Positive Cells Overcome Fibroblasts in Primary Muscle Cultures Grown in the Presence of a 50-10 kDa Cytokine Secreted by Macrophages (original) (raw)
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Neurological Sciences, 2002
In this work we set out to determine if the murine macrophage J774 cell line can be used to produce myogenic growth factors. Activated J774 macrophages were grown in serum-free conditions. The macrophage-conditioned medium (MCM) was then used to treat cultures of primary myoblasts and regenerating muscle tissue, in vitro and in vivo respectively. MCM activity in vitro was tested by analyzing the expression of muscle-specific transcription factors, in parallel with the proliferation and differentiation rates of the cells. The macrophage-secreted factors greatly enhanced the proliferative potential of both rat and human primary myoblasts and were found to be highly muscle-specific. In vivo, MCM administration markedly enhanced the regenerative processes in damaged muscles. The ability to produce large amounts of macrophage-secreted myogenic factor(s) in the absence of serum holds great promise for its biochemical characterization and successive application in therapeutic protocols, both for ex vivo gene therapy and for muscle repair.
PLoS ONE, 2012
Transplantation of muscle precursor cells is of therapeutic interest for focal skeletal muscular diseases. However, major limitations of cell transplantation are the poor survival, expansion and migration of the injected cells. The massive and early death of transplanted myoblasts is not fully understood although several mechanisms have been suggested. Various attempts have been made to improve their survival or migration. Taking into account that muscle regeneration is associated with the presence of macrophages, which are helpful in repairing the muscle by both cleansing the debris and deliver trophic cues to myoblasts in a sequential way, we attempted in the present work to improve myoblast transplantation by coinjecting macrophages. The present data showed that in the 5 days following the transplantation, macrophages efficiently improved: i) myoblast survival by limiting their massive death, ii) myoblast expansion within the tissue and iii) myoblast migration in the dystrophic muscle. This was confirmed by in vitro analyses showing that macrophages stimulated myoblast adhesion and migration. As a result, myoblast contribution to regenerating host myofibres was increased by macrophages one month after transplantation. Altogether, these data demonstrate that macrophages are beneficial during the early steps of myoblast transplantation into skeletal muscle, showing that coinjecting these stromal cells may be used as a helper to improve the efficiency of parenchymal cell engraftment.
Basic Appl Myol, 2004
Macrophages drive muscle regeneration and repair by removing necrotic material and producing key signaling molecules. The array of cytokines/growth factors produced by macrophages and myogenic cells stimulates the proliferation, migration and differentiation of satellite cells. Although the details of such processes are only partially understood, it is known that the administration of purified growth factors can improve the final outcome after traumatic muscle injuries. Also, such approach has proved to be beneficial in myoblast transplantation experiments in animal models. The translation of such procedures into therapeutic protocols is, however, hampered by high costs and the somewhat oversimplified biochemical input compared to the physiological signal network. We have previously reported that peritoneal macrophages could secrete factors capable of increasing the myoblast/myotube yield in cultures of primary rat myoblasts. Recently, we observed that a macrophage cell line could be stimulated to produce a conditioned medium that specifically enhances the proliferation of cultured neonatal primary myoblasts from mouse, rat, chicken, and human fetal myoblasts. The factors did not inhibit differentiation and led to a striking increase in the rate of contractile myotube formation. The factors could also enhance muscle regenerative processes in vivo, thereby suggesting a potential role as an economical and effective tool for the treatment of traumatic and disease-related muscle injuries. Further experiments in this direction and the biochemical characterization of the macrophage-produced myogenic factors are presently underway. The possibility to use the macrophage factors to improve the myoblast yield from diseased-muscle biopsies is also under investigation. Abbreviations: MCM: macrophage-conditioned medium.
The Journal of physiology, 2007
Muscle injury or modified muscle use can stimulate muscle invasion by leucocytes that have the potential to increase tissue damage or promote tissue growth and repair. In the present investigation, we examined the role of macrophages in muscle injury, repair and regeneration during modified muscle loading. Weight-bearing was removed from the hindlimbs of mice for 10 days followed by reloading through normal ambulation. During the unloading period, soleus muscle fibre cross-section decreased by 38%. Prior to the onset of reloading, mice received a series of intraperitoneal injections of anti-F4/80, which binds a mouse macrophage surface antigen. Although anti-F4/80 injections did not affect macrophage numbers in soleus muscles at 2 days of reloading, macrophages were reduced by 86% at 4 days of reloading. Muscle membrane lysis during the reloading period did not differ at 2 days of reloading between anti-F4/80-treated mice and mice that received isotype control antibody. However, con...
ED2+ Macrophages Increase Selectively Myoblast Proliferation in Muscle Cultures
Biochemical and Biophysical Research Communications, 1997
some macrophages, are present at the site of muscle We have previously shown by coculturing myoblasts damage a few hours after injury. Two days after the and macrophages that myotube formation is strongly infiltrating cell population is almost exclusively comincreased in vitro by the presence of an acid stable, posed of recruited monocytes/macrophages, which are heat-labile, soluble growth factor(s) secreted by macinvolved in removing the necrotic muscle (7-10). Afterrophages. In this paper we obtained macrophages wards, myoblasts accumulate and fuse to regenerate from peritoneal washing which also contained limited the lost myofibers.
Experimental Cell Research, 2009
Skeletal muscle regeneration relies on satellite cells, a population of myogenic precursors. Inflammation also plays a determinant role in the process, as upon injury, macrophages are attracted by the damaged myofibers and the activated satellite cells and act as key elements of dynamic muscle supportive stroma. Yet, it is not known how macrophages interact with the more profound stem cells of the satellite cell niche. Here we show that in the presence of a murine macrophage conditioned medium (mMCM) a subpopulation of multipotent cells could be selected and expanded from adult rat muscle. These cells were small, round, poorly adhesive, slow-growing and showed mesenchymal differentiation plasticity. At the same time, mMCM showed clear myogenic capabilities, as experiments with satellite cells mechanically isolated from suspensions of single myofibers showed that the macrophagic factors inhibited their tendency to shift towards adipogenesis. In vivo, intramuscular administrations of concentrated mMCM in a rat model of extensive surgical ablation dramatically improved muscle regeneration. Altogether, these findings suggest that macrophagic factors could be of great help in developing therapeutic protocols with myogenic stem cells.
Altered Macrophage Phenotype Transition Impairs Skeletal Muscle Regeneration
The American Journal of Pathology, 2014
Monocyte/macrophage polarization in skeletal muscle regeneration is ill defined. We used CD11bdiphtheria toxin receptor transgenic mice to transiently deplete monocytes/macrophages at multiple stages before and after muscle injury induced by cardiotoxin. Fat accumulation within regenerated muscle was maximal when ablation occurred at the same time as cardiotoxin-induced injury. Early ablation (day 1 after cardiotoxin) resulted in the smallest regenerated myofiber size together with increased residual necrotic myofibers and fat accumulation. However, muscle regeneration after late (day 4) ablation was similar to controls. Levels of inflammatory cells in injured muscle following early ablation and associated with impaired muscle regeneration were determined by flow cytometry. Delayed, but exaggerated, monocyte [CD11b þ (CD90/B220/CD49b/NK1.1/Ly6G) À (F4/80/I-Ab/CD11c) À Ly6C þ/À ] accumulation occurred; interestingly, Ly6C þ and Ly6C À monocytes were present concurrently in ablated animals and control mice. In addition to monocytes, proinflammatory, Ly6C þ macrophage accumulation following early ablation was delayed compared to controls. In both groups, CD11b þ F4/80 þ cells exhibited minimal expression of the M2 markers CD206 and CD301. Nevertheless, early ablation delayed and decreased the transient accumulation of CD11b þ F4/80 þ Ly6C À CD301 À macrophages; in control animals, the later tissue accumulation of these cells appeared to correspond to that of antiinflammatory macrophages, determined by cytokine production and arginase activity. In summary, impairments in muscle regeneration were associated with exaggerated monocyte recruitment and reduced Ly6C À macrophages; the switch of macrophage/monocyte subsets is critical to muscle regeneration. (Am J Pathol 2014, 184: 1167e1184; http://dx.
A macrophage-mediated factor that increases the high energy phosphate content of skeletal muscle
Journal of Surgical Research, 1985
A marked cellular infiltrate accompanies wounding. The phagocytic and bacteriocidal activities of this infiltrate require increased substrate and Or consumption. This rapid utilization of available oxygen and substrates could jeopardize an already compromised resident cellular component of a wound. Recent studies have demonstrated macrophage-mediated cell stimulatoty agents which induce proliferation of nonlymphoid mesenchymal cells. This study was designed to examine macrophageresident tissue interactions and their possible significance in wounded tissue. A reconstituted wound system was designed which combines the major components of a X-carrageenan skeletal muscle wound (muscle + macrophages). The extensor digitorum longi (EDL) of male Fisher rats were incubated in a standardized fashion [ 121. The groups of EDL were muscle incubated alone, muscle with the addition to the incubate of activated peritoneal macrophages or muscle with the addition of a conditioned supematant from the incubation of activated or nonactivated peritonal macrophages. Muscle ATP and CP content were noted to be increased 46 and 22%, respectively, when macrophages and skeletal muscle were coincubated. Macrophage-conditioned media from activated or nonactivated macrophages increased the ATP and CP muscle content 44 and 37%, respectively. Preliminary characterization of this high energy phosphate (HEP) promoting factor demonstrates it to be heat and cold stable and less than 10,000 Da. Therefore, a macrophage-mediated transferable factor is capable of increasing the HEP content of skeletal muscle in an in vitro system. This may have important consequences in maintaining host Cell integrity fOliOWing injury. 0 1985 Academic press, IX.
Dual and Beneficial Roles of Macrophages During Skeletal Muscle Regeneration
Exercise and Sport Sciences Reviews, 2009
Macrophages are necessary for skeletal muscle regeneration after injury. Muscle recruits inflammatory monocytes/macrophages that switch toward an anti-inflammatory profile upon phagocytosis of debris. In vitro, proinflammatory macrophages stimulate myoblast proliferation, whereas anti-inflammatory macrophages stimulate their differentiation. Thus, macrophages are involved in both phases of skeletal muscle regeneration: first, inflammation and cleansing of necrosis, and then myogenic differentiation and tissue repair.