Mechanical Compatibility of Biomaterials evaluated by Culture System

在本实验中，我们开发了一种培养系统来检测机械刺激对涉及成纤维细胞的胶原凝胶标本的影响。拉伸和压缩应变的大小设置为10%，频率为0.5赫兹，每天24小时，持续1周或2周。通过显微镜下的微拉伸测试，测量了测试后的试件和静态对照试件的弹性模量和最大应力的力学性能。实验和对照样品的力学性能指标均随培养时间的延长而增加。在力学测试中还发现，试验组试件的强化效果比对照组显着，我们进一步利用标记颗粒来测量试件的应变分布，并通过图像分析来测量其位置。强化主要发生在拉伸应力条件为…的试件的中心部位产生压应力的试件两端的S强度最低。机械刺激的影响程度因细胞类型不同而不同。在骨髓基质细胞中，细胞产生的拉应力非常大，甚至在静态条件下，它们也非常收缩，从支撑凝胶的不锈钢t丝网中脱落。另一方面，L细胞产生的拉应力很小，机械刺激的影响很小。体内实验是与以前的体外实验相对应的。在这个动物模型中，股骨-髌腱-胫骨标本固定在不锈钢支架上，移植到背部皮肤下，施加人工重复张应力。如果施加机械刺激，肌腱的最大强度不会降低，但静态条件下的对照试件会降低。因此，在活体内执行机械功能的结缔组织中，组织的命运由机械环境决定。人工材料和活体组织的力学完整性是基于胶原与生物材料之间的强结合，由于细胞特别是成纤维细胞和成骨细胞产生的拉应力可能会使它们在界面上产生应力，这可能导致组织和材料之间生物相容性的差异。较少

In this experiment, we developed a culture system to examine the effect of mechanical stimuli on the collagen gel specimen involving fibroblasts. The magnitude of strains were set to 10% in tension and compression, the frequency was 0.5Hz, 24 hours a day and last 1 or 2 weeks. The mechanical properties of elastic moduli and maximum stress of specimens after testing and the control specimens at static condition were measured by micro tensile testing under microscope. It was found that both indicators of mechanical properties increase in accordance with the culture time in experimental and control specimens. It also found that the strengthening of specimens were more significant in experimental group than control group In mechanical testing we further measure the strains distributions of spesimens by the use of the marker particles which locations were measured by image analyzes. The strenghtening was induced mainly on the central parts of the specimens where the tensile stress condition … More s were realized, whereas both ends of the specimens where compressive stress were generated were least strengthened. The degree of the effects of mechanical stimuli differ among the type of the cells. In bone marrow stromal cells, the tensile stresses generated by the cells were very strong and even the specimens in static conditions shrank very much and they detached from the stainless steel t wire mesh holding the gel. On the other hand, the tensile stress generated by the L cells were very small and very little effect of mechanical stimuli were observed.The in vivo experiments, which were the couterparts of the previous vitro experiments were developed. In this rat model in which a femora-patellar tendon-tibia specimen were fixed in a stainless steel holder and transplanted under the back skin, artificial repetitive tensile stress were applied. The maximum strength of the tendon did not decreased if the mechanical stimuli were applied, but the control specimens under static conditions did. Thus in the connective tissue which carried out mechanical functions in living body, the fate of the tissues is governed by the mechanical environment. It also suggests that the mechanical integrity of the artificial materials and the living tissue is based on the strong binding between collagen and biomaterials, and since the cells especially fibroblasts and osteoblasts generate tensile stress which may datatch them at the interface, it may result in the differences in biocompatibilty among the tissues and materials. Less