A Novel Tension Machine Promotes Bone Marrow Mesenchymal Stem Cell Osteoblastic and Fibroblastic Differentiation by Applying Cyclic Tension

Figure 2

The structure and working principle of iStrain. (a) The structure of iStrain. 1: 6-well BioFlex plate; 2: culture plate fixtures; 3: culture plate support platform; 4: spherical stiffening elements; 5: movable platform; 6: power bank; 7: vertical support column; 8: linear bearings; 9: handles; 10: pedestal; 11: MLSM. (b) The workflow diagram of iStrain. A personalized force pattern is formed on iStrain companion software, and then, the force pattern is transferred to the microcomputer. After start-up, the microcomputer sends commands to the MLSM, which moves linearly according to the preset program. With the cooperation of two linear bearings, the MLSM drives the movable platform together with the spherical stiffening elements above it to move vertically, thus applying force to the elastic bottom of the culture plate and stretching the cells cultured on it. (c) The structure of the spherical stiffening element depends on five variables: , , , , and . is the distance from the rubber membrane to the lowest bottom of the culture plate. is the radius of the rubber membrane. For the BioFlex plates,  mm and  mm. refers to the extension rate, which is determined for each independent experiment. refers to the radius of the spherical part, and refers to its height. and are calculated as follows: ; .

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