The effects of the actin cytoskeleton on the transverse mechanical properties of skeletal muscle cells

This study examined the contributions of actin filaments and actomyosin cytoskeleton to the transverse mechanical properties of skeletal muscle cells. The study is motivated by the goal of understanding the molecular mechanism behind skeletal myoblast transplantation, a promising therapeutic approach for myocardial repair. Using atomic force microscopy (AFM), the apparent elastic modulus, E_app, of the skeletal muscle cells upon treated with either cytochalasin D (CD), an actin depolymerizer, or 2,3-Butanedione 2-Monoxime (BDM), an inhibitor of myosin ATPase, were measured over a 30-minute period of the addition of drug. The appearance of mature sarcomeres was detected on differentiation day 6 with confocal microscopy. Results showed that for both treatments, E_app decreased over time. The decreasing trend was consistent for all differentiation days. Very slight hysteresis was observed during the measurements of E_app, which suggested that viscous contributions were not alter by treatment with either drugs. The decreased elastic modulus, when treated with CD or BDM, suggested that actin filaments and actomyosin cytoskeleton both play a very important role in the elastic properties of the skeletal muscle cells.