Efficient Gene Expression System Using the RTP801 Promoter in the Corpus Cavernosum of High-Cholesterol Diet-Induced Erectile Dysfunction Rats for Gene Therapy

Abstract

Introduction The application of gene therapy for a nonlife-threatening disease, such as erectile dysfunction (ED), requires a higher safety level and more efficacious systems for gene transfer. Aim To establish a novel technique for gene expression in a rat model of hypercholesterolemic ED that uses the RTP801 promoter, a hypoxia-inducible promoter. Methods Two-month-old male Sprague–Dawley rats were fed a diet containing 4% cholesterol and 1% cholic acid, and age-matched control animals were fed a normal diet, for 3 months. Main Outcome Measures Cavernous expression of hypoxia-inducible factor (HIF)-1α was evaluated by Western blot. After intracavernous injection of pSV-Luc or pRTP801-Luc, gene expression was evaluated by luciferase assay, and the gene expression area was evaluated by immunohistochemistry. Results HIF-1α was up-regulated in the corpus cavernosum of hypercholesterolemic rats. Although pSV-Luc did not induce gene expression in either the control or the cholesterol group, pRTP801-Luc significantly induced gene expression in the cholesterol group and resulted in higher luciferase activity than did pSV-Luc up to 14 days after injection. Immunohistochemistry showed that the gene expression area was also greater in the pRTP801-Luc group than in the pSV-Luc group, but the difference was not as great as that in luciferase activity. This suggests that pRTP801-Luc exerts its effect mainly by inducing promoter activity under hypoxia, not by increasing the number of transfected cells. Conclusion The RTP801 promoter-driven gene expression system increased gene expression in the corpus cavernosum tissue of rats with cholesterol-induced ED. This may be a useful system for the development of gene therapy in vasculogenic ED.

Rat rotator cuff tendon-to-bone healing properties are adversely affected by hypercholesterolemia

“…This experimental diet (Research Diets, Inc, New Brunswick, NJ, USA) was formulated as a modification of the standard rat chow and has been shown by us and others to produce elevated TC values in Sprague-Dawley rats after 3 months. 3,14 The other 32 rats received the standard chow and served as controls (CTL group). During a period of 6 months, all rats were allowed food and water ad libitum and were weighed weekly.…”

Delivery of hypoxia-inducible VEGF gene to rat islets using polyethylenimine

“…The RTP801 promoter induced gene expression under hypoxia in human embryonic kidney 293, Neuro2A, and A7R5 smooth muscle cells in vitro (Choi et al 2004;Lee et al 2004Lee et al , 2005. Also, in vivo administration of the RTP801 promoterluciferase plasmid increased luciferase gene expression in ischemic myocardium, injured spinal cord, and ischemic cavernosum (Choi et al 2004;Lee et al 2005Lee et al , 2008. Translational regulation is another hypoxia regulation system for VEGF gene therapy.…”

A guanidinylated bioreducible polymer as a novel gene carrier to the corpus cavernosum of mice with high‐cholesterol diet‐induced erectile dysfunction

“…A decrease in intracavernous oxygen tension, i.e., cavernous hypoxia, as well as an increase in the cavernous expression of hypoxia-inducible factor-1a, was noted in animal models of vasculogenic ED induced by traumatized iliac arteries or a high-cholesterol diet (Azadzoi et al, 1997;Lee et al, 2008). We recently observed that reporter gene expression was profoundly induced by erythropoietin (Epo) enhancer, a hypoxiainducible gene expression system, in the corpus cavernosum tissue of hypercholesterolaemic mice .…”