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-lcDNA was amplified in vitro from normal human liver cells by using RT-PCR and cloned into plasmid vector pLgXSN. The recombinant vector pLghIGF-lSN 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-lSN 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-lSN 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 ofmyoblast-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.