磁共振超短回波及不相干弥散技术动态评价SOX基因长期诱导干细胞修复损伤软骨基质的作用研究

There is lack of effective approach to evaluate the long term ability of stem cell mediate cartilage repair. The small animal model of cartilage repair mediated by SOX overexpression MSCs has been set up and verified its short term effectiveness. The phenotype of the stem cells for chondrogenic differentiation may be degenerated along with the time of therapy. The long term curative effect of SOX overexpression stem cell is unknown for lacking of established large animal model and long term dynamic evaluation approaches. We have already mastered the up to date and robust UTE and IVIM MRI technique, also have some pilot study on that. It can detect the collagen and proteoglycan within the cartilage matrix and evaluate the structure of cartilage with the techniques. That is the ideal method to long term dynamic observing the cartilage repair process. This study constructs large animal model mediated by SOX overexpression MSCs to achieve: 1) evaluate the quantitative accuracy for UTE and IVIM technique in observing the cartilage repair process by stem cells, further to filter the reasonable MRI models and parameters; 2) estimate the long term curative effect of SOX via MRI, histology, physiology and biochemistry and provide useful ideas for clinical translation of stem cell therapy.

干细胞修复软骨的长期效果缺乏有效动态评估手段。SOX相关基因诱导干细胞修复软骨小动物模型已建立，证实其短期有效。随着治疗时间延长，干细胞软骨表型可能出现退化，影响治疗效果，所以评价长期疗效至关重要。由于未曾建立SOX诱导修复软骨的大动物模型，且缺乏长期动态评估手段，SOX诱导干细胞修复软骨的长期效果仍不清楚。目前我们掌握了最先进的磁共振超短回波及不相干弥散技术，并进行了软骨样本及临床测试，可以直接探测软骨基质内的胶原、蛋白多糖等大分含量，并能评价软骨结构信息，有望解决动态评估干细胞修复软骨的难题。本研究拟建立SOX基因诱导软骨修复大动物模型，利用MRI长期动态观察软骨修复过程。继而 1）评价UTE、IVIM技术在观察干细胞修复过程中定量的准确性，筛选最优MRI模型及参数。2）通过MRI及组织生理、生化检测，评价SOX基因长期疗效，为基因诱导干细胞治疗软骨病变的临床转化提供有益思路。

间充质干细胞（MSC）具有定向分化、损伤修复等功能，SOX家族基因可以提高MSC的软骨源性分化能力，是有潜力的软骨修复方法。磁共振超短回波（UTE-MR）技术对富含胶原纤维的骨肌组织具有良好的成像效果，可以为SOX基因诱导MSC向软骨定向分化的研究提供宏观定量参考，为临床转化提供定量指标。本项目完成研究内容如下：1）建立了常规及SOX过表达的MSC细胞系，用于MR成像的软骨类器官模型，以及适用于该模型显影的UTE磁共振成像体系；2）验证了UTE技术对细胞外基质成分定量的准确性，并筛选出了评价软骨生成的最佳UTE评价指标（MMF值）；3）完成了SOX家族基因对软骨分化及修复的研究，利用UTE成像及分子生物学实验从宏观及微观方面对SOX基因的作用进行了分析及评价，确定了SOX-9对软骨形成的作用最强。