Inorganic biomaterials shape the transcriptome profile to induce endochondral differentiation

Minerals play a vital role, working synergistically with enzymes and other cofactors to regulate physiological functions including tissue healing and regeneration. The bioactive characteristics of mineral-based nanomaterials can be harnessed to facilitate in situ tissue regeneration by attracting endogenous progenitor and stem cells and subsequently directing tissue-specific differentiation. Here, we investigate cellular responses of human mesenchymal stem/stromal cells (hMSCs) to traditional bioactive mineral-based nanomaterials, such as hydroxyapatite (nHA), whitlockite (nWH), silicon-dioxide (nSiO2), and the emerging synthetic 2D nanosilicates (nSi). We utilized transcriptome sequencing (RNA-seq) to probe the cellular response and determine the significantly affected signaling pathways due to exposure to these inorganic nanomaterials. Transcriptome profiles of stem cells treated with nanosilicates revealed a stabilized skeletal progenitor state suggestive of endochondral differentiation. This observation is bolstered by enhanced deposition of matrix mineralization in nanosilicate treated stem cells compared to control or other treatments. Specifically, use of 2D nanosilicates directs osteogenic differentiation of stem cells via activation of bone morphogenetic proteins (BMP) and hypoxia-inducible factor 1-alpha (HIF-1a) signaling pathway. This study provides a holistic transcriptomic insight into nanomaterial-cell interactions and predicts downstream effects of nanomaterial induction of endochondral differentiation.矿物质发挥着至关重要的作用，可与酶及其他辅因子协同协作，调控包括组织愈合与再生在内的多种生理功能。矿物基纳米材料的生物活性特性可被用于促进原位组织再生：通过募集内源性祖细胞与干细胞，并后续引导其向组织特异性方向分化。本研究针对人间充质干细胞/基质细胞（human mesenchymal stem/stromal cells, hMSCs）对传统生物活性矿物基纳米材料的细胞应答展开探究，所涉材料包括羟基磷灰石（hydroxyapatite, nHA）、白磷钙石（whitlockite, nWH）、二氧化硅（silicon-dioxide, nSiO₂）以及新型合成二维纳米硅酸盐（synthetic 2D nanosilicates, nSi）。本研究利用转录组测序（RNA-seq）探究细胞应答，并明确暴露于这些无机纳米材料后发生显著变化的信号通路。经纳米硅酸盐处理的干细胞转录组谱显示，其呈现出稳定的骨骼祖细胞状态，提示存在软骨内分化进程。相较于对照组与其他处理组，经纳米硅酸盐处理的干细胞基质矿化沉积水平显著提升，这一结果进一步佐证了上述观察结论。具体而言，二维纳米硅酸盐可通过激活骨形态发生蛋白（bone morphogenetic proteins, BMP）与缺氧诱导因子1-α（hypoxia-inducible factor 1-alpha, HIF-1α）信号通路，引导干细胞向成骨方向分化。本研究全面解析了纳米材料与细胞的相互作用的转录组学特征，并预测了纳米材料诱导软骨内分化的下游效应。