Development of a tensile test system for cells and biological fine fibers

点击翻译按钮获取中文摘要

A tensile test system for cells and biological fine fibers has been designed, and the tensile properties of fibroblasts, vascular smooth muscle calls, and collagen fibers have been first determined with this system.1.The system consists of an inverted fluorescence microscope, micromanipulator, a direct drive linear actuator, a load cell, a video dimension analyzer (VDA), and a thermostatic test chamber. The test chamber and the microscope are mounted on a vibration isolator. A cell or a fiber is gripped with a pair of micropipettes at their fine tips using a cell adhesive or a polymer adhesive. One of the micropipettes is fixed to the load cell; the other one is attached to the linear actuator which is used to stretch the specimen. The load cell is of a cantilever-type; the deflection of the cantilever is measured with a semi-conductor strain gage or a laser displacement meter, and converted into load (accuracy=±0.05μN). Specimen elongation is determined from the distance between the micropipette tips measured with the VDA (resolution=0.24μm).2.The stiffness, maximum load, and elongation to failure of the fibroblasts harvested from the rabbit patellar tendon and then cultured in vitro (diameter at no load=21μm) were 0.02N/m, 0.9μN, 86μm, respectively, and the cell shape was locally irregular during tensile testing.3.The stiffness of the smooth muscle cells harvested from the rabbit thoracic aorta and then cultured in vitro (diameter at no load=32μm) was 0.09N/m in synthetic-typed cells and 0.17N/m in contractile-typed cells.4.The secant modulus, tensile strength, and strain to failure of the collagen fibers obtained from the rabbit patellar tendon (diameter=1μm) were 54MPa, 8.5MPa, and 22%, respectively.