Department of Bioengineering and Aerospace Engineering, Universidad Carlos III de Madrid (UC3M), Madrid, Spain.
Institute of Polymer Science and Technology, CSIC, Madrid, Spain.
J Biomed Mater Res A. 2021 Apr;109(4):500-514. doi: 10.1002/jbm.a.37033. Epub 2020 Jun 29.
It is well-known that fibroblasts play a fundamental role in the contraction of collagen and fibrin hydrogels when used in the production of in vitro bilayered skin substitutes. However, little is known about the contribution of other factors, such as the hydrogel matrix itself, on this contraction. In this work, we studied the contraction of plasma-derived fibrin hydrogels at different temperatures (4, 23, and 37°C) in an isotonic buffer (phosphate-buffered saline). These types of hydrogels presented a contraction of approximately 30% during the first 24 hr, following a similar kinetics irrespectively of the temperature. This kinetics continued in a slowed down manner to reach a plateau value of 40% contraction after 10-15 days. Contraction of commercial fibrinogen hydrogels was studied under similar conditions and the kinetics was completed after 8 hr, reaching values between 20 and 70% depending on the temperature. We attribute these substantial differences to a modulatory effect on the contraction due to plasma proteins which are initially embedded in, and progressively released from, the plasma-based hydrogels. The elastic modulus of hydrogels measured at a constant frequency decreased with increasing temperature in 7-day gels. Rheological measurements showed the absence of a strain-hardening behavior in the plasma-derived fibrin hydrogels. Finally, plasma-derived fibrin hydrogels with and without human primary fibroblast and keratinocytes were prepared in transwell inserts and their height measured over time. Both cellular and acellular gels showed a height reduction of 30% during the first 24 hr likely due to the above-mentioned intrinsic fibrin matrix contraction.
众所周知，成纤维细胞在体外双层皮肤替代物的生产中使用胶原蛋白和纤维蛋白水凝胶时，对于收缩起着至关重要的作用。然而，对于其他因素（如水凝胶基质本身）对收缩的贡献，人们知之甚少。在这项工作中，我们研究了在等渗缓冲液（磷酸盐缓冲盐水）中不同温度（4、23 和 37°C）下等离子衍生纤维蛋白水凝胶的收缩。这些类型的水凝胶在最初的 24 小时内收缩约 30%，无论温度如何，其动力学都相似。这种动力学以较慢的速度继续进行，在 10-15 天后达到 40%收缩的平台值。在类似条件下研究了商业纤维蛋白原水凝胶的收缩，动力学在 8 小时内完成，收缩值在 20%至 70%之间，具体取决于温度。我们将这些显著差异归因于血浆蛋白对收缩的调节作用，这些蛋白最初嵌入并逐渐从基于血浆的水凝胶中释放出来。在 7 天凝胶中，以恒定频率测量的水凝胶弹性模量随温度升高而降低。流变学测量显示，在等离子衍生纤维蛋白水凝胶中不存在应变硬化行为。最后，在 Transwell 插入物中制备了含有和不含有人原代成纤维细胞和角质形成细胞的等离子衍生纤维蛋白水凝胶，并随时间测量其高度。在最初的 24 小时内，细胞和无细胞凝胶的高度均降低了 30%，这可能是由于上述内在纤维蛋白基质收缩所致。
