Role and prospects of regenerative biomaterials in the repair of spinal cord injury

Axonal junction defects and an inhibitory environment after spinal cord injury seriously hinder the regeneration of damaged tissues and neuronal functions. At the site of spinal cord injury, regenerative biomaterials can fill cavities, deliver curative drugs, and provide adsorption sites for transplanted or host cells. Some regenerative biomaterials can also inhibit apoptosis, inflammation and glial scar formation, or further promote neurogenesis, axonal growth and angiogenesis. This review summarized a variety of biomaterial scaffolds made of natural, synthetic, and combined materials applied to spinal cord injury repair. Although these biomaterial scaffolds have shown a certain therapeutic effect in spinal cord injury repair, there are still many problems to be resolved, such as product standards and material safety and effectiveness.

Folic acid contributes to peripheral nerve injury repair by promoting Schwann cell proliferation, migration, and secretion of nerve growth factor

After peripheral nerve injury, intraperitoneal injection of folic acid improves axon quantity, increases axon density and improves electromyography results. However, the mechanisms for this remain unclear. This study explored whether folic acid promotes peripheral nerve injury repair by affecting Schwann cell function. Primary Schwann cells were obtained from rats by in vitro separation and culture. Cell proliferation, assayed using the Cell Counting Kit-8 assay, was higher in cells cultured for 72 hours with 100 mg/L folic acid compared with the control group. Cell proliferation was also higher in the 50, 100, 150, and 200 mg/L folic acid groups compared with the control group after culture for 96 hours. Proliferation was markedly higher in the 100 mg/L folic acid group compared with the 50 mg/L folic acid group and the 40 ng/L nerve growth factor group. In Transwell assays, the number of migrated Schwann cells dramatically increased after culture with 100 and 150 mg/L folic acid compared with the control group. In nerve growth factor enzyme-linked immunosorbent assays, treatment of Schwa nn cell cultures with 50, 100, and 150 mg/L folic acid increased levels of nerve growth factor in the culture medium compared with the control group at 3 days. The nerve growth factor concentration of Schwann cell cultures treated with 100 mg/L folic acid group was remarkably higher than that in the 50 and 150 mg/L folic acid groups at 3 days. Nerve growth factor concentration in the 10, 50, and 100 mg/L folic acid groups was higher than that in the control group at 7 days. The nerve growth factor concentration in the 50 mg/L folic acid group was remarkably higher than that in the 10 and 100 mg/L folic acid groups at 7 days. In vivo, 80 μg/kg folic acid was intraperitoneally administrated for 7 consecutive days after sciatic nerve injury. Immunohistochemical staining showed that the number of Schwann cells in the folic acid group was greater than that in the control group. We suggest that folic acid may play a role in improving the repair of peripheral nerve injury by promoting the proliferation and migration of Schwann cells and the secretion of nerve growth factors.

Bioadaptability:An Innovative Concept for Biomaterials

Biocompatibility is the basic requirement of biomaterials for tissue repair. However, the present concept of biocompatibility has a certain limitation in explaining the phenomena involved in biomaterial-based tissue repair. New materials, in particular those for tissue engineering and regeneration, have been developed with common characteristics, i.e. they participate deeply into important chemical and biological processes in the human body and the interaction between the biomaterials and tissues is far more complex. Understanding the interplay between these biomaterials and tissues is vital for their development and functionalization. Herein, we suggest the concept of bioadaptability of biomaterials. This concept describes the three most important aspects that can determine the performance of biomaterials in tissue repair： 1） the adaptability of the micro-environment created by biomaterials to the native microenvironment in situ; 2） the adaptability of the mechanical properties of biomaterials to the native tissue; 3） the adaptability of the degradation properties of biomaterials to the new tissue formation. The concept of bioadaptability emphasizes both the material＇s characteristics and biological aspects within a certain micro-environment and molecular mechanism. It may provide new inspiration to uncover the interaction mechanism of biomaterials and tissues, to foster the new ideas of functionalization of biomaterials and to investigate the fundamental issues during the tissue repair process by biomaterials. Furthermore, designing biomaterials with such bioadaptability would open a new door for repairing and regenerating organs or tissues. In this review, we summarized the works in recent years on the bioadaptability of biomaterials for tissue repair applications.

聚氨酯材料修复周围神经的新思路与机遇

背景:聚氨酯材料因优异的理化性质在生物医学领域中具有广泛的应用前景,对基于聚氨酯材料构建的神经导管进行仿生设计和功能化修饰,有望进一步解决神经再生修复难题。目的:综述基于聚氨酯材料构建的神经导管在周围神经修复领域的应用现状及进展。方法:设置英文检索词为“polyurethane,PU,polyurethane material,polyurethane biomaterials,nerve regeneration,peripheral nerve injury,nerve repair,nerve scaffold,nerve guidance conduit,nerve conduits”,中文检索词为“聚氨酯,PU,聚氨酯材料,聚氨酯生物材料,神经再生,周围神经损伤,神经修复,神经支架,神经导管”,检索PubMed、Web of Science、中国知网和万方数据库中2014-2024年发表的文献,最终纳入61篇文献进行综述。结果与结论:成分仿生是提高聚氨酯神经导管生物活性的有效策略。通过结构仿生优化聚氨酯神经导管,能够为神经组织再生提供生物引导线索。生物力学仿生聚氨酯神经导管可能在免疫调节和促进轴突生长中发挥重要作用。通过优化聚氨酯材料的导电微环境,有助于重建神经电信号传导通路。聚氨酯神经导管可作为药物载体,发挥抗炎和神经保护作用。联合应用多种设计策略优化聚氨酯神经导管虽然可以在多方面改善受损神经的功能,但由于神经复杂的结构和动态变化的病理生理微环境,神经导管设计策略仍旧有待完善。未来进一步改进和创新神经仿生设计策略,有望为神经组织工程领域的发展提供新的思路和机遇。