T. Scarabelli et al., Apoptosis of endothelial cells precedes myocyte cell apoptosis in ischemia/reperfusion injury, CIRCULATION, 104(3), 2001, pp. 253-256
Citations number
12
Categorie Soggetti
Cardiovascular & Respiratory Systems","Cardiovascular & Hematology Research
Background-Apoptosis contributes to cell loss after ischemia/reperfusion in
jury in the heart. This study describes the time course and level of apopto
sis in different cell types in the intact heart during ischemia/reperfusion
injury.
Methods and Results-Isolated Langendorff-perfused rat hearts were subjected
to perfusion alone (control) or to 35 minutes of regional ischemia, either
alone or followed by 5, 60, or 120 minutes of reperfusion. Sections were s
tained by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labe
ling (TUNEL) and propidium iodide and with anti-von Willebrand factor, anti
-desmin, or anti-active caspase 3 antibodies; they were then visualized by
confocal microscopy. Sections were also examined by electron microscopy, No
TUNEL-positive cells were seen in control hearts or hearts exposed to isch
emia alone. Early in reperfusion, TUNEL staining was colocalized with endot
helial cells from small coronary vessels. Endothelial apoptosis peaked at 1
hour of reperfusion and, at this time, there was clear perivascular locali
zation of apoptotic cardiac myocytes, whose number was inversely proportion
al to their distance from a positive vessel. After 2 hours of reperfusion,
apoptotic cardiac myocytes assumed a more homogeneous distribution. Active
caspase 3 labeling was seen independent of DNA fragmentation during ischemi
a alone, but it colocalized with TUNEL staining over the 3 time points of r
eperfusion, Immunocytochemical findings were confirmed by electron microsco
py and Western blotting.
Conclusions-In the very early stages of reperfusion, apoptosis is first see
n in the endothelial cells from small coronary vessels. The radial spread o
f apoptosis to surrounding cardiac myocytes suggests that reperfusion induc
es the release of soluble pro-apoptotic mediators from endothelial cells th
at promote myocyte apoptosis.