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Abstract

Objectives: The aim of this study was to evaluate whether delivery of rat mesenchymal stem cells (rMSCs) and/or neurotrophins to denervated gastronemius muscles can preserve muscle function. We also sought to address the role of ciliary neurotrophic factor (CNTF) by silencing CNTF expression in rMSCs using RNA interference (RNAi).

Method: Separate groups of denervated animals (Wistar) were separately injected with culture media (sham control), CNTF protein, 2.5×10⁵ rMSCs in which CNTF expression was silenced CNTF by RNAi, 2.5×10⁵ GFP transfected rMSCs, or 2.5×10⁵untreated rMSCs. Muscle function was assessed at different timepoints post-surgery and tibial nerve and gastrocnemius muscle samples were taken at 4, 8 and 12 weeks for histochemistry; neuromuscular junction (NMJ) repair was also examined by electron microscopy.

Results: Fluorescence immunocytochemistry on tissue sections confirmed neurotrophin expression in rMSCs but with little evidence of neuronal differentiation. rMSCs engraftment significantly preserved the function of denervated gastronemius muscle based both on evaluation of muscle function and direct examination of muscle tissue. Further, electron microscopy showed that the density and depth of the junctional folds were visibly reduced at 12 weeks after surgery and transplantation, especially in control group.

Conclusion: Delivery of rMSCs can preserve gastronemius muscle function following denervation. Knockdown of CNTF expression in rMSCs failed to block muscle preservation, although administration of CNTF protein alone inhibited muscle atrophy. The mechanism of action of CNTF is not known but could be at the postjunctional membrane.