Gene transfer of insulin-like growth factor-1 promotes the proliferation of corpus cavernosal smooth muscle cells in vitro in rats

Objective To study whether gene transfer of insulin-like growth factor-1 (IGF-1) can promote the proliferation of corpus cavernosal smooth muscle cells (CCSMCs) in rats and explore the possible mechanism of IGF-1 gene therapy for erectile dysfunction (ED). Methods The pcDNA3.1-IGF-1 vector was constructed and sequenced.The CCSMCs were subjected to primary culture and identified,and divided into 3 groups:pcDNA3.1-IGF-1 group,pcDNA3.1 group (vehicle-only) and control group.The cell proliferation was measured by using methylthiazoletetrazolium (MTT) assay in the three cell strains at 3rd,5th,7th and 9th day after transfection.The enzyme immunoassay (EIA) kit was used to quantify IGF-I levels in in the three cell strains at 24,48 and 96 h after transfection.Results The pcDNA3.1-IGF-1 vector was successfully cloned with correct open reading fragment.The CCSMCs were confirmed by anti-o smooth muscle actin antibodies.Gene transfer of IGF-1 significantly promoted proliferation of CCSMCs in a time-dependent manner at 5th,7th and 9th day (A570:0.72 ±0.08,0.80 ±0.06,0.82 ±0.07,P ＜0.05,respectiyely).As compared with pcDNA3.1 group [(46 ±7),(48 ±9),(50 ± 11 ) μg/L,respectively] and control group [(47 ± 11 ),(52 ± 10),(51 ± 10) μg/L,respectively],the secretion of IGF-1 in CCSMCs was significantly increased in pcDNA3.1-IGF-1 group [(58 ±8 ),(69 ± 1 1 ),(71 ± 8 ) μg/L,respectively] at 24,48 and 96 h ( all P ＜ 0.05 ).Conclusion The gene transfer of IGF-1 promotes the proliferation of CCSMCs in rats and might contribute to the mechanism of using IGF-1 gene therapy for ED. Key words: Insulin-like growth factor-1; Erectile dysfunction; Proliferation; Corpus cavernosum; Smooth muscle cells