Wang Dong-an, Williams Christopher G, Li Qiang, Sharma Blanka, Elisseeff Jennifer H
Department of Biomedical Engineering, Johns Hopkins University, 3400 North Charles Street/Clark Hall 106, Baltimore, MD 21218, USA.
Biomaterials. 2003 Oct;24(22):3969-80. doi: 10.1016/s0142-9612(03)00280-1.
A phosphate-containing and photocrosslinkable polymer, poly(ethylene glycol) di-[ethyl phosphatidyl (ethylene glycol) methacrylate], "PhosPEG-dMA", was synthesized. As a water-soluble macromer, PhosPEG-dMA is suitable for in situ injection and cell-encapsulation by light-induced gelation to produce a novel biocompatible and biodegradable hydrogel for application to cartilage and bone tissue engineering. 1H-NMR, MALDI-TOF mass spectrometry, and elemental analysis were performed to characterize the macromer. Fifteen and 20% (w/v) PhosPEG gels were photopolymerized using UV light with 0.05% photoinitiator. The swelling and water content of the hydrogels was studied and the crosslinking efficiency (density) of the macromers was simulated based on the Peppas-Merrill model. Torsional mechanical analysis of the gels demonstrated a viscoelastic characteristic with high elasticity. The results indicated that, with the fixed PEG-segment size, the greater strength and water-content of the gels depend on the higher crosslinking density. Degradation experiments revealed a linear dry-weight loss of 22.88% and 16.08% from 15% and 20% PhosPEG gels after 9 weeks. The 31P-NMR detected the signals of both phosphate and phosphoric acid in the degrading systems (the gel bulks and the supernatants). Finally, human mesenchymal stem cells (hMSC) were encapsulated into PhosPEG Gel constructs and remained viable as qualitatively demonstrated by "Live/Dead" cell staining assay and MTT assay. The cell-encapsulation efficiency was determined by the characterization of DNA content in each gel construct and the semi-quantitative analysis of the cell viability was also performed by the DNA assay combined with MTT assay.
合成了一种含磷酸盐且可光交联的聚合物聚乙二醇二[乙基磷脂酰（乙二醇）甲基丙烯酸酯]，即“PhosPEG-dMA”。作为一种水溶性大分子单体，PhosPEG-dMA适用于原位注射和通过光诱导凝胶化进行细胞封装，以制备一种新型的生物相容性和可生物降解水凝胶，用于软骨和骨组织工程。通过1H-NMR、基质辅助激光解吸电离飞行时间质谱和元素分析对该大分子单体进行了表征。使用含0.05%光引发剂的紫外光对15%和20%（w/v）的PhosPEG凝胶进行光聚合。研究了水凝胶的溶胀和含水量，并基于Peppas-Merrill模型模拟了大分子单体的交联效率（密度）。凝胶的扭转力学分析表明其具有高弹性的粘弹性特征。结果表明，在聚乙二醇链段尺寸固定的情况下，凝胶更高的强度和含水量取决于更高的交联密度。降解实验显示，9周后15%和20%的PhosPEG凝胶的线性干重损失分别为22.88%和16.08%。31P-NMR检测到了降解体系（凝胶块和上清液）中磷酸盐和磷酸的信号。最后，将人间充质干细胞（hMSC）封装到PhosPEG凝胶构建体中，通过“活/死”细胞染色分析和MTT分析定性证明细胞仍具有活力。通过表征每个凝胶构建体中的DNA含量来确定细胞封装效率，并通过DNA分析结合MTT分析对细胞活力进行半定量分析。
