Assunção-Silva Rita C, Oliveira Cátia Costa, Ziv-Polat Ofra, Gomes Eduardo D, Sahar Abraham, Sousa Nuno, Silva Nuno A, Salgado António J
Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Campus de Gualtar, 4701-057 Braga, Portugal. ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal. R C Assunção-Silva and C C Oliveira contributed equally to this work.
Biomed Mater. 2015 Oct 20;10(5):051001. doi: 10.1088/1748-6041/10/5/051001.
The ability of peripheral nervous system (PNS) axons to regenerate and re-innervate their targets after an injury has been widely recognized. However, despite the considerable advances made in microsurgical techniques, complete functional recovery is rarely achieved, especially for severe peripheral nerve injuries (PNIs). Therefore, alternative therapies that can successfully repair peripheral nerves are still essential. In recent years the use of biodegradable hydrogels enriched with growth-supporting and guidance cues, cell transplantation, and biomolecular therapies have been explored for the treatment of PNIs. Bearing this in mind, the aim of this study was to assess whether Gly-Arg-Gly-Asp-Ser synthetic peptide (GRGDS)-modified gellan gum (GG) based hydrogels could foster an amenable environment for neurite/axonal growth. Additionally, strategies to further improve the rate of neurite outgrowth were also tested, namely the use of adipose tissue derived stem cells (ASCs), as well as the glial derived neurotrophic factor (GDNF). In order to increase its stability and enhance its bioactivity, the GDNF was conjugated covalently to iron oxide nanoparticles (IONPs). The impact of hydrogel modification as well as the effect of the GDNF-IONPs on ASC behavior was also screened. The results revealed that the GRGDS-GG hydrogel was able to support dorsal root ganglia (DRG)-based neurite outgrowth, which was not observed for non-modified hydrogels. Moreover, the modified hydrogels were also able to support ASCs attachment. In contrast, the presence of the GDNF-IONPs had no positive or negative impact on ASC behavior. Further experiments revealed that the presence of ASCs in the hydrogel improved axonal growth. On the other hand, GDNF-IONPs alone or combined with ASCs significantly increased neurite outgrowth from DRGs, suggesting a beneficial role of the proposed strategy for future applications in PNI regenerative medicine.
外周神经系统（PNS）轴突在损伤后再生并重新支配其靶标的能力已得到广泛认可。然而，尽管显微外科技术取得了长足进步，但仍很少能实现完全功能恢复，尤其是对于严重的周围神经损伤（PNIs）。因此，能够成功修复周围神经的替代疗法仍然至关重要。近年来，人们探索了使用富含生长支持和导向线索的可生物降解水凝胶、细胞移植和生物分子疗法来治疗PNIs。考虑到这一点，本研究的目的是评估基于甘氨酸 - 精氨酸 - 甘氨酸 - 天冬氨酸 - 丝氨酸合成肽（GRGDS）修饰的结冷胶（GG）水凝胶是否能为神经突/轴突生长营造适宜的环境。此外，还测试了进一步提高神经突生长速率的策略，即使用脂肪组织衍生干细胞（ASCs）以及胶质细胞源性神经营养因子（GDNF）。为了提高其稳定性并增强其生物活性，将GDNF共价偶联到氧化铁纳米颗粒（IONPs）上。还筛选了水凝胶修饰的影响以及GDNF - IONPs对ASC行为的作用。结果表明，GRGDS - GG水凝胶能够支持基于背根神经节（DRG）的神经突生长，而未修饰的水凝胶则未观察到这种情况。此外，修饰后的水凝胶还能够支持ASCs附着。相比之下，GDNF - IONPs的存在对ASC行为没有正面或负面影响。进一步的实验表明，水凝胶中ASCs的存在促进了轴突生长。另一方面，单独的GDNF - IONPs或与ASCs联合使用显著增加了DRGs的神经突生长，表明所提出的策略在PNI再生医学未来应用中具有有益作用。
