P-A-2. Intracoronary injection of G-CSF ameliorates the

progression of left ventricular remodeling after myocardial

ischemia/reperfusion in rabbits

Hiroshi Hasegawa, Hiroyuki Takano, Hirokazu Shiraishi,

Kazutaka Ueda, Yuriko Niitsuma, Hiroyuki Tadokoro, Issei

Komuro. Department of Cardiovascular Science and Medicine,

Chiba University Graduate School of Medicine, Japan

Background: Although granulocyte colony-stimulating

factor (G-CSF) is known to prevent left ventricular (LV)

remodeling after acute myocardial infarction (AMI), the best

method to administrate G-CSF after percutaneous coronary

intervention (PCI) is not determined.

Methods: After left thoracotomy, the left large coronary

arterial branch of rabbit LV was ligated for 30 min. After ligation

was released, the ascending aorta was clamped and rabbits were

then randomized into 3 groups. (1) control group (CONT);

injection of saline into coronary artery (n=12), (2) G-CSF IC

group (IC); injection of G-CSF (100 Ag/kg, n=15) into coronaryartery, (3) G-CSF SC group (SC); injection of G-CSF subcuta-

neously (10 Ag/kg/day�5 days, n=10). Echocardiography was

performed at preoperation and 14 days after operation. At 14

days, rabbits were sacrificed and the %area of infarcted myocar-

dium to total LV was measured by Masson–Trichrome staining.

Results: Although one CONT rabbits died, no IC and SC

rabbits were dead throughout the examination. In SC rabbits,

the number of white blood cell (WBC) was more increased and

reached the peak at 7 days compared to CONT rabbits. In IC

rabbits, the number of WBC peaked at 1 day and thereafter

decreased rapidly. The degree of LV dilatation and LV

dysfunction were smaller in IC and SC rabbits compared to

CONT rabbits. The %area of infarcted myocardium was

smaller in IC and SC heart compared to CONT heart

(CONT:14.9 T2.2%; IC:10.7T1.2%, p <0.05 vs. CONT;

SC:11.4T1.7%, p <0.05 vs. CONT).

Conclusions: Intracoronary injection of G-CSF is as

effective as subcutaneous injection to protect infarcted myo-

cardium with less increase in WBC. The direct G-CSF injection

into coronary artery after successful PCI may become a novel

therapy for AMI with lower adverse effects.

Keywords: Myocardial infarction; Cytokine; Ischemia/

reperfusion

doi:10.1016/j.yjmcc.2006.08.087

P-A-3. Cross-talk between BMP 2 and leukemia inhibitory

factor through ERK 1/2 and Smad1 in protection against

doxorubicin-induced injury of cardiomyocytes

Mitsuru Masaki, Masahiro Izumi, Yasushi Fujio, Keiko

Takihara, Masatsugu Hori. Department of Cardiovascular

Medicine, Osaka University Graduate School of Medicine,

Japan

The survival of cardiomyocytes is regulated by growth

factors and cytokines such as bone morphogenetic protein

(BMP) 2 and leukemia inhibitory factor (LIF). BMP2 and LIF

induce distinct signal transduction pathways that each activate a

different transcription factor [Smad1 and signal transducing

activating transcriptional factor (Stat) 3, respectively] and

common signal pathway [mitogen-activated protein kinase

(MAPK)]. We previously demonstrated that BMP2 and LIF

protect cardiomyocytes via Smad1 and STAT3 signaling path-

ways, respectively. On the other hand, these signals are known

to act in synergy via synergistic integration of signaling

pathways. Here, we examined interaction between BMP2 and

LIF in primary cultured neonatal rat cardiomyocytes. LIF

sustained phosphorylation/activation of Smad1 by BMP2. The

role of extracellular signal-regulated kinase (ERK) 1/2 cascade

activated by LIF was highlighted by the use of a MAPK/ERK

kinase (MEK) 1/2 inhibitor, U0126, or overexpression of

dominant-negative form of MEK1 that abolished sustained

phosphorylation of Smad1 and cell survival effect induced by

co-stimulation of LIF with BMP2, while BMP2 alone did not

activate ERK1/2. Conversely, overexpression of the constitu-

tive-active form of MEK1 increased BMP2-induced phospho-

rylation of Smad1 without additional LIF. Moreover, BMP2

and LIF synergistically induced bcl-xL mRNA in doxorubi-

cin (DOX)-injured cardiomyocytes. These findings suggest

that the ERK1/2 pathway downstream of LIF is involved in

sustained phosphorylation/activation of Smad1 by BMP2 and

provide a possible mechanism for cooperation between

intracellular signals activated by LIF and BMP2 in protection

against DOX-induced injury of cardiomyocytes.

Keywords: Bone morphogenetic protein 2 (BMP2); Leukemia

inhibitory factor (LIF); Doxorubicin

doi:10.1016/j.yjmcc.2006.08.088

P-A-4. Early apoptotic events induce immature gene

expression and proliferation in adult cardiac myocyte

Emi Maeno, Asuka Shiga, Yoshiki Sawa. Division of

Cardiovascular Surgery, Department of Surgery E1, Osaka

University Graduate School of Medicine

Introduction: Cardiac myocytes following ischemia and

reperfusion injury undergo mostly eventual loss by apoptosis.

Even although previous study reported that damage to

myocardium led to a de-differentiated state resembling that of

immature muscle cells, no study specifically addressed source

of the its cells related to cellular remodeling process and

myocardial regeneration. We therefore hypothesized that

surviving cardiac myocyte of earlier phase than fatal phase of

apoptosis may express immature genes itself and contribute to

remodeling and regeneration.

Methods and results: The first, we made a comparison of

gene expression patterns between infarct left ventricular

specimens at 2–24 h after LAD ligation in vivo and de-

differentiated cardiac myocytes in vitro by RT-PCR. Infarct

tissue was similar to de-differentiated cardiac myocyte in their

expression patterns. That is, the differentiation gene a myosin

heavy chain (MHC) and contraction related gene desmin were

ABSTRACTS / Journal of Molecular and Cellular Cardiology 41 (2006) 1039–1079 1065