Alteration of myoblast phenotype by dimethyl sulfoxide

Bioactive Ingredients in K. pinnata Extract and Synergistic Effects of Combined K. pinnata and Metformin Preparations on Antioxidant Activities in Diabetic and Non-Diabetic Skeletal Muscle Cells

With healthcare costs rising, many affected by ailments are turning to alternative medicine for treatment. More people are choosing to complement their pharmacological regimen with dietary supplements from natural products. In this study, the compound composition of Kalanchoe Pinnata (K. pinnata) and the effects of combined preparations of K. pinnata and metformin on antioxidant activity in human skeletal muscle myoblasts (HSMMs) and human diabetic skeletal muscle myoblasts (DHSMMs) were investigated. Ultraperformance liquid chromatography fusion orbitrap mass spectrometry (UPLC-OT-FTMS) identified biologically active flavanols in K. pinnata. The main compounds identified in locally grown K. pinnata were quercetin, kaempferol, apigenin, epigallocatechin gallate (EGCG), and avicularin. Antioxidant results indicated that a combinatorial preparation of K. pinnata with metformin may modulate antioxidant responses by increasing the enzymatic activity of superoxide dismutase and increasing levels of reduced glutathione. A combination of 50 μM and 150 μg/mL of metformin and K. pinnata, respectively, resulted in a significant increase in reduced glutathione levels in non-diabetic and diabetic human skeletal muscle myoblasts and H2O2-stress-induced human skeletal muscle myoblasts. Additionally, a K. pinnata treatment (400 µg/mL) alone significantly increased catalase (CAT) activity for non-diabetic and diabetic human skeletal muscle myoblasts and a H2O2-stress-induced human skeletal muscle myoblast cell line, while significantly lowering malondialdehyde (MDA) levels. However, the treatment options were more effective at promoting cell viability after 24 h versus 72 h and did not promote cell viability after 72 h in H2O2-stress-induced HSMM cells. These treatment options show promise for treating oxidative-stress-mediated pathophysiological complications associated with type II diabetes.

Effect of Combined K. pinnata and Metformin Preparation on Inflammatory Cytokines in Normal and Diabetic Skeletal Muscle Cells

Diabetes Mellitus is associated with systemic inflammation and oxidative stress, which may play a central role in the development of diabetic complications. In this study, combined preparations of Kalanchoe pinnata and metformin were investigated to determine the effects on inflammatory activity in human skeletal muscle myoblasts (HSMMs) and human diabetic skeletal muscle myoblasts (DHSMMs). Results showed that combinatorial preparations sustained cell viability for 3 days in both HSMM and DHSMM cells. However, a significant decrease in cellular viability occurred for both cell lines on day 5. Results also indicate that combinatorial preparations of K. pinnata may modulate immune responses by significantly upregulating proinflammatory markers, interleukin (IL) 2, and tumor necrosis factor-alpha, and upregulating the anti-inflammatory marker, IL-10, in HSMM and DHSMM cells. The combined preparations significantly downregulated the anti-inflammatory glycoprotein IL-6 in both diabetic and nondiabetic human skeletal muscle cells. The findings suggest that combined preparations of K. pinnata and metformin might be a potential immune-modulating agent that may promote inflammation and adversely affect the outcome of diabetic patients.

Medium composition for effective slow freezing of embryonic cell lines derived from marine medaka (Oryzias dancena)

This study was conducted to identify optimal medium composition for freezing Oryzias dancena embryonic cell lines. Different freezing media consisting of various concentration of dimethyl sulfoxide (DMSO), fetal bovine serum (FBS), and trehalose were prepared and long-term cultured embryonic cell line was frozen in each freezing medium by conventional slow freezing program for 7 days. Through measurement of viability and growth of post-thaw cells frozen in each freezing medium, it was determined that optimal composition of three components was 10 % DMSO, 20 % FBS, and 0.1 M trehalose. The post-thaw cells frozen in optimal freezing medium showed similar morphology and growth rate with non-frozen cells. Next, this condition was applied to two different sets of experiment; (1) freezing of the same cells during expanded period (57 days) and (2) freezing of short-term cultured cells from other batches for 7 days. The viability of post-thaw cells was significantly low and comparable in set 1 and 2, respectively, when compared with the result of long term-cultured cells frozen in optimal freezing medium for 7 days and similar morphology and growth rate with non-frozen counterparts were detected in the post-thaw cells from both sets. In conclusion, this study first reports the optimal medium composition for freezing O. dancena embryonic cells, which can contribute to fish species preservation as well as improvement of cell-based biotechnology by providing stable cell storage.

S100B in myoblasts regulates the transition from activation to quiescence and from quiescence to activation and reduces apoptosis

S100B protein activates IKKβ/NF-κB within myoblasts, thereby inhibiting the expression of MyoD and the MyoD-downstream effectors, myogenin and p21(WAF1), and myoblast differentiation. Herein we show that myoblasts downregulate S100B expression once transferred from proliferation medium to differentiation medium via a p38 MAPK-driven transcriptional mechanism as well as a post-translational, proteasome-dependent mechanism, and that myoblasts that have not been committed to differentiation resume expressing S100B once transferred back to proliferation medium. Likewise, myoblasts downregulate S100B expression once transferred to quiescence medium, and interference with S100B downregulation as obtained by stable overexpression of the protein results in reduced acquisition of quiescence and a faster proliferation upon transfer of the cells from quiescence medium to proliferation medium, compared to controls. These latter effects are dependent on S100B-induced activation of JNK. Moreover, S100B reduces myoblast apoptosis in an MEK-ERK1/2, Akt, JNK, and NF-κB-dependent manner. However, myogenin(+) myoblasts (i.e., myocytes) and myotubes abundantly express S100B likely induced by myogenin. Our results suggest that (1) a timely repression of S100B expression is required for efficient myogenic differentiation; (2) S100B plays an important role in the expansion of the activated (i.e., proliferating) myoblast population; (3) under conditions associated with enhanced expression of S100B, the transition from proliferation to quiescence and from quiescence to proliferation might be altered; and (4) S100B exerts different regulatory effects in myoblasts and myocytes/myotubes/myofibers. This article is part of a Special Issue entitled: 11th European Symposium on Calcium.

The role of stem cells in skeletal and cardiac muscle repair

In postnatal muscle, skeletal muscle precursors (myoblasts) can be derived from satellite cells (reserve cells located on the surface of mature myofibers) or from cells lying beyond the myofiber, e.g., interstitial connective tissue or bone marrow. Both of these classes of cells may have stem cell properties. In addition, the heretical idea that post-mitotic myonuclei lying within mature myofibers might be able to re-form myoblasts or stem cells is examined and related to recent observations for similar post-mitotic cardiomyocytes. In adult hearts (which previously were not considered capable of repair), the role of replicating endogenous cardiomyocytes and the recruitment of other (stem) cells into cardiomyocytes for new cardiac muscle formation has recently attracted much attention. The relative contribution of these various sources of precursor cells in postnatal muscles and the factors that may enhance stem cell participation in the formation of new skeletal and cardiac muscle in vivo are the focus of this review. We concluded that, although many endogenous cell types can be converted to skeletal muscle, the contribution of non-myogenic cells to the formation of new postnatal skeletal muscle in vivo appears to be negligible. Whether the recruitment of such cells to the myogenic lineage can be significantly enhanced by specific inducers and the appropriate microenvironment is a current topic of intense interest. However, dermal fibroblasts appear promising as a realistic alternative source of exogenous myoblasts for transplantation purposes. For heart muscle, experiments showing the participation of bone marrow-derived stem cells and endothelial cells in the repair of damaged cardiac muscle are encouraging.

Long-term viability of cryopreserved cultured epithelial grafts

Human cultured epithelial grafts are frozen for long-term preservation. To assess the viability of these stored grafts, their cell survival rate and colony-forming efficiency of grafts cryopreserved at -135 degrees C and at -80 degrees C were followed over time. Flow cytometry showed that the cell survival rate of the grafts cryopreserved at -135 degrees C for 1 month, 6 months and 1 year averaged 89.3%, 61.7% and 61.6%. Cryopreservation at -80 degrees C maintained cell survival rate as well for 1 month, but after 6 months of cryopreservation survival was reduced at -80 degrees C (35.2%) compared with that of -135 degrees C. In histological examination, the cell structure and basal layer were very well preserved after 6 months of storage at -135 degrees C, but not at -80 degrees C. Cell survival rate at -135 degrees C was also assessed by colony-forming efficiency. Colony-forming efficiency of the grafts cryopreserved for 1 month, 6 months and 1 year averaged 66.1%, 58.5% and 55.1% of control (noncryopreserved) grafts. These findings suggest that, even when cultured epithelial grafts are subjected to long-term cryopreservation, cell viability remains sufficient, reculturing is possible, and that graft banking could be used for clinical applications.

Effects of thiol protease inhibitors on myoblast fusion and myofibril assembly in vitro

To investigate the roles of thiol proteases such as cathepsins and calpains in muscle differentiation, we have treated primary cultures of pectoralis muscle with a variety of protease inhibitors and examined the effects these agents have on myoblast fusion and myofibrillogenesis. We have found that a membrane-permeable inhibitor, E64D, has dramatic effects on both events of muscle differentiation. Cells treated with this inhibitor display gross morphological changes, severe delays in myofibril assembly, and reduced ability to fuse in culture. These morphological changes are correlated with a build up of beta1-integrin throughout the cytoplasm. These effects could also be produced using NH4Cl, a lysosomotrophic agent. In addition, we show that two nonpermeable inhibitors (leupeptin and E64) slightly decrease myoblast fusion, but have no effects on the ability of the cells to form mature myofibrils. These results are discussed in terms of their relevance to the inheritable disease of muscular dystrophy and I-cell disease (mucolipodosis II).

Enhanced expression of the proto-oncogenes fos and raf in the rhabdomyosarcoma cell line BA-HAN-1C after differentiation induction with retinoic acid and N-methylformamide

BA-HAN-IC is a clonal rat rhabdomyosarcoma cell line consisting of proliferating mononuclear tumor cells, some of which spontaneously fuse to form terminally differentiated post-mitotic myotubes. Exposure of BA-HAN-IC cells to retinoic acid (RA) or N-methylformamide (NMF) resulted in a significant inhibition of proliferation (p less than 0.001) and in cellular differentiation, as evidenced by a significant increase in the creatine kinase (CK) activity (p less than 0.05) and the number of terminally differentiated post-mitotic myotubes (p less than 0.001). Furthermore, between 5% (NMF) and 30% (RA) of the mononuclear tumor cells exhibited ultrastructural features of rhabdomyogenic differentiation, not observed in their mononuclear counterparts under standard growth conditions. Although BA-HAN-IC cells responded to both inducers of differentiation, differences in time course and magnitude of both increase of differentiation and growth inhibition were observed. These effects of RA and NMF were preceded by a marked enhancement of c-raf expression which became evident 6 and 12 hr after exposure to RA and NMF, respectively, and which persisted throughout the observation period of 5 days. Furthermore, a transient expression of c-fos could be observed 15 and 30 min after exposure to RA. Our results suggest that c-raf expression might be implicated in the differentiation process of BA-HAN-IC tumor cells.

Heterogeneous response to differentiation induction with different polar compounds in a clonal rat rhabdomyosarcoma cell line (BA-HAN-1C)

The clonal rat rhabdomyosarcoma cell line BA-HAN-1C was tested for its susceptibility to differentiation induction with different polar compounds. This cell line is composed of proliferating mononuclear tumour cells, some of which spontaneously fuse to form terminally differentiated postmitotic myotube-like giant cells. Exposure of BA-HAN-1C cells to dimethylsulphoxide (DMSO), hexamethylene bisacetamide (HMBA), sodium butyrate (NaBut) and N-monomethylformamide (NMF) resulted in a significant inhibition of proliferation (P less than 0.001) and in a simultaneous increase in differentiation. The response was most pronounced after exposure to NMF as evidenced by a marked increase in the creatine kinase activity used as a biochemical marker of differentiation (P less than 0.05) and the number of terminally differentiated myotube-like giant cells (P less than 0.001). Furthermore, about 5% of the mononuclear cells exhibited thick and thin myofilaments which were never observed in the mononuclear cells of the control. In contrast, the effects of DMSO, HMBA and NaBut were exclusively confined to a significant increase in biochemical differentiation (P less than 0.05), whereas no increase in morphological differentiation was observed and the number of myotube-like giant cells even significantly (P less than 0.001) decreased. This heterogeneous response to differentiation induction with different polar compounds probably indicates different mechanisms of action and suggests that the induction of biochemical differentiation might be independently regulated from events leading to cell fusion and terminal differentiation.

Poly-L-methionine sulfoxide: a biologically inert analogue of dimethyl sulfoxide with solubilizing potency

Poly-L-methionine sulfoxide is a water-soluble polymer containing the sulfoxide moiety. The preparation and radiolabeling of this polymer is described and its bioeffects are compared with those of dimethyl sulfoxide. Poly-L-methionine sulfoxide is similar to dimethyl sulfoxide in that it is a potent solubilizer of lipophilic compounds in water. Although the partition coefficient of poly-L-methionine sulfoxide in 1-octanol-water is only 20 times lower than that of dimethyl sulfoxide, it was found not to penetrate into intracellular spaces. In contrast to dimethyl sulfoxide, poly-L-methionine sulfoxide and L-methionine sulfoxide were found to be ineffective in inducing differentiation in murine erythroleukemia cells and inhibiting differentiation of avian neural crest cells, suggesting that compounds effective in these processes must have the ability to penetrate into cells or membrane proteins. Overall lack of bioactivity of poly-L-methionine sulfoxide, combined with low toxicity (2 g/kg, iv, in the mouse with no effect), makes this compound a suitable inert solubilizer and carrier for lipophilic drugs.

Derepression of genes on the human inactive X chromosome: evidence for differences in locus-specific rates of derepression and rates of transfer of active and inactive genes after DNA-mediated transformation

Mouse-human hybrid cells that contained an inactive human X chromosome were treated with agents known to alter gene expression and to perturb DNA methylation. 5-Azacytidine greatly increased the rate of derepression of HPRT on the inactive X, while butyrate and dimethyl sulfoxide had smaller effects. Ethionine did not change the rate of derepression. Derepression of two other X-chromosomal loci, PGK and GPD, was also detected. The rate of derepression of PGK was 20-fold higher than the rate for HPRT. Derepression events at the two loci appeared to be independent. Hybrids expressing derepressed X-chromosomal genes had more variable levels of human enzyme activities when compared to control hybrids. HPRT+ clones did not appear after transfer of purified DNA from a cell hybrid containing an inactive human X into HPRT- recipients, but such clones did appear after transfer of DNA from derivative cells in which HPRT had been derepressed.

Detection of teratogens by differentiating embryonic neural crest cells in culture: evaluation as a screening system

We have tested the effects of teratogenic and nonteratogenic compounds on cultures of differentiating embryonic neural crest cells. Compounds were evaluated for their effects on the growth or differentiation of the cells based on morphologic criteria or on quantitative changes in biochemical markers for the differentiated cells. When metabolic activation may be required, compounds were incubated in the cultures in the presence of the postmitochondrial supernatant fraction of rat liver microsomes. Nine of 11 compounds with proven teratogenic effects in vivo induced readily detectable morphologic changes in differentiating cultures. In contrast, none of the nonteratogenic compounds tested had an effect on these cultures. The use of differentiating cell cultures as a screening system for teratogens is discussed.

Induction by butyrate of differentiated properties in cloned murine rhabdomyosarcoma cells

A cell line derived from the murine rhabdomyosarcoma BW10139 (Dexter, Cancer Res. 37: 3136, 1977) was subcloned and examined with respect to growth and myogenic characteristics in the presence and absence of 1 mM butyrate. Without butyrate, these cells behave as typical transformed cells: they grow rapidly and chaotically, do not form multinucleated muscle fibers and have little or no creatine kinase activity. In the presence of 1 mM sodium butyrate or butyric acid, growth slows, cells become arranged in whorl patterns, and creatine kinase activities increase to levels comparable to those found in normal chick myoblasts immediately prior to cell fusion. The increase in creatine kinase activity is detectable within 2 h exposure to butyrate, reaches a maximum by 24 h, and the elevated level can be maintained for at least six weeks. The induction is reversible upon sequential addition, deletion, and readdition of butyrate to the culture medium. Isoenzyme analyses demonstrated that only the BB form of creatine kinase is induced; MM creatine kinase was not detected. Although formation of multinucleated cells increases after exposure to butyrate, no typical myotubes form. The results suggest that this rhabdomyosarcoma cell line can, under appropriate conditions, re-express some properties characteristic of skeletal muscle, but not the complete muscle phenotype.

Effects of sodium butyrate and dimethylsulfoxide on biochemical properties of human colon cancer cells

Sodium butyrate and dimethylsulfoxide (DMSO) have marked effects on the growth, morphology, and biochemistry of two human colonic adenocarcinoma cell lines in culture. Doubling times were increased between 18% and 660% while cell viability was unaffected. Both cell lines formed colonies in soft agar in the absence of butyrate of DMSO, but no colonies were observed in the presence of these agents. However, no differences in in vivo tumorigenicities, when cells were implanted in athymic mice, were seen following treatment. Gross morphological alterations including cell enlargement, process formation, and cellular flattening occurred during culture in butyrate or DMSO. Acrylamide gel electrophoresis in sodium dodecyl sulfate revealed no change in membrane protein constituents, but autoradiographic analysis of membrane glycoproteins demonstrated differences between treated and untreated cells. Ganglioside compositions were altered, and a sialyltransferase required for the synthesis of GM3 ganglioside was elevated by butyrate. Although cytoplasmic aminooligopeptidase remained unaffected by butyrate or DMSO, brush border-associated activity was enhanced by butyrate. Alkaline phosphatase also rose dramiatically during culture in butyrate but was not enhanced by DMSO.