CKMT1A is a novel potential prognostic biomarker in patients with endometrial cancer.

PURPOSE: The International Federation of Gynecology and Obstetrics (FIGO) stage remains the standard staging system for the assessment of endometrial cancer (EC) prognosis. Thus, we aim to identify the significant genes or biomarkers associated with the stage of endometrial cancer, which may also help reveal the mechanism of EC progression and assess the prognosis of patients with EC. MATERIALS AND METHODS: We compared the mRNA expression levels of EC patients with stages I and II as well as stages III and IV in the Cancer Genome Atlas (TCGA) database. The differentially expressed genes (DEGs) of EC patients at different stages were selected by volcano plot and Venn analysis. Gene Ontology (GO) and Pathways were applied to analyze the identified genes. Protein protein interaction (PPI) network was employed to identify the correlation. The survival analyses based on TCGA database were conducted for further screening. The Human Protein Atlas, quantitative PCR and immunohistochemistry were utilized to confirm the differences in expression of DEGs in endometrial cancer samples at different FIGO stages. RESULTS: CKMT1A was identified as a candidate gene. Through survival analyses, we found that CKMT1A may be a poor prognostic factor in the overall survival of endometrial cancer patients. GO and Pathways revealed that CKMT1A is closely associated with the metabolic process. More importantly, Human Protein Atlas and quantitative PCR confirmed the differences in expression of CKMT1A in endometrial cancer samples at different FIGO stages. CONCLUSION: In summary, this study shows that CKMT1A is a newly identified essential tumor progression regulator of endometrial cancer, which may give rise to novel therapeutic strategies in the management of endometrial cancer patients to prolong its prognosis and prevent tumor progression.

Mitochondrial creatine kinase 1 in non-small cell lung cancer progression and hypoxia adaptation.

BACKGROUND: Hypoxia is a prominent feature of solid cancer. This research aims to expose the role of mitochondrial creatine kinase 1 (CKMT1) in non-small cell lung cancer (NSCLC) progression and hypoxia adaptation. METHODS: The mRNA and protein expression of CKMT1 in NSCLC tissues were detected by using GEPIA web, immunohistochemistry and qRT-PCR. For hypoxia, cells were exposed to the 1% O2 atmosphere. The protein levels of HIF-1α and CKMT1 in H1650 and H1299 cells exposed to hypoxia were determined by western blot. The roles of CKMT1 on the proliferation, invasion and hypoxia adaptation of NSCLC cells were measured by CCK8, colony formation and transwell assays. Luciferase activity assay and HIF1 specific inhibitor (LW6) assay indicated the related function of hypoxia and CKMT1. RESULTS: CKMT1 was highly expressed in NSCLC tissues, and the high level of CKMT1 was significantly correlated with the high pathological grade of NSCLC. Knockdown of CKMT1 inhibited the cell proliferation and invasion of H1650 and H1299 cells, which could be rescued by hypoxia. Hypoxia induced the accumulation of HIF-1α and the expression of CKMT1 in H1650 and H1299 cells. Furthermore, HIF-1 as a transcription factor of CKMT1, could up-regulated the expression of CKMT1 under hypoxia. CONCLUSIONS: In summary, CKMT1 has the potential as a target for NSCLC hypoxic targeted therapy.

Improved Production of Highly Active and Pure Human Creatine Kinase MB.

Human creatine kinase MB (hCKMB) is one of the most preferred biomarkers used for the diagnosis of acute coronary syndrome due to its high sensitivity and specificity. The increasing need for highly purified and biologically active hCKMB in the field of diagnostics makes its production valuable. Currently, the production of hCKMB is mainly achieved in methylotrophic yeast, Pichia pastoris, because the production in Escherichia coli is challenging and generally yields an inactive enzyme with a low quantity. With the aim of finding the best way for the high-yield production of active hCKMB in E. coli, an efficient strategy was developed using a construct allowing tandem expression of each subunit with 2 different tags. The strategy allowed the efficient expression and separate characterization of each subunit and 1-step purification of the heterodimeric protein into homogeneity. The heterodimeric protein displayed more than 11-fold greater specific activity than the commercially available one. The production strategy described in this study shows a clear advantage over the currently used ones and can be made available not only for laboratory scale production but also for commercial production. Our study is also a well-suited example for the studies in which novel protein expression strategies are needed to achieve greater yields with higher purities.

Efficacy of Compression Garments on Recovery From a Simulated Rugby Protocol.

Upton, CM, Brown, FC, and Hill, JA. Efficacy of compression garments on recovery from a simulated rugby protocol. J Strength Cond Res 31(11): 2977-2982, 2017-The aim of this study was to examine the efficacy of lower limb compression garments on recovery in club-level rugby players. Nineteen participants (age, 20.3 ± 1.7 years, height, 184.2 ± 7.5 cm, and body mass, 89.5 ± 9.9 kg) completed a rugby-specific, muscle-damaging protocol before being assigned to a compression garment group (n = 10) or a SHAM ("recovery" drink) treatment (n = 9). The compression group wore the garments for 48 hours after exercise, whereas SHAM consumed a sweetened, low energy drink within an hour of protocol completion. Perceived muscle soreness (PMS), creatine kinase (CK), maximal voluntary isometric contraction (MVIC), and countermovement jump (CMJ) height were measured at baseline, post, 24, and 48 hours after exercise. Perceived muscle soreness was significantly lower in the compression group compared with the SHAM group at both 24 and 48 hours after exercise (p ≤ 0.05). The compression group was also subject to lower CK values than SHAM, as demonstrated by a significant time by group effect (p ≤ 0.05). There was no significant group effect for MVIC or CMJ (p > 0.05). Wearing compression garments after a rugby-specific, muscle-damaging protocol seems to reduce PMS and circulating concentrations of CK, suggesting improved recovery from muscle-damaging exercise.

Decreased creatine kinase is linked to diastolic dysfunction in rats with right heart failure induced by pulmonary artery hypertension.

Our objective was to investigate the role of creatine kinase in the contractile dysfunction of right ventricular failure caused by pulmonary artery hypertension. Pulmonary artery hypertension and right ventricular failure were induced in rats by monocrotaline and compared to saline-injected control animals. In vivo right ventricular diastolic pressure-volume relationships were measured in anesthetized animals; diastolic force-length relationships in single enzymatically dissociated myocytes and myocardial creatine kinase levels by Western blot. We observed diastolic dysfunction in right ventricular failure indicated by significantly steeper diastolic pressure-volume relationships in vivo and diastolic force-length relationships in single myocytes. There was a significant reduction in creatine kinase protein expression in failing right ventricle. Dysfunction also manifested as a shorter diastolic sarcomere length in failing myocytes. This was associated with a Ca(2+)-independent mechanism that was sensitive to cross-bridge cycling inhibition. In saponin-skinned failing myocytes, addition of exogenous creatine kinase significantly lengthened sarcomeres, while in intact healthy myocytes, inhibition of creatine kinase significantly shortened sarcomeres. Creatine kinase inhibition also changed the relatively flat contraction amplitude-stimulation frequency relationship of healthy myocytes into a steeply negative, failing phenotype. Decreased creatine kinase expression leads to diastolic dysfunction. We propose that this is via local reduction in ATP:ADP ratio and thus to Ca(2+)-independent force production and diastolic sarcomere shortening. Creatine kinase inhibition also mimics a definitive characteristic of heart failure, the inability to respond to increased demand. Novel therapies for pulmonary artery hypertension are needed. Our data suggest that cardiac energetics would be a potential ventricular therapeutic target.

Brain high-energy phosphates and creatine kinase synthesis rate under graded isoflurane anesthesia: An in vivo (31) P magnetization transfer study at 11.7 tesla.

PURPOSE: The creatine kinase rate of metabolic adenosine triphosphate (ATP) synthesis is an important metabolic parameter but is challenging to measure in vivo due to limited signal-to-noise ratio and long measurement time. THEORY AND METHODS: This study reports the implementation of an accelerated (31) P Four Angle Saturation Transfer (FAST) method to measure the forward creatine kinase (CK) rate of ATP synthesis. Along with a high-field scanner (11.7 Tesla) and a small sensitive surface coil, the forward CK rate in the rat brain was measured in ∼5 min. RESULTS: Under 1.2% isoflurane, the forward CK rate constant and metabolic flux were, respectively, kf , CK =0.26 ± 0.02 s(-1) and Ff,CK =70.8 ± 4.6 µmol/g/min. As a demonstration of utility and sensitivity, measurements were made under graded isoflurane. Under 2.0% isoflurane, kf , CK =0.16 ± 0.02 s(-1) and Ff,CK =410.0 ± 4.2 µmol/g/min, corresponding to a 38% and 42% reduction, respectively, relative to 1.2% isoflurane. By contrast, the ATP and phosphocreatine concentrations were unaltered. CONCLUSION: This study demonstrated the (31) P FAST measurement of creatine kinase rate of ATP synthesis in rat brain with reasonable temporal resolution. Different isoflurane levels commonly used in animal models significantly alter the CK reaction rate but not ATP and phosphocreatine concentrations.

Transverse myelitis associated with an itchy rash and hyperckemia: neuromyelitis optica associated with dermatitis herpetiformis.

IMPORTANCE: Neuromyelitis optica is associated with severe neurodisability if not recognized and treated promptly. Several autoimmune disorders are associated with this condition and may vary in their presentation. It is essential that clinicians are aware of the uncommon presenting features of neuromyelitis optica and associated autoimmune conditions. OBSERVATIONS: A 53-year-old woman presented with nausea and vomiting and was noted to have an asymptomatic elevated creatinine kinase level, which improved with conservative management. She had a history of iron-deficiency anemia due to long-standing celiac disease that was managed with a gluten-free diet. She then presented with recurrent transverse myelitis and a vesicobullous rash over her arms and feet that was pruritic and excoriating. Skin biopsy results confirmed a clinical diagnosis of dermatitis herpetiformis and antibody test findings against aquaporin-4 were positive, leading to a diagnosis of neuromyelitis optica spectrum disorder. She was treated with methylprednisolone sodium succinate, plasma exchange, and azathioprine and has remained in remission. CONCLUSIONS AND RELEVANCE: This report highlights the association of neuromyelitis optica with dermatitis herpetiformis, which can present even without clinical features of celiac disease. Nausea, vomiting, and asymptomatic hyperCKemia should be recognized as rare presenting features of neuromyelitis optica.

Anti-inflammatory effect of exendin-4 postconditioning during myocardial ischemia and reperfusion.

High mobility group box 1 protein (HMGB1) plays an important role in myocardial ischemia and reperfusion (I/R) injury. Preconditioning of exendin-4 (Ex), a glucagon-like peptide-1 receptor agonist, has been reported to attenuate myocardial I/R injury. The current study investigated whether Ex postconditioning also attenuated myocardial I/R injury and the potential mechanisms. Anesthetized male rats were subjected to ischemia for 30 min and treated with Ex (5 µg/kg, i.v.) 5 min before reperfusion, in the absence and/or presence of exendin (9-39) (an antagonist of glucagon-like peptide-1 receptor, 5 µg/kg, i.v.), followed by reperfusion for 4 h. Lactate dehydrogenase (LDH), creatine kinase (CK), tumor necrosis factor-α, interleukin-6, and infarct size were measured. HMGB1 expression was assessed by immunoblotting. Postconditioning with Ex significantly decreased infarct size and levels of LDH and CK after 4 h reperfusion (all p < 0.05). Ex also significantly inhibited the increase in malondialdehyde level and decreased the level of superoxide dismutase (both p < 0.05). In addition, the increase in HMGB1 expression induced by I/R was significantly attenuated by Ex postconditioning. Administration of exendin (9-39) abolished the protective effect of Ex postconditioning (all p < 0.05). The present study suggests that Ex postconditioning may attenuate myocardial I/R injury, which may in turn be associated with inhibiting inflammation.

Chronic hypoxia enhances expression and activity of mitochondrial creatine kinase and hexokinase in the rat ventricular myocardium.

BACKGROUND: Creatine kinase (CK) and hexokinase (HK) play a key role in myocardial energy homeostasis. We aimed to determine CK and HK expression and enzyme activity in the left (LV) and right (RV) ventricles of rats adapted for 3 weeks to normobaric hypoxia (10 % O2) either continuously (CNH) or intermittently with 1-h or 16-h normoxic episode per day. METHODS: The Real-Time RT-PCR, Western blot, and enzyme-coupled assays were used. In addition, the effect of CNH on the HK co-localization with mitochondria, which can inhibit apoptosis, was assessed using immunofluorescence techniques. RESULTS: CK and HK activities increased in the LV during all hypoxic adaptations, which was consistent with elevated protein levels of mitochondrial mtCKs, cytosolic CKB, HK1, and HK2 isoforms. Enzyme activities also increased in the hypoxic RV, but only CKB protein was elevated. No effect of CNH on HK1 or HK2 co-localization with mitochondria was observed. CONCLUSION: Up-regulation of mtCKs and HK isoforms may stimulate the respiratory chain and help to maintain energy homeostasis of chronically hypoxic myocardium and prevent oxidative stress. In this way, CK and HK enzymes can possibly participate in the establishment of ischemia-resistant phenotype of chronically hypoxic hearts.

Resistance artery creatine kinase mRNA and blood pressure in humans.

Hypertension remains the main risk factor for cardiovascular death. Environmental and biological factors are known to contribute to the condition, and circulating creatine kinase was reported to be the main predictor of blood pressure in the general population. This was proposed to be because of high resistance artery creatine kinase-BB rapidly regenerating ATP for vascular contractility. Therefore, we assessed whether creatine kinase isoenzyme mRNA levels in human resistance arteries are associated with blood pressure. We isolated resistance-sized arteries from omental fat donated by consecutive women undergoing uterine fibroid surgery. Blood pressure was measured in the sitting position. Vessels of 13 women were included, 6 normotensive and 7 hypertensive, mean age 42.9 years (SE, 1.6) and mean systolic/diastolic blood pressure, 144.8 (8.0)/86.5 (4.3) mm Hg. Arteriolar creatine kinase isoenzyme mRNA was assessed using quantitative real-time polymerase chain reaction. Normalized creatine kinase B mRNA copy numbers, ranging from 5.2 to 24.4 (mean, 15.0; SE, 1.9), showed a near-perfect correlation with diastolic blood pressure (correlation coefficient, 0.9; 95% confidence interval, 0.6-1.0) and were well correlated with systolic blood pressure, with a 90% relative increase in resistance artery creatine kinase B mRNA in hypertensives compared with normotensives, normalized copy numbers were, respectively, 19.3 (SE, 2.0) versus 10.1 (SE, 2.1), P=0.0045. To our knowledge, this is the first direct evidence suggesting that resistance artery creatine kinase mRNA expression levels concur with blood pressure levels, almost doubling with hypertension. These findings add to the evidence that creatine kinase might be involved in the vasculature's pressor responses.

Knockdown of creatine kinase B inhibits ovarian cancer progression by decreasing glycolysis.

Creatine kinase plays a key role in the energy homeostasis of vertebrate cells. Creatine kinase B (CKB), a cytosolic isoform of creatine kinase, shows upregulated expression in a variety of cancers. In this research, we confirmed that some ovarian cancer tissues had elevated CKB expression at the protein level. The functions of CKB in ovarian cancer progression were investigated in the ovarian cancer cell line Skov3, which has a high CKB expression. It was found that CKB knockdown inhibited Skov3 cell proliferation and induced apoptosis under hypoxia or hypoglycemia conditions. CKB depletion also sensitized Skov3 to chemotherapeutic agents. Furthermore, the CKB knockdown reduced glucose consumption and lactate production, and increased ROS production and oxygen consumption. This suggested that CKB knockdown decreased cytosolic glycolysis and resulted in a tumor suppressive metabolic state in Skov3 cells. Consequently, we found that the knockdown of CKB induced G2 arrest in cell cycle by elevating p21 expression and affected the PI3K/Akt and AMPK pathways. These findings provide new insights in the role of CKB in cancer cell survival and tumor progression. Our results also suggest that CKB depletion/inhibition in combination with chemotherapeutic agents might have synergistic effects in ovarian cancer therapy.

Expression and localization of creatine kinase in the preimplantation embryo.

Creatine Kinase (CK) catalyses the "creatine shuttle," the reversible conversion of creatine phosphate to creatine with the liberation of ATP. This article examines the potential role of the creatine shuttle in the provision of ATP during mouse preimplantation embryo development. Using quantitative PCR, transcripts of four subunit isoforms of CK--CKM, CKB, CKMT1, and CKMT2--were detectable at all developmental stages, from the presumptive zygote to late blastocyst, but there was no obvious pattern in gene expression. By contrast, total CK biochemical activity, measured by a novel method, was relatively constant from the 2- to 8-cell stage, before exhibiting a significant decrease in activity at the blastocyst stage. Immunocytochemical studies revealed a marked association of CKB with the mitotic spindle in 2- and 4-cell mouse embryos, consistent with the proposition that the creatine shuttle plays a key role in local delivery of ATP during cytokinesis. Endogenous creatine was detected in the blastocyst at a level of 0.53 pmol/embryo. In conclusion, we believe that creatine phosphate can now be added to the list of potential sources of ATP during preimplantation development.

Acute pathophysiological influences of conducted electrical weapons in humans: A review of current literature.

Conducted electrical weapons (CEWs) deliver short high-voltage, low current energy pulses to temporarily paralyze a person by causing muscular contraction. The narrative of this article is a methodical analysis on acute pathophysiological changes within the central nervous system, cardiovascular, neuroendocrine, sympatho-adrenergic and muskuloskeletal system which can occur after application of conducted electrical weapons on human subjects. The results are based on wide-ranging literature analysis and source studies. The majority of the recent scientific publications on humans classify the health risks of an appropriate use of the CEWs device as minor. However, there still is an uncertainty about possible side-effects of these devices. Therefore medical supervision with human application is advised.

Effects of creatine and ß-guanidinopropionic acid and alterations in creatine transporter and creatine kinases expression in acute seizure and chronic epilepsy models.

BACKGROUND: In order to confirm the roles of creatine (Cr) in epilepsy, we investigated the anti-convulsive effects of Cr, creatine transporter (CRT) and creatine kinases (CKs) against chemical-induced acute seizure activity and chronic epileptic seizure activity. RESULTS: Two hr after pilocarpine (PILO)-seizure induction, ubiquitous mitochondrial CK (uMtCK) immunoreactivity was unaltered as compared to control level. However, brain-type cytoplasm CK (BCK) immunoreactivity was decreased to 70% of control level. CRT immunoreactivity was decreased to 60% of control level. Following Cr or Tat-CK treatment, uMtCK or CRT immunoreactivity was unaffected, while BCK immunoreactivity in Cr treated group was increased to 3.6-fold of control levels. ß-Guanidinopropionic acid (GPA, a competitive CRT inhibitor) reduced BCK and CRT expression. In addition, Cr and tat-BCK treatment delayed the beginning of seizure activity after PILO injection. However, GPA treatment induced spontaneous seizure activity without PILO treatment. In chronic epilepsy rats, both uMtCK and CRT immunoreactivities were reduced in the hippocampus. In contrast, BCK immunoreactivity was similar to that observed in control animals. Cr-, GPA and tat-BCK treatment could not change EEG. CONCLUSION: Cr/CK circuit may play an important role in sustaining or exacerbating acute seizure activity, but not chronic epileptic discharge.

Temporal changes in circulating P-selectin, plasminogen activator inhibitor-1, magnesium, and creatine kinase after percutaneous coronary intervention.

OBJECTIVE: This study aims to determine the mechanisms underlying restenosis and ischemia-reperfusion injury of the myocardium after percutaneous coronary intervention (PCI). METHODS: The present study examined serial changes (5 min, 30 min, 2 h, 6 h, and 24 h after PCI) in circulating P-selectin, plasminogen activator inhibitor-1 (PAI-1), magnesium (Mg), and creatine kinase-myocardial band fraction (CK-MB) levels, which may be associated with restenosis and myocardial injury in patients undergoing PCI. The occurrence rates of major adverse cardiovascular events were collected over a six-month follow-up. RESULTS: PCI induced an early elevation of P-selectin, which correlated positively with the inflation pressure used in the PCI procedure. PCI also caused a significant and sustained decrease in serum Mg in PCI patients, without an effect on PAI-1. An increase in CK-MB was observed in PCI patients, although values were within normal reference range. In addition, elevated P-selectin and decreased Mg measured shortly after the coronary angioplasty procedure were associated with recurrent treatment and heart failure, respectively. CONCLUSIONS: Our study demonstrates that PCI induces temporal changes of P-selectin, Mg, and CK-MB, which may be involved in restenosis and ischemia-reperfusion injury. These findings highlight the need for using antiplatelet therapy and Mg to reduce the risks associated with PCI.

AAV-1-mediated gene transfer to skeletal muscle in humans results in dose-dependent activation of capsid-specific T cells.

In a clinical trial for adeno-associated virus serotype 1 (AAV-1)-mediated gene transfer to muscle for lipoprotein lipase (LPL) deficiency, 1 subject from the high-dose cohort experienced a transient increase in the muscle enzyme creatine phosphokinase (CPK) 4 weeks after gene transfer. Simultaneously, after an initial downward trend consistent with expression of LPL, plasma triglyceride levels returned to baseline. We characterized B- and T-cell responses to the vector and the transgene product in the subjects enrolled in this study. IFN-gamma enzyme-linked immunosorbent spot (ELISpot) and intracellular cytokine staining assays performed on peripheral blood mononuclear cells (PBMCs) from the subject who experienced the CPK elevation showed the activation of capsid-specific CD4(+) and CD8(+) T cells. Four of 8 subjects had detectable T-cell responses to capsid with dose-dependent kinetics of appearance. Subjects with detectable T-cell responses to capsid also had higher anti-AAV-1 IgG3 antibody titer. No subject developed B- or T-cell responses to the LPL transgene product. These findings suggest that T-cell responses directed to the AAV-1 capsid are dose-dependent. Whether they also limit the duration of expression of the transgene at higher doses is unclear, and will require additional analyses at later time points.

The role of Arg-96 in Danio rerio creatine kinase in substrate recognition and active center configuration.

In creatine kinases (CKs), the amino acid residue-96 is a strictly conserved arginine. This residue is not directly associated with substrate binding, but it is located close to the binding site of the substrate creatine. On the other hand, the residue-96 is known to be involved in expression in the substrate specificity of various other phosphagen (guanidino) kinases, since each enzyme has a specific residue at this position: arginine kinase (Tyr), glycocyamine kinase (Ile), taurocyamine kinase (His) and lombricine kinase (Lys). To gain a greater understanding of the role of residue-96 in CKs, we replaced this residue in zebra fish Danio rerio cytoplasmic CK with other 19 amino acids, and expressed these constructs in Escherichia coli. All the twenty recombinant enzymes, including the wild-type, were obtained as soluble form, and their activities were determined in the forward direction. Compared with the activity of wild-type, the R96K mutant showed significant activity (8.3% to the wild-type), but 10 mutants (R96Y, A, S, E, H, T, F, C, V and N) showed a weak activity (0.056-1.0%). In the remaining mutants (R96Q, G, M, P, L, W, D and I), the activity was less than 0.05%. Our mutagenesis studies indicated that Arg-96 in Danio CK can be substituted for partially by Lys, but other replacements caused remarkable loss of activity. From careful inspection of the crystal structures (transition state analog complex (TSAC) and open state) of Torpedo cytoplasmic CK, we found that the side chain of R96 forms hydrogen bonds with A339 and D340 only in the TSAC structure. Based on the assumption that CKs consist of four dynamic domains (domains 1-3, and fixed domain), the above hydrogen bonds act to link putative domains 1 and 3 in TSAC structure. We suggest that residue-96 in CK and equivalent residues in other phosphagen kinases, which are structurally similar, have dual roles: (1) one involves in distinguishing guanidino substrates, and (2) the other plays a key role in organizing the hydrogen-bond network around residue-96 which offers an appropriate active center for the high catalytic turnover. The mode of development of the network appears to be unique each phosphagen kinase, reflecting evolution of each enzyme.

[Effect of IGF-1 on proliferation and differentiation of primary human embryonic myoblasts].

OBJECTIVE: To investigate the effect of IGF-1 on the growth of primary human embryonic myoblasts. METHODS: The method of incorporation of 3H-TdR was used to evaluate the ability of proliferation of myoblasts. The count per minute (CPM) values of myoblasts at different concentrations (1, 2, 4, 8, 16 and 32 ng/mL) of IGF-1 were measured, and dose-effect curves were drawn to choose the optional concentration of IGF-1 to promote the proliferation. Then the experimental group of myoblasts received the addition of the optional concentration of IGF-1 in the growth medium, the control group just received the growth medium. The flow cytometry was used to detect the cell cycle. The method of incorporation of 3H-TdR was used to measure the peak-CPM. The myotube fusion rate was measured in myoblasts withdifferent concentrations (0, 5, 10, 15, 20, 25 and 30 ng/mL) of IGF-1 in fusion medium, the dose-effect curves were also drawn, so as to decided the optional concentration of IGF-1 in stimulating differentiation. Fusion medium with optional concentration of IGF-1 was used in experimental group, and the control group just with fusion medium. The fusion rate of myotube and the synthesis of creatine kinase (CK) were detected in both groups. RESULTS: The optional concentration of 5 ng/mL IGF-1 was chosen for stimulating proliferation. It was shown that the time of cell cycle of control was 96 hours, but that of the experimental group was reduced to 60 hours. The results of flow cytometry showed that the time of G1 phase, S phase and G2M phase was 70.03, 25.01 and 0.96 hours respectively in control group, and were 22.66, 16.47 and 20.87 hours respectively in experimental group. The time-CPM value curves showed that the peak-CPM emerged at 96 hours in control group and 48 hours in experimental group, whichwas in agreement with the results of the flow cytometry. The optional concentration stimulating proliferation was 20 ng/mL IGF-1. Compared with control, the quantity of CK was increased by 2,000 mU/mL and the fusion rate was elevated by 30% in experimental group. CONCLUSION: The concentrations of 20 ng/mL IGF-1 can elevat obviously the fusion rate and the quantity of CK. IGF-1 can enhance the proliferation and differentiation of myoblasts via inducing the number of myoblasts at G1 phase and increasing the number of myoblasts at S and G2M phases.

The influence of serum-free culture conditions on skeletal muscle differentiation in a tissue-engineered model.

The influence of differentiation medium (DM) components on C2C12 murine myoblast differentiation has only been studied in monolayer cultures. Serum-free formulations have been applied that omit the use of sera with unknown composition. The goal of the present study was to compare the influence of serum-free media on C2C12 differentiation in 3-dimensional tissue-engineered muscle constructs. Myoblast proliferation and differentiation in media containing Ultroser G (DMU), insulin-like growth factor (IGF)-I (DMI), or both (DMUI) were compared with those induced by more-traditional media containing horse serum (HS) or horse serum and IGF-I (HSI). Effects of the applied media were assessed from gross construct morphology, total protein content, creatine kinase activity, and tissue viability. Addition of IGF-I (HSI) to the standard DM (HS) improved myoblast differentiation in muscle constructs. Even better results were obtained using DMU and DMUI culture conditions. DMI could not induce differentiation or maintain cell viability. Serum-free culture medium supplemented with DMU or DMUI accelerates and improves myoblast differentiation in engineered muscle tissue better than the gold standard HS.