Researchers from Sichuan University and Xiamen University in China have developed 3D-printed self-adhesive bandages that can provide nerve repair drugs.The team’s gauze consists of two click-activated layers of hydrogel and an internal area that can be loaded with regenerative medicine.Once wrapped around the injured nerve site, the device releases the drug in a way that stimulates the growth of glial cells in the peripheral nervous system (PNS).In the future, scientists believe their novel 3D-printed dressing design could help doctors perform extensive nerve repair operations, such as neurological diarrhoea.
The Chinese team’s 3D-printed bandages (pictured) have been shown to store and release drug payloads that strengthen cells.The image is from the journal Advanced Science
New treatments for nerve injuries
Peripheral nerve damage can occur in a variety of diseases, from sports accidents to tumours, but in the affected areas it is almost always accompanied by a loss of sensory function.Although PNS is regenerative and can recover on its own in some cases, much depends on the extent and scale of the injury.
In some cases, neurodiarrhea surgery (specialized surgery) must be deployed to stitch the nerves together, but only 50 percent of treatments are successful, according to the Air Force.To make the program more effective, many scientists are currently working on ways to create more favorable environments that promote cell growth and trigger a more positive response.
In 2019, another team at Sichuan University incorporated PNS drugs into a neuro-guided stent (NGS ‘) designed to be released near the site of an injured nerve.The problem with stent-based approaches is that they are often inaccurate, leading to drug leaks into surrounding tissue and the risk of side effects.
In addition to leakage, NGS’ is tricky to install and is not ideal for use around delicate nerve endings, which require careful treatment to avoid further damage.At the same time, 3D printing shows great potential in the manufacture of NGS’, which can be pre-loaded with drugs and released on site at the site of injury.Based on the additive manufacturing method of injecting the drug, the team set out to create its own biodegradable neural repair solution.
Using the DLP printing process, the team was able to make bandages by injecting the drug’s hydrogel internally.The image is from the journal Advanced Science.
Scientists’ “clickable” 3D-printed bandages
To create their own self-adhesive bandages, the researchers used a digital optical processing (DLP) 3D printer to aggregate a set of clickable functionalized monomers into rectangles.For the second layer of each structure, a different ink was deployed that contained NANOPARTICLES of XMU-MP-1, a drug used to promote the growth of patient proteins and cells.
After rolling and self-adhesive, the gauze is wrapped and the drug-loaded “ground” side is 139 m thick and the polymer side is 110 m thick.To test the bandages’ ability to heal in vivo, the team set out to run a series of biocompatibility tests.Preliminary evaluation shows that additional wound dressings are exposed to “Schwann” cells, which are often critical to maintaining the survival of nerve fibers in PNS.The results showed that the team’s 3D-printed gauze did not have a negative effect on cell activity, and the drug release analysis showed that the hydrogel dissolved within 10 hours.
By wrapping a drug that promotes cell growth in a polymer shell, the researchers were able to precisely control its rate of diffusion.The image is from the journal Advanced Science.
In the next stage, the bandages were injected into the rats’ backs and observed over a period of 15 weeks.The implant did not cause visual inflammation and showed good biocompatibility, demonstrating that the device could be used in the body without causing irritation or rejection.
The team then performed in vivo surgery on the sciatic nerve in rats, during which the surface tension of the 3D-printed hydrogel bandage enabled it to roll and stick to the wound.When the researchers reopened the wound three months later, they found that the nerve had healed completely, and the device had become key to its recovery.After proving during testing that their additional dressings could deploy their drug payloads without damaging nearby tissues, the team decided their approach was a success.With further research and refinement, the scientists hope their bandages can be used in existing surgeries as well as to develop new biomaterials for nerve repair.
3D printing and repairing the nervous system
The idea of using additive manufacturing to aid nerve cell repair is not new in itself, and many researchers have applied the technique in this way in recent years.Scientists at the University of Saskatchewan in Canada have developed a 3D-printed tissue scaffold that could be used to treat damaged peripheral nerves.Bioprinted scaffolds have been shown to be more mechanically stable than previous hydrogels and to show greater cellular activity.
Similarly, researchers at Kyoto University in Japan have devised an innovative 3D-printed way to regenerate nerve tissue.By making cells in the “needle array”, the team was able to inject them directly into the site of the injury.
Elsewhere, scientists at the University of Wollongong in Australia have succeeded in 3D printing nerve cells normally found in the brain.The researchers believe their work could be an important first step toward creating synthetic tissues that could be used to treat a variety of mental disorders.
