Researchers from China’sSichuan UniversityandXiamen大学have developed 3D printed self-adhesive bandages that are capable of delivering nerve-healing drugs.
该团队的制造纱布包括两个点击激活的水凝胶层和一个可以加入再生药物的内部截面。一旦缠绕在受伤的神经的部位，该设备以鼓励周围神经系统（PNS）中神经胶质细胞生长的方式释放药物。
In the future, the scientists believe that their novel 3D printed dressing design, could assist doctors while they carry out widely-used nerve repair operations such as neurorrhaphy.
New treatments for nerve traumas
It’s possible to injure a peripheral nerve in a variety of ways, ranging from sporting incidents to illnesses such as tumors, but they are almost always followed by a loss of sensory function in the affected area. Although the PNS has regenerative capabilities and is able to heal itself in certain situations, this is highly dependent on the size and scale of the injury.
In some cases, neurorrhaphy (a specialized surgery) has to be deployed to stitch the nerves together, but according to research from theUS Air Force，只有50％的治疗方法是成功的。为了使过程更有效，许多科学家目前正在研究创造更有利环境，促进细胞生长并引起更积极反应的方法。
In 2019 another team from Sichuan University incorporated PNS drugs into Nerve Guidance Scaffolds (NGS’) designed to be released near the site of an injured nerve. The problem with scaffold-based methods is that they’re often inaccurate, causing the medication to leak into surrounding tissues, and running the risk of side effects.
除了泄漏外，NGS的安装可能很棘手，这是在细腻的神经末端使用的理想选择，需要仔细治疗以避免进一步的损害。与此同时，3D打印技术显示出可以预载药物并在受伤部位原位释放的NGS的巨大潜力。
Building on this drug-infused additive manufacturing approach, the team set about fabricating their own biodegradable nerve-healing solution.
科学家的“可单击” 3D打印绷带
To create their self-adhesive bandages, the researchers polymerized a set of clickable functionalized monomers into rectangles using a Digital Light Processing (DLP) 3D printer. For the second layer of each structure, a different ink was deployed which contained XMU-MP-1 nanoparticles, a drug used to encourage protein and cell growth in patients.
After rolling and self-adhering, the gauze became a wrap shape with layer thicknesses of 139 µm for the drug-loaded ‘grated’ side, and 110 µm on the polymer side. In order to verify the in vivo healing capabilities of their bandage, the team proceeded to carry out a series of biocompatibility tests.
最初的评估使添加剂的伤口敷料暴露于“ Schwann”细胞，这通常对于使神经纤维保持在PNS中至关重要。结果表明，该团队的3D打印纱布并未对细胞活力产生负面影响，而药物释放分析显示，在十个小时内，水凝胶溶解了。
在下一阶段测试中，将绷带注入实验室大鼠的背面，并在15周内观察到。植入物不会引起视觉炎症，并且表现出良好的生物相容性，证明了这些设备能够在体内使用，而不会导致刺激或身体排斥。
This was followed by in-vivo surgery on the rats’ sciatic nerves, during which, the surface tension of the team’s 3D-printed hydrogel bandage enabled it to roll around and adhere to the affected area. Three months later, the researchers re-opened the wounds and found that the nerve was fully healed, and their device had been central to its recovery.
Having proved during testing that their additive dressing could deploy its drug payload without damaging nearby tissues, the team considered their approach to be a success. With further research and optimization, the scientists hope that their bandage can either be used within existing surgeries or develop novel biomaterials for nerve repair.
3D printing and repairing the nervous system
Using additive manufacturing to aid nerve cell repair isn’t a novel concept in itself, and a number of researchers have applied the technology in this way in recent years.
Scientists from the Canadian萨斯喀彻温大学，，，，have developed3D打印的组织支架that could be used to treat damaged peripheral nerves. The bioprinted scaffolds proved to be more mechanically stable than previous hydrogels and showed greater cell viability too.
同样，研究人员Kyoto University在日本，已经设计了innovative method of 3D printingregenerative nerve tissues. By fabricating the cells inside a ‘needle array,’ the team was able to inject them directly into the site of the injury.
Elsewhere, scientists at the卧龙岗大学，澳大利亚，有成功3D打印神经细胞that are usually found in the brain. According to the researchers, their work could represent an important first step towards the creation of synthetic tissues for treating various mental illnesses.
研究人员的发现在其论文中详细介绍了“A 3D-Printed Self-Adhesive Bandage with Drug Release for Peripheral Nerve Repair。” The study was co-authored by Jiumeng Zhang, Yuwen Chen, Yulan Huang, Wenbi Wu, Xianming Deng, Haofan Liu,Rong Li，Jie Tao，Xiang Li，Xuesong Liu和Maling Gou。
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Featured image shows the polymer-coated hydrogel enclosed within the team’s 3D printed bandages. Image via Advanced Science journal.
