Noninvasive imaging of hypoxia-inducible factor-1α gene therapy for myocardial ischemia.
Hypoxia-inducible factor-1 alpha (HIF-1α) gene therapy holds great promise for the treatment of myocardial ischemia. Both preclinical and clinical evaluations of this therapy are underway and can benefit from a vector strategy that allows noninvasive assessment of HIF-1α expression as an objective measure of gene delivery. We have developed a novel bidirectional plasmid vector (pcTnT-HIF-1α-VP2-TSTA-fluc), which employs the cardiac troponin T (cTnT) promoter in conjunction with a two-step transcriptional amplification (TSTA) system to drive the linked expression of a recombinant HIF-1α gene (HIF-1α-VP2) and the firefly luciferase gene (fluc). The firefly luciferase (FLuc) activity serves as a surrogate for HIF-1α-VP2 expression, and can be noninvasively assessed in mice using bioluminescence imaging after vector delivery. Transfection of cultured HL-1 cardiomyocytes with pcTnT-HIF-1α-VP2-TSTA-fluc led to a strong correlation between FLuc and HIF-1α-dependent vascular endothelial growth factor expression (r(2)=0.88). Intramyocardial delivery of pcTnT-HIF-1α-VP2-TSTA-fluc into infarcted mouse myocardium led to persistent HIF-1α-VP2 expression for 4 weeks, even though it improved neither CD31+ microvessel density nor echocardiographically determined left ventricular systolic function. These results lend support to recent findings of suboptimal efficacy associated with plasmid-mediated HIF-1α therapy. The imaging techniques developed herein should be useful for further optimizing HIF-1α-VP2 therapy in preclinical models of myocardial ischemia.
1 Departments of Radiology, Bioengineering, and Material Science & Engineering, Molecular Imaging Program at Stanford, Stanford University , Stanford, CA 94305.
Ian Y
IY
Chen
Olivier
O
Gheysens
Zongjin
Z
Li
Julia A
JA
Rasooly
Qian
Q
Wang
Ramasamy
R
Paulmurugan
Jarrett
J
Rosenberg
Martin
M
Rodriguez-Porcel
Juergen K
JK
Willmann
David S
DS
Wang
Christopher H
CH
Contag
Robert C
RC
Robbins
Joseph C
JC
Wu
Sanjiv S
SS
Gambhir
D000818:Animals; D002460:Cell Line; D004452:Echocardiography; D005260:Female; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000235:genetics; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics* / Q000378:metabolism; D049409:Luciferases, Firefly / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D009200:Myocardial Contraction; D017202:Myocardial Ischemia / Q000628:therapy*; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism; D018919:Neovascularization, Physiologic; D061848:Optical Imaging / Q000379:methods; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D020107:Troponin T / Q000235:genetics; D042442:Vascular Endothelial Growth Factors / Q000235:genetics / Q000378:metabolism
D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D020107:Troponin T; D042442:Vascular Endothelial Growth Factors; D049409:Luciferases, Firefly