长链非编码RNA在纳米拓扑结构调控干细胞成骨向分化中的作用

Nanoscale geometry can direct stem cell lineage commitment solely by their various, but controllable, geometric cues, which would be very important for their future application in bone tissue engineering and bone regeneration. However, the mechanisms by which nano-geometric cues dictate the osteogenic differentiation of stem cells remain unclear, and there were few researches on the epigenetic mechanisms. Our previous studies demonstrated that nanomaterials promoted the osteogenic differentiation of human adipose-derived mesenchymal stem cells (hASCs) by the epigenetic regulation of histone methylation. Long non-coding RNA (lncRNA) plays an important role in both histone modification and signal transduction pathway, thus making it a potential key juncture between epigenetic regulation and molecular biology mechanism. Therefore, in this study RNA-sequencing will be used to screen the key lncRNA during osteogenic differentiation promoted by nanotopography. Moreover, related signal transduction pathway will be analysed, and the relationship between epigenetic regulation network and molecular biology mechanism will be explored. This further understanding of the mechanism of how nanotopography promote the osteogenic differentiation of hASCs will shed light on the optimization of nanomaterials, to develop new materials with optimized safety and biocompatibility.

纳米材料仅凭借其表面形貌的变化就能够调控干细的分化方向，有望实现骨组织工程支架材料和种植体表面的主动诱导。然而，对于纳米拓扑结构促进干细胞成骨分化的机制目前尚未明确，分子生物学机制仍待深入探索，而表观遗传学机制目前鲜有报导。本课题组率先发现纳米材料能够通过组蛋白修饰的表观遗传学调控方式促进干细胞成骨分化。长链非编码RNA（lncRNA）在组蛋白修饰的表观遗传调控与分子生物学通路中均起到重要作用，很有可能成为连接表观遗传学网络与分子生物学通路之间的重要突破口。本课题将通过高通量筛选，探索钛纳米管促进干细胞成骨向分化的关键lncRNA，研究其作用靶点与相关信号通路，揭示表观遗传学调控网络与分子生物学网络之间的相互作用，为进一步优化材料表面处理方法、研制新型硬组织支架材料、使其具有更优的安全性与生物适配性提供理论基础。

纳米材料能够调控细胞的粘附、迁移、增殖、分化、重编程等重要生物学行为，其调控机制不仅涉及分子生物学通路，表观遗传调控更是起到至关重要的作用。本课题以二氧化钛纳米管和单层片状石墨烯镀层的钛表面分别作为材料表面纳米形貌与化学性质研究的代表，通过高通量测序，筛选关键转录因子以及关键调控通路，分析其对间充质干细胞成骨向分化的影响和表观遗传学调控网络。研究发现，表观遗传调控机制在纳米形貌对间充质干细胞成骨向分化过程中起到重要作用，以二氧化钛纳米管为例，长链非编码RNA，包括LINC00941、LINC01279、ZFAS1，在纳米形貌表面表达显著下调；组蛋白修饰相关酶类，组蛋白去乙酰化酶HDAC1、HDAC2表达下调，组蛋白H3K9去甲基化酶KDM4E表达上调；同时，microRNA也参与到纳米形貌调控干细胞成骨向分化的过程中，其中miR-24-1-5p、miR-24-3p、miR-154-3p、miR-433-5p、miR-589-3p、miR-589-5p在纳米形貌与成骨诱导条件下均表达下调，miR-186-5p纳米形貌与成骨诱导条件下表达上调，miR-770-5p在成骨诱导条件下表达上调并不显著，而在纳米形貌表面表达显著上调。该研究为进一步优化材料表面处理方法、研制应用于骨组织工程的新型硬组织支架材料、使其具有更优的安全性与生物适配性提供重要理论依据。