Abstract：
Recent advances in bone tissue engineering have shown promise for bone repair post osteosarcoma excision. However, conflicting research on mesenchymal stem cells (MSCs) has raised concerns about their potential to either promote or inhibit tumor cell proliferation. It is necessary to thoroughly understand the interactions between MSCs and tumor cells. Most previous studies only focused on the interactions between cells within the tumor tissues. It has been challenging to develop an in vitro model of osteosarcoma excision sites replicating the complexity of the bone microenvironment and cell distribution. In this work, we designed and fabricated modular bioceramic scaffolds to assemble into a co-culture model. Because of the bone-like composition and mechanical property, tricalcium phosphate bioceramic could mimic the bone microenvironment and recapitulate the cell-extracellular matrix interaction. Moreover, the properties for easy assembly enabled the modular units to mimic the spatial distribution of cells in the osteosarcoma excision site. Under this co-culture model, MSCs showed a noticeable tumor-stimulating effect with a potential risk of tumor recurrence. In addition, tumor cells also could inhibit the osteogenic ability of MSCs. To undermine the stimulating effects of MSCs on tumor cells, we present the methods of pre-differentiated MSCs, which had lower expression of IL-8 and higher expression of osteogenic proteins. Both in vitro and in vivo studies confirm that pre-differentiated MSCs could maintain high osteogenic capacity without promoting tumor growth, offering a promising approach for MSCs\' application in bone regeneration. Overall, 3D modular scaffolds provide a valuable tool for constructing hard tissue in vitro models. STATEMENT OF SIGNIFICANCE: Bone tissue engineering using mesenchymal stem cells (MSCs) and biomaterials has shown promise for bone repair post osteosarcoma excision. However, conflicting researches on MSCs have raised concerns about their potential to either promote or inhibit tumor cell proliferation. It remains challenges to develop in vitro models to investigate cell interactions, especially of osteosarcoma with high hardness and special composition of bone tissue. In this work, modular bioceramic scaffolds were fabricated and assembled to co-culture models. The interactions between MSCs and MG-63 were manifested as tumor-stimulating and osteogenesis-inhibiting, which means potential risk of tumor recurrence. To undermine the stimulating effect, pre-differentiation method was proposed to maintain high osteogenic capacity without tumor-stimulating, offering a promising approach for MSCs\' application in bone regeneration.
摘要：
骨组织工程的最新进展已显示出骨肉瘤切除后骨修复的希望。然而,关于间充质干细胞(MSCs)的相互矛盾的研究引发了人们对其促进或抑制肿瘤细胞增殖的潜力的担忧.有必要彻底了解MSCs与肿瘤细胞之间的相互作用。大多数先前的研究仅集中在肿瘤组织内细胞之间的相互作用。开发骨肉瘤切除部位的体外模型复制骨微环境和细胞分布的复杂性一直具有挑战性。在这项工作中,我们设计并制造了模块化生物陶瓷支架，以组装成共培养模型。由于骨样成分和机械性能，磷酸三钙生物陶瓷可以模拟骨骼微环境并概括细胞-细胞外基质的相互作用。此外，易于组装的特性使模块化单元能够模拟细胞在骨肉瘤切除部位的空间分布。在这种共同文化模式下，MSCs显示出明显的肿瘤刺激作用，并具有潜在的肿瘤复发风险。此外,肿瘤细胞也可以抑制MSCs的成骨能力。破坏MSCs对肿瘤细胞的刺激作用,我们介绍了预分化MSCs的方法，IL-8表达较低，成骨蛋白表达较高。体外和体内研究均证实，预分化的MSCs可以保持较高的成骨能力，而不促进肿瘤的生长。为MSCs在骨再生中的应用提供了一种有希望的方法。总的来说,3D模块化支架为构建体外硬组织模型提供了有价值的工具。重要声明：使用间充质干细胞（MSC）和生物材料进行骨组织工程已显示出骨肉瘤切除后骨修复的希望。然而,关于MSCs的相互矛盾的研究引起了人们对其促进或抑制肿瘤细胞增殖的潜力的担忧。开发体外模型来研究细胞相互作用仍然是挑战，特别是骨肉瘤，硬度高，骨组织成分特殊。在这项工作中,制造模块化生物陶瓷支架并组装成共培养模型。MSCs与MG-63之间的相互作用表现为肿瘤刺激和成骨抑制,这意味着肿瘤复发的潜在风险。为了破坏刺激作用，提出了预分化方法，以保持高成骨能力，而不刺激肿瘤，为MSCs在骨再生中的应用提供了一种有希望的方法。
