Li Deqiang, Tang Tingting, Lu Jianxi, Dai Kerong
Department of Orthopedic Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China.
Tissue Eng Part A. 2009 Oct;15(10):2773-83. doi: 10.1089/ten.TEA.2008.0540.
Currently, a tissue-engineered bone is usually constructed using a perfusion bioreactor in vitro. In the perfusion culture, fluid flow can exert shear stress on the cells seeded on scaffold, improving the mass transport of the cells. This experiment studied the effects of flow shear stress and mass transport, respectively, on the construction of a large-scale tissue-engineered bone using the critical-sized beta-tricalcium phosphate scaffold seeded with human bone marrow-derived mesenchymal stem cells (hBMSCs). This was done by changing flow rate and adding dextran into the media, thus changing the media's viscosity. The cells were seeded onto the scaffolds and were cultured in a perfusion bioreactor for up to 28 days with different fluid flow shear stress or different mass transport. When the mass transport was 3 mL/min, the flow shear stress was, respectively, 0.005 Pa (0.004-0.007 Pa), 0.011 Pa (0.009-0.013 Pa), or 0.015 Pa (0.013-0.018 Pa) in different experiment group obtained by simulation and calculation using fluid dynamics. When the flow shear stress was 0.015 Pa (0.013-0.018 Pa), the mass transport was, respectively, 3, 6, or 9 mL/min. After 28 days of culture, the construction of the tissue-engineered bone was assessed by osteogenic differentiation of hBMSCs and histological assay of the constructs. Extracellular matrix (ECM) was distributed throughout the entire scaffold and was mineralized in the perfusion culture after 28 days. Increasing flow shear stress accelerated the osteogenic differentiation of hBMSCs and improved the mineralization of ECM. However, increasing mass transport inhibited the formation of mineralized ECM. So, both flow shear stress and transport affected the construction of the large-scale tissue-engineered bone. Moreover, the large-scale tissue-engineered bone could be better produced in the perfusion bioreactor with 0.015 Pa (0.013-0.018 Pa) of fluid flow shear stress and 3 mL/min of mass transport.
目前,组织工程骨通常在体外使用灌注生物反应器构建。在灌注培养中,流体流动可对接种在支架上的细胞施加剪切应力,改善细胞的物质运输。本实验分别研究了流动剪切应力和物质运输对使用接种人骨髓间充质干细胞(hBMSCs)的临界尺寸β-磷酸三钙支架构建大规模组织工程骨的影响。通过改变流速和向培养基中添加葡聚糖来实现,从而改变培养基的粘度。将细胞接种到支架上,并在灌注生物反应器中以不同的流体流动剪切应力或不同的物质运输条件培养长达28天。当物质运输为3 mL/min时,通过流体动力学模拟和计算在不同实验组中获得的流动剪切应力分别为0.005 Pa(0.004 - 0.007 Pa)、0.011 Pa(0.009 - 0.013 Pa)或0.015 Pa(0.013 - 0.018 Pa)。当流动剪切应力为0.015 Pa(0.013 - 0.018 Pa)时,物质运输分别为3、6或9 mL/min。培养28天后,通过hBMSCs的成骨分化和构建体的组织学分析评估组织工程骨的构建情况。细胞外基质(ECM)分布在整个支架中,并在28天的灌注培养后矿化。增加流动剪切应力加速了hBMSCs的成骨分化并改善了ECM的矿化。然而,增加物质运输抑制了矿化ECM的形成。因此,流动剪切应力和物质运输都影响大规模组织工程骨的构建。此外,在流体流动剪切应力为0.015 Pa(0.013 - 0.018 Pa)和物质运输为3 mL/min的灌注生物反应器中可以更好地生产大规模组织工程骨。