Background Cell transplantation for myocardial repair is limited by early cell death. Gene therapy with human growth hormone （hGH） has been shown to promote angiogensis 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
This study examined the change of p16^INK4a and PNCA protein expression in myocardium after injection of hIGF-1 gene modified skeletal myoblasts into post-infarction rats. HIGF-1 gene modified skeletal myoblasts （hIGF-1-myoblasts） were injected into hind limb muscles of 18 post-infraction rats （experimental group）. Primary-myoblasts were injected into 18 post-infraction rats （control group） and 12 non-infarction rats （sham group）. Expression of p16INK4a and PCNA pro- tein in myocardiums were separately detected immunocytochemically 1, 2 and 4 weeks after the inuection. The level of hIGF-1 and rIGF-1 protein in serum and myocardium were detected by en- zyme-linked immunosorbent assay （ELISA）. Compared with the sham group, the percentage of p^16INK4a and PCNA positive cells reached a peak after 1 week in the control group and the experimental group （P〈0.01）. Moreover, the percentage of p16^INK4a-positive cells in the experimental group was lower than in control group whereas the percentage of PCNA-positive cells was lower in the control group than in the experimental group （P〈0.01）. The percentage of p16^INK4a-positive cells in the experimental group and the percentage of PCNA-positive cells in the control group were close to that in the sham group from the 2nd week （P〉0.05）. ELISA analysis disclosed that the myocardium level of rIGF-1 protein increased gradually in the controls and especially in the experimental group （P〈0.01）. The serum level of rIGF-1 decreased significantly in post-infraction rats, but these conditions were improved in the experimental group （P〈0.01）. The hIGF-1 protein in serum and myocar- dium were detected from the 1st week to the 4th week in the experimental group. Statistical analysis revealed significant associations of myocardium level of hIGF-1 protein with expression of p^16INK4a and PCNA protein （r=–0.323, P〈0.05; r=0.647, P〈0.01）. It is concluded that genetically hIGF-1-myoblast provides a means for constant synthesis and re
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
RONG Shu-lingWANG Yong-jinWANG Xiao-linLU Yong-xinWU YinLIU Qi-yunMI Shao-huaXU Yu-lan
