Abstract 1323: In Vivo Gene Transfer Of SHP-1 SiRNA Alleviates Infarct Size Following Ischemia-reperfusion Injury
Background - The Src homology domain 2 (SH2)-containing tyrosine phosphatase-1 (SHP-1) induces apoptosis due to the death-receptor stimulation. Death domain-containing receptors of the tumor necrosis factor (TNF) family can induce apoptosis in many cells including cardiomyocytes. Apoptosis in the myocardium is linked to ischemia/reperfusion injury. In the present study, we examined the effects of SHP-1 on infarct size in acute myocardial infarction (AMI) following ischemia/reperfusion using small interfering RNA (siRNA) targeting the SHP-1 gene.
Methods and Results - The rat SHP-1 siRNA expression vector (pRNA-U6.1/Neo) was purchased from GenScript Corporation. Thirty-six male Wistar rats (250 –300g) were subjected to left coronary artery (LCA) ligation. After 30 min of LCA occlusion, the temporary ligature on the LCA was released and blood flow was restored. Immediately after LCA ligation, a total of 100ug of SHP-1 siRNA (n=18) or scramble siRNA vector (n=18) was injected into three different sites in the left ventricular wall. At 1 day and 2 days after the injection, the SHP-1 mRNA and the SHP-1 protein levels were significantly higher in the myocardia of rats receiving the scramble siRNA vector than in those of sham-operated rats. However, the SHP-1 siRNA vector significantly suppressed the increase in the SHP-1 mRNA and the SHP-1 protein levels. The SHP-1 siRNA vector increased phospho-Akt and reduced DNA fragmentation compared to the scramble siRNA vector. Finally, the area of myocardial infarction was significantly smaller with the SHP-1 siRNA vector than with the scramble siRNA vector at 2 days after coronary artery reperfusion (23.8 ± 5.5 % vs.37.7 ± 7.7 %, n=6 in each group, mean ± SEM).
Conclusion - SHP-1 in the heart increased from the early stage of ischemia/reperfusion, and this increase was thought to contribute in part to the increased area of myocardial infarction. Suppression of SHP-1 with the SHP-1 siRNA vector markedly reduced the infarct size in AMI following ischemia and reperfusion.