文献：Enzymatically crosslinked and mechanically tunable silk fibroin/pullulan hydrogels for mesenchymal stem cells delivery

文献链接：https://pubmed.ncbi.nlm.nih.gov/29665386/

作者：Tao Lia,1, Xiongbo Songa, Changmei Wengb, Xin Wanga, Jiangyi Wua, Li Sunc, Xiaoyuan Gonga, Wei-Nan Zenga, Liu Yanga, Cheng Chena

相关产品：Pullulan (PL: MW 100 kDa)  普鲁兰多糖

原文摘要：Hydrogels with good biocompatibility, proper degradation rates, and tissue-matched elasticity are widely used in tissue engineering, regenerative medicine, and drug delivery. In this study, enzymatically crosslinked biocompatible hydrogels were successfully developed using silk fibroin (SF) and pullulan (PL) under physiological conditions in the presence of both horseradish peroxidase (HRP) and hydrogen peroxide (H2O2). A series of properties of the hydrogels including gelation time, equilibrium swelling, enzyme degradation, morphology, rheological property, and compression modulus of SF/PL hydrogels were studied by varying the concentration of PL. The results showed that the SF/PL hydrogels had applicable gel-forming rate (ranging from 12 to 60 min), tunable compressive strength (ranging from 7 to 71 kPa) and shear mechanical properties (ranging from 200 to 1470 Pa). The properties of the SF/PL hydrogels were easily modulated by changing the concentration of PL. The compressive modulus of the SF+20%PL hydrogels was 71.4 ± 9.3 kPa, which was in the range of that of musculoskeletal system. In addition, the rabbit bone marrow-derived mesenchymal stem cells (MSCs) were encapsulated in SF/PL hydrogels for 7 days, and cell viability and morphology were observed. Live/dead staining assay demonstrated that the hydrogel system possessed good cytocompatibility. These features support that SF/PL hydrogels have a potential as cell delivery carrier scaffold in musculoskeletal tissue engineering.

普鲁兰多糖（PL）是一种天然的从黑酵母发酵培养基中获得的聚合物。PL作为一种非离子多糖，是中性、可生物降解、非免疫原性和非致cancer的。由于这些化学和物理性质，PL及其化学修饰在生物医学应用中发挥着至关重要的作用。Bulman等发现PL是一种多功能生物粘合剂，能够在关节软骨表面的间充质干细胞（MSCs），并积极影响成骨分化。水凝胶具有良好的生物相容性、适当的降解率和组织匹配的弹性，应用于组织工程、再生医学和药物传递。

图为：PL结构式

酪胺取代羧甲基化PL的合成：

羧甲基PL（CMPL）是在氢氧化钠的存在下，通过PL与氯乙酸钠的反应。TA取代CMPL（CMPL-TA）是通过TA的胺基与CMPL的羧酸基偶联反应合成的。在一个典型的过程中，将CMP溶解在MES缓冲液中。溶液中加入EDC·HCl和575mgNHS。一段时间后，加入含TA的二甲基甲酰胺（DMF）溶液，在室温氮气下搅拌。用氢氧化钠中和反应混合物，然后通过透析对氯化钠进行彻底纯化，再用Milli-Q水进行纯化。所得到的CMPL-TA偶联物在冷冻干燥后被收集。

图为：SF/PL水凝胶的力学性能。

结果表明，SF/PL水凝胶具有适用的凝胶形成速率、可调抗压强度和剪切力学性能。SF/PL水凝胶的性质很容易通过改变PL的浓度来调节。SF+PL水凝胶的压缩模量在肌肉骨骼系统的压缩范围内。另外，将兔骨髓间充质干细胞（MSCs）包裹于SF/PL水凝胶中，观察细胞活力和形态。活/死染色试验表明，该水凝胶体系具有良好的细胞相容性。这些特征支持了SF/PL水凝胶在肌肉骨骼组织工程中具有作为细胞传递载体支架的潜力。