Label-Free Imaging of Composite Hyaluronic Acid Hydrogels in Regenerative Medicine

水凝胶支架越来越多地被用作模拟组织的材料和作为改善 移植干细胞的保留率和存活率。我们最近开发了一种新的化学交换 能够探测体内稳定性的饱和转移(CEST)磁共振成像(MRI)方法 植入型复合透明质酸(HA)水凝胶的明胶分解以“无标签”方式进行。 与裸细胞相比，我们发现移植的神经干细胞在以下情况下显示出更高的存活率 应用水凝胶脚手架。仍然存在的一个主要问题是材料的最佳机械性能 水凝胶，以及这与细胞存活的关系。一方面，对于最初的结构支撑，凝胶不应该 分解得太快了，但另一方面，它们应该在某个时候分解，以便移植的细胞 向外生长并与周围的宿主组织结合。我们的目标是合成一系列复合近... 不同组成和稳定性的红外(NIR)-HA水凝胶的稳定性研究 活体，并将CEST/近红外光学成像结果与使用 生物发光成像(BLI)作为常规读出。使用增强型绿色荧光蛋白(SGFP) 作为一种新的CEST MRI双峰报告基因，我们还将研究CEST MRI是否能够探测到 体内细胞同时存活。我们选择将这种方法应用于神经胶质细胞受限的移植。 转基因肌萎缩侧索硬化症(ALS)小鼠模型中的前体细胞(GRP)，因为我们发现 移植的裸细胞没有水凝胶支架，在恶劣的ALS组织环境中存活很差。

Hydrogel scaffolds are increasingly being used as tissue-mimicking materials and as vehicles to improve transplanted stem cell retention and survival. We have recently developed a new chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) method that is able to probe the in vivo stability and gelatin decomposition of implanted composite hyaluronic acid (HA) hydrogels in a “label-free” fashion. Compared to naked cells, we found that transplanted neural stem cells showed improved survival when hydrogel scaffolding was applied. A major question that remains is the optimal mechanical properties of the hydrogel, and how this relates to cell survival. At the one hand, for initial structural support, the gels should not decompose too fast, but at the other hand they should at some point decompose to allow transplanted cells to grow out and integrate with the surrounding host tissue. Our aim is to synthesize a range of composite near- infrared (NIR)-HA hydrogels with different compositions and stabilities, to image their stability properties in vivo, and to correlate the CEST/NIR optical imaging findings with cell survival as assessed using bioluminescent imaging (BLI) as conventional readout. Using supercharged green fluorescent protein (sGFP) as a new CEST MRI bimodal reporter gene, we will also investigate whether or not CEST MRI is able to probe in vivo cell survival simultaneously. We have chosen to apply this approach to transplantation of glial-restricted precursor cells (GRPs) in a transgenic amyotropic lateral sclerosis (ALS) mouse model, as we have found that transplanted naked cells without hydrogel scaffolding survive poorly in the hostile ALS tissue environment.