Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, Singapore 138669, Singapore.
Biomaterials. 2012 Sep;33(27):6533-41. doi: 10.1016/j.biomaterials.2012.05.043. Epub 2012 Jun 15.
Effective delivery of DNA to direct cell behavior in a well defined three dimensional scaffold offers a superior approach in tissue engineering. In this study, we synthesized biodegradable nanostructured hydrogels with tunable physical properties for cell and gene delivery. The hydrogels were formed via Michael addition chemistry by reacting a four-arm acrylate-terminated PEG with a four-arm thiol-functionalized PEG. Nanosized micelles self-assembled from the amphiphilic PEG-b-polycarbonate diblock copolymer, having reactive end-groups, were chemically incorporated into the hydrogel networks at various contents. The use of Michael addition chemistry allows for in situ hydrogel formation under the physiological conditions. Mechanical property analysis of the hydrogels revealed a correlation between the content of micelles and the storage modulus of the hydrogels. Internal morphology of hydrogels was observed using a field emission scanning electron microscope, which showed that the number and/or size of the pores in the hydrogel increased with increasing micelle content due to reduced crosslinking degree. There exists an optimal micelle content for cell proliferation and gene transfection. MTT assays demonstrated the highest cell viability in the hydrogel with 20% micelles. The gene expression level in hMSCs in the hydrogel with 20% micelles was also significantly higher than that in the hydrogel without micelles. The enhanced cell viability and gene expression in the hydrogel with the optimized micelle content are likely attributed to the physical properties that provide a better environment for cell-matrix interactions. Therefore, incorporating micelles into the hydrogel is a good strategy to control cellular behavior in 3-D through changes in physical properties of the microenvironment.
在明确的三维支架中有效递送到直接细胞行为的 DNA 提供了组织工程中的一种优越方法。在这项研究中，我们合成了具有可调节物理性质的可生物降解的纳米结构水凝胶，用于细胞和基因传递。水凝胶通过迈克尔加成化学反应形成，其中四臂丙烯酰胺封端的 PEG 与四臂硫醇官能化的 PEG 反应。具有反应性末端基团的两亲性 PEG-聚碳酸酯嵌段共聚物自组装成纳米尺寸的胶束，可在各种含量下化学掺入水凝胶网络中。迈克尔加成化学的使用允许在生理条件下进行原位水凝胶形成。水凝胶的机械性能分析表明，胶束含量与水凝胶的储能模量之间存在相关性。使用场发射扫描电子显微镜观察水凝胶的内部形态，结果表明，由于交联度降低，水凝胶中孔的数量和/或尺寸随胶束含量的增加而增加。对于细胞增殖和基因转染，存在最佳的胶束含量。MTT 分析表明，含 20%胶束的水凝胶中细胞活力最高。含 20%胶束的 hMSCs 中的基因表达水平也明显高于不含胶束的水凝胶。在优化的胶束含量的水凝胶中，细胞活力和基因表达的增强可能归因于物理性质，这些性质为细胞-基质相互作用提供了更好的环境。因此，将胶束掺入水凝胶是通过改变微环境的物理性质来控制 3-D 中细胞行为的一种良好策略。
