Heat shock protein 70 gene transfection protects mitochondrial and ventricular function against ischemia-reperfusion injury.
BACKGROUND
Upregulation of heat shock protein 70 (HSP70) is beneficial in cardioprotection against ischemia-reperfusion injury, but the mechanism of action is unclear. We studied the role of HSP70 overexpression through gene therapy on mitochondrial function and ventricular recovery in a protocol that mimics clinical donor heart preservation.


RESULTS
Hemagglutinating virus of Japan (HVJ)-liposome technique was used to transfect isolated rat hearts via intracoronary infusion of either the HSP70 gene (HSP group, n=16) or no gene (CON group, n=16), which was heterotopically transplanted into recipient rats. Four days after surgery, hearts were either perfused on a Langendorff apparatus for 30 minutes at 37 degrees C (preischemia studies [n=8/group]) or perfused for 30 minutes at 37 degrees C, cardioplegically arrested for 4 hours at 4 degrees C, and reperfused for 30 minutes at 37 degrees C (postischemia studies [n=8/group]). Western blotting and immunohistochemistry confirmed HSP70 upregulation in the HSP group. Postischemic mitochondrial respiratory control indices (RCIs) were significantly better preserved in HSP than in CON hearts: NAD(+)-linked RCI values were 9.54+/-1.1 versus 10.62+/-0.46 before ischemia (NS) but 7.98+/-0.69 versus 1.28+/-0.15 after ischemia (P<0.05), and FAD-linked RCI values were 6.87+/-0.88 versus 6.73+/-0.93 before ischemia (NS) but 4.26+/-0.41 versus 1.34+/-0.13 after ischemia (P<0.05). Postischemic recovery of mechanical function was greater in HSP than in CON hearts: left ventricular developed pressure recovery was 72.4+/-6.4% versus 59.7+/-5.3% (P<0.05), maximum dP/dt recovery was 77.9+/-6.6% versus 52.3+/-5.2% (P<0.05), and minimum dP/dt recovery was 72.4+/-7.2% versus 54.8+/-6.9% (P<0.05). Creatine kinase release in coronary effluent after reperfusion was 0.20+/-0.04 versus 0.34+/-0.06 IU. min(-1). g wet wt(-1) (P<0.05) in HSP versus in CON hearts.


CONCLUSIONS
HSP70 upregulation protects mitochondrial function after ischemia-reperfusion injury; this was associated with improved preservation of ventricular function. Protection of mitochondrial function may be important in the development of future cardioprotective strategies.
Jayakumar
J
J
Department of Cardiothoracic Surgery, National Heart and Lung Institute, Imperial College School of Medicine, Royal Brompton and Harefield Hospital, Harefield, Middlesex, UK. jay.jayakumar@harefield.nthames.nhs.uk
Suzuki
K
K
Sammut
I A
IA
Smolenski
R T
RT
Khan
M
M
Latif
N
N
Abunasra
H
H
Murtuza
B
B
Amrani
M
M
Yacoub
M H
MH
D000818:Animals; D015153:Blotting, Western; D015870:Gene Expression; D015316:Genetic Therapy / Q000379:methods; D005822:Genetic Vectors / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology*; D016027:Heart Transplantation; D006801:Humans; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008081:Liposomes; D008297:Male; D008929:Mitochondria, Heart / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D009926:Organ Preservation; D010477:Perfusion; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D018108:Respirovirus / Q000235:genetics; D014162:Transfection; D015854:Up-Regulation / Q000187:drug effects; D016276:Ventricular Function / Q000187:drug effects* / Q000235:genetics
D018840:HSP70 Heat-Shock Proteins; D008081:Liposomes