Influence of a dextran derivative on myosin heavy chain expression during rat skeletal muscle regeneration

We recently described dextran derivatives (RGTA) which stimulate tissue repair in several in vivo models. One of them, RGTA11, has been shown to accelerate crush-induced regeneration and reinnervation of rat EDL and Soleus muscles. In this study we wanted to know if RGTA11 alters the pattern of myosin heavy chain expression during regeneration. In both EDL and Soleus muscles, RGTA11, injected at the moment of the crush, was found to accelerate the shift from neonatal to adult myosin heavy chain isoforms within 2 weeks. The proportion of slow fibers increased considerably, especially in the Soleus where RGTA11 induced a precocious and permanent expression of slow myosin isoform, thus confirming that a more efficient innervation had occurred in the presence of RGTA11. These results illustrate the interesting potential pharmacological use of such dextran derivatives in neuromuscular disease.