Stretching skeletal muscle in vitro: does it replicate in vivo physiology?

Abstract

Skeletal muscle is highly adaptable and responds to changes in loading through exercise or resistance training through a number of mechanisms resulting in increased muscle mass and changes in contractile phenotype. To further understand and study the molecular mechanisms underlying the adaptive response of muscle, a number of in vitro culture systems have been developed that utilise mechanical loading or stretching of the cultured muscle to recapitulate the adaptations observed in vivo. Here we review the use of such stretching regimes for engineered muscle constructs and assess how well these in vitro systems mimic in vivo muscle physiology and adaptation.

Habitual exercise plus dietary supplementation with milk fat globule membrane improves muscle function deficits via neuromuscular development in senescence-accelerated mice

“…To further understand the mechanisms underlying the adaptive response of skeletal muscles in vivo, in vitro culture systems that use mechanical stretching of cultured myotubes have been developed to mimic in vivo muscle physiology (Passey et al 2011), including neuromuscular adaptation in response to exercise (Folland and Williams 2007; Hubatsch and Jasmin 1997; Jasmin et al 1991; Sveistrup et al 1995). Accordingly, we examined the effects of MFGM-derived fractions and sphingomyelin combined with mechanical stretch (as a substitute for exercise in vivo) on the expression of several genes.Treatment of the stretched cells with MFGM, PLF, SLF, or sphingomyelin significantly increased Dok-7 gene expression compared with that in cells that received mechanical stretching alone; this was evident especially in the cells treated with SLF or sphingomyelin (Figure 5).…”

Skeletal muscle–derived cell cultures as potent models in regenerative medicine research

“…Over the last 30 years, a number of in vitro experimental models have been developed that show similarities with muscle in vivo (see Table S1 in supplementary material). In 2003, Li et al studied the induction of differentiation of myogenic cells into fibrotic cells by transforming growth factor‐beta (TGF‐β) in injured skeletal muscles of normal mice.…”

“…For in vitro models of skeletal muscle to be adequate they need to mimic in vivo models and cellular behavior. Muscle fibers undergo force in a longitudinal direction under normal physiological conditions in vivo during growth and exercise, and it is also desirable for in vitro systems to simulate such a pattern . However, the various types of stretching systems available differ with regard to producing uniaxial or multiaxial stretch, which is of great importance to consider when investigating pathophysiological responses in different experiments.…”

Mechanical cues in orofacial tissue engineering and regenerative medicine

“…Moreover, mechanical strain stimulates protein synthesis and fiber growth in glycolytic fast fibers less than both slow and fast oxidative fibers from rat soleus muscle . During exercise, protein synthesis first decreases, to increase again after a lag phase . This is specifically the case in muscles with a high proportion of fast glycolytic fibers, and thus of particular relevance for CLP patients.…”

“…86 During exercise, protein synthesis first decreases, to increase again after a lag phase. [87][88][89][90] This is specifically the case in muscles with a high proportion of fast glycolytic fibers, 87 and thus of particular relevance for CLP patients. These data indicate that specialized protocols are needed for the stimulation of proliferation and differentiation for orofacial muscle cells.…”