No evidence of coronary plaque stabilization by allopurinol in patients with acute coronary syndrome.

BACKGROUND: Allopurinol, a xanthine inhibitor that lowers uric acid concentration, has been proven to reduce inflammation and oxidative stress in patients with cardiovascular disease. However, it is unknown whether these beneficial effects translate into favorable plaque modification in acute coronary syndromes (ACS). This study aimed to investigate whether allopurinol could improve coronary plaque stabilization using coronary computed tomography angiography (CCTA). METHODS: This was a prospective, single-center, randomized, double-blind clinical trial began in March 2019. A total of 162 ACS patients aged 18-80 years with a blood level of high-sensitivity C-reactive protein (hsCRP) â€‹> â€‹2 â€‹mg/L were included. The subjects were randomly assigned in a 1:1 ratio to receive either allopurinol sustained-release capsules (at a dose of 0.25 â€‹g once daily) or placebo for 12 months. The plaque analysis was performed at CCTA. The primary efficacy endpoint was the change in low-attenuation plaque volume (LAPV) from baseline to the 12-month follow-up. RESULTS: Among 162 patients, 54 in allopurinol group and 51 in placebo group completed the study. The median follow-up duration was 14 months in both groups. Compared with placebo, allopurinol therapy did not significantly alter LAPV (-13.4 â€‹± â€‹3.7 â€‹% vs. -17.8 â€‹± â€‹3.6 â€‹%, p â€‹= â€‹0.390), intermediate attenuation plaque volume (-16.1 â€‹± â€‹3.0 â€‹% vs. -16.2 â€‹± â€‹2.9 â€‹%, p â€‹= â€‹0.992), dense calcified plaque volume (12.2 â€‹± â€‹13.7 â€‹% vs. 9.7 â€‹± â€‹13.0 â€‹%, p â€‹= â€‹0.894), total atheroma volume (-15.2 â€‹± â€‹3.2 â€‹% vs. -16.4 â€‹± â€‹3.1 â€‹%, p â€‹= â€‹0.785), remodeling index (2.0 â€‹± â€‹3.9 â€‹% vs. 5.4 â€‹± â€‹3.8 â€‹%, p â€‹= â€‹0.536) or hsCRP levels (-73.6 [-91.6-17.9] % vs. -81.2 [-95.4-47.7] %, p â€‹= â€‹0.286). CONCLUSIONS: Our findings suggest that allopurinol does not improve atherosclerotic plaque stability or inflammation in ACS.

18ß-Glycyrrhetinic Acid Improves Cardiac Diastolic Function by Attenuating Intracellular Calcium Overload.

Ranolazine, a late sodium current inhibitor, has been demonstrated to be effective on heart failure. 18ß-glycyrrhetinic acid (18ß-GA) has the similar inhibitory effect on late sodium currents. However, its effect on diastolic function is still unknown. This study aimed to determine whether 18ß-GA can improve the diastolic function and to explore the underlying mechanisms. Eighty male Sprague Dawley (SD) rats of Langendorff model were randomly divided into the following groups: group A, normal cardiac perfusion group; group B, ischemia-reperfusion group; group C, ischemia-reperfusion with anemoniasulcata toxin II (ATX-II); group D, ranolazine group; and group E, 18ß-GA group with four different concentrations. Furthermore, a pressure-overloaded rat model induced by trans-aortic constriction (TAC) was established. Echocardiography and hemodynamics were used to evaluate diastolic function at 14th day after TAC. Changes of free intracellular calcium (Ca2+) concentration was indirectly detected by laser scanning confocal microscope to confirm the inhibition of late sodium currents. With the intervention of ATX-II on ischemia reperfusion injury group, 5 µmol/L ranolazine, and 5, 10, 20, 40 µmol/L 18ß-GA could improve ATX-II-induced cardiac diastolic dysfunction. 630 mg/kg glycyrrhizin tablets could improve cardiac diastolic function in the pressure-overloaded rats. 18ß-GA and ranolazine had similar effects on reducing the free calcium in cardiomyocytes. The study demonstrates that 18ß-GA and glycyrrhizin could improve diastolic dysfunction induced by ischemia-reperfusion injury in Langendorff-perfused rat hearts and pressure-overloaded rats. The mechanism may be attributed to the inhibition of enhanced late sodium currents.

Relaxin-2 improves diastolic function of pressure-overloaded rats via phospholamban by activating Akt.

BACKGROUND: Relaxin is a peptide hormone which has been demonstrated to be safe and has a therapeutic effect on acute heart failure in clinic trials. However, its effect on diastolic function is still unknown. The aims of the study were to determine whether relaxin could improve the diastolic function in pressure-overloaded rat model and to analyze potential mechanisms. METHODS AND RESULTS: In the present study, a pressure-overloaded rat model induced by transaortic constriction (TAC) was established. Four weeks after TAC, echocardiography was performed and then all the rat models were randomly divided into 3 groups: models without intramyocardial injection (TAC), with intramyocardial injection of empty adenoviral vector (TAC+GFP) and adenoviral vector overexpression relaxin-2 gene (TAC+RLN2). A sham group was also included. Twelve days after intramyocardial injection, echocardiography and hemodynamics were carried out to evaluate diastolic function in sham, TAC, TAC+GFP and TAC+RLN2 groups. Then hearts were harvested for subsequent examinations. The results indicated that relaxin-2 had ameliorated diastolic function in the pressure-overloaded rats. Compared with the TAC and TAC+GFP groups, the relaxin-2 gene transfer increased phosphorylation of Akt at both the Ser473 and Thr308 sites. Meanwhile, it increased the Ser16 and Thr17- phosphorylation levels of phospholamban (PLB). Furthermore, SERCA2 activity was enhanced in the TAC+RLN2 group more than in the TAC and TAC+GFP groups. CONCLUSIONS: These results demonstrated that relaxin-2 gene therapy improved diastolic function in pressure-overloaded rats. The potential mechanism may be that relaxin-2 gene transfer enhances SERCA2 activity in hearts by increasing phospholamban phosphorylation through nuclear-targeted Akt phosphorylation.

Elevated soluble ST2 and depression increased the risk of all-cause mortality and hospitalization in patients with heart failure.

This study aimed to assess the predictive effect of soluble ST2 (sST2) and depressive symptoms in patients with heart failure (HF) and to determine whether the prognosis of HF patients with preserved ejection fraction (HFpEF) differs from those with reduced ejection fraction (HFrEF). A cohort of 233 HF patients was followed for 1 year. Depressive symptoms were evaluated by the Hospital Anxiety and Depression Scale. The primary endpoint was all-cause mortality and HF-related hospitalization. For the analysis of survival, the left ventricular ejection fraction (LVEF) cut-offs for defining HFpEF were set at 50%, 45%, and 40%, respectively. With increasing LVEF, levels of sST2 were gradually decreased (45.2 ng/mL, 35.8 ng/mL, and 32.1 ng/mL in patients with LVEF ≤ 40%, 41% to 49%, and ≥ 50%, respectively, P for trend < 0.001), as well as the prevalence of depressive symptoms (35.4%, 33.3%, and 20.4%, respectively, P for trend = 0.022). After 1-year follow-up, 128 patients (54.9%) achieved the primary endpoint and 47 patients (20.2%) died. Depressive symptoms were independent risk factors of all-cause mortality and HF-related hospitalization. The combined presence of elevated sST2 (> 36.0 ng/mL) and depressive symptoms was associated with a 4.9-fold increased risk of the primary endpoint. Regardless of LVEF cut-offs, the associated risk of adverse outcomes in HFpEF was as high as in HFrEF after adjustment for significant risk factors including sST2 and N-terminal pro-brain natriuretic peptide. In conclusion, depressive symptoms provided additional prognostic information to that of sST2 in HF patients. The prognosis of HFpEF patients was similar to that of HFrEF patients.

Hepatocyte growth factor gene-modified bone marrow-derived mesenchymal stem cells transplantation promotes angiogenesis in a rat model of hindlimb ischemia.

Angiogenic gene therapy and cell-based therapy for peripheral arterial disease(PAD) have been studied intensively currently. This study aimed to investigate whether combining mesenchymal stem cells(MSCs) transplantation with ex vivo human hepatocyte growth factor(HGF) gene transfer was more therapeutically efficient than the MSCs therapy alone in a rat model of hindlimb ischemia. One week after establishing hindlimb ischemia models, Sprague-Dawley(SD) rats were randomized to receive HGF gene-modified MSCs transplantation(HGF-MSC group), untreated MSCs transplantation (MSC group), or PBS injection(PBS group), respectively. Three weeks after injection, angiogenesis was significantly induced by both MSCs and HGF-MSCs transplantation, and capillary density was the highest in the HGF-MSC group. The number of transplanted cell-derived endothelial cells was greater in HGF-MSC group than in MSC group after one week treatment. The expression of angiogenic cytokines such as HGF and VEGF in local ischemic muscles was more abundant in HGF-MSC group than in the other two groups. In vitro, the conditioned media obtained from HGF-MSCs cultures exerted proproliferative and promigratory effects on endothelial cells. It is concluded that HGF gene-modified MSCs transplantation therapy may induce more potent angiogenesis than the MSCs therapy alone. Engraftment of MSCs combined with angiogenic gene delivery may be a promising therapeutic strategy for the treatment of severe PAD.

Diagnosis of heart failure with preserved ejection fraction: which parameters and diagnostic strategies are more valuable?

AIMS: There are no unified criteria for diagnosing heart failure with preserved ejection fraction (HFpEF). The aim of this study was to evaluate the present main diagnostic criteria and to discover which parameters and strategies are more valuable. METHODS AND RESULTS: Echocardiographic data and plasma N-terminal pro-brain natriuretic peptide  levels were assessed in a derivation cohort (n= 236) and a validation cohort (n= 98). Both cohorts included normal controls, patients with hypertensive heart disease without heart failure and patients with HFpEF. In the derivation cohort, the ratio of early mitral inflow velocity to tissue Doppler velocity at lateral mitral annulus (lateral E/e'≥12), left atrial volume index (LAVI≥34 mL/m(2)), and the difference between duration of reversed pulmonary vein atrial systole flow and duration of mitral A wave flow (Ard-Ad>30 ms) had the greatest diagnostic value among all the single parameters. A brief strategy that consisted of either: (i) lateral E/e'≥12; or (ii) 12>lateral E/e'≥8, with either LAVI≥34 mL/m(2) or Ard-Ad>30 ms, provided good diagnostic accuracy for identifying diastolic dysfunction in HFpEF, with a sensitivity of 77% and specificity of 81%. These observations were confirmed in the validation cohort. CONCLUSION: Echocardiographic parameters including lateral E/e', LAVI, and Ard-Ad have the greatest value in diagnosing HFpEF. A brief strategy that included these three parameters had great diagnostic value and would be simple to use in clinic practice.

Recombinant proteins secreted from tissue-engineered bioartificial muscle improve cardiac dysfunction and suppress cardiomyocyte apoptosis in rats with heart failure.

BACKGROUND: Tissue-engineered bioartificial muscle-based gene therapy represents a promising approach for the treatment of heart diseases. Experimental and clinical studies suggest that systemic administration of insulin-like growth factor-1 (IGF-1) protein or overexpression of IGF-1 in the heart exerts a favorable effect on cardiovascular function. This study aimed to investigate a chronic stage after myocardial infarction (MI) and the potential therapeutic effects of delivering a human IGF-1 gene by tissue-engineered bioartificial muscles (BAMs) following coronary artery ligation in Sprague-Dawley rats. METHODS: Ligation of the left coronary artery or sham operation was performed. Primary skeletal myoblasts were retrovirally transduced to synthesize and secrete recombinant human insulin-like growth factor-1 (rhIGF-1), and green fluorescent protein (GFP), and tissue-engineered into implantable BAMs. The rats that underwent ligation were randomly assigned to 2 groups: MI-IGF group (n = 6) and MI-GFP group (n = 6). The MI-IGF group received rhIGF-secreting BAM (IGF-BAMs) transplantation, and the MI-GFP group received GFP-secreting BAM (GFP-BAMs) transplantation. Another group of rats served as the sham operation group, which was also randomly assigned to 2 subgroups: S-IGF group (n = 6) and S-GFP group (n = 6). The S-IGF group underwent IGF-1-BAM transplantation, and S-GFP group underwent GFP-BAM transplantation. IGF-1-BAMs and GFP-BAMs were implanted subcutaneously into syngeneic rats after two weeks of operation was performed. Four weeks after the treatment, hemodynamics was performed. IGF-1 was measured by radioimmunoassay, and then the rats were sacrificed and ventricular samples were subjected to immunohistochemistry. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to examine the mRNA expression of bax and Bcl-2. TNF-α and caspase 3 expression in myocardium was examined by Western blotting. RESULTS: Primary rat myoblasts were retrovirally transduced to secrete rhIGF-1 and tissue-engineered into implantable BAMs containing parallel arrays of postmitotic myofibers. In vitro, they secreted consistent levels of hIGF (0.4 - 1.2 µg×BAM(-1)×d(-1)). When implanted into syngeneic rat, IGF-BAMs secreted and delivered rhIGF. Four weeks after therapy, the hemodynamics was improved significantly in MI rats treated with IGF-BAMs compared with those treated with GFP-BAMs. The levels of serum IGF-1 were increased significantly in both MI and sham rats treated with IGF-BAM. The mRNA expression of bax was lower and Bcl-2 expression was higher in MI-IGF group than MI-GFP group (P < 0.05). Western blotting assay showed TNF-α and caspase 3 expression was lower in MI-IGF group than MI-GFP group after therapy. CONCLUSIONS: rhIGF-1 significantly improves left ventricular function and suppresses cardiomyocyte apoptosis in rats with chronic heart failure. Genetically modified tissue-engineered BAMs provide a method delivering recombinant protein for the treatment of heart failure.

Recombinant human growth hormone secreted from tissue-engineered bioartificial muscle improves left ventricular function in rat with acute myocardial infarction.

BACKGROUND: Experimental studies and preliminary clinical studies have suggested that growth hormone (GH) treatment may improve cardiovascular parameters in chronic heart failure (CHF). Recombinant human GH (rhGH) has been delivered by a recombinant protein, by plasmid DNA, and by genetically engineered cells with different pharmacokinetic and physiological properties. The present study aimed to examine a new method for delivery of rhGH using genetically modified bioartificial muscles (BAMs), and investigate whether the rhGH delivered by this technique improves left ventricular (LV) function in rats with CHF. METHODS: Primary skeletal myoblasts were isolated from several Sprague-Dawley (SD) rats, cultured, purified, and retrovirally transduced to synthesize and secrete human rhGH, and tissue-engineered into implantable BAMs. Ligation of the left coronary artery or sham operation was performed. The rats that underwent ligation were randomly assigned to 2 groups: CHF control group (n = 6) and CHF treatment group (n = 6). The CHF control group received non-rhGH-secreting BAM (GFP-BAMs) transplantation, and the CHF treatment group received rhGH-secreting BAM (GH-BAMs) transplantation. Another group of rats served as the sham operation group, which was also randomly assigned to 2 subgroups: sham control group (n = 6) and sham treatment group (n = 6). The sham control group underwent GFP-BAM transplantation, and the sham treatment group underwent GH-BAM transplantation. GH-BAMs and GFP-BAMs were implanted subcutaneously into syngeneic rats with ligation of the left coronary artery or sham operation was performed. Eight weeks after the treatment, echocardiography was performed. hGH, insulin-like growth factor-1 (IGF-1) and TNF-alpha levels in rat serum were measured by radioimmunoassay and ELISA, and then the rats were killed and ventricular samples were subjected to immunohistochemistry. RESULTS: Primary rat myoblasts were retrovirally transduced to secrete rhGH and tissue-engineered into implantable BAMs containing parallel arrays of postmitotic myofibers. In vitro, they secreted 1 to 2 microg of bioactive rhGH per day. When implanted into syngeneic rat, GH-BAMs secreted and delivered rhGH. Eight weeks after therapy, LV ejection fraction (EF) and fractional shortening (FS) were significantly higher in CHF rats treated with GH-BAMs than in those treated with GFP-BAMs ((65.0 +/- 6.5)% vs (48.1 +/- 6.8)%, P < 0.05), ((41.3 +/- 7.4)% vs (26.5 +/- 7.1)%, P < 0.05). LV end-diastolic dimension (LVEDD) was significantly lower in CHF rats treated with GH-BAM than in CHF rats treated with GFP-BAM (P < 0.05). The levels of serum GH and IGF-1 were increased significantly in both CHF and sham rats treated with GH-BAM. The level of serum TNF-alpha decreased more significantly in the CHF treatment group than in the CHF control group. CONCLUSIONS: rhGH significantly improves LV function and prevents cardiac remodeling in rats with CHF. Genetically modified tissue-engineered bioartificial muscle provides a method delivering recombinant protein for the treatment of heart failure.

Effects of transplanted myoblasts transfected with human growth hormone gene on improvement of ventricular function of rats.

BACKGROUND: Cell transplantation for myocardial repair is limited by early cell death. Gene therapy with human growth hormone (hGH) has been shown to promote angiogenesis and attenuate apoptosis in the experimental animal. This study was conducted to explore the effects of myoblast-based hGH gene therapy on heart function restoration and angiogenesis after myocardial infarction, and to compare the differences between myoblast-based hGH gene therapy and myoblast therapy. METHODS: Myoblasts were isolated from several SD rats, cultured, purified, and transfected with plasmid pLghGHSN and pLgGFPSN. Radioimmunoassay (RIA) was used to detect the expression of hGH in these myoblasts. SD rats underwent the ligation of the left anterior descending coronary artery so as to establish a heart ischemia model. Thirty surviving rats that underwent ligation were randomly divided into 3 equal groups 2 weeks after left coronary artery occlusion: pLghGHSN group received myoblast infected with hGH gene transplantation; pLgGFPSN group received myoblast infected with GFP gene transplantation; control group: received cultured medium only. Four weeks after the injection the surviving rat underwent evaluation of cardiac function by echocardiography. The rats were killed and ventricular samples were undergone immunohistochemistry with hematoxylin-eosin and factor VIII. Cryosection was analyzed by fluorescence microscopy to examine the expression of green fluorescent protein. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to examine the mRNA expression of vascular endothelial growth factor (VEGF), bax and Bcl-2. hGH expression in myocardium was examined by Western blot. RESULTS: Myoblast can be successfully isolated, cultured and transfected. The expression of hGH in transfected myoblast was demonstrated with RIA. Four weeks after therapy, the cardiac function was improved significantly in pLghGHSN group and pLgGFPSN group. Fractional shortening (FS) and ejection fraction (EF) in pLghGHSN group were elevated significantly compared with pLgGFPSN group and control group after therapy (FS: 36.9+/-5.3 vs 29.5+/-3.5, 21.8+/-2.9; EF: 56.9+/-4.3 vs 47.1+/-3.6, 38.4+/-4.8, P<0.05). Left ventricular end-diastolic dimension (LVEDD) and heart infracted size in pLghGHSN group were decreased significantly compared with pLgGFPSN group and control group after therapy (LVEDD: 5.9+/-0.3 vs 6.8+/-0.2, 8.6+/-0.3; heart infracted size: (34.5+/-4.2)% vs (40.0+/-3.9)%, (46.1+/-3.8)%, P<0.05); Green fluorescence was detected in cryosection of pLgGFPSN group. The capillary density of the pLgGFPSN group was significantly greater than those of the pLghGHSN group and control group (P<0.05). The mRNA expression of VEGF and Bcl-2/bax in pLghGHSN group was higher than in pLgGFPSN group or control group (P<0.05). The expression of hGH gene in myocardium tissue can be detected by Western blot assay in pLghGHSN group. CONCLUSIONS: Transplantation of heart cells transfected with hGH induced greater angiogenesis and effect of antiapoptosis than transplantation of cells transfected with GFP. Combined GH gene transfer and cell transplantation provided an effective strategy for improving postinfarction ventricular function.

Isolation and characterization of human umbilical cord mesenchymal stem cells with hematopoiesis-supportive function and other potentials.

BACKGROUND AND OBJECTIVES: Adult bone marrow (BM) is the major source of mesenchymal stem cells (MSC) for cell therapy. However, aspiration of BM involves invasive procedures. We isolated MSC from human full term umbilical cord tissues (UC). The biological characteristics of MSC derived from UC (UC-MSC) were further determined and compared with normal adult bone marrow-derived MSC (BM-MSC). DESIGN AND METHODS: MSC were isolated from UC by enzyme digestion and cultured in appropriate growth medium. The isolation efficiency, cell yield, colony-forming unit-fibroblast (CFU-F) frequency, growth kinetics, phenotypic characteristics, multi-lineage differentiation capacity, cytokine spectrum as well as hematopoiesis-supportive function of UC-MSC were determined and compared with those of BM-MSC. RESULTS: MSC were successfully isolated from all 36 UC and six BM samples we collected for this study. The mean number of nucleated cells isolated from UC was 1yen106/cm and the yield of adherent cells was 8.6yen105/cm. UC-MSC shared most of the characteristic of BM-MSC, including fibroblastic-like morphology, immunophenotype, cell cycle status, adipogenic and osteogenic differentiation potentials, and hematopoiesis-supportive function. The CFU-F frequency was higher in UC nucleated cells (1:1609 +/- 0.18) than in BM nucleated cells (1:35700 +/- 0.01) (p < 0.05). Furthermore, in comparison with BM-MSC, the UC-MSC had a higher proliferation capacity and lower levels of expression of CD106 and HLA-ABC (p < 0.05). Immunofluoresent and western blot assays revealed that UC-MSC had a higher percentage of neuron specific enolase-positive cells than had BM-MSC after neuronal induction. Finally, reverse transcriptase polymerase chain reaction analysis showed that UC-MSC had a cytokine spectrum very similar to that of BM-MSC, including expression of the mRNA of stem cell factor, leukemia inhibitor factor, macrophage-colony stimulating factor, Flt3-ligand, interleukin-6, vascular endothelial growth factor and stromal-derived factor-1, but UC-MCS additionally expressed mRNA of granulocyte macrophage and granulocyte colony-stimulating factors. After co-culture with CD34+ cord blood cells for 5 weeks, no significant difference in colony-forming cells was observed between the CD34+ cells/UC-MSC and CD34+ cells/BM-MSC co-cultures (p > 0.05). INTERPRETATION AND CONCLUSIONS: We have established a protocol to isolate abundant MSC from human umbilical cords with a 100% success rate. The comparative study indicates that UC is an excellent alternative to BM as a source of MSC for cell therapies.

[Construction of human growth hormone lentiviral vector and its expression in murine skeletal myoblasts].

The aim of this study is to construct a lentiviral vector encoding human growth hormone, and to achieve the long, efficient and stable expression in murine skeletal myoblasts. Primary skeletal myoblasts were isolated from Sprague-Dawley rats and cultured by enzymatic digestion. We tested them by Desmin immunohistochemistry stains and found their viability was up to 94% by Trypan blue. Human growth hormone (hGH) cDNA was subcloned into expression vector pLenti6/V5-D-TOPO to construct recombinant pLenti6/V5-hGH. The pLenti6/V5-hGH and the contructed pLenti6/V5-EGFP were transfected into murine skeletal myoblasts by the Lipofectamin 2000. Through counting by the Confocal Laser Scanning Microscope, we identified the transfection efficency. We added the blasticidin to the 6-well plate with lids and obtained stable myoblasts expressing hGH. The concentration of human growth hormone (hGH) in cell culture medium was detected by Radioimmunoassay (RIA). Polymerase Chain Reaction (PCR) and DNA sequence showed hGH cDNA had been correctly inserted into pLenti6/V5-D-TOPO vector. Bright green fluorescence of the transfected cells could be observed under the Confocal Laser Scanning Microscope after 24 h transfection with pLenti6/V5-EGFP plasmids, and the transfection rate reached 40%. The difference was distinct (P < 0.01) between the pLenti6/V5- hGH groups and control groups in the secretive level of human growth hormone. After 8 weeks, the expression of human growth hormone was still stable. Then, we validated the biological characterization of the rhGH by the enzyme-link immunosorbent assay (ELISA) of the Insulin-like growth factor I (IGF-1). These results demonstrate we have successfully constructed the recombinant pLenti6/V5-hGH plasmids and accomplished rhGH long, efficient and stable expression ectopic in skeletal muscle myoblasts.

Effects of recombinant retroviral vector mediated human insulin like growth factor-1 gene transfection on skeletal muscle growth in rat.

BACKGROUND: This study transferred a recombinant gene encoding human insulin like growth factor-1 (hIGF-1) into modified primary skeletal myoblasts with a retroviral vector (pLgXSN) and determined whether the hIGF-1 promoted growth of skeletal muscle in rat. METHODS: hIGF-1cDNA was amplified in vitro from normal human liver cells by using RT-PCR and cloned into plasmid vector pLgXSN. The recombinant vector pLghIGF-1SN and control vector pLgGFPSN were transfected into packaging cell PT67 and G418 was used to select positive colony. Myoblasts were infected with a high titre viral supernatant and transduction efficiency was evaluated as GFP expression. The expression of hIGF-1 mRNA in myoblasts was investigated by immunocytochemistry and RT-PCR. MTT assays detected the growth of myoblasts in vitro. Myoblasts transduced with pLghIGF-1SN were injected into hind limb muscles of 10 - 12 week male SD rats. Formed tissues were harvested 4 weeks later. Myocyte diameter, mean weight of hind limb and body were measured to evaluate the skeletal muscle growth. RESULTS: Recombinant retroviral plasmid vector pLghIGF-1SN was constructed successfully. The titre of the packaged recombinant retrovirus was 1 x 10(6) cfu/ml. The transfection rate of PT67 cells reached 100% after G418 screening. hIGF-1 expression was positive in myoblast-IGF-1. The proliferation rate of myoblast-IGF-1 in vitro was higher than GFP-myoblast or myoblast (P < 0.05). The mean weights of hind limb and body of rats injected myoblast-IGF-1 were higher than those of the rats injected with myoblast-GFP or myoblast (P < 0.05). Myocyte diameter had a significant increase in IGF-1 group compared to GFP group and myoblast group (P < 0.05). CONCLUSIONS: The transfection of the human IGF-1 gene mediated by a retroviral vector can promote the growth of skeletal muscle in rats. Genetically modified primary skeletal myoblasts provide a possibly effective approach to treat some skeletal muscle diseases.