高表达FoxO1抑制猪骨骼肌成肌细胞的分化

FoxO1(Forkhead box O1)是调控肌肉生长、代谢和细胞分化的重要转录因子,但其在成肌细胞分化中的作用还不甚清楚。为了研究FoxO1对哺乳动物成肌细胞分化的影响,以原代培养的长白仔猪成肌细胞作为实验材料,用2%马血清诱导分化,采用实时荧光定量PCR、Western blotting和脂质体转染等方法检测FoxO1及早期和晚期生肌调节因子MyoD和myogenin在猪成肌细胞分化过程中的表达变化。结果显示,在猪成肌细胞分化过程中,FoxO1mRNA表达量显著增加,但总蛋白量变化不显著,其磷酸化水平显著上调。同时,高表达FoxO1的猪成肌细胞中,生肌调节因子MyoD和myogenin mRNA表达受到显著抑制,而MyoD蛋白变化不显著,myogenin却显著下调(P0.05)。以上结果表明,FoxO1能够推迟猪成肌细胞的分化时间并抑制分化;同时推测,FoxO1可能通过抑制生肌调节因子的表达控制骨骼肌纤维类型的终末分化。     

重组肌肉抑制素功能分析及其对鸡肌肉发育的抑制作用

肌肉抑制素 (myostatin)为TGF β超家族成员 ,具有典型的TGF β家族成员特有的分子结构与功能。为了深入阐明肌肉抑制素的作用机制 ,研究了重组肌肉抑制素蛋白对鸡胚成肌细胞和小鼠C2 C1 2 成肌细胞增殖与分化的作用 ,同时制备了肌肉抑制素特异性抗体。实验结果表明 ,重组肌肉抑制素对于成肌细胞的增殖过程具有极强的抑制作用 ,主要表现为抑制细胞周期由G1 期向S期的过渡 ,细胞生长速度显著变慢 ;同时重组肌肉抑制素也抑制成肌细胞分化为多核的融合肌管细胞 ,抑制肌肉分化标志myogenin和MHC的表达。由重组蛋白质制备的抗体能够特异性地识别人、小鼠、大鼠和鸡肌肉组织的内源肌肉抑制素。此外 ,通过免疫荧光技术还证实 ,肌肉抑制素主要定位于胞液中     

外源性瘦素通过丝裂素活化蛋白激酶抑制猪骨骼肌成肌细胞分化

研究瘦素(leptin)对猪骨骼肌成肌细胞分化的影响, 并探讨其可能的作用机制。原代培养猪骨骼肌成肌细胞, 通过倒置显微镜定性观察细胞分化的形态学变化; 肌酸激酶(CK)活性测定法定量分析成肌细胞分化程度; 细胞免疫化学方法分析myogenin的表达情况; 免疫印迹技术(Western Blot)检测丝裂素活化蛋白激酶(mitogen activated protein kinase, MAPK)的表达变化。结果显示, 在猪骨骼肌成肌细胞分化过程中, 外源性leptin减少细胞核融合和肌管形成, 呈浓度和时间依赖性地显著降低CK活性( P < 0.05), 并显著抑制myogenin和MAPK的蛋白表达( P < 0.05)。以上结果说明, leptin抑制猪骨骼肌成肌细胞分化, 并且这种作用可能是通过激活MAPK 信号转导通路实现的。研究结果显示, leptin在骨骼肌成肌细胞分化过程中可能具有重要作用。     

TNF-α通过ERK和MAPK信号途径抑制猪骨骼肌成肌细胞分化

研究肿瘤坏死因子α(TNFα-)对猪骨骼肌成肌细胞分化的影响,并探讨其可能的作用机制。原代培养猪骨骼肌成肌细胞,通过倒置显微镜定性观察细胞分化的形态学变化;生肌指数和肌酸激酶(CK)活性定量分析成肌细胞分化程度;细胞免疫化学法分析肌球蛋白重链(MyHC)的蛋白表达情况;采用特异性抑制剂探讨TNFα-可能的作用信号途径。结果显示:在猪骨骼肌成肌细胞分化过程中,外源性TNFα-减少细胞核融合和肌管形成;浓度依赖性地显著降低生肌指数和CK活性(P<0.05);并显著抑制MyHC蛋白表达(P<0.05);TNFα- SB205380或TNFα- PD98059处理组与TNFα-处理组相比,其CK活性和myogenin蛋白表达显著回升(P<0.05)。结果表明:TNFα-抑制猪骨骼肌成肌细胞分化,并且这种作用可能是通过激活细胞外信号调节激酶(ERK)和促分裂原活化蛋白激酶(MAPK)信号转导通路实现的。研究结果暗示TNFα-在猪骨骼肌成肌细胞分化过程中可能具有重要作用。     

过表达miR-155抑制C2C12成肌分化

为明确miR-155在C2C12成肌分化中的作用及分子机制,本研究构建了miR-155过表达腺病毒载体,运用过表达miR-155的腺病毒感染C2C12,并诱导其成肌分化。通过形态学观察,成肌标志基因mRNA和蛋白表达水平的检测,以及双荧光素酶报告基因系统对预测的miR-155靶基因(TCF4)的验证,结果表明,C2C12细胞分化中,过表达miR-155明显降低了肌管的形成,成肌标志基因MyoG和MyHC的mRNA表达量极显著地下降(P0.01),而MyoD差异不显著(P0.05),成肌标志基因蛋白检测结果与mRNA检测结果一致;进一步研究显示miR-155与预测的TCF4基因的3'UTR 3个靶点(1487-1493,1516-1522,4532-4583)中的1个(4532-4538)结合,并发现过表达miR-155显著降低了TCF4的mRNA水平(P0.05)。表明miR-155可能通过靶向TCF4抑制C2C12成肌分化。     

miR-143-3p促进C2C12成肌细胞分化

MicroRNAs (miRNAs) 是一类小非编码RNA,近年研究发现其在骨骼肌发育调控中发挥重要作用.为探明miR-143-3p在C2C12成肌细胞分化中的调控作用,采用 real-time PCR 检测了miR-143-3p在小鼠各组织及C2C12成肌细胞分化过程中的表达;使用miR-143-3p 的模拟物和特异性抑制剂分别处理细胞,采用 real-time PCR 和 Western印迹分别检测成肌因子 MyoG和成肌标志基因 MyHC mRNA和蛋白水平的变化;用免疫荧光染色的方法观察肌管的形成.结果显示,miR-143-3p在小鼠各组织中均有表达,并且随着细胞分化表达量逐渐增加;C2C12成肌细胞过表达 miR-143-3p,与对照组相比,成肌调控因子MyoG和成肌标志基因MyHC 的mRNA和蛋白表达均显著升高,肌管数量明显增多;抑制剂处理结果显示,细胞分化被显著抑制.检测miR-143-3p对MyHC各亚型表达的影响发现,miR-143-3p表达的变化并不直接影响MyHC各亚型的表达.以上结果说明, miR-143-3p在骨骼肌和成肌细胞中均有表达,能够促进C2C12成肌细胞分化,但并不直接调控MyHCs的表达.     

干扰Sirt2促进C2C12成肌细胞分化

Sirt2是组蛋白去乙酰化酶(HDAC III)家族成员之一, 对细胞周期、自噬、脂肪细胞分化、神经细胞存活等生物学过程的调节发挥重要作用. 目前,Sirt2在肌肉发育过程中的研究尚未见报道.本文通过构建Sirt2慢病毒干扰载体,侵染C2C12成肌细胞,并用细胞免疫荧光化学、real-time PCR 和Western印迹方法,检测其对成肌分化标志基因及相关信号通路因子的影响. 结果显示,干扰质粒shRNA 663处理C2C12细胞后,Sirt2 mRNA及蛋白质表达水平与对照相比显著下调(P<0.01);C2C12细胞分化第4 d,MyoD,MyoG,MyHC mRNA及蛋白质表达均显著增加(P<0.01); PI3K,AKT,FoxO1磷酸化水平明显升高. 结果表明,Sirt2可通过PI3K/AKT/FOXO1信号通路来促进成肌细胞分化,是肌生成的一个潜在调节因子.     

C2C12成肌细胞诱导肌性分化过程中miR-101a的表达

以C2C12成肌细胞为模型,在分化培养基中诱导C2C12建立体外肌性细胞分化模型.以poly (A)3′-端加尾和实时定量PCR方法研究miR-101a在C2C12细胞分化过程中的表达情况.结果发现,在细胞转入分化培养基进行肌性分化的1-5 d中,miR-101a的表达量逐渐增加,提示miR-101a可能在肌肉发生中发挥调控作用.     

Egr1对小鼠成肌细胞C2C12分化的影响

早期生长反应蛋白1(early growth response protein 1,Egr1)作为转录因子在细胞增殖、分化及凋亡等许多生物学过程中都扮演着重要角色,但是其对小鼠成肌细胞C2C12分化的影响尚不明确。该研究采用Western blot和免疫荧光技术检测Egr1在C2C12细胞分化过程中的表达规律及定位。利用CRISPR(clustered regularly interspaced short palindromic repeats)/Cas9技术分别激活和抑制Egr1的表达,进而探讨Egr1对C2C12细胞分化的影响。结果显示,随着C2C12细胞分化的进行,Egr1的表达量在分化的第5 d达到峰值,随后呈下降趋势。Egr1表达定位于C2C12的细胞核与细胞质中,随着分化的进行,其在细胞核和细胞质中的表达量均显著升高。分别激活或抑制Egr1后,C2C12细胞肌管融合率以及肌肉分化标志分子肌细胞生成蛋白(myogenin,MYOG)和肌球蛋白重链2(myosin heavy chain 2,MYH2)水平均显著增加或降低。该研究结果表明,Egr1能够促进体外小鼠成肌细胞C2C12的分化。     

二十二碳六烯酸对大鼠脂肪细胞增殖分化的影响

体外培养大鼠脂肪细胞,分别以0 μmol/L（对照组）、40 μmol/L（低剂量组）和160 μmol/L（高剂量组）的二十二碳六烯酸（DHA）处理细胞。采用台盼蓝排斥试验和MTT比色法检测细胞活性及增殖状况;油红O染色化学比色法定量分析细胞内脂肪生成及细胞分化程度;逆转录聚合酶链反应 (RT-PCR) 分析过氧化物酶增殖物激活受体γ2（PPARγ2）mRNA表达情况,探讨DHA对前体脂肪细胞增殖分化的影响及其可能机制。结果显示,各组细胞活力及MTT测得的光密度值(OD值)均低于对照组,160μmol/L组在60～72h作用显著（P<0.05）;脂肪细胞经DHA处理后, 160μmol/L组细胞油红O染色的OD值及PPARγ2 mRNA表达量均显著下降(P<0.01)。以上结果说明,DHA对脂肪细胞增殖分化均有一定抑制作用,高剂量DHA（160μmol/L）可显著减少细胞内脂肪的合成、抑制脂肪细胞分化,PPARγ2 mRNA表达量的下降可能是DHA抑制细胞分化的部分原因。     

Characterization of proliferating human skeletal muscle-derived cells in vitro: differential modulation of myoblast markers by TGF-beta2

Adult human skeletal muscle-derived cells (HuSkMC) propagated in vitro are under investigation as a cell-based therapy for the treatment of myocardial infarction. We have characterized HuSkMC with respect to cell identity and state of differentiation as a prerequisite to their clinical use. Flow cytometric analysis of propagated HuSkMC revealed a population of cells that expressed the myoblast markers CD56 and desmin. The presence of myoblasts in these cultures was further confirmed by their capacity to form myotubes and increase creatine kinase activity when cultured in low serum conditions. The non-myoblast fraction of these propagated cells expressed TE7, a marker associated with the fibroblast phenotype. Spontaneous differentiation of myoblasts occurred during serial propagation of HuSkMC, as judged by myotube formation, thereby reducing the myoblast representative fraction with continued cell expansion. We examined transforming growth factor beta2 (TGF-beta2) for its utility in controlling this spontaneous differentiation of adult human myoblasts in vitro. Propagation of HuSkMC in the presence of 1 ng/ml TGF-beta2 for 5 days decreased desmin expression within the myoblast population and caused a parallel reduction of creatine kinase activity. CD56 expression was unaffected, indicating a differential regulation of these myoblast markers. The reduction in desmin expression and creatine kinase activity was, however, reversible upon the removal of TGF-beta. These data collectively indicate that TGF-beta2 restrained differentiation of adult human skeletal myoblasts during propagation without causing irreversible loss of the myoblast phenotype, demonstrating the potential utility of using TGF-beta2 during cultivation and expansion of HuSkMC intended for therapeutic implantation.     

rhCNTF对鸡胚感觉与运动神经元神经营养作用的比较

在无血清培养条件下,观察了重组人睫状营养因子（ｒｈＣＮＴＦ）对鸡胚背根节感觉神经元及腹角运动神经元的营养作用。结果表明ｒｈＣＮＴＦ对这两类神经元均有明显的促存活作用,并呈一定的剂量／效应关系。ｒｈＣＮＴＦ浓度在０．５ｎｇ／ｍｌ以下时无作用,１．０－１．５ｎｇ／ｍｌ时已有促神经元存活作用,４ｎｇ／ｍｌ时作用最明显,再增加到１００ｎｇ／ｍｌ神经元存活数无进一步增加。比较培养７天时两类神经元存活数发现感觉神经元对ＣＮＴＦ缺乏的敏感性高于运动神经元,提示ＣＮＴＦ对运动神经元的促存活作用只是它多种类型神经元营养作用中较弱的一环     

Biochemical markers of endothelial dysfunction in patients with endocrine and essential hypertension

The aim of our study was to evaluate potential differences in the concentration of biochemical markers of endothelial dysfunction between essential hypertension, endocrine hypertension (pheochromocytoma, primary hyperaldosteronism) and control healthy group and to assess a potential relationship between these markers of endothelial dysfunction and vasopressor substances overproduced in endocrine hypertension. We have investigated 21 patients with moderate essential hypertension, 29 patients with primary hyperaldosteronism, 24 subjects with pheochromocytoma and 26 healthy volunteers. Following parameters of endothelial dysfunction were measured, von Willebrand factor (vWf), plasminogen activator (t-PA) and E-selectin (E-sel). Clinical blood pressure was measured according to the European Society of Hypertension recommendations. We found significantly higher levels of the von Willebrand factor in patients with essential hypertension in comparison with a control group (114+/-20 IU/dl vs 90+/-47 IU/dl; P=0.04) and patients with primary hyperaldosteronism (114+/-20 IU/dl vs 99+/-11 IU/dl; P=0.01). Patients with endocrine hypertension revealed increased levels of vWF compared to the control group, but these differences did not reach statistical significance. Levels of t-PA were increased in patients with pheochromocytoma in comparison with the control group (4.6+/-1.9 ng/ml vs 3.4+/-0.9 ng/ml; P=0.01) and with primary hyperaldosteronism (4.6+/-1.9 ng/ml vs 3.4+/-1.1 ng/ml; P<0.01). In case of E-selectin we found lower levels in patients with pheochromocytoma in comparison with other groups, but they differed significantly only with primary hyperaldosteronism (40.2+/-15.0 ng/ml vs 51.3+/-23.0 ng/ml; P=0.05). Our study did not reveal any convincing evidence of differences in the levels of biochemical markers of endothelial dysfunction between essential and endocrine hypertension. No correlation between the biochemical markers of endothelial dysfunction and vasopressor substances activated in endocrine hypertension was found.     

Growth factors and growth hormone enhance in vitro embryo production and post-thaw survival of vitrified bovine blastocysts

The objective of this study was to assess the influence of specific growth factors and growth hormone (GH) in the culture medium on in vitro embryo production and post-thaw survival of vitrified blastocysts. In total, 1673 bovine oocytes were used for evaluating the nuclear status of the oocytes after in vitro maturation (n=560) or for in vitro fertilization (IVF, n=1113) and distributed in five treatment groups: (1). medium only control; (2). activin (10 ng/ml); (3). epidermal growth factor (EGF) (10 ng/ml); (4). insulin 5 microg/ml and (5). GH (100 ng/ml). There was an increase (P<0.05 and P<0.01, respectively) in the percentage of oocytes that reached meta phase II, developed to blastocysts and hatched, as well as in the blastocyst cell number in the groups treated with activin, EGF and GH compared to controls. There was no significant difference between insulin and control groups. A total of 465 blastocysts were vitrified in a three-step protocol using ethylene glycol and polyvinylpyrrolidone. After thawing, embryos were cultured in five treatments groups as described above. Groups EGF and GH had higher (P<0.05) survival rates with a mean blastocyst survival of 95.0+/-1.5 and 93.1+/-3.5%, respectively, while mean hatching rate was higher for EGF and activin groups (75.3+/-3.4 and 62.0+/-3.2%, respectively). Thawed control blastocysts had a mean cell count of 52.7+/-3.3%. With the exception of insulin, all growth factors and GH tested showed higher (P<0.01) total cell numbers when compared to controls. In conclusion, addition of growth factors and GH in the culture media has favorable effects on in vitro maturation, in vitro embryo production, and post-thaw survival of vitrified blastocysts.     

Role of insulin-like growth factor binding protein-3 (IGFBP-3) in the differentiation of primary human adult skeletal myoblasts

Although muscle satellite cells were identified almost 40 years ago, little is known about the induction of their proliferation and differentiation in response to physiological/pathological stimuli or to growth factors/cytokines. In order to investigate the role of the insulin-like growth factor (IGF)/IGF binding protein (IGFBP) system in adult human myoblast differentiation we have developed a primary human skeletal muscle cell model. We show that under low serum media (LSM) differentiating conditions, the cells secrete IGF binding proteins-2, -3, -4 and -5. Intact IGFBP-5 was detected at days 1 and 2 but by day 7 in LSM it was removed by proteolysis. IGFBP-4 levels were also decreased at day 7 in the presence of IGF-I, potentially by proteolysis. In contrast, we observed that IGFBP-3 initially decreased on transfer of cells into LSM but then increased with myotube formation. Treatment with 20 ng/ml tumour necrosis factor-alpha (TNFalpha), which inhibits myoblast differentiation, blocked IGFBP-3 production and secretion whereas 30 ng/ml IGF-I, which stimulates myoblast differentiation, increased IGFBP-3 secretion. The TNFalpha-induced decrease in IGFBP-3 production and inhibition of differentiation could not be rescued by addition of IGF-I. LongR(3)IGF-I, which does not bind to the IGFBPs, had a similar effect on differentiation and IGFBP-3 secretion as IGF-I, both with and without TNFalpha, confirming that increased IGFBP-3 is not purely due to increased stability conferred by binding to IGF-I. Furthermore reduction of IGFBP-3 secretion using antisense oligonucleotides led to an inhibition of differentiation. Taken together these data indicate that IGFBP-3 supports myoblast differentiation.     

重组人睫状神经营养因子蛋白质定量检测方法的建立

采用ELISA双抗体夹心法,建立一种快速灵敏的定量检测rhCNTF成品蛋白含量的方法。结果显示,rhC-NTF抗原浓度在(0～25)ng范围内线性良好(r>0.99),灵敏度为0.3ng/ml,与其他重组细胞因子无交叉反应,样品的检测结果与理论含量相吻合,CV<15%,该方法检测速度快、重复性好、灵敏度高、特异性好。     

Lysophosphatidic acid stimulates nuclear and cytoplasmic maturation of golden hamster immature oocytes in vitro via cumulus cells

Lysophosphatidic acid (LPA), a member of the phospholipid autacoid family, is induced in incubated human follicular fluid by lysophospholipase D. It is well known that LPA functions as a growth factor and the hypothesis that LPA in human follicular fluid takes a part in meiosis of oocytes is quite plausible. We studied the effects of LPA on the maturation of golden hamster immature oocytes in vitro. Hamster oocytes with a germinal vesicle were cultured in Tyrode's albumin lactate pyruvate (TALP) medium with 10(-5) M LPA, 10 ng/ml epidermal growth factor (EGF), 30 ng/ml insulin-like growth factor-1, 1 ng/ml tumor growth factor-alpha or 1 ng/ml basic fibroblast growth factor. The nuclear maturation rates in the LPA and EGF groups were significantly higher than in the control group and the other growth factors did not show any stimulatory effect (LPA group; 74.3% [75/101], EGF group; 82.4% [89/108] vs. control group; 60.2% [59/98], p < 0.05, p < 0.01, respectively). When the cells of cumulus were removed, EGF and LPA did not increase the nuclear maturation rates. Cotreatment EGF and LPA did not significantly enhance the stimulatory effect observed with LPA alone on maturation in vitro. The penetration rate determined by the zona-free hamster oocyte test was significantly higher in the LPA group than in the control group (26.7% vs. 13.2%, p < 0.05) and was comparable with that of oocytes matured in vivo. In conclusion, LPA stimulates the nuclear and cytoplasmic maturation of hamster immature oocytes via cumulus cells.     

Effect of bone morphogenetic protein-6 on haemopoietic stem cells and cytokine production in normal human bone marrow stroma

Normal human bone marrow stroma cells include stem cells for both haemopoietic and osteochondrogenic lineages and express both bone morphogenetic protein (BMP) type I and type II receptors. As a member of the TGF-beta super-family, BMP-6 binds to both BMP type I and type II receptors and is involved in the developmental processes of renal and hepatic systems as well as of human foetal intestine. Also, BMP-6 induces osteoblastic differentiation of pluripotent mesenchymal cells and is an autocrine stimulator of chondrocyte differentiation. The present study was carried out to investigate the effect of BMP-6 on human cobblestone-area-forming cells (CAFC), that represent the functional primitive repopulating haemopoietic stem cell in long-term bone marrow culture. Also, the effect of BMP-6 on marrow stroma production of interleukin-6, -11 and their common receptor gp130 that is expressed in haemopoietic stem cells and is indispensable for their proliferation and tri-lineage differentiation was examined. Moreover, the effect of BMP-6 on marrow stroma release of soluble adhesion molecule VCAM-1 mediating the primitive haemopoietic stem cell adhesion to marrow stroma was examined. The number of CAFC was significantly reduced after BMP-6 treatment from 88+/-10 per 10(5)cells in control cultures in a dose dependent manner to only 48+/-3 per 10(5)cells in 50 ng/ml BMP-6-treated cultures, P< 0.01. Quantitative ELISA measurement revealed 50 ng/ml BMP-6 was able to significantly reduce IL-6 and IL-11 production from marrow stroma, P< 0.01. Also, BMP-6 significantly increased soluble gp130 release by 7.4-fold in 50 ng/ml BMP-6-treated marrow stroma cultures. The profound rapid increase in this natural antagonist of human IL-6 cytokine family may reduce the gp130 signaling. Also, the soluble VCAM-1 released increased by two-fold in 50 ng/ml BMP-6-treated marrow stroma cultures. The marked increase in the soluble form may exert an antagonist effect on the function of VCAM-1 (ligand for VLA4). Recently, blocking the VLA4/VCAM-1 adhesion pathway was shown to mobilise haemopoietic CD34 positive cells in normal individuals. Also, we previously observed a significantly lower expression of VLA4 (CD49d) on G-CSF-mobilised blood CD34 positive cells than on bone marrow CD34 positive cells before mobilisation in the same normal donors. Since BMP are currently being used in clinical trials for bone repair and fracture healing, the present results suggest a possible role for BMP-6 in mobilising CD34 positive cells for transplantation. Further in vitro tests are required to evaluate this potential mobilising role of BMP-6 in human long-term bone marrow culture.     

Mechanical strain applied to human fibroblasts differentially regulates skeletal myoblast differentiation

Cyclic short-duration stretches (CSDS) such as those resulting from repetitive motion strain increase the risk of musculoskeletal injury. Myofascial release is a common technique used by clinicians that applies an acyclic long-duration stretch (ALDS) to muscle fascia to repair injury. When subjected to mechanical strain, fibroblasts within muscle fascia secrete IL-6, which has been shown to induce myoblast differentiation, essential for muscle repair. We hypothesize that fibroblasts subjected to ALDS following CSDS induce myoblast differentiation through IL-6. Fibroblast conditioned media and fibroblast-myoblast cocultures were used to test fibroblasts' ability to induce myoblast differentiation. The coculture system applies strain to fibroblasts only but still allows for diffusion of potential differentiation mediators to unstrained myoblasts on coverslips. To determine the role of IL-6, we utilized myoblast unicultures ± IL-6 (0-100 ng/ml) and cocultures ± α-IL-6 (0-200 μg/ml). Untreated uniculture myoblasts served as a negative control. After 96 h, coverslips (n = 6-21) were microscopically analyzed and quantified by blinded observer for differentiation endpoints: myotubes per square millimeter (>3 nuclei/cell), nuclei/myotube, and fusion efficiency (%nuclei within myotubes). The presence of fibroblasts and fibroblast conditioned media significantly enhanced myotube number (P < 0.05). However, in coculture, CSDS applied to fibroblasts did not reproduce this effect. ALDS following CSDS increased myotube number by 78% and fusion efficiency by 96% vs. CSDS alone (P < 0.05). Fibroblasts in coculture increase IL-6 secretion; however, IL-6 secretion did not correlate with enhanced differentiation among strain groups. Exogenous IL-6 in myoblast uniculture failed to induce differentiation. However, α-IL-6 attenuated differentiation in all coculture groups (P < 0.05). Fibroblasts secrete soluble mediators that have profound effects on several measures of myoblast differentiation. Specific biophysical strain patterns modify these outcomes, and suggest that myofascial release after repetitive strain increases myoblast differentiation and thus may improve muscle repair in vivo. Neutralization of IL-6 in coculture significantly reduced differentiation, suggesting fibroblast-IL-6 is necessary but not sufficient in this process.