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The cell migration velocity in response to increasing concentration of exogenous HGF in the intact soleus muscles. Note: In the intact soleus muscles without HGF treatment, no cell migration was detected. Values are expressed as mean±SD. *p<0.05.
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The transplantation of myogenic cells is a potentially effective therapy for muscular dystrophy. However, this therapy has achieved little success because the diffusion of transplanted myogenic cells is limited. Hepatocyte growth factor (HGF) is one of the primary triggers to induce myogenic cell migration in vitro. However, to our knowledge, wheth...
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... investigate whether the velocity of cell migration was affected by the difference of exogenous HGF concen- tration, the cell migration velocity was quantitated in each HGF concentration. As a result, the velocity of 100 ng/ml HGF-triggered cell migration was significantly higher than that of 25 ng/ml HGF-triggered cell migration (p<0.05) (Fig. ...Similar publications
This paper presents an overview of the state of the art about the late effects of ionizing radiation on skeletal muscle, helping new research and showing unexplored areas. For this, it was evaluated the interest reported by the scientific literature regarding the late effects in skeletal muscle resulting from exposure to ionizing radiation. Origina...
Long non-coding RNAs (lncRNAs) have been implicated in fundamental and diverse biological processes, including myogenesis. However, the molecular mechanisms involved in this process remain largely unexplored. This study found that H19 affected the differentiation of porcine satellite cells (PSCs) by directly binding to the DNA/RNA-binding protein T...
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... HGF/c-Met pathway induces migration of hematopoietic progenitors and facilitates stress-induced mobilization from the bone marrow [35,107,108]. HGF/c-Met promotes chemotaxis of satellite cells as well [109][110][111][112][113], which is required for myoblast directional motility and myocyte fusion during adult skeletal muscle restoration [113]. ...
... The migration of skeletal muscle satellite cells was also addressed by intravital imaging. In confirmation of the in vitro studies, it was documented by live observations that exogenous HGF induces cell migration in the rat soleus muscle [110], where the cells are prompted to move by the tissue damage [265]. However, in these works no specific markers of the myogenic progenitors were utilized. ...
With the advancements in the field of adult stem and progenitor cells grows the recognition that the motility of primitive cells is a pivotal aspect of their functionality. There is accumulating evidence that the recruitment of tissue-resident and circulating cells is critical for organ homeostasis and effective injury responses, whereas the pathobiology of degenerative diseases, neoplasm and aging, might be rooted in the altered ability of immature cells to migrate. Furthermore, understanding the biological machinery determining the translocation patterns of tissue progenitors is of great relevance for the emerging methodologies for cell-based therapies and regenerative medicine. The present article provides an overview of studies addressing the physiological significance and diverse modes of stem and progenitor cell trafficking in adult mammalian organs, discusses the major microenvironmental cues regulating cell migration, and describes the implementation of live imaging approaches for the exploration of stem cell movement in tissues and the factors dictating the motility of endogenous and transplanted cells with regenerative potential.
... Muscle strength exercise is an important therapeutic technique in physical therapy, which is often performed for recovery from disuse atrophy. Although the precise mechanism of satellite cell activation induced by hepatocyte growth factor (HGF) is unclear, it is one of the key events in this recovery process [1][2][3][4][5] . In fact, previous studies using experimental animal models have demonstrated that satellite cell activation and HGF production are induced by activities that cause continuous muscle contraction, such as high-intensity running for 30 min, synergist muscle ablation, contralateral continuous overloading by ablation of a sciatic nerve, and reloading [6][7][8][9][10][11][12][13][14] . ...
[Purpose] The present study aimed to determine the effects of short muscle strength exercise on hepatocyte growth factor expression and satellite cell activation. [Subjects] The study included 72 2-12-week-old male Sprague-Dawley rats. [Methods] The rat plantaris muscle was contracted with a 5-min electrical stimulation of the sciatic nerve, and then, the mRNA expressions of hepatocyte growth factor and myogenic regulatory factors in the plantaris muscle were determined, and the phosphorylation of the hepatocyte growth factor receptor (c-Met) was examined. [Results] The mRNA expressions of hepatocyte growth factor and myogenic regulatory factors increased after a short muscle contraction compared to that un-contraction. Immunofluorescence analysis showed the expression of hepatocyte growth factor protein and the possibility that downstream biological changes occurred in the hepatocyte growth factor-bound c-Met. [Conclusion] Our results demonstrated that activation of satellite cells induced hepatocyte growth factor expression during muscle contraction with a short 5-min electrical stimulation, which simulates short muscle strength exercise in physical therapy. The present study provides evidence for the use of short muscle strength exercise in physical therapy.
... Ishido and Kasuga used a novel real-time imaging method, based on optical imaging, within rat soleus muscles to examine the relationship between exogenous HGF addition and myoblast migration. They demonstrated enhanced cell migration velocity due to HGF, as well as induced MyoD expression in response to HGF treatment (Ishido and Kasuga 2012). This was also one of the first studies to demonstrate that exogenous HGF triggers satellite cell migration within intact rat soleus muscles , providing insight for future satellite cell-based therapies. ...
Skeletal muscle repair requires the migration of myoblasts (activated satellite cells) both to the injury site and then within the wound to facilitate cellular alignment in preparation for differentiation, fusion and eventual healing. Along this journey, the cells encounter a range of soluble and extracellular matrix factors which regulate their movement and ultimately determine how successful the repair process will be. Sub-optimal migration can lead to a number of scenarios, including reduced myoblast numbers entering the wound, poor alignment and insufficient differentiation to correctly repair the damage. It is therefore critical that all aspects of myoblast migration are understood, particularly in response to the changing growth and matrix factor profile prevalent following skeletal muscle injury. Since 1962, when Boyden first introduced his chemotactic chamber, numerous in vitro migration assays have been developed to mimic the wound more closely. These have increased in complexity to account for the complex micro-environment found in vivo during muscle repair and include a range of modified cell exclusion, chemotactic and three-dimensional assays. This review describes and discusses these advances and highlights the importance they have in expanding our understanding of myoblast migration dynamics.
... Similarly, c-Met expression is up regulated in tissue regeneration with injury (Michalopoulos and DeFrances, 1997) as well as in hypoxic conditions as seen in tumors (Pennacchietti et al., 2003). HGF has demonstrated motogenic effects on myoblasts (Kawamura et al., 2004) and recently, presumptive satellite cells exhibited a faster in vivo migration velocity to increasing doses of exogenous HGF (Ishido and Kasuga, 2012). Thus, by decreasing endogenous HGF secretion and associated autocrine/paracrine signals, the satellite cell may be maximizing ability to home to a site of HGF release. ...
Skeletal muscle regeneration is a multifaceted process requiring the spatial and temporal coordination of myogenesis as well as angiogenesis. Hepatocyte growth factor (HGF) plays a pivotal role in myogenesis by activating satellite cells (SC) in regenerating muscle and likely plays a role as a contributor to revascularization. Moreover, repair of a functional blood supply is critical to ameliorate tissue ischemia and restore skeletal muscle function, however effects of hypoxia on satellite cell-mediated angiogenesis remain unclear. The objective of this study was to examine the role of HGF and effect of hypoxia on the capacity of satellite cells to promote angiogenesis. To characterize the role of HGF, a microvascular fragment (MVF) culture model coupled with satellite cell conditioned media (CM) was employed. The activity of HGF was specifically blocked in SC CM reducing sprout length compared to control CM. In contrast, MVF sprout number did not differ between control or HGF-deficient SC CM media. Next, we cultured MVF in the presence of CM from satellite cells exposed to normoxic (20% O 2) or hypoxic (1% O 2) conditions. Hypoxic CM recapitulated a MVF angiogenic response identical to HGF deficient satellite cell CM. Hypoxic conditions increased satellite cell HIF-1a protein abundance and VEGF mRNA abundance but decreased HGF mRNA abundance compared to normoxic satellite cells. Consistent with reduced HGF gene expression, HGF promoter activity decreased during hypoxia. Taken together, this data indicates that hypoxic modulation of satellite cell-mediated angiogenesis involves a reduction in satellite cell HGF expression.
... Moreover, this study indicated that satellite cells migrated toward an injured site in injured muscle, while no spatiotemporal change in satellite cells occurred in intact muscle. In addition, by in vivo real-time imaging, we reported that cell migration was induced by exogenous HGF in intact skeletal muscle; and that the cell migration velocity was enhanced in response to an increasing exog- enous HGF concentration in skeletal muscles, suggesting that migrating cells may be satellite cells 27) . Thus, these reports raise the possibility that satellite cell mobility may be artificially regulated using exogenous HGF. ...
Adult mammalian skeletal muscles possess a stem cell population, called muscle satellite cells. Satellite cells mainly contribute to restoring damaged or diseased muscles. The migration of satellite cells plays an important role in muscle regeneration, and it has been traditionally thought that satellite cell migration is regulated by lamellipodial/filopodial formation. In addition, it has recently been thought that blebbing/amoeboid formation plays an important role in satellite cell migration. On the other hand, the method/mechanism(s) of the migration of satellite cells located within skeletal muscles in vivo has barely been elucidated. However, because, in recent years, in vivo real-time imaging of satellite cell migration in skeletal muscles has been reported, it is expected to markedly expand our understanding of satellite cell migration in vivo. This review will focus on the regulatory mechanism of satellite cell migration in vitro and new insights into in vivo satellite cell mobility using real-time imaging.
Adult skeletal muscle has robust regenerative capabilities due to the presence of a resident stem cell population called satellite cells. Muscle injury leads to these normally quiescent cells becoming molecularly and metabolically activated and embarking on a program of proliferation, migration, differentiation, and fusion culminating in the repair of damaged tissue. These processes are highly coordinated by paracrine signaling events that drive cytoskeletal rearrangement and cell-cell communication. Pannexins are a family of transmembrane channel proteins that mediate paracrine signaling by ATP release. It is known that Pannexin1 (Panx1) is expressed in skeletal muscle, however, the role of Panx1 during skeletal muscle development and regeneration remains poorly understood. Here we show that Panx1 is expressed on the surface of myoblasts and its expression is rapidly increased upon induction of differentiation and that Panx1 –/– mice exhibit impaired muscle regeneration after injury. Panx1 –/– myoblasts activate the myogenic differentiation program normally, but display marked deficits in migration and fusion. Mechanistically, we show that Panx1 activates P2 class purinergic receptors, which in turn mediate a lipid signaling cascade in myoblasts. This signaling induces bleb-driven amoeboid movement that in turn supports myoblast migration and fusion. Finally, we show that Panx1 is involved in the regulation of cell-matrix interaction through the induction of ADAMTS (Disintegrin-like and Metalloprotease domain with Thrombospondin-type 5) proteins that help remodel the extracellular matrix. These studies reveal a novel role for lipid-based signaling pathways activated by Panx1 in the coordination of myoblast activities essential for skeletal muscle regeneration.
Large skeletal muscle defects that result in volumetric muscle loss (VML) result in the destruction of the basal lamina, which removes key signaling molecules such as hepatocyte growth factor (HGF) from the wound site, eliminating the endogenous capacity of these injuries to regenerate. We recently showed that HGF-loaded fibrin microthreads increased the force production in muscle tissues after 60 days in a mouse VML model. In this study, we created an in vitro, 3D microscale outgrowth assay system designed to mimic cell recruitment in vivo, and investigated the effect of HGF-loaded, crosslinked fibrin microthreads on myoblast recruitment to predict the results observed in vivo. This outgrowth assay discretely separated the cellular and molecular functions (migration, proliferation, and chemotaxis) that direct outgrowth from the wound margin, creating a powerful platform to model cell recruitment in axially aligned tissues, such as skeletal muscle. The degree of cross-linking was controlled by pH and microthreads crosslinked using physiologically neutral pH (EDCn) facilitated the release of active HGF; increasing the two-dimensional migration and three-dimensional outgrowth of myoblasts twofold. While HGF adsorbed to uncrosslinked microthreads, it did not enhance myoblast migration, possibly due to the low concentrations that were adsorbed. Regardless of the amount of HGF adsorbed on the microthreads, myoblast proliferation increased significantly on stiffer, crosslinked, microthreads. Together, the results of these studies show that HGF loaded onto EDCn microthreads supported enhanced myoblast migration and recruitment and suggest that our novel outgrowth assay system is a robust in vitro screening tool that predicts the performance of fibrin microthreads in vivo.
Cellular or molecular dynamics and function are continuously changing in vivo. Their properties also vary under the influence of tissue micro-environment. Dynamic information of a cell or a molecule obtained through intravital imaging allows spatio-temporal analysis of various phenomena in a living body. However, a common hurdle in achieving high resolution imaging is the motion artifact which is caused by motion of organs, such as breathing, cardiac contractions, pulsatile blood flow or peristalsis. In this section, we will introduce the techniques for the fluorescence imaging in a living mouse in real time at cellular level resolution.
