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Serial measurement of serum basic fibroblast growth factor in patients with acute cerebral infarction
Neuroscience Letters 393 (2006) 56–59
Serial measurement of serum basic fibroblast growth factor in patients with acute cerebral infarction Huailian Guo a,∗ , Li Huang a , Min Cheng a , Xin Jin b , Yafeng Zhao c , Ming Yi a a
Department of Neurology, People’s Hospital, Peking University, 11 Xi Zhi Men Nan Da Jie, Beijing 100044, China b Department of Neurology, Fuxing Hospital, 100045 Beijing, China c Department of Neurology, Shougang Hospital, 100041 Beijing, China Received 2 August 2005; received in revised form 15 September 2005; accepted 16 September 2005
Abstract Basic fibroblast growth factor (bFGF) has been reported to be involved in the pathophysiological changes following cerebral infarction. Basic fibroblast growth factor is upregulated in the brain and conduces to neuroprotection and angiogenesis in experimental brain ischemia, but the change of serum bFGF in cerebral infarction patients has not been reported. In the present study, we investigated the dynamic changes of serum bFGF in 30 patients with acute cerebral infarction and found that serum bFGF increased significantly after cerebral infarction compared with the control group (p < 0.05). Serum bFGF peaked on day 3 (15.46 ± 5.58 pg/ml; p < 0.01) and remained significantly elevated on day 14 following cerebral infarction. In this study, it was also found that the levels of bFGF with large infarction were higher at each time point than those with moderate or small infarction (p < 0.05). There was a positive correlation between the peak level of bFGF and improvement of clinical neurological deficits scored by Scandinavian Stroke Scale (SSS) (r = 0.596; p < 0.05). These results suggest that the serum bFGF level increased significantly after cerebral infarction and the level of serum bFGF could be of value to estimate the infarction size and clinical prognosis. © 2005 Elsevier Ireland Ltd. All rights reserved. Keywords: Cerebral infarction; Brain ischemia; Stroke; Basic fibroblast growth factor; Infarction size; Scandinavian Stroke Scale
bFGF is a heparin-binding growth factor with multiple biological properties and is widely distributed in the central nervous system (CNS) [2]. Both neurons and glial cells are capable of synthesizing bFGF and it acts as angiogenic factor as it is a potent mitogen for most mesoderm-derived cells (including fibroblasts, smooth muscle cells, pericytes, etc). bFGF stimulates endothelial cell migration [18], proliferation [4], sprouting [11], and tube formation [7]. Several previous studies have elucidated how bFGF promotes angiogenesis in the brain after brain ischemia in animal models [12]. bFGF is also considered to be a neurotrophic factor since it protects neurons against events such as hypoxia [1], neurotoxicity [15], and hypoglycemia injury [14]. In vitro bFGF can induce nerve fiber extension and support the survival of neurons [13,19,20]. Due to the angiogenic, neurotropic, and vessel-dilating [16] properties of bFGF as well as the wide distribution in the CNS, bFGF has been implicated in a number of neurological dis-
∗
Corresponding author. Tel.: +86 10 68314422x5375; fax: +86 10 82801151. E-mail address: [email protected] (H. Guo).
0304-3940/$ – see front matter © 2005 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.neulet.2005.09.043
orders including cerebral infarction. It has been reported that bFGF is upregulated in the brain in experimental brain ischemia [3,10], but the change of serum bFGF in cerebral infarction has not be reported. The purpose of this study was to observe the dynamic change of serum bFGF level in patients with acute cerebral infarction and examine the relationship between the infarction size, the improvement of neurological function, and serum bFGF level. The result of this study may be helpful in understanding more about the pathophysiological changes following cerebral infarction and exploring the clinical application of bFGF in cerebral infarction. The approval for the study was obtained from the local ethics committee and all the patients and controls gave informed consent before participating in this study. The 30 patients with acute supratentorial cerebral infarction were chosen from those admitted to the Department of Neurology, People’s Hospital of Peking University within 48 h after cerebral infarction. Cerebral infarction was confirmed by head CT or MRI scan. Excluded from the study were patients with (a) previous transient ischemic attack (TIA) or stroke or head trauma; (b) severe cardiac, renal, or hepatic disease; (c) cancerous disease; (d) recent history of
H. Guo et al. / Neuroscience Letters 393 (2006) 56–59
infection or infection after admission. Control data was collected from 20 patients undergoing medical examinations having had no recent infection or history of cerebral infarction or transient ischemic attack or head trauma or serious illness, and matched with patient group in sex, age, hypertension, diabetes mellitus, hyperlipidemia, and cardiac disease. Blood samples were taken from cubital vein immediately upon admission (within 48 h), then taken again 3, 7, and 14 days after cerebral infarction. Samples were centrifuged (2000 r/min, 10 min) to segregate serum, then stored at −70 ◦ C till assay. bFGF levels were measured with the method of ELISA. The bFGF immunoassay kit was obtained from R&D systems (Minneapolis, MN, USA). The beginning time of cerebral infarction is the time when a symptom or sign of cerebral infarction appeared. For patients who woke to find symptom or sign of stroke, the beginning time of stroke attack was recorded as the time when he/she went to bed. All patients were evaluated by head CT or MRI. According to the largest diameter of infarct (d), patients were classified as having a large infarction (LI; d > 4 cm), a moderate infarction (MI; 1.5 cm < d < 4 cm) or a small infarction (SI; d < 1.5 cm). Clinical examination was performed on admission (within 48 h) and 20 days after cerebral infarction. The clinical neurology deficits were scored according to the 58-points Scandinavian Stroke Scale (SSS). And the improvement of neurological function of patients was evaluated by SSS (SSS equaled SSS on day 20 subtracted SSS within 48 h). Statistical analysis was performed to identify differences in bFGF levels over time after cerebral infarction as well as infarction size, and to correlate bFGF expression to the improvement of neurological function. The mean bFGF concentrations at four selected time points were compared with control value by the one-sample t-test. The Student–Newman–Keuls test (q-test) was employed to test the differences between bFGF concentrations of patient group at four selected time points. Differences of bFGF levels between SI, MI, and LI subgroups were assessed with ANOVA; all analyses were two-tailed. The relationship between the peak level of bFGF and SSS was determined by Spearman linear correlation analysis. Results were expressed as mean ± S.D. Values were considered significant at p < 0.05. The statistical package SPSS 10.0 was used for all analyses. Thirty patients (19 men and 11 women) aged from 43 to 82 years (mean age 67.5 years) and 20 controls (12 men and 8 women) aged 42–74 years (mean age 62.6 years) were included in this study. Eight patients had large infarction, 10 had moderate infarction, and 12 had small infarction. There was no significant difference in sex ratio, age, or complications with hypertension, diabetes, or hyperlipidemia (p > 0.05; Table 1). The mean levels of bFGF in patients were significantly higher at all selected time points (within 48 h, on day 3, on day 7, and on day 14 after cerebral infarction) than that of the control group (p < 0.05). Expression levels of bFGF were upregulated acutely, just within 48 h after cerebral infarction. Then, levels peaked on day 3 following cerebral infarction (15.46 ± 5.58 pg/ml) and remained significantly elevated on day 14 following cerebral infarction (Table 2).
57
Table 1 Characteristics of patients with cerebral infarction
n Mean age (years) Gender (M/F) Number of patients with hypertension Number of patients with diabetes Number of patients with hyperlipidemia
Patients
Controls
30 67.5 ± 11.2 19/11 21 9 16
20 62.6 ± 9.2 12/8 12 6 13
Table 2 Serum bFGF levels in patients with acute cerebral infarction at different time points Group
n
Control
20
Patients Within 48 h Day 3 Day 7 Day 14
30
bFGF levels (pg/ml) 5.35 ± 2.09 11.72 15.46 10.08 8.87
± ± ± ±
3.61* 5.58*,∆ 4.07* 2.49*
Data are expressed by mean ± S.D. * p < 0.05 compared with control group. p < 0.01 compared with bFGF levels within 48 h, on day 7, and on day 14.
The serum levels of bFGF related to infarct volume. Comparison of serum bFGF levels in patients with large infarction, moderate infarction, and small infarction subgroup revealed that the bFGF levels in patients with large infarction were higher at each time point than those with moderate infarction or small infarction (p < 0.05; Table 3). There was a positive correlation between the peak levels of bFGF and the improvement of SSS rating (SSS; r = 0.596, p < 0.05; Fig. 1). For this analysis the peak bFGF level of each patient was used. In this study, we investigated the changes in serum bFGF levels following cerebral infarction. Additionally, we analyzed the relationship between serum bFGF levels and infarct volume as well as the relation between expression of bFGF and improvement of neurological deficits so as to determine the clinical significance of serum bFGF in cerebral infarction. Basic fibroblast growth factor is a single-strained polypeptide consisting of 154 amino acids, with PI of 9.6 and molecular weight equal to18 kDa. bFGF is a potent stimulator of angiogenesis, which is an important process to improve reperfusion of ischemic tissue, to promote the survival of neurons, and to relieve the neurological deficits after cerebral infarction[8,9]. bFGF also has neurotrophic and vessel-dilating properties. Due Table 3 Serum bFGF levels (pg/ml) in patients with large infarct (LI), moderate infarct (MI), and small infarct (SI) subgroups at different time points Group n
Within 48 h
SI MI LI
8.51 ± 3.05 10.39 ± 2.42 8.13 ± 2.93 7.53 ± 2.59 11.32 ± 3.37 16.73 ± 2.80 10.15 ± 2.54 8.45 ± 2.37 16.57 ± 4.13* 21.48 ± 5.71* 13.22 ± 3.41* 11.26 ± 3.68*
*
12 10 8
Day 3
Day 7
p < 0.05 compared with MI and SI subgroups.
Day 14
58
H. Guo et al. / Neuroscience Letters 393 (2006) 56–59
Fig. 1. Correlation between the peak bFGF level of each patient and SSS. Analysis was by Spearman linear correlation (r = 0.596, p < 0.05).
to the angiogenic, neurotropic, and vessel-dilating [16] properties, bFGF seems to play prominent roles in cerebral infarction, and to contribute to angiogenesis and neuroprotection during and after cerebral infarction. It is well documented that in the animal model of brain ischemia, the expression of bFGF is acutely increased in brain and the high level of bFGF is maintained for a relatively long period [3,10]. Previous research reported that bFGF gene expression peaks on day 1 and bFGF protein levels peak on day 3 following experimental cerebral infarction [6]. In the present study, we found a rapid and significant increase in serum bFGF following cerebral infarction. Serum bFGF levels peaked on day 3 and remained elevated on day 14 following cerebral infarction. Moreover, the results showed that expression of bFGF related to infarct volume; the serum bFGF levels in LI subgroup are significantly higher than that in MI or SI subgroup. This finding suggests that bFGF should be an indicator of infarction size. Under ischemic conditions, bFGF was acutely upregulated in brain tissue [3], which can protect neurons and promote angiogenesis in infarct area so as to improve regional cerebral blood flow. The large-size infarction induces more brain tissue to participate in the above-mentioned response to ischemia while it also leads to severe breakage of blood–brain barrier (BBB). Thus, the overexpression of bFGF in brain tissue can permeate through the impaired BBB into blood so that serum bFGF concentration increases greatly. Findings of this study revealed that there was a positive correlation between the peak bFGF levels and improvement of SSS rating. This correlation indicates that endogenous bFGF is beneficial to the recovery of neurological deficits. This result coincides with previous findings in which bFGF administration can improve recovery from neurological deficits in experimental infarction models [5,17]. Since the sample size of 30 patients and 20 controls in this study is not large, and similar findings of the dynamic changes of bFGF levels in acute cerebral infarction patients have not been reported, more evidence would substantiate stronger conclusions related to these findings.
In this study, the serum bFGF level is still elevated on 14 days after the onset of the cerebral infarction. The change of the serum bFGF after 14 days of cerebral infarction still needs further study. Since patients suffering a cerebral infarction are typically released from the hospital 2–4 weeks following admission in People’s Hospital, Peking University, we chose to cease observation before patients began to be released and were, therefore, unable to follow patients past day 14 following the onset of the cerebral infarction. In conclusion, the dynamic change in serum bFGF levels after cerebral infarction indicates that bFGF plays a role in the pathophysiological process of cerebral infarction. Measurement of serum bFGF levels may be of value to estimate infarction size and clinical prognosis. In this study, we found that endogenous bFGF benefits recovery from cerebral infarction. This finding indicates that bFGF administration might be a promising approach in the therapy of the cerebral infarction. Further studies should be completed to ascertain the therapeutic potential of bFGF administration. Acknowledgements The serum bFGF was assayed in the Neuroscience Research Institute, Peking University. The authors would like to thank Dr. Sonya G. Lehto and Prof. You Wan for critical reading of the manuscript. This work was supported by the grant for Oversea Returnee from the Ministry of Education of China and the “211” fund of Peking University. References [1] Y. Akaneya, Y. Enokido, M. Takahashi, H. Hatanaka, In vitro model of hypoxia: basic fibroblast growth factor can rescue cultured CNS neurons from oxygen-deprived cell death, J. Cereb. Blood Flow Metab. 13 (1993) 1029–1032. [2] F.P. Eckenstein, G.D. Shipley, R. Nishi, Acidic and basic fibroblast growth factors in the nervous system: distribution and differential alteration of levels after injury of central versus peripheral nerve, J. Neurosci. 11 (1991) 412–419. [3] S.P. Finklestein, C.G. Caday, M. Kano, D.J. Berlove, C.Y. Hsu, M. Moskowitz, M. Klagsbrun, Growth factor expression after stroke, Stroke 21 (Suppl. 11) (1990) III122–III124. [4] D. Gospodarowicz, N. Ferrara, L. Schweigerer, G. Neufeld, Structural characterization and biological functions of fibroblast growth factor, Endocr. Rev. 8 (1987) 95–114. [5] N. Jiang, S.P. Finklestein, T. Do, C.G. Caday, M. Charette, M. Chopp, Delayed intravenous administration of basic fibroblast growth factor (bFGF) reduces infarct volume in a model of focal cerebral ischemia/reperfusion in the rat, J. Neurol. Sci. 139 (1996) 173– 179. [6] T. Kawamata, E.K. Speliotes, S.P. Finklestein, The role of polypeptide growth factors in recovery from stroke, Adv. Neurol. 73 (1997) 377– 382. [7] M. Klagsbrun, The fibroblast growth factor family: structural and biological properties, Prog. Growth Factor Res. 1 (1989) 207–235. [8] J. Krupinski, J. Kaluza, P. Kumar, S. Kumar, J.M. Wang, The role of angiogenesis in patients with cerebral ischemic stroke, Stroke 25 (1994) 1794–1798. [9] J. Krupinski, J. Kaluza, P. Kumar, J.M. Wang, S. Kumar, Prognostic value of blood vessel density in ischemic stroke, Lancet 342 (1993) 742.
H. Guo et al. / Neuroscience Letters 393 (2006) 56–59 [10] T.N. Lin, J. Te, M. Lee, G.Y. Sun, C.Y. Hsu, Induction of basic fibroblast growth factor (bFGF) expression following focal cerebral ischemia, Brain Res. Mol. Brain Res. 49 (1997) 255–265. [11] R.R. Lobb, E.M. Alderman, J.W. Fett, Induction of angiogenesis by bovine brain-derived Class 1 heparin-binding growth factor, Biochemistry 24 (1985) 4969–4973. [12] M.K. Lyons, R.E. Anderson, F.B. Meyer, Basic fibroblast growth factor promotes in vivo cerebral angiogenesis in chronic forebrain ischemia, Brain Res. 558 (1991) 315–320. [13] S. Matsuda, H. Saito, N. Nishiyama, Effect of basic fibroblast growth factor on neurons cultured from various regions of postnatal rat brain, Brain Res. 520 (1990) 310–316. [14] M.P. Mattson, Y. Zhang, S. Bose, Growth factors prevent mitochondrial dysfunction, loss of calcium homeostasis, and cell injury, but not ATP depletion in hippocampal neurons deprived of glucose, Exp. Neurol. 121 (1993) 1–13. [15] K. Nozaki, S.P. Finklestein, M.F. Beal, Basic fibroblast growth factor protects against hypoxia-ischemia and NMDA neurotoxicity in neonatal rats, J. Cereb. Blood Flow Metab. 13 (1993) 221–228.
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[16] S. Rosenblatt, K. Irikura, C.G. Caday, S.P. Finklestein, M.A. Moskowitz, Basic fibroblast growth factor dilates rat pial arterioles, J. Cereb. Blood Flow Metab. 37 (1994) 445–452. [17] R. Tanaka, Y. Miyasaka, K. Yada, T. Ohwada, T. Kameya, Basic fibroblast growth factor increases regional cerebral blood flow and reduces infarct size after experimental ischemia in a rat model, Stroke 26 (1995) 2154–2158. [18] V.P. Terranova, R. DiFlorio, R.M. Lyall, S. Hic, R. Friesel, T. Maciag, Human endothelial cells are chemotactic to endothelial cell growth factor and heparin, J. Cell Biol. 101 (1985) 2330–2334. [19] K. Unsicker, H. Reichert-Preibsch, R. Schmidt, B. Pettmann, G. Labourdette, M. Sensenbrenner, Astroglial and fibroblast growth factors have neurotrophic functions for cultured peripheral and central nervous system neurons, Proc. Natl. Acad. Sci. U.S.A. 84 (1987) 5459– 5463. [20] P. Walicke, W.M. Cowan, N. Ueno, A. Baird, R. Guillemin, Fibroblast growth factor promotes survival of cerebral cortical neurons of dissociated hippocampal neurons and enhances neurite extension, Proc. Natl. Acad. Sci. U.S.A. 83 (1986) 3012–3016.
Serial measurement of serum basic fibroblast growth factor in patients with acute cerebral infarction Huailian Guo a,∗ , Li Huang a , Min Cheng a , Xin Jin b , Yafeng Zhao c , Ming Yi a a
Department of Neurology, People’s Hospital, Peking University, 11 Xi Zhi Men Nan Da Jie, Beijing 100044, China b Department of Neurology, Fuxing Hospital, 100045 Beijing, China c Department of Neurology, Shougang Hospital, 100041 Beijing, China Received 2 August 2005; received in revised form 15 September 2005; accepted 16 September 2005
Abstract Basic fibroblast growth factor (bFGF) has been reported to be involved in the pathophysiological changes following cerebral infarction. Basic fibroblast growth factor is upregulated in the brain and conduces to neuroprotection and angiogenesis in experimental brain ischemia, but the change of serum bFGF in cerebral infarction patients has not been reported. In the present study, we investigated the dynamic changes of serum bFGF in 30 patients with acute cerebral infarction and found that serum bFGF increased significantly after cerebral infarction compared with the control group (p < 0.05). Serum bFGF peaked on day 3 (15.46 ± 5.58 pg/ml; p < 0.01) and remained significantly elevated on day 14 following cerebral infarction. In this study, it was also found that the levels of bFGF with large infarction were higher at each time point than those with moderate or small infarction (p < 0.05). There was a positive correlation between the peak level of bFGF and improvement of clinical neurological deficits scored by Scandinavian Stroke Scale (SSS) (r = 0.596; p < 0.05). These results suggest that the serum bFGF level increased significantly after cerebral infarction and the level of serum bFGF could be of value to estimate the infarction size and clinical prognosis. © 2005 Elsevier Ireland Ltd. All rights reserved. Keywords: Cerebral infarction; Brain ischemia; Stroke; Basic fibroblast growth factor; Infarction size; Scandinavian Stroke Scale
bFGF is a heparin-binding growth factor with multiple biological properties and is widely distributed in the central nervous system (CNS) [2]. Both neurons and glial cells are capable of synthesizing bFGF and it acts as angiogenic factor as it is a potent mitogen for most mesoderm-derived cells (including fibroblasts, smooth muscle cells, pericytes, etc). bFGF stimulates endothelial cell migration [18], proliferation [4], sprouting [11], and tube formation [7]. Several previous studies have elucidated how bFGF promotes angiogenesis in the brain after brain ischemia in animal models [12]. bFGF is also considered to be a neurotrophic factor since it protects neurons against events such as hypoxia [1], neurotoxicity [15], and hypoglycemia injury [14]. In vitro bFGF can induce nerve fiber extension and support the survival of neurons [13,19,20]. Due to the angiogenic, neurotropic, and vessel-dilating [16] properties of bFGF as well as the wide distribution in the CNS, bFGF has been implicated in a number of neurological dis-
∗
Corresponding author. Tel.: +86 10 68314422x5375; fax: +86 10 82801151. E-mail address: [email protected] (H. Guo).
0304-3940/$ – see front matter © 2005 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.neulet.2005.09.043
orders including cerebral infarction. It has been reported that bFGF is upregulated in the brain in experimental brain ischemia [3,10], but the change of serum bFGF in cerebral infarction has not be reported. The purpose of this study was to observe the dynamic change of serum bFGF level in patients with acute cerebral infarction and examine the relationship between the infarction size, the improvement of neurological function, and serum bFGF level. The result of this study may be helpful in understanding more about the pathophysiological changes following cerebral infarction and exploring the clinical application of bFGF in cerebral infarction. The approval for the study was obtained from the local ethics committee and all the patients and controls gave informed consent before participating in this study. The 30 patients with acute supratentorial cerebral infarction were chosen from those admitted to the Department of Neurology, People’s Hospital of Peking University within 48 h after cerebral infarction. Cerebral infarction was confirmed by head CT or MRI scan. Excluded from the study were patients with (a) previous transient ischemic attack (TIA) or stroke or head trauma; (b) severe cardiac, renal, or hepatic disease; (c) cancerous disease; (d) recent history of
H. Guo et al. / Neuroscience Letters 393 (2006) 56–59
infection or infection after admission. Control data was collected from 20 patients undergoing medical examinations having had no recent infection or history of cerebral infarction or transient ischemic attack or head trauma or serious illness, and matched with patient group in sex, age, hypertension, diabetes mellitus, hyperlipidemia, and cardiac disease. Blood samples were taken from cubital vein immediately upon admission (within 48 h), then taken again 3, 7, and 14 days after cerebral infarction. Samples were centrifuged (2000 r/min, 10 min) to segregate serum, then stored at −70 ◦ C till assay. bFGF levels were measured with the method of ELISA. The bFGF immunoassay kit was obtained from R&D systems (Minneapolis, MN, USA). The beginning time of cerebral infarction is the time when a symptom or sign of cerebral infarction appeared. For patients who woke to find symptom or sign of stroke, the beginning time of stroke attack was recorded as the time when he/she went to bed. All patients were evaluated by head CT or MRI. According to the largest diameter of infarct (d), patients were classified as having a large infarction (LI; d > 4 cm), a moderate infarction (MI; 1.5 cm < d < 4 cm) or a small infarction (SI; d < 1.5 cm). Clinical examination was performed on admission (within 48 h) and 20 days after cerebral infarction. The clinical neurology deficits were scored according to the 58-points Scandinavian Stroke Scale (SSS). And the improvement of neurological function of patients was evaluated by SSS (SSS equaled SSS on day 20 subtracted SSS within 48 h). Statistical analysis was performed to identify differences in bFGF levels over time after cerebral infarction as well as infarction size, and to correlate bFGF expression to the improvement of neurological function. The mean bFGF concentrations at four selected time points were compared with control value by the one-sample t-test. The Student–Newman–Keuls test (q-test) was employed to test the differences between bFGF concentrations of patient group at four selected time points. Differences of bFGF levels between SI, MI, and LI subgroups were assessed with ANOVA; all analyses were two-tailed. The relationship between the peak level of bFGF and SSS was determined by Spearman linear correlation analysis. Results were expressed as mean ± S.D. Values were considered significant at p < 0.05. The statistical package SPSS 10.0 was used for all analyses. Thirty patients (19 men and 11 women) aged from 43 to 82 years (mean age 67.5 years) and 20 controls (12 men and 8 women) aged 42–74 years (mean age 62.6 years) were included in this study. Eight patients had large infarction, 10 had moderate infarction, and 12 had small infarction. There was no significant difference in sex ratio, age, or complications with hypertension, diabetes, or hyperlipidemia (p > 0.05; Table 1). The mean levels of bFGF in patients were significantly higher at all selected time points (within 48 h, on day 3, on day 7, and on day 14 after cerebral infarction) than that of the control group (p < 0.05). Expression levels of bFGF were upregulated acutely, just within 48 h after cerebral infarction. Then, levels peaked on day 3 following cerebral infarction (15.46 ± 5.58 pg/ml) and remained significantly elevated on day 14 following cerebral infarction (Table 2).
57
Table 1 Characteristics of patients with cerebral infarction
n Mean age (years) Gender (M/F) Number of patients with hypertension Number of patients with diabetes Number of patients with hyperlipidemia
Patients
Controls
30 67.5 ± 11.2 19/11 21 9 16
20 62.6 ± 9.2 12/8 12 6 13
Table 2 Serum bFGF levels in patients with acute cerebral infarction at different time points Group
n
Control
20
Patients Within 48 h Day 3 Day 7 Day 14
30
bFGF levels (pg/ml) 5.35 ± 2.09 11.72 15.46 10.08 8.87
± ± ± ±
3.61* 5.58*,∆ 4.07* 2.49*
Data are expressed by mean ± S.D. * p < 0.05 compared with control group. p < 0.01 compared with bFGF levels within 48 h, on day 7, and on day 14.
The serum levels of bFGF related to infarct volume. Comparison of serum bFGF levels in patients with large infarction, moderate infarction, and small infarction subgroup revealed that the bFGF levels in patients with large infarction were higher at each time point than those with moderate infarction or small infarction (p < 0.05; Table 3). There was a positive correlation between the peak levels of bFGF and the improvement of SSS rating (SSS; r = 0.596, p < 0.05; Fig. 1). For this analysis the peak bFGF level of each patient was used. In this study, we investigated the changes in serum bFGF levels following cerebral infarction. Additionally, we analyzed the relationship between serum bFGF levels and infarct volume as well as the relation between expression of bFGF and improvement of neurological deficits so as to determine the clinical significance of serum bFGF in cerebral infarction. Basic fibroblast growth factor is a single-strained polypeptide consisting of 154 amino acids, with PI of 9.6 and molecular weight equal to18 kDa. bFGF is a potent stimulator of angiogenesis, which is an important process to improve reperfusion of ischemic tissue, to promote the survival of neurons, and to relieve the neurological deficits after cerebral infarction[8,9]. bFGF also has neurotrophic and vessel-dilating properties. Due Table 3 Serum bFGF levels (pg/ml) in patients with large infarct (LI), moderate infarct (MI), and small infarct (SI) subgroups at different time points Group n
Within 48 h
SI MI LI
8.51 ± 3.05 10.39 ± 2.42 8.13 ± 2.93 7.53 ± 2.59 11.32 ± 3.37 16.73 ± 2.80 10.15 ± 2.54 8.45 ± 2.37 16.57 ± 4.13* 21.48 ± 5.71* 13.22 ± 3.41* 11.26 ± 3.68*
*
12 10 8
Day 3
Day 7
p < 0.05 compared with MI and SI subgroups.
Day 14
58
H. Guo et al. / Neuroscience Letters 393 (2006) 56–59
Fig. 1. Correlation between the peak bFGF level of each patient and SSS. Analysis was by Spearman linear correlation (r = 0.596, p < 0.05).
to the angiogenic, neurotropic, and vessel-dilating [16] properties, bFGF seems to play prominent roles in cerebral infarction, and to contribute to angiogenesis and neuroprotection during and after cerebral infarction. It is well documented that in the animal model of brain ischemia, the expression of bFGF is acutely increased in brain and the high level of bFGF is maintained for a relatively long period [3,10]. Previous research reported that bFGF gene expression peaks on day 1 and bFGF protein levels peak on day 3 following experimental cerebral infarction [6]. In the present study, we found a rapid and significant increase in serum bFGF following cerebral infarction. Serum bFGF levels peaked on day 3 and remained elevated on day 14 following cerebral infarction. Moreover, the results showed that expression of bFGF related to infarct volume; the serum bFGF levels in LI subgroup are significantly higher than that in MI or SI subgroup. This finding suggests that bFGF should be an indicator of infarction size. Under ischemic conditions, bFGF was acutely upregulated in brain tissue [3], which can protect neurons and promote angiogenesis in infarct area so as to improve regional cerebral blood flow. The large-size infarction induces more brain tissue to participate in the above-mentioned response to ischemia while it also leads to severe breakage of blood–brain barrier (BBB). Thus, the overexpression of bFGF in brain tissue can permeate through the impaired BBB into blood so that serum bFGF concentration increases greatly. Findings of this study revealed that there was a positive correlation between the peak bFGF levels and improvement of SSS rating. This correlation indicates that endogenous bFGF is beneficial to the recovery of neurological deficits. This result coincides with previous findings in which bFGF administration can improve recovery from neurological deficits in experimental infarction models [5,17]. Since the sample size of 30 patients and 20 controls in this study is not large, and similar findings of the dynamic changes of bFGF levels in acute cerebral infarction patients have not been reported, more evidence would substantiate stronger conclusions related to these findings.
In this study, the serum bFGF level is still elevated on 14 days after the onset of the cerebral infarction. The change of the serum bFGF after 14 days of cerebral infarction still needs further study. Since patients suffering a cerebral infarction are typically released from the hospital 2–4 weeks following admission in People’s Hospital, Peking University, we chose to cease observation before patients began to be released and were, therefore, unable to follow patients past day 14 following the onset of the cerebral infarction. In conclusion, the dynamic change in serum bFGF levels after cerebral infarction indicates that bFGF plays a role in the pathophysiological process of cerebral infarction. Measurement of serum bFGF levels may be of value to estimate infarction size and clinical prognosis. In this study, we found that endogenous bFGF benefits recovery from cerebral infarction. This finding indicates that bFGF administration might be a promising approach in the therapy of the cerebral infarction. Further studies should be completed to ascertain the therapeutic potential of bFGF administration. Acknowledgements The serum bFGF was assayed in the Neuroscience Research Institute, Peking University. The authors would like to thank Dr. Sonya G. Lehto and Prof. You Wan for critical reading of the manuscript. This work was supported by the grant for Oversea Returnee from the Ministry of Education of China and the “211” fund of Peking University. References [1] Y. Akaneya, Y. Enokido, M. Takahashi, H. Hatanaka, In vitro model of hypoxia: basic fibroblast growth factor can rescue cultured CNS neurons from oxygen-deprived cell death, J. Cereb. Blood Flow Metab. 13 (1993) 1029–1032. [2] F.P. Eckenstein, G.D. Shipley, R. Nishi, Acidic and basic fibroblast growth factors in the nervous system: distribution and differential alteration of levels after injury of central versus peripheral nerve, J. Neurosci. 11 (1991) 412–419. [3] S.P. Finklestein, C.G. Caday, M. Kano, D.J. Berlove, C.Y. Hsu, M. Moskowitz, M. Klagsbrun, Growth factor expression after stroke, Stroke 21 (Suppl. 11) (1990) III122–III124. [4] D. Gospodarowicz, N. Ferrara, L. Schweigerer, G. Neufeld, Structural characterization and biological functions of fibroblast growth factor, Endocr. Rev. 8 (1987) 95–114. [5] N. Jiang, S.P. Finklestein, T. Do, C.G. Caday, M. Charette, M. Chopp, Delayed intravenous administration of basic fibroblast growth factor (bFGF) reduces infarct volume in a model of focal cerebral ischemia/reperfusion in the rat, J. Neurol. Sci. 139 (1996) 173– 179. [6] T. Kawamata, E.K. Speliotes, S.P. Finklestein, The role of polypeptide growth factors in recovery from stroke, Adv. Neurol. 73 (1997) 377– 382. [7] M. Klagsbrun, The fibroblast growth factor family: structural and biological properties, Prog. Growth Factor Res. 1 (1989) 207–235. [8] J. Krupinski, J. Kaluza, P. Kumar, S. Kumar, J.M. Wang, The role of angiogenesis in patients with cerebral ischemic stroke, Stroke 25 (1994) 1794–1798. [9] J. Krupinski, J. Kaluza, P. Kumar, J.M. Wang, S. Kumar, Prognostic value of blood vessel density in ischemic stroke, Lancet 342 (1993) 742.
H. Guo et al. / Neuroscience Letters 393 (2006) 56–59 [10] T.N. Lin, J. Te, M. Lee, G.Y. Sun, C.Y. Hsu, Induction of basic fibroblast growth factor (bFGF) expression following focal cerebral ischemia, Brain Res. Mol. Brain Res. 49 (1997) 255–265. [11] R.R. Lobb, E.M. Alderman, J.W. Fett, Induction of angiogenesis by bovine brain-derived Class 1 heparin-binding growth factor, Biochemistry 24 (1985) 4969–4973. [12] M.K. Lyons, R.E. Anderson, F.B. Meyer, Basic fibroblast growth factor promotes in vivo cerebral angiogenesis in chronic forebrain ischemia, Brain Res. 558 (1991) 315–320. [13] S. Matsuda, H. Saito, N. Nishiyama, Effect of basic fibroblast growth factor on neurons cultured from various regions of postnatal rat brain, Brain Res. 520 (1990) 310–316. [14] M.P. Mattson, Y. Zhang, S. Bose, Growth factors prevent mitochondrial dysfunction, loss of calcium homeostasis, and cell injury, but not ATP depletion in hippocampal neurons deprived of glucose, Exp. Neurol. 121 (1993) 1–13. [15] K. Nozaki, S.P. Finklestein, M.F. Beal, Basic fibroblast growth factor protects against hypoxia-ischemia and NMDA neurotoxicity in neonatal rats, J. Cereb. Blood Flow Metab. 13 (1993) 221–228.
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[16] S. Rosenblatt, K. Irikura, C.G. Caday, S.P. Finklestein, M.A. Moskowitz, Basic fibroblast growth factor dilates rat pial arterioles, J. Cereb. Blood Flow Metab. 37 (1994) 445–452. [17] R. Tanaka, Y. Miyasaka, K. Yada, T. Ohwada, T. Kameya, Basic fibroblast growth factor increases regional cerebral blood flow and reduces infarct size after experimental ischemia in a rat model, Stroke 26 (1995) 2154–2158. [18] V.P. Terranova, R. DiFlorio, R.M. Lyall, S. Hic, R. Friesel, T. Maciag, Human endothelial cells are chemotactic to endothelial cell growth factor and heparin, J. Cell Biol. 101 (1985) 2330–2334. [19] K. Unsicker, H. Reichert-Preibsch, R. Schmidt, B. Pettmann, G. Labourdette, M. Sensenbrenner, Astroglial and fibroblast growth factors have neurotrophic functions for cultured peripheral and central nervous system neurons, Proc. Natl. Acad. Sci. U.S.A. 84 (1987) 5459– 5463. [20] P. Walicke, W.M. Cowan, N. Ueno, A. Baird, R. Guillemin, Fibroblast growth factor promotes survival of cerebral cortical neurons of dissociated hippocampal neurons and enhances neurite extension, Proc. Natl. Acad. Sci. U.S.A. 83 (1986) 3012–3016.