Bovine adipofibroblasts, 3T3-L1 cells, L-6 myogenic cells, and sheep satellite cells were allowed to proliferate for 48 h. Oil red-O (ORO) was dissolved in three different solvents isopropanol, propylene glycol and triethyl phosphate. At 48 h, the proliferative cultures were stained with the three stains. ORO stain prepared in both propylene glycol and triethyl phosphate resulted in bright red droplets appearing in all cultures, whereas ORO dissolved in isopropanol was not taken up by any of the cells. These data suggest that certain preparations of ORO may stain cells in non-adipogenic lineages as well as undifferentiated preadipocytes. Caution must be exercised when choosing solvents for ORO in differentiation studies using cells of the fat/adipose lineage.

Myostatin is a member of the TGF-β superfamily and a potent negative regulator of muscle growth and development in mammals. Its expression is limited primarily to skeletal muscle in mammals, but occurs in many different fish tissues, although quantitative measurements of the embryonic and tissue-specific expression profiles are lacking. A recent phylogenetic analysis of all known myostatin genes identified a novel paralogue in zebrafish, zfMSTN-2, and prompted the reclassification of the entire subfamily to include MSTN-1 and -2 sister clades in the bony fishes. The differential expression profiles of both genes were therefore determined using custom RNA panels generated from pooled (100-150/sampling) embryos at different stages of development and from individual adult tissues. High levels of both transcripts were transiently present at the blastula stage, but were undetectable throughout gastrulation (7 hpf). Levels of zfMSTN-2 peaked during early somitogenesis (11 hpf), returned to basal levels during late somitogenesis and did not begin to rise again until hatching (72 hpf). By contrast, zfMSTN-1 mRNA levels peaked during late somitogenesis (15.5-19 hpf), returned to baseline at 21.5 hpf and eventually rose 25-fold by 72 hpf. In adults, both transcripts were present in a wide variety of tissues, including some not previously known to express myostatin. Expression of zfMSTN-1 was highest in brain, muscle, heart and testes and was 1-3 log orders above that in other tissues. It was also greater than zfMSTN-2 expression in most tissues, nevertheless, levels of both transcripts increased almost 600-fold in spleens of fish subjected to stocking stress. Myostatin expression was also detected in mouse spleens, suggesting that myostatin may influence immune cell development in mammals as well as fish. These studies indicate that zfMSTN-1 and -2 gene expression is differentially regulated in developing fish embryos and in adult tissues. The increased expression of both genes in spleens from stressed fish is further supportive of an immunomodulatory role and may explain increased disease susceptibility associated with stocking stress.

BackgroundHundreds of genes, including muscle creatine kinase (MCK), are differentially expressed in fast- and slow-twitch muscle fibers, but the fiber type-specific regulatory mechanisms are not well understood.ResultsModulatory region 1 (MR1) is a 1-kb regulatory region within MCK intron 1 that is highly active in terminally differentiating skeletal myocytes in vitro. A MCK small intronic enhancer (MCK-SIE) containing a paired E-box/myocyte enhancer factor 2 (MEF2) regulatory motif resides within MR1. The SIE's transcriptional activity equals that of the extensively characterized 206-bp MCK 5'-enhancer, but the MCK-SIE is flanked by regions that can repress its activity via the individual and combined effects of about 15 different but highly conserved 9- to 24-bp sequences. ChIP and ChIP-Seq analyses indicate that the SIE and the MCK 5'-enhancer are occupied by MyoD, myogenin and MEF2. Many other E-boxes located within or immediately adjacent to intron 1 are not occupied by MyoD or myogenin. Transgenic analysis of a 6.5-kb MCK genomic fragment containing the 5'-enhancer and proximal promoter plus the 3.2-kb intron 1, with and without MR1, indicates that MR1 is critical for MCK expression in slow- and intermediate-twitch muscle fibers (types I and IIa, respectively), but is not required for expression in fast-twitch muscle fibers (types IIb and IId).ConclusionsIn this study, we discovered that MR1 is critical for MCK expression in slow- and intermediate-twitch muscle fibers and that MR1's positive transcriptional activity depends on a paired E-box MEF2 site motif within a SIE. This is the first study to delineate the DNA controls for MCK expression in different skeletal muscle fiber types.

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ObjectiveInflammation and fibrosis are intertwined in multiple disease processes. We have previously found that over-expression of urokinase plasminogen activator in macrophages induces spontaneous macrophage accumulation and fibrosis specific to the heart in mice. Understanding the relationship between inflammation and fibrosis in the heart is critical to developing therapies for diverse myocardial diseases. Therefore, we sought to determine if uPA induces changes in macrophage function that promote cardiac collagen accumulation.Methods and ResultsWe analyzed the effect of the uPA transgene on expression of pro-inflammatory (M1) and pro-fibrotic (M2) genes and proteins in hearts and isolated macrophages of uPA overexpressing mice. We found that although there was elevation of the pro-inflammatory cytokine IL-6 in hearts of transgenic mice, IL-6 is not a major effector of uPA induced cardiac fibrosis. However, uPA expressing bone marrow-derived macrophages are polarized to express M2 genes in response to IL-4 stimulation, and these M2 genes are upregulated in uPA expressing macrophages following migration to the heart. In addition, while uPA expressing macrophages express a transcriptional profile that is seen in tumor–associated macrophages, these macrophages promote collagen expression in cardiac but not embryonic fibroblasts.ConclusionsUrokinase plasminogen activator induces an M2/profibrotic phenotype in macrophages that is fully expressed after migration of macrophages into the heart. Understanding the mechanisms by which uPA modulates macrophage function may reveal insights into diverse pathologic processes.

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BACKGROUND Clinical trials report improvements in function and perfusion with direct injection of bone marrow cells into the hearts of patients with ischemic cardiomyopathy. Preclinical data suggest these cells improve vascular density, which would be expected to decrease fibrosis and inflammation. OBJECTIVES We tested the hypothesis that bone marrow stem cells (CD34+) will improve histologic measurements of vascularity, fibrosis, and inflammation in human subjects undergoing left ventricular assist device (LVAD) placement as a bridge to cardiac transplantation. METHODS Subjects with ischemic cardiomyopathy who were scheduled for placement of an LVAD as a bridge to transplantation underwent bone marrow aspiration the day prior to surgery; the bone marrow was processed into cell fractions (bone marrow mononuclear cells, CD34+, and CD34−). At LVAD implantation, all fractions and a saline control were injected epicardially into predetermined areas and each injection site marked. At transplant, injected areas were collected. Data were analyzed by paired Student t test comparing the effect of cell fractions injected within each subject. RESULTS Six subjects completed the study. There were no statistically significant differences in complications with the procedure versus control subjects. Histologic analysis indicated that myocardium injected with CD34+ cells had decreased density of endothelial cells compared to saline-injected myocardium. There were no significant differences in fibrosis or inflammation between groups; however, density of activated fibroblasts was decreased in both CD34+ and CD34− injected areas. CONCLUSIONS Tissue analysis does not support the hypothesis that bone marrow-derived CD34+ cells promote increased vascular tissue in humans with ischemic cardiomyopathy via direct injection.

This study evaluated the ability of common ergogenic supplement components to alter satellite cell proliferative activity in vitro. Compounds studied were cinnamic acid, ferulic acid, L-glutathione, β-hydroxybutyric acid, calcium-β-hydroxy-β-methylbutyrate monohydrate, DL-thioctic acid (α-lipoic acid), and ornithine α-ketoglutarate. Satellite cells were exposed to different levels of ergogenic test compound for a specified amount of time and analyzed by counting mononucleated and multinucleated cells. At the levels evaluated, none of these compounds altered satellite cell proliferation over that of control cultures (p > 0.05). Four of the compounds were shown to alter satellite cell differentiation over control cultures (p < 0.05), but due to the small amounts of fusion, the biological relevance is in question (e.g. differences in small numbers). These data suggest that a few of the ergogenic compounds examined by this laboratory do influence satellite cell activity in vitro. However, additional studies are vital in order to define the biological relevance of our observations.