Xu Yichi, Yin Heyong, Chu Jin, Eglin David, Serra Tiziano, Docheva Denitsa
AO Research Institute Davos, Clavadelerstrasse 8, Davos Platz, Switzerland.
Biomater Sci. 2021 Feb 21;9(4):1237-1245. doi: 10.1039/d0bm01127d. Epub 2021 Feb 12.
The uniform and aligned arrangement of tendon cells is a marker of tendon tissue morphology and the embodiment of its biological anisotropy. However, most of the hydrogels used for tendon tissue engineering do not present anisotropic structures. In this work, a magnetically-responsive nanocomposite hydrogel composed of collagen type I (COL I) and aligned iron oxide nanoparticles (IOPs) was investigated for potential application in tendon tissue engineering. COL I with a mixture of remotely aligned IOPs (A/IOPs) and human tendon stem/progenitor cells (COL I-A/IOPs-hTSPCs) was prepared and the alignment of IOPs was induced under a remote magnetic field. Following the gelation of COL I, a stable and anisotropic nanocomposite COL I-A/IOPs hydrogel was formed. In addition, hTSPCs embedded in COL I with random IOPs (COL I-R/IOPs-hTSPCs) and in pure COL I (COL I-hTSPCs) were used as control groups. Cell viability, proliferation, morphology, cell row formation, and alignment of IOPs and hTSPCs were evaluated over time. In addition, a comprehensive gene expression profile of 48 different genes, including tendon-related genes and lineage/cross-linking genes, was obtained by implementing designer quantitative RT-PCR plates. The hTSPCs morphology followed the orientation of the anisotropic COL I-A/IOPs hydrogel with increased row formation in comparison to pristine COL I and COL-R/IOPs. Moreover, higher proliferation rate and significant upregulation of tendon gene markers were measured in comparison to hTSPCs cultivated in the COL I-R/IOPs and COL I. Thus, we suggest that providing the cells with aligned focal contact points, namely the aligned IOPs, is sufficient to provoke an immense effect on the formation of aligned cell rows. Taken together, we report a novel strategy for directing stem cell behavior without the use of exogenous growth factors or pre-aligned COL I fibers, and propose that anisotropic nanocomposite hydrogels hold great potential for tendon tissue engineering applications.
肌腱细胞的均匀排列和定向排列是肌腱组织形态的标志及其生物各向异性的体现。然而，大多数用于肌腱组织工程的水凝胶并不具有各向异性结构。在本研究中，对一种由I型胶原蛋白（COL I）和定向排列的氧化铁纳米颗粒（IOPs）组成的磁响应纳米复合水凝胶在肌腱组织工程中的潜在应用进行了研究。制备了含有远程定向IOPs混合物（A/IOPs）和人肌腱干/祖细胞的COL I（COL I-A/IOPs-hTSPCs），并在远程磁场作用下诱导IOPs定向排列。COL I凝胶化后，形成了稳定的各向异性纳米复合COL I-A/IOPs水凝胶。此外，将随机分布的IOPs嵌入COL I中的hTSPCs（COL I-R/IOPs-hTSPCs）和纯COL I中的hTSPCs（COL I-hTSPCs）用作对照组。随时间评估细胞活力、增殖、形态、细胞行形成以及IOPs和hTSPCs的排列情况。此外，通过使用定制的定量RT-PCR板，获得了包括肌腱相关基因和谱系/交联基因在内的48种不同基因的综合基因表达谱。与原始COL I和COL-R/IOPs相比，hTSPCs的形态遵循各向异性COL I-A/IOPs水凝胶的方向，细胞行形成增加。此外，与在COL I-R/IOPs和COL I中培养的hTSPCs相比，测量到更高的增殖率和肌腱基因标志物的显著上调。因此，我们认为为细胞提供定向的粘着斑位点，即定向的IOPs，足以对定向细胞行的形成产生巨大影响。综上所述，我们报道了一种无需使用外源性生长因子或预定向COL I纤维来指导干细胞行为的新策略，并提出各向异性纳米复合水凝胶在肌腱组织工程应用中具有巨大潜力。
