Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO, 80303, USA.
The BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, 80303, USA.
Macromol Biosci. 2020 Dec;20(12):e2000268. doi: 10.1002/mabi.202000268. Epub 2020 Sep 13.
The role viscoelasticity in fibrotic disease progression is an emerging area of interest. Here, a fast-relaxing hydrogel system is exploited to investigate potential crosstalk between calcium signaling and mechanotransduction. Poly(ethylene glycol) (PEG) hydrogels containing boronate and triazole crosslinkers are synthesized, with varying ratios of boronate to triazole crosslinks to systematically vary the extent of stress relaxation. Valvular interstitial cells (VICs) encapsulated in hydrogels with the highest levels of stress relaxation (90%) exhibit a spread morphology by day 1 and are highly aligned (80 ± 2%) by day 5. Key myofibroblast markers, including α-smooth muscle actin (αSMA) and collagen 1a1 (COL1A1), are significantly elevated. VIC myofibroblast activation decreases by 42 ± 18% through inhibition of mechanotransduction, independently of VIC morphology and alignment. Calcium signaling through a transient receptor potential vanilloid 4 (TRPV4) is found to regulate VIC spreading, alignment, and activation in a time dependent manner. Inhibition of calcium signaling at early time points results in disturbed cell alignment, decreased mechanotransduction, and diminished activation, while inhibition at later time points only causes partially reduced myofibroblast activation. These results suggest a potential crosstalk mechanism, where calcium signaling acts upstream of mechanosensing and can regulate VIC myofibroblast activation independently of mechanotransduction.
黏弹性在纤维化疾病进展中的作用是一个新兴的研究领域。在这里，我们利用一种快速松弛的水凝胶系统来研究钙信号和机械转导之间的潜在串扰。合成了含有硼酸酯和三唑交联剂的聚乙二醇（PEG）水凝胶，通过改变硼酸酯与三唑交联剂的比例来系统地改变应力松弛的程度。在具有最高应力松弛程度（90%）的水凝胶中包封的心脏瓣膜间质细胞（VICs）在第 1 天表现出展开的形态，并且在第 5 天高度对齐（80 ± 2%）。关键的成纤维细胞标志物，包括α-平滑肌肌动蛋白（αSMA）和胶原 1a1（COL1A1），显著升高。通过抑制机械转导，VIC 成纤维细胞的激活减少了 42 ± 18%，这与 VIC 的形态和对齐无关。发现瞬时受体电位香草醛 4（TRPV4）介导的钙信号通过时间依赖性方式调节 VIC 的铺展、对齐和激活。在早期时间点抑制钙信号会导致细胞对齐紊乱、机械转导减少和激活减弱，而在晚期时间点抑制钙信号仅导致成纤维细胞激活部分减少。这些结果表明存在一种潜在的串扰机制，其中钙信号在上游作用于机械感知，并可独立于机械转导调节 VIC 成纤维细胞的激活。
