Department of Biomedical Engineering, Duke University, 136 Hudson Hall, Durham, NC 27708, USA.
J Biomech. 2011 Jul 28;44(11):2150-7. doi: 10.1016/j.jbiomech.2011.05.024. Epub 2011 Jun 16.
Human endothelial cells derived from umbilical cord blood (hCB-ECs) represent a promising cell source for endothelialization of tissue engineered blood vessels. hCB-ECs cultured directly above human aortic smooth muscle cells (SMCs), which model native and tissue engineered blood vessels, produce a confluent endothelium that responds to flow like normal human aortic endothelial cells (HAECs). The objective of this study was to quantify the elastic modulus of hCB-ECs cocultured with SMCs under static and flow conditions using atomic force microscopy (AFM). Cytoskeleton structures were assessed by AFM cell surface imaging and immunofluorescence of F-actin. The elastic moduli of hCB-ECs and HAECs were similar and significantly smaller than the value for SMCs in monoculture under static conditions (p<0.05). In coculture, hCB-ECs and HAECs became significantly stiffer with moduli 160-180% larger than their corresponding values in monoculture. While the moduli of hCB-ECs and HAECs almost doubled in monoculture and flow condition, their corresponding values in coculture declined after exposure to flow. Both the number and diameter of cortical stress fiber per cell width increased in coculture and/or flow conditions, whereas the subcortical stress fiber density throughout the cell interior increased by a smaller amount. These findings indicate that changes to biomechanical properties in coculture and/or exposure to flow are correlated with changes in the cortical stress fiber density. For ECs, fluid shear stress appeared to have greater effect on the elastic modulus than the presence of SMCs and changes to the elastic modulus in coculture may be due to EC-SMC communication.
人脐带来源的内皮细胞（hCB-ECs）是组织工程血管内皮化的有前途的细胞来源。hCB-ECs 直接培养在人主动脉平滑肌细胞（SMCs）上，模拟天然和组织工程血管，产生一个连续的内皮细胞，对流动有反应，类似于正常的人主动脉内皮细胞（HAECs）。本研究的目的是使用原子力显微镜（AFM）定量测量在静态和流动条件下与 SMC 共培养的 hCB-ECs 的弹性模量。通过 AFM 细胞表面成像和 F-肌动蛋白的免疫荧光评估细胞骨架结构。hCB-ECs 和 HAECs 的弹性模量与 SMCs 在静态条件下的单培养相似，且显著小于 SMCs（p<0.05）。在共培养中，hCB-ECs 和 HAECs 的弹性模量显著增大，比其单培养时的相应值增大 160-180%。虽然 hCB-ECs 和 HAECs 的模量在单培养和流动条件下几乎增加了一倍，但它们在共培养中的相应值在暴露于流动后下降。细胞宽度内的皮质应力纤维的数量和直径在共培养和/或流动条件下增加，而整个细胞内部的亚皮质应力纤维密度增加的幅度较小。这些发现表明，共培养和/或暴露于流动引起的生物力学性质的变化与皮质应力纤维密度的变化有关。对于 ECs，流体切应力对弹性模量的影响似乎大于 SMCs 的存在，并且共培养中弹性模量的变化可能是由于 EC-SMC 通讯所致。
