基于共轭聚合物荧光探针的在体干细胞-支架双示踪研究

Many of the tissues in the human body do not have the capacity to regenerate, so damage to these tissues is irreversible. Patients suffering from organ damage must rely on organ transplantation to regain functions. However, the severe limitation in the number of available donors, leaving thousands of patients on waiting lists. To address the issues related to the tissue damage and organ transplantation, stem cell based tissue engineering has emerged as an interdisciplinary research field that using biomaterials based scaffolds to regulate the adhesion, proliferation and differentiation of stem cells to develop functional substitutes for patients with damaged tissues. However, the in vivo distribution, degradation of biomaterials and the interactions between stem cells and biomaterials are still unclear, which hinders the clinical application of tissue engineered grafts. Therefore, it is vital to understand the degradation of scaffolds and study the stem cell-scaffold interactions during tissue regeneration. Herein, we introduce two conjugated polymer (CP) nanodots poly(phenylene ethynylene)(PPE) and poly(9,9-dioctylfluorene-alt-benzothiadiazole) (PFBT) with distinct emissions as non-invasive fluorescent probes with high brightness and low cytotoxicity for tracking of mesenchymal stem cells (MSCs) and their supportive electrospun nanofibrous scaffold to reveal the degradation of scaffold and their interactions during skin regeneration in a mouse model.

组织器官缺损或功能丧失是人类健康所面临的主要危害之一，基于干细胞的组织工程通过构建模拟细胞外基质的生物支架对干细胞增殖、分化进行调节促进组织再生，为修复缺损组织器官提供了新的途径。然而，移植后支架在体内的降解规律及体内干细胞与支架间的相互作用机制尚不明确，限制干细胞-支架复合物的临床应用。因此，示踪干细胞-支架的复合物，从而揭示其移植后的命运具有重要的科学意义。基于双示踪技术可同时准确定位两个被标记物，并获得二者在体内的滞留、分布等信息的特点，本课题拟利用发射波长可区分的两种共轭聚合物荧光纳米粒子实现对干细胞-静电纺纳米纤维支架复合物在小鼠皮肤再生模型中的长期双示踪，揭示纳米纤维支架在体内的降解及结构变化规律，明确干细胞与纳米纤维支架在体内的相互作用关系，阐明干细胞-支架复合物在促进皮肤再生中的机理。为干细胞-支架复合物在缺损组织器官修复与功能重建中可靠、安全、有效的应用提供理论依据。

组织器官缺损或功能丧失一直是人类健康所面临的主要危害之一。随着组织工程的发展，多种生物材料被制备成模拟细胞外基质的生物支架为干细胞增殖分化、组织再生提供理想的支持。了解细胞和支架的相互作用是有效引导细胞行为，促进组织再生的基本前提。针对移植后支架在体内的降解规律及体内干细胞与支架间的相互作用机制不清楚的关键科学问题，本课题制备了两种发射波长可区分的共轭聚合物荧光纳米粒子，研究了其在在体双示踪（细胞与支架、细胞与细胞），揭示组织再生机理中的应用。主要研究成果包括：1）通过在体双示踪干细胞及支架，明确了干细胞与支架间的相互作用规律及支架在体降解规律，揭示了干细胞-支架复合物促进皮肤再生的机理；2）通过在体示踪并调控干细胞的心肌分化，实现了microRNA转染后的干细胞促进梗死区域的心肌组织的修复，揭示了microRNA转染干细胞促心肌修复的机理为促进干细胞心肌分化及与在体正常心肌组织的原位整合；3）通过在体双示踪干细胞及内皮细胞，促进了皮肤伤口的愈合，揭示了双细胞（干细胞及内皮细）治疗皮肤损伤的机理为促进组织血管化。在本项目的资助下，课题负责人作为第一或共同第一，或通讯作者在Theranostics、ACS Applied Materials & Interfaces (4)、Acta Biomaterialia、Drug Discovery Today（2）等国际期刊发表SCI论文9篇，培养硕士研究生2名，共同培养博士生2名。