Abstract：
The synthesis and assembly of mature, organized elastic fibers remains a limitation to the clinical use of many engineered tissue replacements. There is a critical need for a more in-depth understanding of elastogenesis regulation for the advancement of methods to induce and guide production of elastic matrix structures in engineered tissues that meet the structural and functional requirements of native tissue. The dramatic increase in elastic fibers through normal pregnancy has led us to explore the potential role of mechanical stretch in combination with pregnancy levels of the steroid hormones 17β-estradiol and progesterone on elastic fiber production by human uterine myometrial smooth muscle cells in a three-dimensional (3D) culture model. Opposed to a single strain regimen, we sought to better understand how the amplitude and frequency parameters of cyclic strain influence elastic fiber production in these myometrial tissue constructs (MTC). Mechanical stretch was applied to MTC at a range of strain amplitudes (5%, 10%, and 15% at 0.5 Hz frequency) and frequencies (0.1 Hz, 0.5 Hz, 1 Hz, and constant 0 Hz at 10% amplitude), with and without pregnancy-level hormones, for 6 days. MTC were assessed for cell proliferation, matrix elastin protein content, and expression of the main elastic fiber genes, tropoelastin (ELN) and fibrillin-1 (FBN1). Significant increases in elastin protein and ELN and FBN1 mRNA were produced from samples subjected to a 0.5 Hz, 10% strain regimen, as well as samples stretched at higher amplitude (15%, 0.5 Hz) and higher frequency (1 Hz, 10%); however, no significant effects because of third-trimester mimetic hormone treatment were determined. These results establish that a minimum level of strain is required to stimulate the synthesis of elastic fiber components in our culture model and show this response can be similarly enhanced by increasing either the amplitude or frequency parameter of applied strain. Further, our results demonstrate strain alone is sufficient to stimulate elastic fiber production and suggest hormones may not be a significant factor in regulating elastin synthesis. This 3D culture model will provide a useful tool to further investigate mechanisms underlying pregnancy-induced de novo elastic fiber synthesis and assembly by uterine smooth muscle cells.
摘要：
成熟的合成和组装，有组织的弹性纤维仍然限制了许多工程化组织替代物的临床使用。对于在满足天然组织的结构和功能要求的工程化组织中诱导和引导弹性基质结构的产生的方法的进步,存在对弹性生成调节的更深入理解的关键需求。正常妊娠期间弹性纤维的急剧增加使我们探索了机械拉伸与类固醇激素17β-雌二醇和孕酮的妊娠水平相结合对3D培养模型中人子宫肌层平滑肌细胞产生弹性纤维的潜在作用。与单一菌株方案相反，我们试图更好地了解循环应变的振幅和频率参数如何影响这些子宫肌层组织构建体(MTC)中弹性纤维的产生.在一系列应变幅度(5%，10%,和15%在0.5赫兹频率)和频率(0.1赫兹，0.5Hz,1Hz,并且在10%振幅下恒定为0Hz)，有和没有怀孕水平的荷尔蒙，6天。评估MTC的细胞增殖，基质弹性蛋白含量，和主要弹性纤维基因的表达，弹性蛋白（ELN）和原纤蛋白-1（FBN1）。弹性蛋白显著增加，和ELN和FBN1mRNA从样品中产生0.5Hz，10%应变方案，以及在较高振幅下拉伸的样品(15%，0.5Hz）和更高的频率（1Hz，10%)；然而，未发现妊娠晚期模拟激素治疗有显著影响.这些结果建立了一个最低水平的应变是所需的刺激弹性纤维成分的合成在我们的培养模型，并表明可以通过增加施加应变的振幅或频率参数来类似地增强该响应。Further,我们的结果证明，单用菌株就足以刺激弹性纤维的产生，并表明激素可能不是调节弹性蛋白合成的重要因素。该3D培养模型将提供有用的工具来进一步研究妊娠诱导的子宫平滑肌细胞从头弹性纤维合成和组装的潜在机制。
