Poster Presentations

Abstract

BACKGROUND Human skeletal muscle myoblasts are exposed to a variety of mechanical forces during in vivo conditions. These forces affects both cell orientation, proliferation and differentiation. Different models for mechanical stimulation have been tested, but one, uniaxial cyclic tensile strain (CTS), has to our knowledge not been tested on human primary skeletal muscle myoblasts. Previous research on this model has provided knowledge about cell alignment, signaling, protein expression and gene transcription when tested on murine myoblast cell line, C2C12. However, whether the same findings is existing for a human primary cell line is of great interest to explore. In this thesis we demonstrate that primary human myoblasts, HSMM, are comparable to murine myoblasts, C2C12, in a model, that applies CTS to the cells. RESULTS The effects CTS on HSMM were thoroughly investigated and compared to those of C2C12. Both HSMM and C2C12 subjected to uniaxial CTS acquired a uniform orientation perpendicular to the direction of strain. Myogenic markers, myogenin and MHC showed significant enhancement of differentiation in both HSMM and C2C12 cultures, despite no significant difference was detected for early myogenic markers, Myf-5 and MyoD1. Cells fusion was observed already at day 2 for C2C12 and day 5 for HSMM. Assembly of sarcomeric structures was found within both control and CTS groups for both HSMM and C2C12 in form of actin and myosin cross-striations. CONCLUSION The effect of CTS on myogenic differentiation was verified for both C2C12 and HSMM cell lines, with an enhanced myogenic profile. Cytoskeleton rearrangement in response to elongation of the stress fibers aligned the cells uniformly in a perpendicular angle to the direction of strain. The enhanced myogenic properties experienced in this thesis may prove valuable in future experiments trying to unravel the true potential of primary human skeletal muscle myoblasts in regenerative medicine and tissue engineering.