Wang Shaofei, Jeffries Eric, Gao Jin, Sun Lijie, You Zhengwei, Wang Yadong
State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University , 2999 North Renmin Road, Shanghai 201620, P. R. China.
Departments of Bioengineering, Chemical Engineering, Surgery, and the McGowan Institute, University of Pittsburgh , 3700 O'Hara Street, Pittsburgh, Pennsylvania 15261, United States.
ACS Appl Mater Interfaces. 2016 Apr 20;8(15):9590-9. doi: 10.1021/acsami.5b12379. Epub 2016 Apr 8.
Successful regeneration of nerves can benefit from biomaterials that provide a supportive biochemical and mechanical environment while also degrading with controlled inflammation and minimal scar formation. Herein, we report a neuroactive polymer functionalized by covalent attachment of the neurotransmitter acetylcholine (Ach). The polymer was readily synthesized in two steps from poly(sebacoyl diglyceride) (PSeD), which previously demonstrated biocompatibility and biodegradation in vivo. Distinct from prior acetylcholine-biomimetic polymers, PSeD-Ach contains both quaternary ammonium and free acetyl moieties, closely resembling native acetylcholine structure. The polymer structure was confirmed via (1)H nuclear magnetic resonance and Fourier-transform infrared spectroscopy. Hydrophilicity, charge, and thermal properties of PSeD-Ach were determined by tensiometer, zetasizer, differential scanning calorimetry, and thermal gravimetric analysis, respectively. PC12 cells exhibited the greatest proliferation and neurite outgrowth on PSeD-Ach and laminin substrates, with no significant difference between these groups. PSeD-Ach yielded much longer neurite outgrowth than the control polymer containing ammonium but no the acetyl group, confirming the importance of the entire acetylcholine-like moiety. Furthermore, PSeD-Ach supports adhesion of primary rat dorsal root ganglions and subsequent neurite sprouting and extension. The sprouting rate is comparable to the best conditions from previous report. Our findings are significant in that they were obtained with acetylcholine-like functionalities in 100% repeating units, a condition shown to yield significant toxicity in prior publications. Moreover, PSeD-Ach exhibited favorable mechanical and degradation properties for nerve tissue engineering application. Humidified PSeD-Ach had an elastic modulus of 76.9 kPa, close to native neural tissue, and could well recover from cyclic dynamic compression. PSeD-Ach showed a gradual in vitro degradation under physiologic conditions with a mass loss of 60% within 4 weeks. Overall, this simple and versatile synthesis provides a useful tool to produce biomaterials for creating the appropriate stimulatory environment for nerve regeneration.
神经的成功再生可受益于生物材料，这些材料能提供支持性的生化和机械环境，同时在可控炎症和最小疤痕形成的情况下降解。在此，我们报告一种通过神经递质乙酰胆碱（Ach）共价连接功能化的神经活性聚合物。该聚合物由聚（癸二酰二甘油酯）（PSeD）分两步轻松合成，PSeD先前已在体内证明具有生物相容性和生物降解性。与先前的乙酰胆碱仿生聚合物不同，PSeD-Ach同时含有季铵和游离乙酰基部分，与天然乙酰胆碱结构极为相似。聚合物结构通过氢核磁共振和傅里叶变换红外光谱得以确认。PSeD-Ach的亲水性、电荷和热性能分别通过张力计、zeta电位仪、差示扫描量热法和热重分析来测定。PC12细胞在PSeD-Ach和层粘连蛋白底物上表现出最大的增殖和神经突生长，这些组之间无显著差异。PSeD-Ach产生的神经突生长比含有铵但不含乙酰基的对照聚合物长得多，证实了整个乙酰胆碱样部分的重要性。此外，PSeD-Ach支持原代大鼠背根神经节的黏附以及随后的神经突萌发和延伸。萌发率与先前报告中的最佳条件相当。我们的发现意义重大，因为它们是在100%重复单元中具有乙酰胆碱样功能的情况下获得的，而先前的出版物表明这种情况会产生显著毒性。此外，PSeD-Ach在神经组织工程应用中表现出良好的机械和降解性能。加湿后的PSeD-Ach弹性模量为76.9 kPa，接近天然神经组织，并且能够从循环动态压缩中很好地恢复。PSeD-Ach在生理条件下显示出逐渐的体外降解，4周内质量损失60%。总体而言，这种简单通用的合成方法为生产生物材料提供了一种有用的工具，用于为神经再生创造合适的刺激环境。
