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Migration of transplanted myogenic cells occurs during both embryogenesis and regeneration of skeletal muscles and is important for successful myoblast transplantation, but little is known about factors that promote chemotaxis of these cells. Tumor necrosis factor-α (TNF-α) is known to induce chemotactic effect on several cell types. In this study, we investigated its influence on the in vitro and in vivo motility of C2C12 and primary myoblasts. In the in vitro test performed in the blind-well Boyden chambers, we showed that TNF-α (50–400 U/ml) significantly enhanced the ability of myogenic cells to migrate. The dose–response curve for this factor was bell shaped, with maximum activity in the 200 U/ml range. In the in vivo test, intramuscular administration of TNF-α was performed by an Alzet pump connected to a perforated polyethylene microtube inserted in the tibialis anterior (TA) of CD1 mice. In these experiments, myoblasts were injected under the muscle epimysium. The recipient mice were immunosuppressed with FK506. Our results showed that, 5 days after myoblast transplantation, cells migrated further in the muscles infused with TNF-α than in the muscles not exposed to TNF-α. TNF-α not only has a chemotactic activity but may also modify cell migration via its action on matrix metalloproteinase (MMP) expression. The proteolytic activities of the MMPs secreted in the muscles were thus also assessed by gelatin zymography. The results showed an increased of MMP-2 and MMP-9 transcripts in the TNF-α-infused muscles injected with myogenic cells. Myoblast migration during transplantation may be enhanced by overlapping gradients of several effector molecules such as TNF-α, interferon-γ (INF-γ), and interleukins, released at the site of muscle injury. We propose that TNF-α may promote myoblast migration directly through chemotactic activity and indirectly by enhancing MMP activity at the site of muscle injury.
*Centro Dino Ferrari, Institute of Clinical Neurology, University of Milan, Milan, Italy 2:
†Unité de recherche en Génétique humaine, Centre hospitalier de l’Universit, Laval, Ste-Foy, Québec, Canada 3:
‡IRCCS Ospedale Maggiore Policlinico, Milano, Italy
Publication date: January 1, 2003
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Cell Transplantation publishes original, peer-reviewed research and review articles on the subject of cell transplantation and its application to human diseases. To ensure high-quality contributions from all areas of transplantation, separate section editors and editorial boards have been established. Articles deal with a wide range of topics including physiological, medical, preclinical, tissue engineering, and device-oriented aspects of transplantation of nervous system, endocrine, growth factor-secreting, bone marrow, epithelial, endothelial, and genetically engineered cells, among others. Basic clinical studies and immunological research papers are also featured. To provide complete coverage of this revolutionary field, Cell Transplantation will report on relevant technological advances, and ethical and regulatory considerations of cell transplants. Cell Transplantation is now an Open Access journal starting with volume 18 in 2009, and therefore there will be an inexpensive publication charge, which is dependent on the number of pages, in addition to the charge for color figures. This will allow work to be disseminated to a wider audience and also entitle the corresponding author to a free PDF, as well as prepublication of an unedited version of the manuscript.