Persistent muscle fiber regeneration in long term denervation. Past, present, future

  • Ugo Carraro Department of Neurorehabilitation, Foundation San Camillo Hospital, I.R.C.C.S., Venice, Italy.
  • Simona Boncompagni CeSI, Center for Research on Aging, Department of Neuroscience, Imaging and Clinical Sciences, University G. d’Annunzio of Chieti, Italy.
  • Valerio Gobbo C.N.R. Institute of Neuroscience, Department of Biomedical Science, University of Padova, Italy.
  • Katia Rossini Translational Myology, Interdepartmental Research Center of Myology of the University of Padova (CIR-Myo), Department of Biomedical Science, Padova, Italy; Ludwig Boltzmann Institute of Electrical Stimulation and Physical Rehabilitation, Vienna, Austria.
  • Sandra Zampieri Translational Myology, Interdepartmental Research Center of Myology of the University of Padova (CIR-Myo), Department of Biomedical Science, Padova, Italy; Ludwig Boltzmann Institute of Electrical Stimulation and Physical Rehabilitation, Vienna, Austria.
  • Simone Mosole Translational Myology, Interdepartmental Research Center of Myology of the University of Padova (CIR-Myo), Department of Biomedical Science, Padova, Italy; Ludwig Boltzmann Institute of Electrical Stimulation and Physical Rehabilitation, Vienna, Austria.
  • Barbara Ravara Translational Myology, Interdepartmental Research Center of Myology of the University of Padova (CIR-Myo), Department of Biomedical Science, Padova, Italy; Ludwig Boltzmann Institute of Electrical Stimulation and Physical Rehabilitation, Vienna, Austria.
  • Alessandra Nori Translational Myology, Interdepartmental Research Center of Myology of the University of Padova (CIR-Myo), Department of Biomedical Science, Padova, Italy.
  • Roberto Stramare CIR-Myo, Department of Medicine, Radiology Unit, University of Padova, Italy.
  • Francesco Ambrosio Antalgic Laboratory, Department of Medicine, University of Padova, Italy.
  • Francesco Piccione Department of Neurorehabilitation, Foundation San Camillo Hospital, I.R.C.C.S., Venice, Italy.
  • Stefano Masiero CIR-Myo, Department of Neuroscience, Rehabilitation Unit, University of Padova, Italy.
  • Vincenzo Vindigni CIR-Myo, Department of Neuroscience, Plastic Surgery Unit, University of Padova, Italy.
  • Paolo Gargiulo Department of Science, Education, Innovation, Landspitali University Hospital, Reykjavik, Iceland.
  • Feliciano Protasi CeSI, Center for Research on Aging, Department of Neuroscience, Imaging and Clinical Sciences, University G. d’Annunzio of Chieti, Italy.
  • Helmut Kern Ludwig Boltzmann Institute of Electrical Stimulation and Physical Rehabilitation, Vienna; Department of Physical Medicine, Wilhelminenspital, Vienna, Austria.
  • Amber Pond Anatomy Department, Southern Illinois University, School of Medicine, Carbondale, Illinois, United States.
  • Andrea Marcante | endriu83@gmail.com Department of Neurorehabilitation, Foundation San Camillo Hospital, I.R.C.C.S., Venice, Italy.

Abstract

Despite the ravages of long term denervation there is structural and ultrastructural evidence for survival of muscle fibers in mammals, with some fibers surviving at least ten months in rodents and 3-6 years in humans. Further, in rodents there is evidence that muscle fibers may regenerate even after repeated damage in the absence of the nerve, and that this potential is maintained for several months after denervation. While in animal models permanently denervated muscle sooner or later loses the ability to contract, the muscles may maintain their size and ability to function if electrically stimulated soon after denervation. Whether in mammals, humans included, this is a result of persistent de novo formation of muscle fibers is an open issue we would like to explore in this review. During the past decade, we have studied muscle biopsies from the quadriceps muscle of Spinal Cord Injury (SCI) patients suffering with Conus and Cauda Equina syndrome, a condition that fully and irreversibly disconnects skeletal muscle fibers from their damaged innervating motor neurons. We have demonstrated that human denervated muscle fibers survive years of denervation and can be rescued from severe atrophy by home-based Functional Electrical Stimulation (h-bFES). Using immunohistochemistry with both non-stimulated and the h-bFES stimulated human muscle biopsies, we have observed the persistent presence of muscle fibers which are positive to labeling by an antibody which specifically recognizes the embryonic myosin heavy chain (MHCemb). Relative to the total number of fibers present, only a small percentage of these MHCemb positive fibers are detected, suggesting that they are regenerating muscle fibers and not pre-existing myofibers re-expressing embryonic isoforms. Although embryonic isoforms of acetylcholine receptors are known to be re-expressed and to spread from the end-plate to the sarcolemma of muscle fibers in early phases of muscle denervation, we suggest that the MHCemb positive muscle fibers we observe result from the activation, proliferation and fusion of satellite cells, the myogenic precursors present under the basal lamina of the muscle fibers. Using morphological features and molecular biomarkers, we show that severely atrophic muscle fibers, with a peculiar cluster reorganization of myonuclei, are present in rodent muscle seven-months after neurectomy and in human muscles 30-months after complete Conus-Cauda Equina Syndrome and that these are structurally distinct from early myotubes. Beyond reviewing evidence from rodent and human studies, we add some ultrastructural evidence of muscle fiber regeneration in long-term denervated human muscles and discuss the options to substantially increase the regenerative potential of severely denervated human muscles not having been treated with h-bFES. Some of the mandatory procedures, are ready to be translated from animal experiments to clinical studies to meet the needs of persons with longterm irreversible muscle denervation. An European Project, the trial Rise4EU (Rise for You, a personalized treatment for recovery of function of denervated muscle in long-term stable SCI) will hopefully follow.

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Published
2015-03-11
Keywords:
Human muscle, Conus-Cauda Equina syndrome, Spinal cord injury, Permanent muscle denervation, Severe atrophy and nuclear clumpings, Muscle fiber regeneration, Homebased functional electrical stimulation (h-b FES), Recovery of tetanic contractility, Myogeni
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How to Cite
Carraro, U., Boncompagni, S., Gobbo, V., Rossini, K., Zampieri, S., Mosole, S., Ravara, B., Nori, A., Stramare, R., Ambrosio, F., Piccione, F., Masiero, S., Vindigni, V., Gargiulo, P., Protasi, F., Kern, H., Pond, A., & Marcante, A. (2015). Persistent muscle fiber regeneration in long term denervation. Past, present, future. European Journal of Translational Myology, 25(2), 77-92. https://doi.org/10.4081/ejtm.2015.4832

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