Multiple stimulations for muscle–nerve–blood vessel unit in compensatory hypertrophied skeletal muscle of rat surgical ablation model

Abstract

Tissue inflammation and multiple cellular responses in the compensatory enlarged plantaris (OP Plt) muscle induced by surgical ablation of synergistic muscles (soleus and gastrocnemius) were followed over 10 weeks after surgery. Contralateral surgery was performed in adult Wistar male rats. Cellular responses in muscle fibers, blood vessels and nerve fibers were analyzed by immunohistochemistry and electron microscopy. Severe muscle fiber damage and disappearance of capillaries associated with apparent tissue edema were observed in the peripheral portion of OP Plt muscles during the first week, whereas central portions were relatively preserved. Marked cell activation/proliferation was also mainly observed in peripheral portions. Similarly, activated myogenic cells were seen not only inside but also outside of muscle fibers. The former were likely satellite cells and the latter may be interstitial myogenic cells. One week after surgery, small muscle fibers, small arteries and capillaries and several branched-muscle fibers were evident in the periphery, thus indicating new muscle fiber and blood vessel formation. Proliferating cells were also detected in the nerve bundles in the Schwann cell position. These results indicate that the compensatory stimulated/enlarged muscle is a suitable model for analyzing multiple physiological cellular responses in muscle-nerve-blood vessel units under continuous stretch stimulation.

Origin and hierarchy of basal lamina-forming and -non-forming myogenic cells in mouse skeletal muscle in relation to adhesive capacity and Pax7 expression in vitro

“…This is direct proof that satellite cells are not involved in BL formation during the parent muscle fiber regeneration. This mechanism may also be the cause of the branched muscle fiber formation that is frequently seen in repeatedly and/or chronically damaged muscles, such as in the mdx mouse (Tamaki et al 1993), after repeated injection of bupivacaine-hydrochloride (Tamaki and Akatsuka 1994) and in the compensatory enlarged muscle (Tamaki et al 1996(Tamaki et al , 2009b, because the crosssectional profile of branched muscle fibers (Tamaki et al 1996;2009b) was similar to the photograph in Fig. 4e-g.…”

“…For this purpose, the mouse compensatory enlarged skeletal muscle (plantaris) model induced by surgical ablation of synergistic muscles (soleus and gastrocnemius) was used for in vivo stimulation of myogenic cells located inside and outside the muscle fiber BL (Tamaki et al 2009a;2009b). We then examined the BL formation of all activated myogenic cells, as we hypothesized that satellite cells do not possess their own BL, as they should originally operate inside the muscle fiber BL (BL − myogenic cells).…”

Plasticity and Physiological Role of Stem Cells Derived from Skeletal Muscle Interstitium: Contribution to Muscle Fiber Hyperplasia and Therapeutic Use

“…These two factors are thought to account for the postnatal increase in total muscle mass [33]. This is also the case in "muscle fiber hypertrophy", such as that occurring after heavy resistance exercise [34][35][36][37][38][39] or in the compensatory enlarged muscle [40][41][42]. Therefore, satellite cells are considered "myoblast precursors" mainly working in the myofiber basal lamina cylinder.…”

Effective fiber hypertrophy in satellite cell-depleted skeletal muscle

“…Thus, if satellite cells are necessary for hypertrophy, then the growth challenge provided by SA is guaranteed to be sufficient to require satellite cells. In addition to fiber hypertrophy, the SA model has also been reported to induce both fiber hyperplasia and regeneration, providing the opportunity to assess the necessity of satellite cells in these distinct processes (Tamaki et al, 2009b).…”