to the creation of a bespoke framework from biomaterial and cells. Photo credit: (Saman Naghieh), author provided
Researchers are working on the implementation of 3D printed structures for patients suffering from nerve injuries and other injuries.
After the manufactured alginate structure has been implanted into a patient, the big question is whether it has sufficient mechanical stability to tolerate the forces exerted by tissues in the body. We have developed a novel numerical model to predict the mechanical behavior of alginate structures.
Our studies will help understand the cell response, which is the main factor to consider when evaluating the success of the alginate structures.
Saman Naghieh is a designer and research fellow at the University of Saskatchewan.
This article first appeared on The Conversation.