Sun Yuqiao, Li Wen, Wu Xiaoli, Zhang Na, Zhang Yongnu, Ouyang Songying, Song Xiyong, Fang Xinyu, Seeram Ramakrishna, Xue Wei, He Liumin, Wu Wutian
Key Laboratory of Biomaterials of Guangdong Higher Education Institutes, Department of Biomedical Engineering, College of Life Science and Technology, Jinan University , Guangzhou, Guangdong, 510632, China.
School of Biomedical Science, LKS Faculty of Medicine, The University of Hong Kong , Pokfulam, Hong Kong SAR, 000000, PR China.
ACS Appl Mater Interfaces. 2016 Jan 27;8(3):2348-59. doi: 10.1021/acsami.5b11473. Epub 2016 Jan 13.
Self-assembling peptide (SAP) RADA16-I (Ac-(RADA)4-CONH2) has been suffering from a main drawback associated with low pH, which damages cells and host tissues upon direct exposure. In this study, we presented a strategy to prepare nanofiber hydrogels from two designer SAPs at neutral pH. RADA16-I was appended with functional motifs containing cell adhesion peptide RGD and neurite outgrowth peptide IKVAV. The two SAPs were specially designed to have opposite net charges at neutral pH, the combination of which created a nanofiber hydrogel (-IKVAV/-RGD) characterized by significantly higher G' than G″ in a viscoelasticity examination. Circular dichroism, Fourier transform infrared spectroscopy, and Raman measurements were performed to investigate the secondary structure of the designer SAPs, indicating that both the hydrophobic/hydrophilic properties and electrostatic interactions of the functional motifs play an important role in the self-assembling behavior of the designer SAPs. The neural progenitor cells (NPCs)/stem cells (NSCs) fully embedded in the 3D-IKVAV/-RGD nanofiber hydrogel survived, whereas those embedded within the RADA 16-I hydrogel hardly survived. Moreover, the -IKVAV/-RGD nanofiber hydrogel supported NPC/NSC neuron and astrocyte differentiation in a 3D environment without adding extra growth factors. Studies of three nerve injury models, including sciatic nerve defect, intracerebral hemorrhage, and spinal cord transection, indicated that the designer -IKVAV/-RGD nanofiber hydrogel provided a more permissive environment for nerve regeneration than the RADA 16-I hydrogel. Therefore, we reported a new mechanism that might be beneficial for the synthesis of SAPs for in vitro 3D cell culture and nerve regeneration.
自组装肽（SAP）RADA16-I（Ac-(RADA)4-CONH2）一直存在一个与低pH值相关的主要缺点，即直接暴露时会损害细胞和宿主组织。在本研究中，我们提出了一种在中性pH值下由两种定制的SAP制备纳米纤维水凝胶的策略。RADA16-I被附加了包含细胞粘附肽RGD和神经突生长肽IKVAV的功能基序。这两种SAP经过特殊设计，在中性pH值下具有相反的净电荷，它们的组合形成了一种纳米纤维水凝胶（-IKVAV/-RGD），在粘弹性测试中其特征是储能模量（G'）显著高于损耗模量（G″）。进行了圆二色性、傅里叶变换红外光谱和拉曼测量以研究定制SAP的二级结构，表明功能基序的疏水/亲水性质和静电相互作用在定制SAP的自组装行为中都起着重要作用。完全嵌入3D-IKVAV/-RGD纳米纤维水凝胶中的神经祖细胞（NPC）/干细胞（NSC）存活了下来，而嵌入RADA 16-I水凝胶中的细胞几乎无法存活。此外，-IKVAV/-RGD纳米纤维水凝胶在不添加额外生长因子的情况下，在三维环境中支持NPC/NSC向神经元和星形胶质细胞分化。对三种神经损伤模型的研究，包括坐骨神经缺损、脑出血和脊髓横断，表明定制的-IKVAV/-RGD纳米纤维水凝胶比RADA 16-I水凝胶为神经再生提供了更有利的环境。因此，我们报道了一种可能有利于合成用于体外三维细胞培养和神经再生的SAP的新机制。
