Development of a method to measure viscoelasticity of cardiomyocytes using scanning probe microscope

We%20developed%20a%20method%20to%20measure%20viscoelasticity%20of%20cardiomyocytes%20from%20animals.%20Rats%20were%20anesthetized%20with%20pentobarbital，%20and%20the%20hearts%20were%20retrogradely%20perfused%20with%20collagenase%20to%20isolate%20cells.%20The%20cells%20were%20incubated%20for%204%20hour%20(37%E2%84%83，%205%20%CC_2)%20in%20a%20laminin-coated%20dish，%20during%20which%20the%20cells%20firmly%20attached%20to%20the%20dish.%20We%20made%20a%20circuit%20and%20modified%20a%20scanning%20probe%20microscope%20so%20that%20we%20were%20able%20to%20control%20the%20vertical%20position%20of%20the%20probe%20with%20a%20piezoelectric%20device%20according%20to%20external%20command.%20We%20also%20developed%20a%20software%20to%20impose%20command%20and%20to%20measure%20the%20position%20of%20the%20piezoelectric%20device%20and%20the%20bending%20of%20the%20cantilever.%20When%20we%20imposed%20a%20sinusoidal%20vibration，%20the%20bending%20of%20the%20cantilever%20was%20in%20phase，%20indicating%20the%20viscosity%20of%20the%20superfusate%20is%20negligible.We%20measured%20the%20changes%20in%20elasticity%20of%20cells%20during%20cardiac%20cycle%20by%20subjecting%20the%20cell%20to%20electrical%20stimulation，%20but%20the%20results%20indicated%20no%20significant%20changes.%20As%20it%20is%20known%20osmotic%20stress%20do%20change%20elasticity，%20we%20conjectured%20that%20the%20probe%20detects%20the%20local%20elasticity，%20and%20the%20changes%20in%20probe%20size%20seem%20necessary%20to%20detect%20the%20myocardial%20cellular%20elasticity%20changes.%20The%20lack%20of%20preload%20seems%20to%20contribute%20the%20small%20changes%20in%20elasticity.We%20were%20not%20able%20to%20collect%20sufficient%20healthy%20cells%20either%20by%20superfusion%20with%20collagenase%20with%20or%20without%20ultrasonic%20agitation，%20或%20超级%20融合%20与%20酶。

We developed a method to measure viscoelasticity of cardiomyocytes from animals. Rats were anesthetized with pentobarbital, and the hearts were retrogradely perfused with collagenase to isolate cells. The cells were incubated for 4 hour (37℃, 5 %CC_2) in a laminin-coated dish, during which the cells firmly attached to the dish. We made a circuit and modified a scanning probe microscope so that we were able to control the vertical position of the probe with a piezoelectric device according to external command. We also developed a software to impose command and to measure the position of the piezoelectric device and the bending of the cantilever. When we imposed a sinusoidal vibration, the bending of the cantilever was in phase, indicating the viscosity of the superfusate is negligible.We measured the changes in elasticity of cells during cardiac cycle by subjecting the cell to electrical stimulation, but the results indicated no significant changes. As it is known osmotic stress do change elasticity, we conjectured that the probe detects the local elasticity, and the changes in probe size seem necessary to detect the myocardial cellular elasticity changes. The lack of preload seems to contribute the small changes in elasticity.We were not able to collect sufficient healthy cells either by superfusion with collagenase with or without ultrasonic agitation, or super fusion with protease.