Department of Biomedical Engineering, University of Minnesota, 7-105 Hasselmo Hall, 312 Church Street South East, Minneapolis, Minnesota 55455, United States.
Biomacromolecules. 2011 Apr 11;12(4):1126-36. doi: 10.1021/bm101451k. Epub 2011 Mar 8.
Injectable hyaluronic acid (HA) hydrogels cross-linked via disulfide bond are synthesized using a thiol-disulfide exchange reaction. The production of small-molecule reaction product, pyridine-2-thione, allows the hydrogel formation process to be monitored quantitatively in real-time by UV spectroscopy. Rheological tests show that the hydrogels formed within minutes at 37 °C. Mechanical properties and equilibrium swelling degree of the hydrogels can be controlled by varying the ratio of HA pyridyl disulfide and macro-cross-linker PEG-dithiol. Degradation of the hydrogels was achieved both enzymatically and chemically by disulfide reduction with distinctly different kinetics and profiles. In the presence of hyaluronidase, hydrogel mass loss over time was linear and the degradation was faster at higher enzyme concentrations, suggesting surface-limited degradation. The kinetics of hydrogel erosion by glutathione was not linear, nor did the erosion rate correlate linearly with glutathione concentration, suggesting a bulk erosion mechanism. A cysteine-containing chemokine, stromal cell-derived factor 1α, was successfully encapsulated in the hydrogel and released in vitro without chemical alteration. Several different cell types, including fibroblasts, endothelial cells, and mesenchymal stem cells, were successfully encapsulated in the hydrogels with high cell viability during and after the encapsulation process. Substantial cell viability in the hydrogels was maintained up to 7 days in culture despite the lack of adhesion between the HA matrix and the cells. The facile synthesis of disulfide-cross-linked, dual-responsive degradable HA hydrogels may enable further development of bioactive matrices potentially suitable for tissue engineering and drug delivery applications.
通过二硫键交联的可注射透明质酸（HA）水凝胶是使用巯基-二硫键交换反应合成的。小分子反应产物吡啶-2-硫酮的产生允许通过紫外光谱实时定量监测水凝胶形成过程。流变学测试表明，水凝胶可以在 37°C 下在数分钟内形成。通过改变 HA 吡啶二硫键和大分子交联剂 PEG-二硫醇的比例，可以控制水凝胶的机械性能和平衡溶胀度。通过二硫键还原，水凝胶可以进行酶促和化学降解，其动力学和曲线明显不同。在透明质酸酶存在下，水凝胶的质量随时间线性损失，酶浓度越高，降解速度越快，这表明存在表面限制的降解。谷胱甘肽对水凝胶侵蚀的动力学不是线性的，侵蚀速率也与谷胱甘肽浓度没有线性关系，这表明存在整体侵蚀机制。含有半胱氨酸的趋化因子基质细胞衍生因子 1α 被成功包裹在水凝胶中，并在体外释放，没有发生化学变化。几种不同的细胞类型，包括成纤维细胞、内皮细胞和间充质干细胞，在封装过程中和封装后都成功地被包裹在水凝胶中，细胞活力很高。尽管 HA 基质与细胞之间缺乏粘附，但在培养物中，水凝胶中的细胞活力仍可维持长达 7 天。二硫键交联的、双响应可降解 HA 水凝胶的简便合成方法可能会进一步开发出适合组织工程和药物输送应用的生物活性基质。
