Effects Of Simulated Microgravity On3D Cultured Myocardial Cells Encapsulated Alginate

Microgravity caused changes in physiological function of astronaut in spaceflight. These changes include the cardiovascular system, muscle system, the immunesystem and the skeletal system. Among them, the cardiovascular system change ispathological process, which caused the astronauts can’t finish the homework space,and even the main cause of sudden death. Among those studies, the potential risksassociated with cardiovascular system have been a central concern in the study of thehuman physiologic adaptation to the microgravity environment. Therefore, toinvestigate the effects of microgravity on cardiac structure and function and itsmechanism is impotent, which to ensure the health and effective work of astronautsin space flight.It is costly and limited opportunities for microgravity experiments in space;therefore, the ground simulation of microgravity effect is the main way of using. Inorder to reflection effect of simulated microgravity on myocardial cell in vivo, in thisstudy, three-dimensional myocardial cell is used to study effect of simulatedmicrogravity on myocardial cell structure and function. Using tissue engineeringbiotechnique, we provided the new carriers (alginate/collagen/chitosan hydrogel) toinvestigate the effect of simulated microgravity on biological characteristic ofcardiac cells. The results by a rheometer and SEM showed that the new carrierssystem was mechanically stable and porous scaffolds which allow cells to grow inthree-dimensional model. To evaluate whether the carriers are suitable to support thegrowth of mammalian cells, the viability of H9c2cells was assessed by MTT assayand the electrophysiologic characteristics of cardiac myocytes was investigate. Theresults showed that the viability of cells within carriers steadily increased, and thespontaneous and synchronous contraction of the whole cardiac cell-carriers wasmaintained more than two months.In order to prove the alginate carriers encapsulated cell system for the reliabilityof the effect of simulated microgravity, it was observed the simulated microgravityeffect on H9c2microfilament cultured in alginate microcapsules and cytodexes, andthe biological characteristics of breast cancer cells cultured in simulated microgravity effect. The results showed that simulated microgravity effect usedNASA-RCCS with15rpm leaded to microfilament change in two carriers anddifferent biological alteration in two phenotypical dissimilar human breast cancercell lines, which was proved be suitable for alginate encapsulation of cells to studythe effect of simulated microgravity.Furthermore, the effect of simulated microgravity with the establishedthree-dimensional cell culture model on structure, proliferation and apoptosis ofcardiomyocyte was analysed. The results showed that simulated microgravity effectused alginate carriers decreased cardiomyocytes proliferation, lead to cytoskeletondepolymerization, induced apoptosis in72hr. However, under2D rotation systemH9c2cells showd decreased cell area and cytoskeleton damage on day8, while noeffect was observed on cell proliferation;Finally, effect of simulated microgravity on myocardial cells pulse functionwas observed. Simulated microgravity effect changed the frequency of myocardialcontractility. Furthermore, at the molecular level analysis of the impact of channelsprotein expression used transfer sodium, potassium and calcium ion, and signaltransduction of Cx43gap junction protein expression. Study found that cell modelsand animal models of simulated microgravity in the microgravity on the geneencoding sodium channel SCN5a expression did not cause significant impact, whilethe remaining changes the action potential of the structural basis, leading heart theoccurrence of disorders.In this study, the mitochondrial specific probe Mito Tracker Red, reactiveoxygen species probe DCFH-DA, Rhodamine123, and antioxidant enzyme activityassay kits were used. The results revealed that3D rotation caused by simulatedmicrogravity effect mitochondrial distribution, structure and dysfunction, leaded tomyocardial oxidative stress in myocardial cells, increased antioxidant enzymeactivity and heat shock protein and transcription factor NF-κB expression.In summary, this study established a three-dimensional carrier systerm foreffects of simulated microgravity. It indicated simulated microgravity at the cellularlevel changed myocardial structure and function, and impacted expression of ionchannels protein; and that simulated microgravity lead to the occurrence of oxidativestress. And in vivo experiments, simulated microgravity change the expression of iontchannel protein.