Basic fibroblast growth factor promotes epidermal growth factor responsiveness and survival of mesencephalic neural precursor cells

Epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) induce proliferation of neural precursor cells from several central nervous system regions in vitro. We have previously described two neural precursor cell populations from 13.5 days postcoitium (dpc) mesencephalon, one forming colonies in response to EGF, present in the ventral mesencephalon, and other forming colonies in response to EGF + bFGF, mainly present in the dorsal mesencephalon. In the present work, we show that 13.5 dpc dorsal mesencephalic cells required bFGF only for 1 h to form colonies in response to EGF alone, indicating that these two growth factors act in sequence rather than simultaneously. Absence of bFGF at the beginning of the culture gave rise to very few colonies, even after the addition of EGF + bFGF, suggesting that cells responsive to bFGF were very labile in the primary culture condition. This result is in contrast with cells pretreated with bFGF, which could survive for up to 5 days in the absence of bFGF or EGF, and then were capable of efficiently forming colonies in response to EGF. Basic FGF was also able to support survival of EGF‐responsive neural precursors from both ventral and dorsal mesencephalon. The population requiring bFGF to form colonies in response to EGF was identified at different developmental stages (11.5–15.5 dpc), with higher contribution to the total number of neural precursors cells detected (EGF‐responsive plus bFGF‐responsive) at early stages and in the dorsal region. We show that the differentiation effect of bFGF resulted in the appearance of the mRNA coding for the EGF receptor. Our data suggest that bFGF‐responsive neural precursors are the source of EGF‐responsive neural precursors. © 1999 John Wiley & Sons, Inc. J Neurobiol 40: 14–27, 1999     

Basic fibroblast growth factor promotes epidermal growth factor responsiveness and survival of mesencephalic neural precursor cells.

Epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) induce proliferation of neural precursor cells from several central nervous system regions in vitro. We have previously described two neural precursor cell populations from 13.5 days postcoitium (dpc) mesencephalon, one forming colonies in response to EGF, present in the ventral mesencephalon, and other forming colonies in response to EGF + bFGF, mainly present in the dorsal mesencephalon. In the present work, we show that 13.5 dpc dorsal mesencephalic cells required bFGF only for 1 h to form colonies in response to EGF alone, indicating that these two growth factors act in sequence rather than simultaneously. Absence of bFGF at the beginning of the culture gave rise to very few colonies, even after the addition of EGF + bFGF, suggesting that cells responsive to bFGF were very labile in the primary culture condition. This result is in contrast with cells pretreated with bFGF, which could survive for up to 5 days in the absence of bFGF or EGF, and then were capable of efficiently forming colonies in response to EGF. Basic FGF was also able to support survival of EGF-responsive neural precursors from both ventral and dorsal mesencephalon. The population requiring bFGF to form colonies in response to EGF was identified at different developmental stages (11.5-15.5 dpc), with higher contribution to the total number of neural precursors cells detected (EGF-responsive plus bFGF-responsive) at early stages and in the dorsal region. We show that the differentiation effect of bFGF resulted in the appearance of the mRNA coding for the EGF receptor. Our data suggest that bFGF-responsive neural precursors are the source of EGF-responsive neural precursors.     

Basic fibroblast growth factor (FGF) promotes cartilage repair in vivo

Although it has been clearly established that basic fibroblast growth factor (FGF) is a potent mitogen for chondrocytes in vitro, there is little evidence that it can stimulate this cell type in vivo. In an effort to address this problem, we examined the effect of an intraarticular administration of basic FGF. Alzet osmotic pumps delivering the mitogen to the site of injury promotes the healing of intra-chondrial lesions by stimulating chondrocyte proliferation and the formation of extracellular matrix. The observation that chronic infusions of basic FGF can elicit a repair response at the site of injury suggests that this growth factor may have therapeutic applications that extend beyond its capacity to induce neovascularization. The results also suggest that one of the ways that the perichondrium mediates cartilage repair may be by the local production of FGF-like mitogens.     

碱性成纤维细胞生长因子与肿瘤

碱性成纤维细胞生长因子（basic fibroblast growth factor,bFGF) 作为多种细胞的致裂源,与肿瘤的关系近几年来受到关注,本文概述了有关bFGF与肿瘤关系的研究进展。     

Ascorbic acid increases the yield of dopaminergic neurons derived from basic fibroblast growth factor expanded mesencephalic precursors

CNS precursors derived from E12 rat mesencephalon proliferate in the presence of basic fibroblast growth factor and differentiate in vitro into functional dopaminergic neurons, which upon transplantation alleviate behavioral symptoms in a rat model of Parkinson's disease. Here we show that the efficiency of dopaminergic differentiation decreases in the mesencephalic precursors that were proliferated or passaged for extended periods in vitro. Ascorbic acid treatment restored dopaminergic differentiation in these precursors and led to a greater than 10-fold increase in dopamine neuron yield compared with untreated cultures. The effect of ascorbic acid was stereospecific and could not be mimicked by any other antioxidants. The expression of sodium-dependent vitamin C transporter, a recently identified stereospecific ascorbic acid transporter, was maintained in mesencephalic precursors for extended in vitro periods. Pre-treatment of in vitro expanded mesencephalic precursors with ascorbic acid might facilitate the large-scale generation of dopaminergic neurons for clinical transplantation.     

Basic fibroblast growth factor in Alzheimer's disease

We have examined the presence of basic fibroblast growth factor (FGF) in normal and in Alzheimer brains, studied the distribution of the mitogen by immunohistochemical techniques, measured the quantities of growth factor in selected areas of the brain (Brodmann areas 10/11 and 20/21), characterized the molecular forms by Western blotting and determined its sites of synthesis by in situ hybridization. Although the same molecular forms of basic FGF are found in control and Alzheimer brains, basic FGF is increased in the brains of Alzheimer's patients. Furthermore, basic FGF is not distributed in an identical fashion to normal and Alzheimer brains, but is found in association with the lesions that characterize this disease. In normal controls (n = 5), basic FGF was found to be widely distributed throughout the three brain regions examined (prefrontal cortex, hippocampus, and hypothalamus). Immunoreactivity was observed within astrocytes in both the grey and white matter, as well as within neuronal perikarya. Brain tissues that were obtained from Alzheimer patients (N = 4) showed a substantial increase in the overall specific staining of astrocytes and neurons, particularly in areas of reactive gliosis. Focal concentration of immunoreactive basic FGF was evident within the neuritic plaques, and could be clearly seen in association with the neurofibrillary tangles present within neuronal perikarya. The possibility that basic FGF expression in the CNS is linked to the pathogenesis of the disease is discussed.     

Basic fibroblast growth factor in rat salivary glands

We studied the occurrence and localization of basic fibroblast growth factor (bFGF) in rat salivary glands using a specific monoclonal antibody. It was shown that the extract of rat salivary glands has a pronounced stimulatory activity on the growth of bovine capillary endothelial cells, which is blocked by the addition of an antibody against bFGF. The concentration of bFGF in the submandibular/sublingual gland, as determined by radioimmunoassay, was 80% that in the brain. Immunocytochemistry revealed bFGF-immunoreactivity localized primarily in the epithelial cells lining the striated ducts and excretory ducts of the parotid, sublingual and submandibular glands. In addition, intense bFGF-immunoreactivity was observed in the granular convoluted tubule of the submandibular gland, localized predominantly in the agranular pillar cells, which lay in small numbers among the majority of weakly immunostained cells containing many apical secretory granules. At the electron-microscopic level, the immunoreactive material was distributed diffusely in the cytoplasmic matrix and nuclei of all immunoreactive cells, whereas it was absent from all cytoplasmic organelles including the secretory granules. These results indicate that bFGF is localized in different cellular and subcellular compartments from those of other growth factors in the duct system of rat salivary glands.     

Agonists of fibroblast growth factor receptor induce neurite outgrowth and survival of cerebellar granule neurons

Fibroblast growth factor receptor (FGFR) signaling is pivotal in the regulation of neurogenesis, neuronal differentiation and survival, and synaptic plasticity both during development and in adulthood. In order to develop low molecular weight agonists of FGFR, seven peptides, termed hexafins, corresponding to the β6‐β7 loop region of the FGF 1, 2, 3, 8, 9, 10, and 17, were synthesized. This region shares a homologous amino acid sequence with the FG‐loop region of the second fibronectin Type III module of the neural cell adhesion molecule (NCAM) that binds to the FGFR. Hexafins were shown by surface plasmon resonance to bind to FGFR1‐IIIc‐Ig2‐3 and FGFR2‐IIIb‐Ig2‐3. The heparin analog sucrose octasulfate inhibited hexafin binding to FGFR1‐IIIc‐Ig2‐3 indicating overlapping binding sites. Hexafin‐binding to FGFR1‐IIIc resulted in receptor phosphorylation, but inhibited FGF1‐induced FGFR1 phosphorylation, indicating that hexafins act as partial agonists. Hexafin2, 3, 8, 10, and 17 (but not 1 or 9) induced neurite outgrowth from cerebellar granule neurons (CGNs), an effect that was abolished by two inhibitors of FGFR, SU5402 and inositol hexaphosphate (IP6) and a diacylglycerol lipase inhibitor, RHC‐80267. The neuritogenic effects of selected hexafins could also be inhibited by FGF1 which by itself did not induce neurite outgrowth. Moreover, hexafin1, 3, 9, 10, and 17 (but not 2 or 8) promoted survival of CGNs induced to undergo apoptosis. Thus, selected hexafins induced neuronal differentiation and survival, making them promising pharmacological tools for the study of functional FGFR regulation in development of the nervous system. © 2009 Wiley Periodicals, Inc. Develop Neurobiol 2009     

Cortical astrocytes activated by basic fibroblast growth factor secrete molecules that stimulate differentiation of mesencephalic dopaminergic neurons.

In reactive gliosis, astrocytes undergo morphological and biochemical changes which can be mimicked in vitro by treatment with bFGF (basic fibroblast growth factor) or cAMP. To investigate the influence of activated cortical astrocytes on central nervous system (CNSD) neurons, we studied the effect of the supernatant from bFGF-treated astrocytes on the development of dopaminergic neurons from rat mesencephalon. Conditioned medium of untreated astrocytes stimulated dopamine uptake of mesencephalic cultures. After activation of astrocytes with bFGF this effect was greatly enhanced. It was significantly more potent than stimulating effects of other neurotrophic factors. The supernatant of these astrocytes increased the biochemical differentiation but not the survival of dopaminergic neurons in our cell culture system. Trypsin digestion and gel chromatography revealed that the activity was due to one or several proteins with molecular mass above 5 kDa. We excluded the participation of several factors known to be produced by astrocytes or that are neurotrophic for substantia nigra cultures. In particular, we provide evidence that bFGF, BDNF, NT-3, Il-1, Il-6, S100 beta and alpha 2-macroglobulin were not involved in the effect of the conditioned medium. In vitro stimulation of astrocytes therefore triggers the expression of currently uncharacterized factors which influence the biochemical differentiation of mesencephalic dopaminergic neurons, the cells that degenerate in Parkinson's disease.     

Basic fibroblast growth factor promotes bone marrow stromal cell transplantation-mediated neural regeneration in traumatic brain injury

The current study was designed to evaluate the effects of basic fibroblast growth factor (bFGF) on human BMSC (hBMSC) transplantation-mediated neural regeneration in traumatic brain injury (TBI). Fibrin gel was used as a delivery vehicle to release bFGF locally in the TBI sites in a controlled manner. To test this hypothesis, hBMSCs suspended in fibrin gel containing bFGF were transplanted to rat TBI sites. Transplantation of hBMSCs suspended in fibrin gel without bFGF served as a control. hBMSC transplantation and bFGF treatment showed enhanced neural tissue regeneration than that of the control. The infarction volume and apoptotic activity of the transplanted hBMSCs were significantly decreased, and functional outcomes were significantly improved in the hBMSC transplantation and bFGF treatment group than in the control group. This study demonstrates that bFGF significantly enhances histological and functional recovery when used in hBMSC transplantation therapy in TBI.     

碱性成纤维细胞生长因子研究进展

碱性成纤维细胞生长因子是细胞生长和分化的重要调节因子,具有促血管生成、细胞增殖、细胞趋化、细胞迁移等活性,在细胞分化和机体发育过程中发挥重要作用。碱性成纤维细胞生长因子通过与细胞膜表面的特异性配体结合,进而引发细胞内的一系列级联反应,从而产生各种生物学效应。本文对碱性成纤维细胞生长因子的生物学基础、信号转导、生物学功能以及临床应用研究进展作一综述。     

Basic fibroblast growth factor is cardioprotective in ischemia-reperfusion injury

To examine whether basic fibroblast growth factor (bFGF) administered to the heart by perfusion can improve cardiac resistance to injury we employed an isolated rat heart model of ischemia-reperfusion injury and determined the extent of functional recovery in bFGF-treated and control hearts. Global ischemia was simulated by interruption of flow for 60 min. Recovery of developed force of contraction (DF), recorded after reestablishment of flow for 30 min, reached 63.8±1.5% and 96.5±3.5% of preischemic levels in control and bFGF-treated hearts (10 g/heart), respectively, indicating that bFGF induced significantly improved recovery of mechanical function. Recoveries of the rates of contraction or relaxation were also significantly improved in bFGF-treated hearts. Extent of myocardial injury, assessed by determination of phosphocreatine kinase in the effluent, was reduced as a result of bFGF treatment. As a first step towards understanding the mechanism and direct cellular target(s) of bFGF-induced cardioprotection, we investigated its fate after perfusion. Perfusion of 10 g bFGF/heart resulted in a 4-fold increase in bFGF associated with the heart compared to control levels, as estimated by biochemical fractionation and immunoblotting. Immunofluorescent staining of the bFGF-perfused hearts revealed intense anti-bFGF staining in association with blood vessels as well as the periphery of cardiomyocytes, suggesting that the latter may be a target for direct bFGF action. In conclusion, our findings of bFGF-induced increases in cardiac resistance to, and improved functional recovery from, ischemia-reperfusion injury indicate that bFGF may have clinical applications in the treatment of ischemic heart disease.     

Basic fibroblast growth factor induces retinal regeneration in vivo

In the present study, we have investigated the effect of basic fibroblast growth factor (bFGF) on retinal regeneration in the stage 22-24 chick embryo. The neural retina was surgically removed in ovo leaving the retinal pigment epithelium (RPE) intact and then slow-release, plastic implants containing bFGF were inserted into the eye. Light microscopic examination of eyes 7 days later revealed that bFGF induced retinal regeneration in a dose-dependent manner. The absence of the RPE in these eyes and the reversed polarity of the regenerated neural retina is consistent with the hypothesis that this process occurs by transdifferentiation of the RPE. This represents the first time that a known molecule has been shown to induce retinal regeneration in vivo.     

Basic fibroblast growth factor inhibits osteoclast-like cell formation

Basic fibroblast growth factor (bFGF) inhibited osteoclast-like cell formation in co-cultures of mouse bone marrow cells either with the mouse stromal cell line, ST2, or with primary osteoblastic cells. Basic FGF significantly inhibited the osteoclast-like cell formation, induced by 1α,25-dihydroxyvitamin D₃[1α, 25(OH)₂D₃] when the cytokine was added to the culture, at an intermediate stage, suggesting that bFGF inhibits the differentiation of the osteoclast progenitors. With regard to target cells, bFGF directly affected ST2; it increased [³H]thymidine uptake and decreased the number of alkaline phosphatase-positive cells. In contrast, bFGF had no inhibitory effect on the colony formation of bone marrow cells induced by macrophage colony stimulating factor in methylcellulose culture. In addition, ST2 cells treated with bFGF produced similar amounts of colony forming activity to those without the cytokine. These findings indicated that the bFGF is not involved in the proliferation of progenitor cells even in the presence of ST2 cells. Furthermore, bFGF inhibited osteoclast-like cell formation induced not only by 1α,25(OH)₂D₃, but also by prostaglandin E₂ and by interleukin-11. These results suggest that bFGF inhibits the common site of osteoclast-like cell formation, as induced by different mechanisms. Our data also indicated that the target cells for bFGF in inhibiting osteoclast formation are not osteoclast progenitors but stromal cells such as ST2 and osteoblastic cells, which support osteoclast development. © 1996 Wiley-Liss, Inc.     

Basic fibroblast growth factor and epidermal growth factor downmodulate the growth of hematopoietic cells in long-term stromal cultures

The bone marrow microenvironment consists of stromal cells and extracellular matrix components which act in concert to regulate the growth and differentiation of hematopoietic stem cells. There is little understanding of the mechanisms which modulate the regulatory role of stromal cells. This study examined the hypothesis that mesenchymal growth factors such as basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) modulate stromal cell activities and thereby influence the course of hematopoiesis. Both bFGF and EGF were potent mitogens for marrow stroma. However, both factors proved to be inhibitory to hematopoiesis in primary log-term marrow cultures. Inhibition was also observed when hematopoietic cells and bFGF or EGF were added to subconfluent irradiated stromal layers, demonstrating that the decline of hematopoiesis was not due to overgrowth of the stromal layer. Loss of hematopoietic support in bFGF and EGF was dose-dependent. Removal of bFGF and EGF permitted stromal layers to regain their normal capacity to support hematopoiesis. In stroma-free long-term cultures, neither factor affected CFU-GM expansion. Basic FGF slightly enhanced granulocyte-macrophage colony forming unit (CFU-GM) cloning efficiency in short-term agarose culture. Basic FGF did not reduce the levels of interleukin-6 (IL-6), GM-CSF, or G-CSF released by steady state or IL-1-stimulated stroma. Similarly, the constitutive levels of steel factor (SF) mRNA and protein were not affected by bFGF. Basic FGF did not alter the level of TGF-β1 in stromal cultures. We conclude that bFGF and EGF can act as indirect negative modulators of hematopoietic growth in stromal cultures. The actual mediators of regulation, whether bound or soluble, remain to be identified. © 1995 Wiley-Liss, Inc.     

Basic fibroblast growth factor in atria and ventricles of the vertebrate heart

Extracts from atrial and ventricular heart tissue of several species (chicken, rat, sheep, and cow) are strongly mitogenic for chicken skeletal myoblasts, with the highest apparent concentration of biological activity in the atrial extracts. Using several approaches (biological activity assay and biochemical and immunological analyses), we have established that (a) all cardiac extracts contain an 18,000-D peptide which is identified as basic fibroblast growth factor (bFGF) since it elutes from heparin-Sepharose columns at salt concentrations greater than 1.4 M and is recognized by bFGF-specific affinity-purified antibodies; (b) bFGF is more abundant in the atrial extracts in all species so examined; (c) avian cardiac tissue extracts contain the highest concentration of immunoreactive bFGF; and (d) avian ventricles contain a higher relative molecular mass (23,000-D) bFGF-like peptide which is absent from atrial extracts. Examination of frozen bovine cardiac tissue sections by indirect immunofluorescence using anti-bFGF antibodies shows bFGF-like reactivity associated with nuclei and intercalated discs of muscle fibers. There is substantial accumulation of bFGF around atrial but not ventricular myofibers, resulting most likely from more extensive endomysium in the atria. Blood vessels and single, nonmuscle, connective tissue cells react strongly with the anti- bFGF antibodies. Higher bFGF content and pericellular distribution in atrial muscles suggest a correlation with increased regenerative potential in this tissue. Distribution within the myofibers is intriguing, raising the possibility for an intimate and continuous involvement of bFGF-like components with normal myocardial function.