Li Aonan, Sasaki Jun-Ichi, Abe Gabriela L, Katata Chihiro, Sakai Hirohiko, Imazato Satoshi
Department of Dental Biomaterials, Osaka University Graduate School of Dentistry, Osaka, Japan.
Department of Advanced Functional Materials Science, Osaka University Graduate School of Dentistry, Osaka, Japan.
Stem Cells Int. 2023 May 9;2023:5367887. doi: 10.1155/2023/5367887. eCollection 2023.
Bone organoids offer a novel path for the reconstruction and repair of bone defects. We previously fabricated scaffold-free bone organoids using cell constructs comprising only bone marrow-derived mesenchymal stem cells (BMSCs). However, the cells in the millimetre-scale constructs were likely to undergo necrosis because of difficult oxygen diffusion and nutrient delivery. Dental pulp stem cells (DPSCs) are capable of differentiating into vascular endothelial lineages and have great vasculogenic potential under endothelial induction. Therefore, we hypothesized that DPSCs can serve as a vascular source to improve the survival of the BMSCs within the bone organoid. In this study, the DPSCs had greater sprouting ability, and the proangiogenic marker expressions were significantly greater than those of BMSCs. DPSCs were incorporated into the BMSC constructs at various ratios (5%-20%), and their internal structures and vasculogenic and osteogenic characteristics were investigated after endothelial differentiation. As a result, the DPSCs are differentiated into the CD31-positive endothelial lineage in the cell constructs. The incorporation of DPSCs significantly suppressed cell necrosis and improved the viability of the cell constructs. In addition, lumen-like structures were visualized by fluorescently labelled nanoparticles in the DPSC-incorporated cell constructs. The vascularized BMSC constructs were successfully fabricated using the vasculogenic ability of the DPSCs. Next, osteogenic induction was initiated in the vascularized BMSC/DPSC constructs. Compared with only BMSCs, constructs with DPSCs had increased mineralized deposition and a hollow structure. Overall, this study demonstrated that vascularized scaffold-free bone organoids were successfully fabricated by incorporating DPSCs into BMSC constructs, and the biomimetic biomaterial is promising for bone regenerative medicine and drug development.
骨类器官为骨缺损的重建和修复提供了一条新途径。我们之前使用仅由骨髓间充质干细胞（BMSCs）组成的细胞构建体制造了无支架骨类器官。然而，毫米级构建体中的细胞由于氧气扩散困难和营养物质输送问题，很可能会发生坏死。牙髓干细胞（DPSCs）能够分化为血管内皮谱系，并且在内皮诱导下具有很大的血管生成潜力。因此，我们假设DPSCs可以作为血管来源来提高骨类器官内BMSCs的存活率。在本研究中，DPSCs具有更强的发芽能力，促血管生成标志物的表达明显高于BMSCs。将DPSCs以不同比例（5%-20%）掺入BMSC构建体中，在内皮分化后研究其内部结构以及血管生成和成骨特性。结果，DPSCs在细胞构建体中分化为CD31阳性的内皮谱系。DPSCs的掺入显著抑制了细胞坏死并提高了细胞构建体的活力。此外，在掺入DPSC的细胞构建体中，通过荧光标记的纳米颗粒可以观察到类似管腔的结构。利用DPSCs的血管生成能力成功制造了血管化的BMSC构建体。接下来，在血管化的BMSC/DPSC构建体中开始进行成骨诱导。与仅含BMSCs的构建体相比，含有DPSCs的构建体矿化沉积增加且具有中空结构。总体而言，本研究表明通过将DPSCs掺入BMSC构建体中成功制造了血管化的无支架骨类器官，这种仿生生物材料在骨再生医学和药物开发方面具有广阔前景。
