Nestin Expression Reflects Formation, Revascularization and Reinnervation of New Myofibers in Regenerating Rat Hind Limb Skeletal Muscles

Abstract

This work provides a comprehensive view of expression and distribution patterns of the intermediate filament nestin in rat regenerating skeletal muscles. Regeneration was induced by heterochronous isotransplantation of extensor digitorum longus (EDL) or soleus muscles from 15-day-old rats into the EDL muscle of adult female inbred Lewis rats. Recipients were sacrificed by anesthetic overdose and the host muscles with the graft were excised after 7-, 16-, 21- and 29-day survival, fixed in 10% formalin solution and immunohistochemically stained. In the regenerating skeletal muscle maximal nestin expression was observed in newly formed myoblasts and myotubes and it decreased in the course of skeletal myofiber development. We demonstrate the phenomenon of a peripheral concentration of nestin expression within the differentiating myofibers called ‘lateralization’, which may represent a mechanism of nestin elimination during the development of skeletal myofibers. Furthermore, nestin has been detected in newly formed endothelial cells of blood vessels growing into the regenerated area and also in peripheral nerves innervating the graft as well as the host muscle. In conclusion, according to our results, nestin represents an ideal marker for skeletal muscle regeneration, as its expression reflects processes of development, revascularization and reinnervation of new myofibers.

Expression of nestin, desmin and vimentin in intact and regenerating muscle spindles of rat hind limb skeletal muscles

“…Therefore, nestin expression decreases during diVerentiation of the newly formed muscle cells in regenerating spindles; mature intrafusal myoWbers are devoid of nestin immunoreactivity. This Wnding is in accordance with studies demonstrating nestin down-regulation in the course of the extrafusal myoWber diVerentiation (Aarimaa et al 2004;Carlsson et al 1999;Bíqková et al 2008;Sejersen and Lendahl 1993;Vaittinen et al 2001). The down-regulation of nestin during cell diVerentiation, normal development or regeneration has been described as a characteristic feature of this intermediate Wlament protein.…”

“…DiVerences in the intensity of nestin immunoreactivity in individual intrafusal myoWbers of this muscle spindle may be explained by the diVerent degree of survival and/or regeneration. More mature myoWbers reveal a weaker nestin immunopositivity, whereas less developed myoWbers express nestin more strongly, similarly as is the case in regenerating extrafusal myoWbers (Bíqková et al 2008).…”

“…In the adult extrafusal myoWbers, nestin is expressed in a selective manner in the sarcoplasm of neuromuscular and myotendinous junctions (Carlsson et al 1999;Vaittinen et al 1999;Bíqková et al 2008). It is tempting to speculate whether nestin is expressed in motor endplates of intrafusal myoWbers in muscle spindles as well.…”

“…In mature skeletal myoWbers, nestin is expressed in a selective manner only in the sarcoplasm of neuromuscular and myotendinous junctions (Carlsson et al 1999;Vaittinen et al 1999), whereas desmin is expressed throughout the full length of myoWbers forming an interlinking scaVold around myoWbrils with connections to the sarcolemma and the nuclear membrane. In our previous work, we described expression of nestin, desmin and vimentin in the regenerating extrafusal Wbers of rat skeletal muscles (Bíqková et al 2008). In the regenerating extrafusal Wbers, the maximal nestin expression was detected in newly formed myoblasts and myotubes and this expression decreased in the course of skeletal myoWber development.…”

“…We have also demonstrated the phenomenon of a peripheral concentration of nestin expression within the diVerentiating myoWbers called "lateralization", which may represent a mechanism of nestin elimination during development of skeletal myoWbers. Furthermore, nestin was detected in newly formed endothelial cells of blood vessels growing into areas of regenerating skeletal muscles and also in Schwann cells of peripheral nerves innervating the intact as well as the regenerating skeletal muscle (Bíqková et al 2008).…”