Nirmalanandhan Victor S, Dressler Matthew R, Shearn Jason T, Juncosa-Melvin Natalia, Rao Marepalli, Gooch Cynthia, Bradica Gino, Butler David L
Department of Biomedical Engineering, University of Cincinnati, 2901 Campus Drive, 837 Engineering Research Center, Cincinnati, OH 45221-0048, USA.
J Biomech Eng. 2007 Dec;129(6):919-23. doi: 10.1115/1.2800828.
Our group has shown that numerous factors can influence how tissue engineered tendon constructs respond to in vitro mechanical stimulation. Although one study showed that stimulating mesenchymal stem cell (MSC)-collagen sponge constructs significantly increased construct linear stiffness and repair biomechanics, a second study showed no such effect when a collagen gel replaced the sponge. While these results suggest that scaffold material impacts the response of MSCs to mechanical stimulation, a well-designed intra-animal study was needed to directly compare the effects of type-I collagen gel versus type-I collagen sponge in regulating MSC response to a mechanical stimulus. Eight constructs from each cell line (n=8 cell lines) were created in specially designed silicone dishes. Four constructs were created by seeding MSCs on a type-I bovine collagen sponge, and the other four were formed by seeding MSCs in a purified bovine collagen gel. In each dish, two cell-sponge and two cell-gel constructs from each line were then mechanically stimulated once every 5 min to a peak strain of 2.4%, for 8 h/day for 2 weeks. The other dish remained in an incubator without stimulation for 2 weeks. After 14 days, all constructs were failed to determine mechanical properties. Mechanical stimulation significantly improved the linear stiffness (0.048+/-0.009 versus 0.015+/-0.004; mean+/-SEM (standard error of the mean ) N/mm) and linear modulus (0.016+/-0.004 versus 0.005+/-0.001; mean+/-SEM MPa) of cell-sponge constructs. However, the same stimulus produced no such improvement in cell-gel construct properties. These results confirm that collagen sponge rather than collagen gel facilitates how cells respond to a mechanical stimulus and may be the scaffold of choice in mechanical stimulation studies to produce functional tissue engineered structures.
我们的研究小组已经表明，许多因素会影响组织工程化肌腱构建体对体外机械刺激的反应。虽然一项研究表明，刺激间充质干细胞（MSC）-胶原海绵构建体可显著提高构建体的线性刚度和修复生物力学性能，但另一项研究表明，当胶原凝胶取代海绵时，并未产生这种效果。虽然这些结果表明支架材料会影响MSC对机械刺激的反应，但需要进行精心设计的动物体内研究，以直接比较I型胶原凝胶与I型胶原海绵在调节MSC对机械刺激反应方面的效果。在专门设计的硅树脂培养皿中创建了每个细胞系的八个构建体（n = 8个细胞系）。四个构建体是通过将MSC接种到I型牛胶原海绵上创建的，另外四个是通过将MSC接种到纯化的牛胶原凝胶中形成的。在每个培养皿中，然后对每个细胞系的两个细胞-海绵构建体和两个细胞-凝胶构建体每隔5分钟进行一次机械刺激，达到2.4%的峰值应变，每天刺激8小时，持续2周。另一个培养皿在培养箱中放置2周不进行刺激。14天后，所有构建体均进行力学性能测试。机械刺激显著提高了细胞-海绵构建体的线性刚度（0.048±0.009对0.015±0.004；平均值±SEM（均值标准误差）N/mm）和线性模量（0.016±0.004对0.005±0.001；平均值±SEM MPa）。然而，相同的刺激并未改善细胞-凝胶构建体的性能。这些结果证实，胶原海绵而非胶原凝胶有助于细胞对机械刺激的反应，并且可能是机械刺激研究中用于产生功能性组织工程结构的首选支架。
