The Promotion Effects of Bioreactor for Mechanical and Electrical Stimulations on the Reconstruction of Muscle Tissue(1/3)

In Taiwan, cardiovascular disease is the second among the top ten leading causes of death. Following significant injury such as myocardial infarction, the myocardium has limited regenerative potential. Therefore, cell therapy has been investigated to promote the repair of damaged heart tissues. However, cells expanded ex vivo always lose their functions and cannot couple to the host tissue because static culture condition is too far from dynamic cardiac environment. Consequently, we would like to develop a bioreactor to achieve a mature tissue-engineered myocardium in vitro. To electrically and mechanically treat cells simultaneously, a conductive substrate with high stretchability is essentially demanded. Polypyrrole (PPy) will be deposited onto elastic polydimethylsiloxane (PDMS) to form a conductive stretchable substrate. In addition, thermo-sensitive poly (N-isoproylacrylamide) (PNIPAAm) will be grafted on the surface, by which intact engineered cell sheets can be completely detached through temperature regulation. The conductivity of PNIPAAm-PPy/PDMS constructs during stretching will be evaluated to determine their applicable strain range, and the cyclic stretching will also be performed to ensure their reliability. Furthermore, detached cell sheets will be examined of their viability and cardiac properties. Once the PNIPAAm-PPy/PDMS constructs are successfully fabricated, they will be utilized for bioreactor application. A 3-layered device will be manufactured by computer numerical control (CNC) processing. When cells are seeded on this bioreactor, they can be mechanically and/or electrically stimulated. Because cytoskeleton is sensitive to environmental cues, it is expected that the combination of these two physical stimulations can synergistically control cell morphology. Regarding to the cardiomyogensis, mechanical and electrical treatments can both mimic the environmental cues in myocardium, and thus cell differentiation toward cardiac phenotype should be highly promoted. Finally, we will further validate the feasibility of engineered cell sheets on healing myocardial infarction. Comparing to untreated cardiac cells, mechanically and electrically treated cells should be highly promoted of their myogenesis. In addition, the cell sheet method preserve cell-cell interaction and cell-ECM linage, thus their communication and survival rates should be highly improved, which may facilitate electrical coupling to the native myocardium without arrhythmia. Through echocardiography analysis, these engineered cell sheets should significantly heal myocardial infarction and recover heart function. In addition to promote myogensis for tissue engineering application, this device can also be used as an disease model to understand the etiology of muscle disease such as Duchene muscular dystrophy, by which the clinical treatment and drug development can be highly promoted.