Skip Navigation

Cardiovascular Research 2005 65(2):446-456; doi:10.1016/j.cardiores.2004.10.008
This Article
Right arrow Abstract Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow E-letters: Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when E-letters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Right arrow Disclaimer
Google Scholar
Right arrow Articles by Sugano, Y.
Right arrow Articles by Ogawa, S.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Sugano, Y.
Right arrow Articles by Ogawa, S.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Copyright © 2004, European Society of Cardiology

Granulocyte colony-stimulating factor attenuates early ventricular expansion after experimental myocardial infarction

Yasuo Sugano, Toshihisa Anzai*, Tsutomu Yoshikawa, Yuichiro Maekawa, Takashi Kohno, Keitaro Mahara, Kotaro Naito and Satoshi Ogawa

Division of Cardiology, Department of Medicine, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan

* Corresponding author. Tel.: +81 3 5363 3793; fax: +81 3 3353 2502. Email address: anzai{at}cpnet.med.keio.ac.jp

Received 7 May 2004; revised 1 October 2004; accepted 4 October 2004


   Abstract
Top
 Abstract
1. Introduction
 2. Methods
 3. Results
 4. Discussion
 References
 
Objective: In the early phase after transmural myocardial infarction (MI), the infarcted myocardium undergoes replacement by scar tissue, which is essential for preserving the structural integrity of the infarcted tissue. Transforming growth factor (TGF)-β1, which is known as a fibrotic cytokine, plays a pivotal role in the reparative fibrosis after MI. It is reported that granulocyte colony-stimulating factor (G-CSF) can accelerate wound healing. The aim of our study was to investigate the effect of G-CSF on early ventricular expansion after MI.

Methods: MI was induced by ligation of the left coronary artery in male Wistar rats. G-CSF (20 µg/kg/day, MI-GCSF) or saline (MI-saline) was injected subcutaneously 3 h after MI and every 24 h thereafter for 7 days. Hemodynamic and echocardiographic studies were performed at 14 days. Expression of TGF-β1 and procollagen type I and type III mRNA in both the infarcted and noninfarcted areas was studied by quantitative RT-PCR at 1, 3, 7, and 14 days after MI. Histological studies were performed at 7 days.

Results: MI-GCSF had higher LV max dP/dt, lower LV end-diastolic pressure, and smaller LV end-diastolic and end-systolic dimensions compared to MI-saline. Infarct size was not different between MI-GCSF and MI-saline. Expression of TGF-β1 mRNA in the infarcted area at 3 days was significantly higher in MI-GCSF than in MI-saline. Expression of procollagen type I and type III mRNA in the infarcted area at 3 days was higher in MI-GCSF compared to MI-saline, and the peak mRNA levels were earlier in MI-GCSF. In the noninfarcted area, there was no difference in TGF-β1 mRNA expression between MI-GCSF and MI-saline. Histologically, collagen accumulation in the infarcted area at 7 days was more prominent in MI-GCSF than in MI-saline.

Conclusion: G-CSF treatment improves early post-infarct ventricular expansion through promotion of reparative collagen synthesis in the infarcted area, suggesting some beneficial effect of G-CSF on the infarct healing process.

KEYWORDS Cytokines; Fibrosis; Growth factors; Infarction; Remodeling


   1. Introduction
Top
 Abstract
 1. Introduction
2. Methods
 3. Results
 4. Discussion
 References
 
As a consequence of large myocardial infarction (MI), the process of complex architectural myocardial alterations, referred to as ventricular remodeling, is initiated. Acute myocyte loss and breakdown of extracellular matrix induce early ventricular expansion, which is associated with deleterious cardiac function in the late phase [1,2]. Replacement by collagen fibers is essential in preserving the structural integrity of infarcted tissue and protects against increased dilatation of the left ventricle (LV) [3–5]. Cytokines play major roles in this healing process, among which transforming growth factor (TGF)-β1, a fibrotic cytokine, is extremely important in reparative fibrosis [6–8].

It is well known that infarct size and transmurality are determinants of the ventricular remodeling process, as there is evidence that early reperfusion of the infarcted artery limits the extent of myocardial necrosis and attenuates ventricular enlargement [1]. The infarct repair process, involving inflammation and collagen synthesis, is another important factor that affects ventricular remodeling. While an excessive inflammatory reaction in the infarcted myocardium is associated with poor clinical outcomes, such as ventricular rupture or congestive heart failure [9–11], anti-inflammatory therapy after MI using corticosteroid leads to catastrophic results, by delaying collagen accumulation and scar formation, in both clinical and experimental settings [12–14]. These findings suggest that inflammation is essential for the appropriate infarct healing process.

Granulocyte colony-stimulating factor (G-CSF), a 20-kDa glycoprotein, is known to induce granulopoiesis [15]. It was reported that G-CSF in combination with stem cell factor improved ventricular remodeling after MI through myocyte regeneration by way of transdifferentiation of bone marrow stem cells [16]. However, recent reports suggested that hematopoietic stem cells do not transdifferentiate into cardiac myocytes after MI [17,18]. G-CSF has been described as having immunoregulatory properties in addition to inducing cell differentiation [19]. This cytokine can induce earlier healing in cutaneous wounds by acting on the inflammatory system [20,21]. Therefore, especially in the environment of the early phase of MI, where intense inflammation occurs, it is possible that G-CSF affects the healing process by modulating the inflammatory reaction and collagen synthesis.

We hypothesized that administration of G-CSF after MI attenuates early ventricular expansion through accelerating reparative fibrosis in the infarcted area. Accordingly, we investigated whether G-CSF administration affects post-MI ventricular function and whether such effects are associated with myocardial fibrotic cytokine expression and collagen synthesis.


   2. Methods
Top
 Abstract
 1. Introduction
 2. Methods
3. Results
 4. Discussion
 References
 
All procedures were performed in accordance with the Keio University animal care guidelines, which conform to the Guide for the Care and Use of Laboratory Animals published by the US National Institutes of Health (NIH Publication No. 85-23, revised 1996).

2.1. Animals and surgical procedure
Left ventricular MI was created in 9-week-old male Wistar rats (Sankyo Laboratory Service, Tokyo, Japan) weighing 200–230 g, by left coronary artery ligation as previously described [22]. Briefly, rats were anesthetized with intraperitoneal pentobarbital, intubated, and then ventilated with positive end-expiratory pressure. After left thoracotomy and pericardiotomy, the left coronary artery was permanently ligated 2 mm from the origin with a 6-0 silk suture, and then the chest was closed. Limb lead ECG was constantly monitored throughout the procedure, and the induction of MI was identified by ST segment elevation in lead II (Fig. 1). Coronary ligation was performed in 162 rats. The same procedure was performed for sham-operated control (n=11), but the coronary ligature was left untied. MI rats surviving the operation for 3 h (n=131) were randomly assigned to two groups: (1) recombinant human G-CSF (20 µg/kg/day, Kyowa Hakko Kogyo, Tokyo, Japan) administered subcutaneously for 7 days (MI-GCSF, n=63), and (2) placebo-treated control (MI-saline, n=68). Rats were housed under standardized conditions with free access to standard diet and drinking water. Eighty-seven rats (MI-saline, n=44; MI-GCSF, n=43) survived and were sacrificed 1, 3, 7, and 14 days after surgery according to the study protocol.


Figure 1
View larger version (9K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 1 Representative ECG trace in lead II, showing ST segment elevation as index of ischemia induced by left coronary artery ligation.

 
2.2. Peripheral neutrophil count
A 0.5 ml blood sample was serially (on days 1, 3, 7, and 14) drawn from the tail vein to measure peripheral neutrophil count. Total white blood cell count was determined with an automated hematology analyzer (XE-2100, Sysmex, Kobe, Japan). Peripheral blood smears were stained with Wright–Giemsa, and neutrophil count was obtained after differential cell counting of white blood cells performed under a light microscope on 200 stained cells. Five animals in each group were studied.

2.3. Echocardiographic, hemodynamic and heart weight measurements
Animals (sham-operated rats, n=7; MI-saline, n=10; MI-GCSF, n=9) were lightly anesthetized with intraperitoneal pentobarbital 2 weeks after MI. Two-dimensional and M-mode echocardiographic (8.5-MHz linear transducer; EnVisor C, Philips Medical Systems, Andover, MA, USA) images were obtained to assess LV end-diastolic dimension (LVEDD) and LV end-systolic dimension (LVESD) at the mid-papillary muscle level and LV fractional shortening (FS) was calculated: FS (%)=[(LVEDD–LVESD)/LVEDD] x 100. After echocardiography, a miniature pressure transducer (SPC-320, Millar Instruments, Houston, TX, USA) was placed in the right carotid artery and then advanced retrogradely into the LV. Electrocardiogram and pressure were recorded continuously on a PC using a data acquisition system (PowerLab, ADInstruments, Colorado Springs, CO, USA). LV pressure, rate of rise in LV pressure (dP/dt), and heart rate were obtained. LV systolic pressure, maximum and minimum values of dP/dt, and heart rate were determined by averaging the data of 10 consecutive beats. The hearts were excised, divided into LV and RV, and each was weighed separately. The investigators who performed these procedures were blinded regarding sham vs. MI and saline vs. G-CSF.

2.4. Total RNA and protein isolation
At 1, 3, 7, and 14 days after surgery, rats were sacrificed for RNA and protein analysis. Twenty-four animals in each group (six each at 1, 3, 7, and 14 days post-MI) were studied. After the hearts were rapidly excised, the RV free wall was trimmed away, and the infarcted area was cut from the noninfarcted region. The infarct border was included in the infarcted area. Both infarcted and noninfarcted tissues were snap frozen in liquid nitrogen, and then preserved at –80 °C. LV of sham-operated rats (on day 14, n=4) was collected for control.

Total RNA was isolated by a modification of the acid guanidinium thiocyanate and phenol/chroloform extraction method. After homogenizing the heart tissues with a Polytron homogenizer in Trizol-Reagent (Invitrogen, Carlsbad, CA, USA), total RNA was extracted with chloroform and samples were centrifuged at 12,000 x g for 15 min at 4 °C. RNA was precipitated by addition of isopropanol, and the pellet was dissolved in diethyl pyrocarbonate water. Total RNA concentration was determined by spectrophotometric analysis at 260 nm. For Western blot analysis, frozen tissue was homogenized in PBS buffer containing 0.5% Triton X-100, 0.01% sodium azide, and protease inhibitors. After centrifugation at 16,000 x g for 30 min at 4 °C, the supernatants were collected. Protein concentrations were measured using Coomassie protein assay reagent (Pierce Biotechnology, Rockford, IL, USA) based on the Bradford assay.

2.5. Real-time quantitative RT-PCR
Real-time quantitative RT-PCR of each sample was carried out with a TaqMan RNA PCR kit and ABI PrismTM 7700 Sequence Detection System (Applied Biosystems, Foster City, CA, USA) according to the manufacturer's instructions. Sequence-specific PCR primers and TaqMan probes for TGF-β1, procollagen type I and type III, interleukin (IL)-6, and tumor necrosis factor (TNF)-{alpha} were designed using Primer Express software version 1.7 (Applied Biosystems); see Table 1 for details. Reverse transcription was performed at 48 °C for 30 min using TaqMan Reverse Transcription reagents (Applied Biosystems). PCR reactions were performed in triplicate for 10 min at 95 °C for DNA polymerase activation, followed by 40 cycles of 15 s at 95 °C and 1 min at 60 °C with a final 25 °C hold, using a PCR reaction mixture containing 25 µl Mastermix (TaqMan, Applied Biosystems), 900 nM forward and reverse primers, 200 nM TaqMan probe, and 200 ng cDNA in a total volume of 50 µl. The threshold number of cycles (CT) was calculated by determining the point at which the fluorescence intensity was 10 times larger than the standard deviation of the baseline fluorescence. For each sample, CT values were subtracted from that of the housekeeping gene, GAPDH, to generate the CT value.


View this table:
[in this window]
[in a new window]

  		Table 1 Primer sets and TaqMan probes used for real-time quantitative RT-PCR analysis

 
2.6. Western blot analysis
Western blot analysis was carried out as previously described [22]. Equal amounts of 50 µg protein were electrophoresed on 10% SDS polyacrylamide gels (150 V, 60 min). Proteins were electroblotted onto nitrocellulose membranes (Amersham Biosciences, Piscataway, NJ, USA) for 60 min at 100 V. After blocking with 5% non-fat dried milk in PBS for 60 min, the membranes were incubated with rabbit polyclonal anti-rat TGF-β1 antibody (1:200, Santa Cruz Biotechnology, Santa Cruz, CA, USA) for 60 min, followed by exposure to horseradish peroxidase-linked anti-rabbit immunogloblin (1:5000, Amersham) for 30 min. The immunoblots were developed by enhanced chemiluminofluorescence method. The signals were quantified by densitometry (GS-800, Bio-Rad, Hercules, CA, USA).

2.7. Infarct size and expansion index measurement
At 7 days after MI, 30 mM potassium chloride was injected intravenously to cause cardiac arrest in diastole. The hearts (n=5 in each group) were excised, fixed with 10% formaldehyde, and embedded in paraffin for histological analysis, including measurement of infarct size, expansion index, collagen volume fraction, and infiltrating neutrophils. After fixation, the hearts were cut transversely from apex to base into four equal slices. The sections were stained with hematoxylin–eosin and Masson's trichrome. The boundary lengths of the infarcted and noninfarcted endocardial and epicardial surfaces of all slices were traced using Scion Image software (Scion, Frederick, MD, USA), and the infarct size was determined as the percentage of infarcted epicardium and endocardium of the LV [23]. The area of the LV cavity and total LV, and thickness of the septum and scar in sections at the papillary muscle level were measured, and then the expansion index was calculated as previously described [24]: Expansion Index=(LV Cavity Area/Total LV Area) x (Noninfarcted Septal Thickness/Scar Thickness). The investigators who performed the measurements of infarct size, expansion index, collagen volume fraction, and infiltrating neutrophil count were blinded as to MI-saline vs. MI-GCSF.

2.8. Collagen volume fraction
To analyze collagen accumulation, the sections were stained with picrosirius red. Deparaffinized sections were incubated with picrosirius red (0.1%) in saturated picric acid solution for 90 min. Sixteen separate areas of high power fields in each section were visualized under polarized light and photographed with the same exposure time. The collagen volume fraction (CVF) in the infarcted and noninfarcted area was calculated as the percentage of stained tissue in the sum of muscle area and connective tissue [25] by densitometric method using Scion Image software (Scion).

2.9. Immunohistochemistry
Immunohistochemical studies were performed by immunoperoxidase methods. Paraffin-embedded specimens were cut into 6-µm-thick sections and mounted on slides, followed by deparaffinization in xylene and dehydration through a graded series of ethanol concentrations. After washing the sections, they were incubated with polyclonal rabbit anti-human myeloperoxidase antibody (MPO, DAKO, Glostrup, Denmark) for 60 min to identify the infiltration of granulocytes. The sections were then treated with peroxidase-conjugated anti-rabbit antibody (Envison kit, DAKO) for 30 min. The reaction was visualized with 3,3'-diamino-benzidine tetrahydrochloride (DAB) as a substrate (DAKO). Neutrophil quantitation was performed by counting the number of MPO-positive cells in 10 grid fields with a total area of 0.1 mm2.

2.10. Statistics
All data were expressed as mean ± S.E.M. Comparisons between two groups were performed using Student's t-test. When more than two groups were analyzed, one-way analysis of variance followed by Scheffe's post hoc test was employed. A value of P<0.05 was considered significant.


   3. Results
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
4. Discussion
 References
 
3.1. Peripheral neutrophil count
Neutrophil counts in the drawn peripheral blood are shown in Fig. 2. After MI was induced, the peripheral neutrophil count in MI-saline was increased on day 1, and then decreased. The neutrophil count in MI-GCSF showed a greater increase than that in MI-saline on day 1, was elevated until day 7, and decreased thereafter. Thus, there was a prolonged augmented response of peripheral neutrophil count to G-CSF after MI induction.


Figure 2
View larger version (14K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 2 Peripheral neutrophil counts after MI. The increase of neutrophil count was greater and more prolonged in MI-GCSF group (lhblk) than in MI-saline group (bullet). *P<0.05 vs. MI-saline.

 
3.2. LV functional analysis
Left and right ventricular weight per body weight, heart rate and left ventricular systolic pressure in both the MI-GCSF and MI-saline groups did not differ significantly on day 14. Left ventricular end-diastolic pressure (LVEDP) was lower in MI-GCSF than in MI-saline (Table 2). Maximum dP/dt was higher in MI-GCSF than in MI-saline. MI-GCSF had significantly lower LVEDD and LVESD, and higher FS compared to MI-saline (Table 2).


View this table:
[in this window]
[in a new window]

  		Table 2 Heart weight, echocardiographic and hemodynamic data 14 days after induction of MI or sham operation

 
3.3. Myocardial RNA expression
mRNA expression of TGF-β1 in the infarcted area of MI-saline was elevated on day 1, peaked on day 3 up to approximately 7.5-fold compared to that of sham-operated rats, and then slowly declined. TGF-β1 mRNA expression in the infarcted area of MI-GCSF also showed a peak level on day 3, the same as MI-saline, whereas the maximum value of MI-GCSF was significantly higher than that of MI-saline (Fig. 3A). In the noninfarcted area, mRNA expression level of TGF-β1 did not differ between the two groups during the entire study period (Fig. 3B). Procollagen type I and type III mRNA expression levels in the infarcted area of MI-GCSF reached their peaks on day 3, whereas those of MI-saline increased gradually, showing peaks on day 7, and then decreased. Their peak expression was earlier and higher in MI-GCSF compared with MI-saline (Fig. 3C,D). No difference in IL-6 and TNF-{alpha} mRNA expression levels in the infarcted area was observed between MI-saline and MI-GCSF at each time point (Fig. 3E,F).


Figure 3
View larger version (32K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 3 Real-time quantitative RT-PCR analyses of TGF-β1 gene expression in infarcted (A) and noninfarcted (B) myocardium, and of procollagen type I (C), type III (D), IL-6 (E), and TNF-{alpha} (F) gene expression in infarcted myocardium. Bars represent mRNA levels relative to GAPDH mRNA level for MI-saline (open bars) and MI-GCSF (closed bars). Data are presented as the ratio to sham. Values are mean ± S.E.M. *P<0.05 vs. MI-saline.

 
3.4. Western blot analysis
Levels of TGF-β1 protein in the infarcted area at different time point were analyzed by Western blotting. We mainly observed bands corresponding to the latent form of TGF-β1 at 50 kDa in each lane (Fig. 4). There was an increase in TGF-β1 protein in the infarcted area in both the MI-GCSF and MI-saline groups compared to sham at each time point. Highest TGF-β1 expression was noted on day 3 in each group, and MI-GCSF showed significantly higher expression of TGF-β1 than MI-saline.


Figure 4
View larger version (34K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 4 Western blot analysis of TGF-β1 in infarcted myocardium. Bars represent protein levels relative to sham for MI-saline (open bars) and MI-GCSF (closed bars). Values are mean ± S.E.M. *P<0.05 vs. MI-saline. {dagger}P<0.05 vs. sham.

 
3.5. Infarct size and morphology
Both MI-GCSF and MI-saline groups had similar infarct size (49 ± 3% vs. 50 ± 2%, P=NS, Fig. 5). However, MI-GCSF showed less chamber dilatation and less ventricular hypertrophy in the noninfarcted area (Fig. 6A,B). The expansion index was significantly lower in MI-GCSF than in MI-saline (1.51 ± 0.09 vs. 1.81 ± 0.07, P<0.05, Fig. 5). High-power field of Masson's trichrome-stained sections showed more collagen accumulation in the infarcted area in MI-GCSF than in MI-saline (Fig. 6C,D).


Figure 5
View larger version (11K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 5 Infarct size and expansion index in MI-saline and MI-GCSF groups. Values are mean ± S.E.M. *P<0.05 vs. MI-saline.

 

Figure 6
View larger version (99K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 6 Representative Masson's trichrome-stained cross sections of infarcted hearts and magnified images of infarcted area (A, C: MI-saline; B, D: MI-GCSF). Scale bars represent 1 mm (A, B) and 50 µm (C, D).

 
3.6. CVF and neutrophil infiltration
Representative picrosirius red-stained sections with polarized light are shown in Fig. 7A (MI-saline) and B (MI-GCSF). Quantitative analysis indicated that CVF in the infarcted area was significantly greater in MI-GCSF compared to that in MI-saline (24 ± 2% vs. 18 ± 2%, P<0.05, Fig. 7C), although CVF in the noninfarcted area did not differ between the two groups (3.2 ± 0.5% vs. 3.5 ± 0.6%, P=NS, Fig. 7D). MPO staining showed that infiltrating neutrophil count in the infarcted myocardium was not significantly different between MI-GCSF and MI-saline (33 ± 3 vs. 35 ± 3 cells/mm2, P=NS).


Figure 7
View larger version (91K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 7 Representative picrosirius red-stained sections of infarcted area in MI-saline (A) and MI-GCSF (B) groups, showing characteristic bright yellow of collagen fibrils under polarized light. Scale bar indicates 100 µm. Collagen volume fraction of infarcted (C) and noninfarcted (D) myocardium. Values are mean ± S.E.M. *P<0.05 vs. MI-saline.

 

   4. Discussion
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
 4. Discussion
References
 
This study demonstrated that G-CSF administration after MI attenuates post-infarct ventricular expansion, in association with increased TGF-β1 and collagen expression in the infarcted area during the early phase of MI. Collagen analysis showed more markedly enhanced collagen deposition in G-CSF-treated MI than in control MI. G-CSF administration after MI might be beneficial to attenuate infarct expansion through accelerating reparative fibrosis in the infarcted area.

4.1. Effects of G-CSF on post-MI remodeling
Since the hypothesis that bone marrow hematopoietic stem cells regenerate infarcted myocardium was proposed, G-CSF has received attention as a cytokine that mobilizes bone marrow stem cells into the peripheral circulation [26,27]. Previously, G-CSF administration in combination with stem cell factor was reported to have a beneficial effect on LV remodeling after MI by inducing the differentiation of mobilized hematopoietic stem cells into cardiac myocytes [16]. Contrary to this concept, recent studies revealed that hematopoietic stem cells do not transdifferentiate into cardiac myocytes, but develop into mature hematopoietic cells under ischemic conditions [17,18,28]. Our data, showing no difference in infarct size after G-CSF treatment, appear to be consistent with their data. Another recent report showed an increase in neovascularization and a decrease in apoptosis in the border zone, partly explaining the beneficial effect of cytokine therapy [29]. However, in the permanent coronary occlusion model with a large MI, salvage of the border zone could not fully prevent infarct expansion. Shortly after coronary ligation, inflammatory cells such as neutrophils, monocytes and macrophages infiltrate, and then the necrotic myocytes in the injured myocardium are replaced by collagen fibers [23]. This process uniformly occurs in the whole infarcted area, and determines the degree of early infarct expansion. It is likely that the potential benefit of cytokine therapy might be derived from its impact on the repair process within the damaged tissue.

Our current study suggested that accelerated collagen accumulation caused by G-CSF was associated with better LV function after MI. Collagen synthesis, which is promoted by TGF-β1, has different significance in infarcted and noninfarcted areas [7,30–33]. Although inappropriately deposited collagen fibers in noninfarcted areas during the late phase of MI would lead to increased wall stiffness and decreased contractility of the LV, the formation of a collagen network as a replacement for necrotic myocardium may be an essential process. The accumulation of collagen fibers, which is known as reparative fibrosis, may reinforce the flail myocardium in order to yield stress tolerance and limit ventricular expansion. In an experimental model using β2-adrenergic receptor transgenic mice, the resultant increase of collagen content in the infarcted area was associated with a lower risk of cardiac rupture and less infarct expansion during the acute phase of MI [34]. In other studies using osteopontin knockout mice or rats with ETA receptor blockade, decreased collagen content in the infarcted area was associated with enhanced infarct expansion, suggesting the significance of collagen synthesis in post-MI remodeling [35,36]. Among fibrillar collagens, type I and type III are the major components in the MI heart. A previous study showed that mRNA levels of these collagens were increased around day 2, reaching a peak level on day 7 [33]. Our data, in which expression of procollagen type I and type III mRNA in the infarcted area was upregulated as early as 3 days after MI, suggested promotion of reparative fibrosis by G-CSF treatment. The enhanced TGF-β1 mRNA expression level in the early phase of MI by G-CSF treatment might contribute to early collagen synthesis in fibroblasts. Moreover, the mRNA levels of procollagens in the noninfarcted area did not differ between MI-saline and MI-GCSF. These findings might indicate that, at least within 2 weeks, reactive fibrosis in the noninfarcted myocardium was not promoted by G-CSF.

In our experimental system, we mainly observed bands corresponding to 50 kDa in immunoblotting for TGF-β1. Presumably the bands represent the 50 kDa small latent TGF-β1 complex, which consists of mature TGF-β1 and latency associated protein, as previously described [37,38]. TGF-β1 is secreted in a latent form within the extracellular matrix, and is converted to biologically active TGF-β1 by proteases under tight regulation. It was reported that the 50 kDa small latent complex of TGF-β1 possesses bioactivity [38], and is essential for regulation of the bioavailability of this cytokine [39]. Hence, the increase in expression of the latent TGF-β1 complex by G-CSF in our experiment would reflect, to a certain extent, the augmented activity of TGF-β1, which stimulates fibroblast proliferation and promotes the synthesis of extracellular matrix components.

One possible mechanism responsible for the greater collagen content in the G-CSF-treated infarcted heart appears to be the property of this cytokine to modulate the inflammatory reaction. It is recognized that the inflammatory process is essential for ventricular remodeling. We have reported that an extreme inflammatory response after MI was related to a poor clinical outcome such as ventricular rupture or congestive heart failure [9,10]. However, when inflammation is completely suppressed by corticosteroid, reparative fibrosis contributing to cardiac geometric maintenance would be delayed disadvantageously [12–14,40]. There have been several lines of evidence that G-CSF modulates the inflammatory response and promotes the repair process after tissue damage. Administration of G-CSF resulted in facilitated healing of diabetic foot ulcers and doxorubicin-induced skin wounds, and enhanced early endothelialization in implanted vascular grafts [20,41,42]. Besides, G-CSF has a profibrotic property, enhancing the expression of TGF-β1 in peripheral inflammatory cells [43,44]. In bleomycin-induced acute lung injury rats, G-CSF exacerbated pulmonary fibrosis [45]. Therefore, the profibrotic character of this cytokine may be the driving force to accelerate wound healing.

The effect of G-CSF on circulating cytokine levels should also be considered. In addition to increasing the number of neutrophils, G-CSF alters the production of other cytokines such as TNF-{alpha} [46]. It is possible that treatment with G-CSF might affect post-MI remodeling through altered systemic cytokine profiles. Nevertheless, serum cytokine levels including those of TNF-{alpha}, IL-6, and TGF-β1 were not significantly changed in our experimental setting (data not shown). Local rather than systemic effects on cytokine production would be plausible as mechanisms of the improved post-MI remodeling by G-CSF treatment.

G-CSF receptors have been identified not exclusively on neutrophils lineage cells, but also on monocytes, macrophages, and lymphocytes [47–50]. G-CSF stimulates a variety of different cellular activities depending on the cells to which they bind. Its effect on the repair process may be mediated through a synergistic effect on local immunological effector cells and the mediators they produce. During the early phase of MI, G-CSF may act on the infiltrating cells and promote the secretion of cytokines including TGF-β1 predominantly in the infarcted area where the inflammatory cells concentrate. It is possible that G-CSF may play a role to preserve structural integrity through collagen synthesis and accumulation.

4.2. Limitations
Our current experiments were performed in rats. Since differences in the responsiveness to G-CSF between species have been described [51], caution is needed when applying these results to practical use. The dose of injected G-CSF in the present study was much lower than that in previously described studies using a murine MI model in order to mobilize bone marrow stem cells into the peripheral circulation [16,29]. A relatively low dose of G-CSF might be sufficient to promote the wound healing process rather than tissue regeneration [41]. In addition, our results were obtained in an open-chest permanent coronary occlusion model. However, in the practical situation, MI is chiefly caused by spontaneous plaque rupture and thrombus formation, and is mostly treated with reperfusion therapy. A recent clinical trial showed that intracoronary infusion of peripheral blood stem cells mobilized by G-CSF after coronary stenting in MI led to a high rate of restenosis, which was assumed to be due to the effect on neointimal proliferation [52]. The timing and duration of G-CSF administration are also issues that remain to be addressed. TGF-β1 contributes to myocardial hypertrophy and heart failure by acting in concert with angiotensin II [53]. Prolonged upregulation of TGF-β1 might ultimately result in deterioration of the heart's condition. Further studies including a longer-term observation are needed to confirm the effectiveness and safety of G-CSF therapy.

4.3. Conclusion
Our results indicate that G-CSF treatment improves early post-infarct cardiac remodeling, through, at least in part, promotion of reparative collagen synthesis in the infarcted area, suggesting a beneficial effect of G-CSF on the infarct healing process.


   Acknowledgements
 
This work was supported by a Grant-in-Aid for Scientific Research 14570693 (T.A.) and 16790433 (Y.S.) from the Japan Ministry of Education, Culture, Sports, Science and Technology.


   Notes
 
Time for primary review 23 days


   References
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
 4. Discussion
 References
 

  1. Pfeffer M.A., Braunwald E. Ventricular remodeling after myocardial infarction. Experimental observations and clinical implications. Circulation (1990) 81:1161–1172.[Abstract/Free Full Text]
  2. Sutton M.G., Sharpe N. Left ventricular remodeling after myocardial infarction: pathophysiology and therapy. Circulation (2000) 101:2981–2988.[Free Full Text]
  3. Jugdutt B.I., Amy R.W. Healing after myocardial infarction in the dog: changes in infarct hydroxyproline and topography. J. Am. Coll. Cardiol. (1986) 7:91–102.[Abstract]
  4. Whittaker P., Boughner D.R., Kloner R.A. Role of collagen in acute myocardial infarct expansion. Circulation (1991) 84:2123–2134.[Abstract/Free Full Text]
  5. Weber K.T., Sun Y., Tyagi S.C., Cleutjens J.P. Collagen network of the myocardium: function, structural remodeling and regulatory mechanisms. J. Mol. Cell. Cardiol. (1994) 26:279–292.[CrossRef][Web of Science][Medline]
  6. Deten A., Holzl A., Leicht M., Barth W., Zimmer H.G. Changes in extracellular matrix and in transforming growth factor beta isoforms after coronary artery ligation in rats. J. Mol. Cell. Cardiol. (2001) 33:1191–1207.[CrossRef][Web of Science][Medline]
  7. Sun Y., Weber K.T. Infarct scar: a dynamic tissue. Cardiovasc. Res. (2000) 46:250–256.[Abstract/Free Full Text]
  8. Herskowitz A., Choi S., Ansari A.A., Wesselingh S. Cytokine mRNA expression in postischemic/reperfused myocardium. Am. J. Pathol. (1995) 146:419–428.[Abstract]
  9. Anzai T., Yoshikawa T., Shiraki H., Asakura Y., Akaishi M., Mitamura H., et al. C-reactive protein as a predictor of infarct expansion and cardiac rupture after a first Q-wave acute myocardial infarction. Circulation (1997) 96:778–784.[Abstract/Free Full Text]
  10. Takahashi T., Anzai T., Yoshikawa T., Maekawa Y., Asakura Y., Satoh T., et al. Serum C-reactive protein elevation in left ventricular remodeling after acute myocardial infarction–role of neurohormones and cytokines. Int. J. Cardiol. (2003) 88:257–265.[CrossRef][Web of Science][Medline]
  11. Frangogiannis N.G., Smith C.W., Entman M.L. The inflammatory response in myocardial infarction. Cardiovasc. Res. (2002) 53:31–47.[Abstract/Free Full Text]
  12. Hammerman H., Kloner R.A., Hale S., Schoen F.J., Braunwald E. Dose-dependent effects of short-term methylprednisolone on myocardial infarct extent, scar formation, and ventricular function. Circulation (1983) 68:446–452.[Free Full Text]
  13. Silverman H.S., Pfeifer M.P. Relation between use of anti-inflammatory agents and left ventricular free wall rupture during acute myocardial infarction. Am. J. Cardiol. (1987) 59:363–364.[CrossRef][Web of Science][Medline]
  14. Roberts R., DeMello V., Sobel B.E. Deleterious effects of methylprednisolone in patients with myocardial infarction. Circulation (1976) 53:I204–I206.[Medline]
  15. Clark S.C., Kamen R. The human hematopoietic colony-stimulating factors. Science (1987) 236:1229–1237.[Abstract/Free Full Text]
  16. Orlic D., Kajstura J., Chimenti S., Limana F., Jakoniuk I., Quaini F., et al. Mobilized bone marrow cells repair the infarcted heart, improving function and survival. Proc. Natl. Acad. Sci. U. S. A. (2001) 98:10344–10349.[Abstract/Free Full Text]
  17. Balsam L.B., Wagers A.J., Christensen J.L., Kofidis T., Weissman I.L., Robbins R.C. Haematopoietic stem cells adopt mature haematopoietic fates in ischaemic myocardium. Nature (2004) 428:668–673.[CrossRef][Medline]
  18. Murry C.E., Soonpaa M.H., Reinecke H., Nakajima H., Nakajima H.O., Rubart M., et al. Haematopoietic stem cells do not transdifferentiate into cardiac myocytes in myocardial infarcts. Nature (2004) 428:664–668.[CrossRef][Medline]
  19. Hartung T. Immunomodulation by colony-stimulating factors. Rev. Physiol. Biochem. Pharmacol. (1999) 136:1–164.[Web of Science][Medline]
  20. Gough A., Clapperton M., Rolando N., Foster A.V., Philpott-Howard J., Edmonds M.E. Randomised placebo-controlled trial of granulocyte-colony stimulating factor in diabetic foot infection. Lancet (1997) 350:855–859.[CrossRef][Web of Science][Medline]
  21. Edmonds M., Bates M., Doxford M., Gough A., Foster A. New treatments in ulcer healing and wound infection. Diabetes Metab. Res. Rev. (2000) 16(Suppl. 1):S51–S54.[CrossRef][Web of Science][Medline]
  22. Takahashi T., Anzai T., Yoshikawa T., Maekawa Y., Mahara K., Iwata M., et al. Angiotensin receptor blockade improves myocardial beta-adrenergic receptor signaling in postinfarction left ventricular remodeling: a possible link between beta-adrenergic receptor kinase-1 and protein kinase C epsilon isoform. J. Am. Coll. Cardiol. (2004) 43:125–132.[Abstract/Free Full Text]
  23. Fishbein M.C., Maclean D., Maroko P.R. Experimental myocardial infarction in the rat: qualitative and quantitative changes during pathologic evolution. Am. J. Pathol. (1978) 90:57–70.[Abstract]
  24. Alhaddad I.A., Tkaczevski L., Siddiqui F., Mir R., Brown E.J. Jr. Aspirin enhances the benefits of late reperfusion on infarct shape. A possible mechanism of the beneficial effects of aspirin on survival after acute myocardial infarction. Circulation (1995) 91:2819–2823.[Abstract/Free Full Text]
  25. Whittaker P., Kloner R.A., Boughner D.R., Pickering J.G. Quantitative assessment of myocardial collagen with picrosirius red staining and circularly polarized light. Basic Res. Cardiol. (1994) 89:397–410.[CrossRef][Web of Science][Medline]
  26. Orlic D., Kajstura J., Chimenti S., Jakoniuk I., Anderson S.M., Li B., et al. Bone marrow cells regenerate infarcted myocardium. Nature (2001) 410:701–705.[CrossRef][Medline]
  27. Jackson K.A., Majka S.M., Wang H., Pocius J., Hartley C.J., Majesky M.W., et al. Regeneration of ischemic cardiac muscle and vascular endothelium by adult stem cells. J. Clin. Invest. (2001) 107:1395–1402.[CrossRef][Web of Science][Medline]
  28. Norol F., Merlet P., Isnard R., Sebillon P., Bonnet N., Cailliot C., et al. Influence of mobilized stem cells on myocardial infarct repair in a nonhuman primate model. Blood (2003) 102:4361–4368.[Abstract/Free Full Text]
  29. Ohtsuka M., Takano H., Zou Y., Toko H., Akazawa H., Qin Y., et al. Cytokine therapy prevents left ventricular remodeling and dysfunction after myocardial infarction through neovascularization. FASEB J. (2004) 18:851–853.[Abstract/Free Full Text]
  30. Desmouliere A., Geinoz A., Gabbiani F., Gabbiani G. Transforming growth factor-beta 1 induces alpha-smooth muscle actin expression in granulation tissue myofibroblasts and in quiescent and growing cultured fibroblasts. J. Cell Biol. (1993) 122:103–111.[Abstract/Free Full Text]
  31. O'Kane S., Ferguson M.W. Transforming growth factor βs and wound healing. Int. J. Biochem. Cell Biol. (1997) 29:63–78.[CrossRef][Web of Science][Medline]
  32. Litwin S.E., Litwin C.M., Raya T.E., Warner A.L., Goldman S. Contractility and stiffness of noninfarcted myocardium after coronary ligation in rats. Effects of chronic angiotensin converting enzyme inhibition. Circulation (1991) 83:1028–1037.[Abstract/Free Full Text]
  33. Cleutjens J.P., Verluyten M.J., Smiths J.F., Daemen M.J. Collagen remodeling after myocardial infarction in the rat heart. Am. J. Pathol. (1995) 147:325–338.[Abstract]
  34. Gao X.M., Dilley R.J., Samuel C.S., Percy E., Fullerton M.J., Dart A.M., et al. Lower risk of postinfarct rupture in mouse heart overexpressing beta 2-adrenergic receptors: importance of collagen content. J. Cardiovasc. Pharmacol. (2002) 40:632–640.[CrossRef][Web of Science][Medline]
  35. Trueblood N.A., Xie Z., Communal C., Sam F., Ngoy S., Liaw L., et al. Exaggerated left ventricular dilation and reduced collagen deposition after myocardial infarction in mice lacking osteopontin. Circ. Res. (2001) 88:1080–1087.[Abstract/Free Full Text]
  36. Fraccarollo D., Galuppo P., Bauersachs J., Ertl G. Collagen accumulation after myocardial infarction: effects of ETA receptor blockade and implications for early remodeling. Cardiovasc. Res. (2002) 54:559–567.[Abstract/Free Full Text]
  37. Jung J.C., Park G.T., Kim K.H., Woo J.H., An J.M., Kim K.C., et al. Differential expression of transforming growth factor-beta in the interstitial tissue of testis during aging. J. Cell. Biochem. (2004) 92:92–98.[CrossRef][Web of Science][Medline]
  38. Baillie R., Coombes R.C., Smith J. Multiple forms of TGF-beta 1 in breast tissues: a biologically active form of the small latent complex of TGF-beta 1. Eur. J. Cancer (1996) 32A:1566–1573.[CrossRef]
  39. Annes J.P., Munger J.S., Rifkin D.B. Making sense of latent TGFbeta activation. J. Cell Sci. (2003) 116:217–224.[Abstract/Free Full Text]
  40. Kloner R.A., Fishbein M.C., Lew H., Maroko P.R., Braunwald E. Mummification of the infarcted myocardium by high dose corticosteroids. Circulation (1978) 57:56–63.[Abstract/Free Full Text]
  41. Vargel I., Erdem A., Ertoy D., Pinar A., Erk Y., Altundag M.K., et al. Effects of growth factors on doxorubicin-induced skin necrosis: documentation of histomorphological alterations and early treatment by GM-CSF and G-CSF. Ann. Plast. Surg. (2002) 49:646–653.[CrossRef][Web of Science][Medline]
  42. Bhattacharya V., Shi Q., Ishida A., Sauvage L.R., Hammond W.P., Wu M.H. Administration of granulocyte colony-stimulating factor enhances endothelialization and microvessel formation in small-caliber synthetic vascular grafts. J. Vasc. Surg. (2000) 32:116–123.[CrossRef][Web of Science][Medline]
  43. Zavala F., Abad S., Ezine S., Taupin V., Masson A., Bach J.F. G-CSF therapy of ongoing experimental allergic encephalomyelitis via chemokine- and cytokine-based immune deviation. J. Immunol. (2002) 168:2011–2019.[Abstract/Free Full Text]
  44. Hirayama Y., Sakamaki S., Matsunaga T., Kuroda H., Kusakabe T., Akiyama T., et al. Granulocyte-colony stimulating factor enhances the expression of transforming growth factor-beta mRNA in CD4-positive peripheral blood lymphocytes in the donors for allogeneic peripheral blood stem cell transplantation. Am. J. Hematol. (2002) 69:138–140.[CrossRef][Web of Science][Medline]
  45. Azoulay E., Herigault S., Levame M., Brochard L., Schlemmer B., Harf A., et al. Effect of granulocyte colony-stimulating factor on bleomycin-induced acute lung injury and pulmonary fibrosis. Crit. Care Med. (2003) 31:1442–1448.[CrossRef][Web of Science][Medline]
  46. Xu S., Hoglund M., Hakansson L., Venge P. Granulocyte colony-stimulating factor (G-CSF) induces the production of cytokines in vivo. Br. J. Haematol. (2000) 108:848–853.[CrossRef][Web of Science][Medline]
  47. Shieh J.H., Peterson R.H., Moore M.A. Modulation of granulocyte colony-stimulating factor receptors on murine peritoneal exudate macrophages by tumor necrosis factor-alpha. J. Immunol. (1991) 146:2648–2653.[Abstract]
  48. Boneberg E.M., Hareng L., Gantner F., Wendel A., Hartung T. Human monocytes express functional receptors for granulocyte colony-stimulating factor that mediate suppression of monokines and interferon-gamma. Blood (2000) 95:270–276.[Abstract/Free Full Text]
  49. Morikawa K., Morikawa S., Nakamura M., Miyawaki T. Characterization of granulocyte colony-stimulating factor receptor expressed on human lymphocytes. Br. J. Haematol. (2002) 118:296–304.[CrossRef][Web of Science][Medline]
  50. Franzke A., Piao W., Lauber J., Gatzlaff P., Konecke C., Hansen W., et al. G-CSF as immune regulator in T cells expressing the G-CSF receptor: implications for transplantation and autoimmune diseases. Blood (2003) 102:734–739.[Abstract/Free Full Text]
  51. Wheeler J.G., Huffine M.E., Childress S., Sikes J. Comparison of colony stimulation factors on in vitro rat and human neutrophil function. Biol. Neonate (1994) 66:214–220.[Web of Science][Medline]
  52. Kang H.J., Kim H.S., Zhang S.Y., Park K.W., Cho H.J., Koo B.K., et al. Effects of intracoronary infusion of peripheral blood stem-cells mobilised with granulocyte-colony stimulating factor on left ventricular systolic function and restenosis after coronary stenting in myocardial infarction: the MAGIC cell randomised clinical trial. Lancet (2004) 363:751–756.[CrossRef][Web of Science][Medline]
  53. Rosenkranz S. TGF-beta(1) and angiotensin networking in cardiac remodeling. Cardiovasc. Res. (2004) 63:423–432.[Abstract/Free Full Text]

Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 Am. J. Physiol. Heart Circ. Physiol.Home page
G. E. Gonzalez, I. M. Seropian, M. L. Krieger, J. Palleiro, M. A. Lopez Verrilli, M. M. Gironacci, S. Cavallero, L. Wilensky, V. H. Tomasi, R. J. Gelpi, et al.
Effect of early versus late AT1 receptor blockade with losartan on postmyocardial infarction ventricular remodeling in rabbits
Am J Physiol Heart Circ Physiol, July 1, 2009; 297(1): H375 - H386.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Heart Circ. Physiol.Home page
H. Okada, G. Takemura, K.-i. Kosai, A. Tsujimoto, M. Esaki, T. Takahashi, S. Nagano, H. Kanamori, S. Miyata, Y. Li, et al.
Combined therapy with cardioprotective cytokine administration and antiapoptotic gene transfer in postinfarction heart failure
Am J Physiol Heart Circ Physiol, March 1, 2009; 296(3): H616 - H626.
[Abstract] [Full Text] [PDF]

Home page
 Cardiovasc ResHome page
T. Kohno, T. Anzai, K. Naito, T. Miyasho, M. Okamoto, H. Yokota, S. Yamada, Y. Maekawa, T. Takahashi, T. Yoshikawa, et al.
Role of high-mobility group box 1 protein in post-infarction healing process and left ventricular remodelling
Cardiovasc Res, February 15, 2009; 81(3): 565 - 573.
[Abstract] [Full Text] [PDF]

Home page
 Cardiovasc ResHome page
Z. Cheng, L. Ou, Y. Liu, X. Liu, F. Li, B. Sun, Y. Che, D. Kong, Y. Yu, and G. Steinhoff
Granulocyte colony-stimulating factor exacerbates cardiac fibrosis after myocardial infarction in a rat model of permanent occlusion
Cardiovasc Res, December 1, 2008; 80(3): 425 - 434.
[Abstract] [Full Text] [PDF]

Home page
 J. Immunol.Home page
K. Naito, T. Anzai, Y. Sugano, Y. Maekawa, T. Kohno, T. Yoshikawa, K. Matsuno, and S. Ogawa
Differential Effects of GM-CSF and G-CSF on Infiltration of Dendritic Cells during Early Left Ventricular Remodeling after Myocardial Infarction
J. Immunol., October 15, 2008; 181(8): 5691 - 5701.
[Abstract] [Full Text] [PDF]

Home page
 Ann. Thorac. Surg.Home page
S. Fukui, S. Kitagawa-Sakakida, S. Kawamata, G. Matsumiya, N. Kawaguchi, N. Matsuura, and Y. Sawa
Therapeutic Effect of Midkine on Cardiac Remodeling in Infarcted Rat Hearts
Ann. Thorac. Surg., February 1, 2008; 85(2): 562 - 570.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Pathol.Home page
H. Morimoto, M. Takahashi, Y. Shiba, A. Izawa, H. Ise, M. Hongo, K. Hatake, K. Motoyoshi, and U. Ikeda
Bone Marrow-Derived CXCR4+ Cells Mobilized by Macrophage Colony-Stimulating Factor Participate in the Reduction of Infarct Area and Improvement of Cardiac Remodeling after Myocardial Infarction in Mice
Am. J. Pathol., September 1, 2007; 171(3): 755 - 766.
[Abstract] [Full Text] [PDF]

Home page
 CirculationHome page
D. E. Sosnovik, M. Nahrendorf, N. Deliolanis, M. Novikov, E. Aikawa, L. Josephson, A. Rosenzweig, R. Weissleder, and V. Ntziachristos
Fluorescence Tomography and Magnetic Resonance Imaging of Myocardial Macrophage Infiltration in Infarcted Myocardium In Vivo
Circulation, March 20, 2007; 115(11): 1384 - 1391.
[Abstract] [Full Text] [PDF]

Home page
 Eur Heart J SupplHome page
H. Ince, T. C. Rehders, S. Kische, S. Drawert, E. Adolf, T. Kleinfeldt, M. Petzsch, and C. A. Nienaber
G-CSF in the setting of acute myocardial infarction
Eur. Heart J. Suppl., December 1, 2006; 8(suppl_H): H40 - H45.
[Abstract] [Full Text] [PDF]

Home page
 FASEB J.Home page
E. Deindl, M.-M. Zaruba, S. Brunner, B. Huber, U. Mehl, G. Assmann, I. E. Hoefer, J. Mueller-Hoecker, and W.-M. Franz
G-CSF administration after myocardial infarction in mice attenuates late ischemic cardiomyopathy by enhanced arteriogenesis
FASEB J, May 1, 2006; 20(7): 956 - 958.
[Abstract] [Full Text] [PDF]

Home page
 Cardiovasc ResHome page
P. Kanellakis, N. J. Slater, X.-J. Du, A. Bobik, and D. J. Curtis
Granulocyte colony-stimulating factor and stem cell factor improve endogenous repair after myocardial infarction
Cardiovasc Res, April 1, 2006; 70(1): 117 - 125.
[Abstract] [Full Text] [PDF]

Home page
 JAMAHome page
D. Zohlnhofer, I. Ott, J. Mehilli, K. Schomig, F. Michalk, T. Ibrahim, G. Meisetschlager, J. von Wedel, H. Bollwein, M. Seyfarth, et al.
Stem Cell Mobilization by Granulocyte Colony-Stimulating Factor in Patients With Acute Myocardial Infarction: A Randomized Controlled Trial
JAMA, March 1, 2006; 295(9): 1003 - 1010.
[Abstract] [Full Text] [PDF]

Home page
 J Am Coll CardiolHome page
T. Yano, T. Miura, P. Whittaker, T. Miki, J. Sakamoto, Y. Nakamura, Y. Ichikawa, Y. Ikeda, H. Kobayashi, K. Ohori, et al.
Macrophage Colony-Stimulating Factor Treatment After Myocardial Infarction Attenuates Left Ventricular Dysfunction by Accelerating Infarct Repair
J. Am. Coll. Cardiol., February 7, 2006; 47(3): 626 - 634.
[Abstract] [Full Text] [PDF]

Home page
 JEMHome page
M. T. Kuhlmann, P. Kirchhof, R. Klocke, L. Hasib, J. Stypmann, L. Fabritz, M. Stelljes, W. Tian, M. Zwiener, M. Mueller, et al.
G-CSF/SCF reduces inducible arrhythmias in the infarcted heart potentially via increased connexin43 expression and arteriogenesis
J. Exp. Med., January 23, 2006; 203(1): 87 - 97.
[Abstract] [Full Text] [PDF]

Home page
 Circ. Res.Home page
L. C. Becker
Yin and Yang of MCP-1
Circ. Res., April 29, 2005; 96(8): 812 - 814.
[Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow E-letters: Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when E-letters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Right arrow Disclaimer
Google Scholar
Right arrow Articles by Sugano, Y.
Right arrow Articles by Ogawa, S.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Sugano, Y.
Right arrow Articles by Ogawa, S.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?