Enhanced cardioprotective effects by coexpression of two isoforms of hepatocyte growth factor from naked plasmid DNA in a rat ischemic heart disease model

Background: The therapeutic potential of pCK-HGF-X7, a naked DNA designed to express two isoforms of hepatocyte growth factor (HGF ₇₂₃ and HGF ₇₂₈), was studied in the rat ischemic heart disease model. Methods: First, the kinetics of gene expression was examined by injecting pCK-HGF-X7 DNA into the rat heart. Second, the cardioprotective effects were compared between the two naked DNA constructs, expressing a single (HGF ₇₂₈) or both isoforms (HGF ₇₂₈ and HGF ₇₂₃) of HGF, in the rat ischemic heart disease model. The ischemic injury to the rat heart was created by ischemia-reperfusion in the anterior descending artery. The respective naked DNA constructs were injected into the anterior wall of the rat heart with the ischemia-reperfusion injury. Cardiac function, capillary density and anti-fibrotic activity were compared between the two naked DNA constructs. Results: The intramyocardial administration of pCK-HGF-X7 resulted in transient and localized HGF expression for 3weeks. At its peak, approximately 678pg (per mg of tissue protein) of HGF was produced in the injected heart without an increase of HGF protein level in other tissues, and serum. pCK-HGF-X7 more efficiently improved the left ventricular ejection fraction and the systolic anterior wall thickness, increased the capillary density, and inhibited myocardial fibrosis, in a statistically significant manner, compared to the identical vector encoding HGF ₇₂₈ only. Conclusions: These results demonstrate that transfer of the genomic-cDNA hybrid expressing both isoforms of the HGF gene might provide higher therapeutic effects than the cDNA sequence producing HGF ₇₂₈ alone in the treatment of ischemic heart disease.