Early expression of angiogenesis factors in acute myocardial ischemia and infarction.
BACKGROUND
When the myocardium is deprived of blood, a process of ischemia, infarction, and myocardial remodeling is initiated. Hypoxia-inducible factor 1 (HIF-1) is a transcriptional activator of vascular endothelial growth factor (VEGF) and is critical for initiating early cellular responses to hypoxia. We investigated the temporal and spatial patterns of expression of the alpha subunit of HIF-1 (HIF-1alpha) and VEGF in specimens of human heart tissue to elucidate the early molecular responses to myocardial hypoxia.


METHODS
Ventricular-biopsy specimens from 37 patients undergoing coronary bypass surgery were collected. The specimens were examined by microscopy for evidence of ischemia, evolving infarction, or a normal histologic appearance. The specimens were also analyzed with the reverse-transcriptase polymerase chain reaction for HIF-1alpha and VEGF messenger RNA (mRNA) expression and by immunohistochemical analysis for the location of the HIF-1alpha and VEGF proteins.


RESULTS
HIF-1alpha mRNA was detected in myocardial specimens with pathological evidence of acute ischemia (onset, <48 hours before surgery) or early infarction (onset, <24 hours before surgery). In contrast, VEGF transcripts were seen in specimens with evidence of acute ischemia or evolving infarction (onset, 24 to 120 hours before surgery). Patients with normal ventricles or evidence of infarction in the distant past had no detectable levels of either VEGF mRNA or HIF-1alpha mRNA. HIF-1alpha immunoreactivity was detected in the nuclei of myocytes and endothelial cells, whereas VEGF immunoreactivity was found in the cytoplasm of endothelial cells lining capillaries and arterioles.


CONCLUSIONS
An increase in the level of HIF-1alpha is an early response to myocardial ischemia or infarction. This response defines, at a molecular level, one of the first adaptations of human myocardium to a deprivation of blood. HIF-1alpha is a useful temporal marker of acutely jeopardized myocardium.
Lee
S H
SH
Division of Cardiothoracic Surgery, University of California, San Diego, 92103-8892, USA.
Wolf
P L
PL
Escudero
R
R
Deutsch
R
R
Jamieson
S W
SW
Thistlethwaite
P A
PA
D000208:Acute Disease; D000368:Aged; D043925:Angiogenesis Inducing Agents / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D016228:Endothelial Growth Factors / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006352:Heart Ventricles / Q000473:pathology; D006801:Humans; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008222:Lymphokines / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000378:metabolism* / Q000473:pathology; D017202:Myocardial Ischemia / Q000378:metabolism* / Q000473:pathology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011446:Prospective Studies; D012333:RNA, Messenger / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D043925:Angiogenesis Inducing Agents; D004268:DNA-Binding Proteins; D016228:Endothelial Growth Factors; C497442:HIF1A protein, human; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008222:Lymphokines; D009687:Nuclear Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors