In Vitro Simulation of Microgravity Induced Muscle Loss Successfully Increases Expression of Key In Vivo Atrophy Markers

Abstract

In Vitro Simulation of Microgravity Induced Muscle Loss Successfully Increases Expression of Key In Vivo Atrophy Markers by Charles P. Harding, Master of Science Utah State University, 2018 Major Professor: Dr. Elizabeth Vargis Department: Biological Engineering Muscular atrophy, defined as the loss of muscle tissue, is a serious issue for immobilized patients on Earth and in human spaceflight, where microgravity prevents normal muscle loading. In vitro modeling is an important step in understanding atrophy mechanisms and testing countermeasures before animal trials. The most ideal environment for modeling must be empirically determined to best mimic known responses in vivo. To simulate microgravity conditions, murine C2C12 myoblasts were cultured in a rotary cell culture system (RCCS). Alginate encapsulation was compared against polystyrene microcarrier beads as a substrate for culturing these adherent muscle cells. Changes after culture under simulated microgravity were characterized by assessing mRNA expression of MuRF1, MAFbx, Caspase 3, Akt2, mTOR, Ankrd1, and Foxo3. Protein concentration of myosin heavy chain 4 (Myh4) was used as a differentiation marker. Cell morphology and substrate structure were evaluated with brightfield and fluorescent imaging.