Recovery of damaged skeletal muscle cells in hypoxic and cyclic stretch conditions

Abstract

The skeletal muscle occupies about 40% of the mass of human body and has a very important function to control the skeletal movement and maintain the shape of our body. Such skeletal muscle damage often occurs. When a damage occurs, it takes a long time to fully recover, but also suffer from pain and discomfort. Therefore, the recovery of such damaged skeletal muscles needs to be more effective and efficient. In this thesis, we aim to develop a model of skeletal muscle damage based on microfluidic devices and to understand the effect of hypoxia and periodic stress on the recovery of damaged muscle cells. The purpose of this study is to confirm effective and efficient method of recovery of skeletal muscle. In order to carry out this research, a microfluidic device with single channels was designed, and the myogenic differentiation was induced in this device and confirmed to be myotube. The myotubes were then damaged by chemical and mechanical methods. Hydrogen peroxide (H2O2) was used to induce chemical damage, and a verified lab-made cell stretcher was used to induce mechanical damage. The intensities of 8-hydroxydeoxyguanosine (8-OHdG), myosin heavy chain, and reactive oxygen species in myotube and the myotube diameter were quantified for damage confirmation. As a result, we could identify muscle damage through two damage inducing methods. After damage confirmation, to investigate the effect of hypoxia and cyclic stretch on recovery, we established four recovery conditions for 12 hours, with and without cyclic stretch in normoxia and hypoxia. As a result, it was confirmed that hypoxia and cyclic stretch facilitated the recovery of muscle cells, respectively, and the recovery was best performed in the hypoxia with the cyclic stretch condition.