Ravishankar Prashanth, Tandon Ishita, Balachandran Kartik
Department of Biomedical Engineering, University of Arkansas, 700 W Research Center Blvd, Fayetteville, AR, 72701, USA.
Department of Biomedical Engineering, University of Arkansas, 122 John A. White Jr. Engineering Hall, Fayetteville, AR, 72701, USA.
Cardiovasc Eng Technol. 2022 Dec;13(6):872-885. doi: 10.1007/s13239-022-00623-5. Epub 2022 May 2.
Endothelial progenitor cells (EPCs) have been used as an autologous or allogeneic source in multiple tissue engineering applications. EPCs possess high proliferative and tissue regeneration potential. The effect of shear stress on EPCs has been extensively studied but the role of cyclic mechanical strain on EPCs remains to be understood. In this study, we focused on examining the role of uniaxial cyclic strain on EPCs cultured on three-dimensional (3D) anisotropic composites that mimic healthy and diseased aortic valve tissue matrix compositions.
The composites were fabricated by combining centrifugal jet spun fibers with photocrosslinkable gelatin and glycosaminoglycan hydrogels. A custom-designed uniaxial cyclic stretcher was used to provide the necessary cyclic stimulation to the EPC-seeded 3D composites. The samples were cyclically strained at a rate of 1 Hz at 15% strain mimicking the physiological condition experienced by aortic valve, with static conditions serving as controls. Cell viability was high in all conditions. Immunostaining revealed reduced endothelial marker (CD31) expression with increased smooth muscle cell marker, SM22α, expression when subjected to cyclic strain. Functional analysis through Matrigel assay agreed with the immunostaining findings with reduced tubular structure formation in strained conditions compared to EPC controls. Additionally, the cells showed reduced acLDL uptake compared to controls which are in alignment with the EPCs undergoing differentiation.
Overall, we show that EPCs lose their endothelial progenitor phenotype, and have the potential to be differentiated into mesenchymal-like cells through cyclic mechanical stimulation.
内皮祖细胞（EPCs）已被用作多种组织工程应用中的自体或异体来源。EPCs具有高增殖和组织再生潜力。剪切应力对EPCs的影响已得到广泛研究，但循环机械应变对EPCs的作用仍有待了解。在本研究中，我们重点研究单轴循环应变对培养在模拟健康和病变主动脉瓣组织基质成分的三维（3D）各向异性复合材料上的EPCs的作用。
通过将离心喷射纺丝纤维与可光交联明胶和糖胺聚糖水凝胶相结合制备复合材料。使用定制设计的单轴循环拉伸器为接种EPCs的3D复合材料提供必要的循环刺激。样品以1Hz的频率、15%的应变进行循环拉伸，模拟主动脉瓣所经历的生理状况，静态条件作为对照。在所有条件下细胞活力都很高。免疫染色显示，在循环应变条件下，内皮标志物（CD31）表达减少，平滑肌细胞标志物SM22α表达增加。通过基质胶试验进行的功能分析与免疫染色结果一致，与EPCs对照相比，在应变条件下管状结构形成减少。此外，与对照相比，细胞的乙酰化低密度脂蛋白摄取减少，这与EPCs正在分化一致。
总体而言，我们表明EPCs失去其内皮祖细胞表型，并且有通过循环机械刺激分化为间充质样细胞的潜力。
