In this study an experimental rig is developed to investigate the influence of tissue constraint and cyclic loading on cell alignment and active cell force generation in uniaxial and biaxial engineered tissues constructs. Addition of contractile cells to collagen hydrogels dramatically increases the measured forces in uniaxial and biaxial constructs under dynamic loading. This increase in measured force is due to active cell contractility, as is evident from the decreased force after treatment with cytochalasin-D. Prior to dynamic loading, cells are highly aligned in uniaxially constrained tissues but are uniformly distributed in biaxially constrained tissues, demonstrating the importance of tissue constraints on cell alignment. Dynamic uniaxial stretching resulted in a slight increase in cell alignment in the centre of the tissue, whereas dynamic biaxial stretching had no significant effect on cell alignment. Our active modelling framework accurately predicts our experimental trends and suggests that a slightly higher (3%) total SF formation occurs at the centre of a biaxial tissue compared to the uniaxial tissue. However, high alignment of SFs and lateral compaction in the case of the uniaxially constrained tissue results in a significantly higher (75%) actively generated cell contractile stress, compared to the biaxially constrained tissue. These findings have significant implications for engineering of contractile tissue constructs.

在这项研究中，开发了一种实验装置，以研究组织约束和循环载荷对单轴和双轴工程组织构建体中细胞排列和主动细胞力生成的影响。将收缩细胞添加到胶原蛋白水凝胶中会大大增加动态载荷下单轴和双轴结构中测得的力。测得力的这种增加是由于活动细胞的收缩性所致，从用细胞松弛素-D处理后力的降低可以明显看出这一点。在动态加载之前，细胞在单轴约束的组织中高度对齐，但在双轴约束的组织中均匀分布，这证明了组织约束对细胞对齐的重要性。动态单轴拉伸导致组织中心的细胞排列略有增加，动态双轴拉伸对细胞排列没有明显影响。我们的主动建模框架准确地预测了我们的实验趋势，并表明与单轴组织相比，双轴组织的中心总SF形成量略高（3％）。但是，与双轴约束组织相比，在单轴约束组织的情况下，SF的高度对齐和侧向压实会导致主动产生的细胞收缩应力明显更高（75％）。这些发现对收缩组织构造的工程设计具有重要意义。我们的主动建模框架准确地预测了我们的实验趋势，并表明与单轴组织相比，双轴组织的中心总SF形成量略高（3％）。但是，与双轴约束组织相比，在单轴约束组织的情况下，SF的高度对齐和侧向压实会导致主动产生的细胞收缩应力明显更高（75％）。这些发现对收缩组织构造的工程设计具有重要意义。我们的主动建模框架准确地预测了我们的实验趋势，并表明与单轴组织相比，双轴组织的中心总SF形成量略高（3％）。但是，与双轴约束组织相比，在单轴约束组织的情况下，SF的高度对齐和侧向压实会导致主动产生的细胞收缩应力明显更高（75％）。这些发现对收缩组织构造的工程设计具有重要意义。