Basic fibroblast growth factor promotes bone ingrowth in porous hydroxyapatite

The effect of basic fibroblast growth factor on tissue ingrowth and differentiation in porous hydroxyapatite of coralline origin was studied in a bone chamber model. The hydroxyapatite with or without basic fibroblast growth factor was placed in 22 mm3 titanium bone conduction chambers implanted bilaterally in rat tibiae. Ingrowing bone could enter the cylindrical interior of the chamber only at 1 end. It then penetrated the porous hydroxyapatite inside the chamber. The distance that the ingrown tissue had reached into the material then was measured on histologic slides. Because fibrous tissue always reached further into the material than did bone, both total tissue ingrowth and bone ingrowth distances were measured. In implants supplemented with 0.04 microg basic fibroblast growth factor in a hyaluronate gel carrier, the bone ingrowth distance was increased by 70% at 6 weeks, as compared with paired controls in the contralateral leg. The total tissue ingrowth distance also was increased by 58%. When the dose of basic fibroblast growth factor was increased to 1.0 microg, still using the hyaluronate carrier, there was no difference in bone ingrowth compared with controls, but this dose still increased the total tissue ingrowth. In hydroxyapatite with 1.5 microg basic fibroblast growth factor without hyaluronate gel at 4 weeks, no increase in bone ingrowth was shown, but total tissue ingrowth was increased. At 6 weeks, bone ingrowth and total tissue ingrowth were increased by 41% and 33%, respectively. With a lower dose of 0.15 microg without carrier, only the total ingrowth distance was increased. The results suggest that basic fibroblast growth factor may promote tissue ingrowth into porous hydroxyapatite and that bone ingrowth may be increased by appropriate doses. The hyaluronate gel carrier reduced the optimal dose.     

Basic fibroblast growth factor in experimental and clinical bacterial meningitis

Basic fibroblast growth factor (bFGF), a neurotrophic factor in the CNS, is expressed at high levels in response to seizures or strokes. We examined the expression of bFGF during experimental bacterial meningitis and the levels of bFGF in the cerebrospinal fluid (CSF) of children with bacterial meningitis. For the experimental study, a mouse model of meningitis was established by intracranial injection of Streptococcus pneumoniae. Twenty-four hours after induced meningitis, the brains were sectioned and stained immunohistochemically for bFGF. Neutrophils and macrophages infiltrating the leptomeninges and the ventricles exhibited strong bFGF immunoreactivity. The neurons in the areas adjacent to the inflamed ventricles also showed enhanced bFGF expression. For the clinical study, we used an enzyme immunoassay to measure bFGF in CSF in 18 children with bacterial meningitis, 12 with aseptic meningitis, and 18 controls. The CSF levels of bFGF were twice as high in children with bacterial meningitis (medians 6.75-7.21 pg/mL) compared with those who had aseptic meningitis (2.9 pg/mL) or in control subjects (2.65 pg/mL, p < 0.0001, respectively). In patients with bacterial meningitis who survived, CSF bFGF decreased significantly after 24-50 h of antibiotic therapy (p < 0.0005). Patients who developed major sequelae or died had much higher levels of CSF bFGF than those without (134.9 pg/mL versus 7.38 pg/mL, p < 0.05). These findings of enhanced immunoreactivity of bFGF in experimental bacterial meningitis and an association of CSF levels of bFGF with disease severity in childhood bacterial meningitis suggest a biologic role for this neurotrophic factor in the pathophysiology of bacterial meningitis.     

Basic fibroblast growth factor (bFGF) contributes to the enlargement of brown adipose tissue during cold acclimation

The contribution of basic fibroblast growth factor to brown adipose tissue (BAT) enlargement during cold acclimation was investigated using rat brown adipocytes in primary culture. After cold exposure (at 5 degrees C) for 28 days, the level of bFGF messenger ribonucleic acid (mRNA) in BAT of cold-acclimated rats was markedly increased with the increase in the BAT weight. In addition, the blood plasma from cold-acclimated rats considerably enhanced the expression of basic fibroblast growth factor mRNA in rat brown adipocytes. Likewise, the blood plasma from cold-acclimated rats significantly stimulated the growth of rat brown adipocyte precursor cells compared with that from warm-acclimated rats, whereas there was no difference of effect between the two blood plasmas on the growth of bovine capillary endothelial cells. Basic fibroblast growth factor, but not platelet-derived growth factor stimulated the growth of brown adipocyte precursor cells. The conditioned medium from brown adipocyte primary culture markedly stimulated the growth of bovine capillary endothelial cells and the effect was inhibited considerably by antibasic fibroblast growth factor antibody. These results suggest that some factors concerned with the growth of brown adipocyte precursor cells are present in the blood plasma from cold-acclimated rats, and that basic fibroblast growth factor produced by brown adipocytes may significantly contribute to BAT enlargement by autocrine mechanisms during cold exposure.     

Basic fibroblast growth factor prevents cAMP-induced apoptosis in cultured Schwann cells

The periplasmic-flagellum (PF) proteins of Triton X-100-soluble and Triton X-100-insoluble sodium dodecyl sulfate-treated fractions from reference and field strains of Serpulina hyodysenteriae, Serpulina innocens, and Serpulina pilosicoli were characterized by Western blotting with a rabbit polyclonal antibody (PAb) specific for the 44-kDa PF sheath protein of S. hyodysenteriae (Z. Li, F. Dumas, D. Dubreuil, and M. Jacques, J. Bacteriol. 175:8000-8007, 1993) and a murine monoclonal antibody (MAb), designated 7G2, specific for the PF core FlaB proteins of S. hyodysenteriae. The MAb 7G2 reacted with a conserved epitope present in the 37-, 34-, and 32-kDa PF core FlaB proteins of all Serpulina species. This suggested that the core FlaB proteins are conserved among porcine Serpulina species. An immunoreactive band of approximately 44 kDa was present with all S. hyodysenteriae, S. innocens, and S. pilosicoli strains that were reacted with the PAb. The specificities of the PAb and the MAb for the FlaA1 and FlaB proteins of Serpulina species were confirmed by N-terminal amino acid sequencing of 44- and 37-kDa proteins, respectively, of S. hyodysenteriae and S. pilosicoli. Results from this study provide further evidence that the 44-kDa protein FlaA1 and the 37-, 34-, and 32-kDa FlaB proteins are conserved among porcine Serpulina species.     

Basic fibroblast growth factor promotes the proliferation of human megakaryocyte progenitor cells

Basic fibroblast growth factor (bFGF), a multifunctional growth factor produced by bone marrow stromal cells, is known to be a potent modulator of hematopoiesis. Because bFGF is present in both human megakaryocytes (MKs) and platelets, we have hypothesized that this growth factor might affect human megakaryocytopoiesis. To test this hypothesis, either low density bone marrow (BM) cells (LDBM), a human BM subpopulation (CD34+ DR+) enriched for the colony-forming unit megakaryocyte (CFU-MK) or a BM subpopulation (CD34+ DR-) enriched for the more primitive burst-forming unit megakaryocyte (BFU-MK) were assayed in the presence of this growth factor. The effect of bFGF on MK colony formation differed according to the cell population assayed. bFGF alone had on MK colony-stimulating activity (MK-CSA) when either CD34+ DR+ or CD34+ DR- BM cells were cloned, but exhibited MK-CSA equivalent to that of interleukin-3 (IL-3) when LDBM cells were used as the target cell population. The MK-CSA of bFGF was inhibited by the addition of neutralizing antisera to either IL-3 and/or granulocyte-macrophage colony-stimulating factor (GM-CSF) but not IL-6. The addition of excess amounts of either IL-3 or GM-CSF to cultures containing bFGF plus anti-IL-3 or anti-GM-CSF reversed the inhibition by the corresponding antisera. The addition of bFGF and IL-3 to assays containing CD34+ DR+ or CD34+ DR- cells increased the size of both CFU-MK- and BFU-MK-derived colonies, respectively, when compared with assays containing IL-3 alone. This increase in MK colony size mediated by bFGF was not affected by addition of either an anti-GM-CSF or anti-IL-6 neutralizing antisera. When LDBM cells were assayed, bFGF alone increased CFU-MK-derived colony size when compared with control values. However, this potentiation of MK colony size by bFGF could be reversed by the addition of either anti-IL-3 or anti-GM-CSF but not anti-IL-6 antisera. In addition, the effects of bFGF and IL-3 on the size of MK colonies cloned from LDBM were not additive. These results suggest that bFGF affects human megakaryocytopoiesis by directly promoting MK progenitor cell proliferation and stimulating BM accessory cells to release growth factor(s) with MK-CSA, such as IL-3 and GM-CSF. We conclude that bFGF, likely produced by cellular components of the BM microenvironment, plays an important role in the control of human megakaryocytopoiesis.     

Basic fibroblast growth factor and insulinlike growth factor I support the growth of human septal chondrocytes in a serum-free environment

OBJECTIVE: To determine if insulinlike growth factor I (IGF-I) and basic fibroblast growth factor (bFGF), individually or in combination, support the growth and viability of human septal chondrocytes in a serum-free medium (SFM) and a serum-enhanced culture medium. DESIGN: Chondrocytes were recovered from enzymatically digested human septal cartilage and were plated for monolayer culture in a newly developed medium. The medium included Dulbecco modified Eagle medium mixed 1:1 with Ham F12 medium and a supplement of known amounts of 2 growth factors-bFGF (100 ng/mL) and IGF-I (100 ng/mL)-used in combination and separately. RESULTS: The combination of IGF-I and bFGF enhanced chondrocyte growth and maintained a high degree of viability in SFM and 10% fetal calf serum. After an initial lag, the SFM, augmented with both growth factors, produced a comparable number of viable cells (4.25+/-0.31 x 10(4)) to that of the medium with 10% fetal calf serum (4.64+/-0.35 x 10(4)) by the seventh day of the experiment. Combined with the 2 growth factors, 10% fetal calf serum provided the greatest proliferation by the end of the experiment. However, the overall mean cell counts for the IGF-I- and bFGF-enhanced SFM were not statistically different. CONCLUSIONS: The combination of IGF-I and bFGF in a serum-free and a serum-supplemented environment supports the growth and viability of human septal chondrocytes in short-term culture. In an SFM, the results obtained approximate those produced in a medium enhanced with 10% fetal calf serum.     

Basic fibroblast growth factor receptors and their prognostic value in human breast cancer

We performed a saturation binding study with 125I-labeled FGF (fibroblast growth factor)-2 in a nonselected series of 250 human primary breast cancers. Two hundred twenty-five breast cancer biopsies possessed bFGFR (basic FGF receptor). The median dissociation constant was 0.35 nM (range, 0.014-1.9), and the median concentration was 1126 fmol/mg protein (range, 49-7328). FGFR-1 was localized, using a specific monoclonal antibody, in cancerous cells and in epithelial cells in normal breast or in benign tumors. In all of the tissues studied, light stromal cell staining was also observed. Thus, the localization of FGFR-1 in carcinoma cells supports the hypothesis that an important part of FGF-2 binding reflects binding to FGFR-1. bFGFR concentrations were positively correlated to estrogen receptor and progesterone receptor levels. Cox univariate analyses showed that the bFGFR (> or = upper quartile) was associated to longer relapse-free survival [P = 0.004; RR (risk ratio), 0.46] and overall survival (P = 0.001; RR, 0.35); age, estrogen receptor levels, progesterone receptor levels, node involvement, tumor diameter, and histoprognostic grading were prognostic, also. In Cox multivariate analyses, only the bFGFR, age, node involvement, and histoprognostic grading were prognostic factors; the bFGFR was associated with longer relapse-free survival (P = 0.03; RR, 0.4) and overall survival (P = 0.009; RR, 0.3). The present study confirms that FGF could be an important regulator of human breast cancer growth and that patients with a high level of bFGFR had a better prognosis.     

Basic fibroblast growth factor reduces lactic acid-induced neuronal injury in rat hippocampal neurons

OBJECTIVE: To evaluate the long-term effects of lactic acidosis and to examine a potential neuroprotective role of basic fibroblast growth factor (bFGF) on hippocampal neurons. DESIGN: Long-term observation in a cell-culture study. SETTING: University research laboratory. SUBJECTS: Adult, differentiated, primary rat hippocampal neurons. INTERVENTIONS: Neurons were exposed to medium acidified with 20 mM lactic acid, pH 6.2, for a 10-min period, and maintained untreated or in the presence of bFGF (500 pg/mL, 1 ng/mL, 10 ng/mL, 20 ng/mL) applied after exposure. MEASUREMENTS AND MAIN RESULTS: Viability was analyzed by a dye inclusion/enzyme activity test and morphology by phase contrast and immunofluorescence microscopy. [3H]Arachidonic acid (AA) release was measured by liquid scintillation spectrometry. All cultures appeared to be unchanged during the first days after exposure to lactic acidosis. Neurodegeneration became apparent within 3 days. Seven days after exposure, cell survival decreased to 60% in lactic acidosis-injured, untreated cultures. Morphologic damage appeared as a 50% reduction in axonal and 25% reduction in dendritic arborizations. AA release increased to four-fold enhanced levels relative to control values. bFGF (1, 20, and 10 ng/ mL) enhanced neuronal viability (p < .05), and 10 ng/mL bFGF induced a maximal increase in live cells to 80% of controls. Axonal arborizations increased to 50% and dendritic arborizations to 75% of controls after 10 ng/mL bFGF (p< .05). bFGF in a dose of 20 ng/ mL enhanced axonal branching to 40% and dendrites in number and branching to 50% of controls (p< .05). bFGF (500 pg/mL, and 1 and 10 ng/mL) decreased enhanced AA (p < .05), and 10 ng/mL bFGF maximally reduced increased AA to two-fold enhanced values relative to controls. CONCLUSIONS: In vulnerable neurons, exposure to moderate lactic acidosis induces a process of cell injury with long latency. bFGF applied postinjury reduces the delayed neurodegeneration and may have neuroprotective efficacy in new therapeutic strategies to ischemia-induced cerebral injury.     

Basic fibroblast growth factor expression as a predictor of prognosis in pediatric high-grade gliomas

Clinical and histopathological factors fail to adequately predict outcomes in children with high-grade gliomas, indicating a need to identify relevant biological markers of tumor behavior to guide therapeutic decision-making. Basic fibroblast growth factor (bFGF) is a mitogenic and angiogenic factor that has been observed to be overexpressed in a significant percentage of malignant gliomas, although the prognostic significance of this expression is unknown. To address this issue, the expression status of bFGF was examined immunohistochemically in a series of 27 archival pediatric malignant non-brainstem gliomas treated consecutively at our institution between 1975 and 1992. Tumors were categorized based on expression levels, and the association between expression status and outcome was examined. Sixteen cases showed high levels of expression of bFGF, and 11 showed low levels. There was no correlation between expression status and either tumor histology, patient age, or tumor location. However, there was a significant difference in outcome between patients with high levels of bFGF immunoreactivity and those with low expression. Median progression-free survival was >66 months in the low bFGF group as compared to 6 months in the high bFGF group (P = 0.006). Median overall survival was >66 months in the low bFGF group as compared to 18 months in the high bFGF group (P = 0.03). Tumor bFGF expression seems to be strongly associated with outcome in children with high-grade gliomas and, consequently, may serve as a biological correlate of patient prognosis in conjunction with other prognostic variables.     

Basic fibroblast growth factor impregnated hydrogel microspheres for embolization of cerebral arteriovenous malformations

To assess the prevention of recanalization at embolized sites in cerebral arteriovenous malformations, the authors devised a novel embolic material, hydrogel microspheres prepared from poly(ethylene glycol) diacrylate impregnated with basic fibroblast growth factor. In this article, preparation of the microspheres, and preliminary study of in vitro and in vivo performance are discussed. Poly(ethylene glycol) diacrylate, prepared from end capping of poly(ethylene glycol) (molecular weights, 1,000, 2,000, and 4,000) with acryloyl chloride and benzophenone derived poly(ethylene glycol), prepared from poly(ethylene glycol) (molecular weight, 2,000) with benzoyl benzoic acid chloride as a photoinitiator, were dissolved in a buffer solution with or without basic fibroblast growth factor. The mixed solution was dropped stepwise into liquid paraffin with stirring. Ultraviolet light irradiation resulted in the formation of relatively rigid hydrogel microspheres (diameter, 100-400 microm). The in vitro study showed that the higher the molecular weight of poly(ethylene glycol) diacrylate used, the faster the release rate of immobilized protein. Canine kidneys were embolized with these microspheres via the femoral artery using a microcatheter. Histologic examination showed that microspheres occluded arterioles. The degree of accumulation of fibroblasts and extracellular matrix were larger for basic fibroblast growth factor impregnated microspheres than for nonimpregnated ones. Basic fibroblast growth factor released from microspheres may help regenerate tissues at arteriovenous malformation sites, and recanalization is expected to be prevented.     

Expression of transforming growth factor-alpha (TGF-alpha) in cholesteatoma

BACKGROUND: This report describes the measurement of convergent eye movements and calculation of the spatial convergence point from the angular eye position data. These measurements were made in the dark while the subject experienced inertial motion aboard a centrifuge. This was an exploratory experiment with the goal of evaluating the eyes' convergence in the dark, and to see if this convergence point is dependent on inertial motion. METHODS: The subject was rotated in the dark on NAMRL's Coriolis Acceleration Platform in Pensacola, FL. The pupil positions were tracked by two helmet-mounted infrared cameras connected to a computer-controlled data acquisition system. We used the position data to calculate the angles through which the eyes rotated, and then applied trigonometric principles to construct the line of sight for each eye for any instant in time. The intersection of these two lines of sight was the convergence point. RESULTS: With the binocular eye-tracking system, we could accurately determine an accelerating subject's convergence point to within 10%, if the point was less than 1.5 m away from the subject. At convergence distances greater than 1.5 m, the angular movements of the two eyes became so small that determining a convergence point was difficult.     

Basic fibroblast growth factor is neither necessary nor sufficient for the development of retinal neovascularization

Basic fibroblast growth factor (FGF2) is constitutively expressed in the retina and its expression is increased by a number of insults, but its role in the retina is still uncertain. This study was designed to test the hypothesis that altered expression of FGF2 in the retina affects the development of retinal neovascularization. Mice with targeted disruption of the Fgf2 gene had no detectable expression of FGF2 in the retina by Western blot, but retinal vessels were not different in appearance or total area from wild-type mice. When FGF2-deficient mice were compared with wild-type mice in a murine model of oxygen-induced ischemic retinopathy, they developed the same amount of retinal neovascularization. Transgenic mice with a rhodopsin promoter/Fgf2 gene fusion expressed high levels of FGF2 in retinal photoreceptors but developed no retinal neovascularization or other abnormalities of retinal vessels; in the ischemic retinopathy model, they showed no significant difference in the amount of retinal neovascularization compared with wild-type mice. These data indicate that FGF2 expression is not necessary nor sufficient for the development of retinal neovascularization. This suggests that agents that specifically antagonize FGF2 are not likely to be useful adjuncts in the treatment of retinal neovascularization and therapies designed to increase FGF2 expression are not likely to be complicated by retinal neovascularization.     

Basic fibroblast growth factor supports human olfactory neurogenesis by autocrine/paracrine mechanisms

Throughout life, olfactory sensory neurons are renewed from a population of dividing stem cells. Little is known about the molecular mechanisms that regulate the activation, self-renewal and differentiation of olfactory neuronal precursors; however, evidence indicates that soluble mediators may play a central role in olfactory neurogenesis. To identify molecules that regulate olfactory self-renewal and differentiation, we have recently established, cloned and propagated in vitro primary long-term cell cultures from the human fetal olfactory neuroepithelium. Here we show that primary human olfactory neuroblasts synthesize and release biologically active basic fibroblast growth factor which, in turn, supports neuroblast growth by autocrine/paracrine mechanisms. The growth-promoting activity of basic fibroblast growth factor is dose dependent and is accompanied by morphological changes of the cells and by an increase in the expression of neuronal-related genes. These observations indicate that endogenous basic fibroblast growth factor participates in controlling olfactory self-renewal and suggest that this cytokine represents a key regulatory element of olfactory neurogenesis.     

Characterization of recombinant human fibroblast growth factor (FGF)-10 reveals functional similarities with keratinocyte growth factor (FGF-7)

A newly identified member of the fibroblast growth factor (FGF) family, designated FGF-10, is expressed during development and preferentially in adult lung. The predicted FGF-10 protein is most related to keratinocyte growth factor (KGF, or FGF-7). The latter is unique among FGFs in that it binds and signals only through the FGF receptor (FGFR2b) isoform KGF receptor (KGFR) expressed specifically by epithelial cells. In order to examine the biological and biochemical properties of human FGF-10, we isolated the cDNA and expressed its encoded protein in bacteria. The recombinant protein (rFGF-10) was a potent mitogen for Balb/MK mouse epidermal keratinocytes with activity detectable at 0.1 nM and maximal at around 5 nM. Within this concentration range, FGF-10 did not stimulate DNA synthesis in NIH/3T3 mouse fibroblasts. rFGF-10 bound the KGFR with high affinity comparable to that of KGF, and did not bind detectably to either the FGFR1c (Flg) or FGFR2c (Bek) receptor isoforms. The mitogenic activity of FGF-10 could be distinguished from that of KGF by its different sensitivity to heparin and lack of neutralization by a KGF monoclonal antibody. These results indicate that FGF-10 and KGF have similar receptor binding properties and target cell specificities, but are differentially regulated by components of the extracellular matrix.     

Basic fibroblast growth factor in serum and urine of patients with head and neck cancer

Between 1996 and 1997 serum and urine levels of basic fibroblast growth factor (b-FGF) in patients with head and neck cancer were measured to answer the following questions: i) Are increased levels of b-FGF in serum and urine detectable in patients with malignant head and neck tumors? ii) Do these parameters correlate with tumor stage and differentiation of tumors? iii) Is there an association between growth behaviour (local or metastatic growth) and b-FGF levels in serum and/or urine? Eighty-nine patients with head and neck cancer as well as 45 patients with diseases unrelated to cancer were investigated. Detectable levels of b-FGF were found in the serum and urine of patients with malignant head and neck tumors. In addition, there was a significant correlation between tumor size and b-FGF levels in either serum or urine. No association of b-FGF concentrations with degree of histologic differentiation and tumor growth behaviour was observed. The results of this study demonstrate that b-FGF levels are elevated in serum and urine of patients with head and neck cancer. These findings suggest an involvement of b-FGF in the formation of solid tumors.     

Induction of basic fibroblast growth factor mRNA by basic fibroblast growth factor in Müller cells

PURPOSE: To investigate the induction of basic fibroblast growth factor (bFGF) gene expression in cultured rat Müller cells by bFGF and to study the mechanism of induction. METHODS: Müller cells from 1- to 3-day-old Sprague-Dawley rats were isolated and cultured with Dulbecco's modified Eagle's medium with 10% fetal calf serum. Cultured cells were identified by immunocytochemistry using antibodies against vimentin, carbonic anhydrase II, and glutamine synthetase. Cells of passages 1 through 4 were treated with bFGF, the protein kinase C (PKC) inhibitor, H-7; calphostin C, or the PKC activator, PMA; and protein kinase A (PKA) inhibitor, H-89; as well as the adenylate cylase activator, forskolin; or the adenylate cyclase inhibitor, SQ22536. Northern blot analysis was performed to determine the mRNA expression of bFGF, ciliary neurotrophic factor (CNTF) and brain-derived neurotrophic factor (BDNF). RESULTS: Addition of bFGF to culture medium induced bFGF gene expression in a dose- and time-dependent manner. Induction of bFCF mRNA started at a bFGF concentration of 0.1 ng/ml. The bFGF mRNA level was elevated by 2-fold at 1 ng/ml of bFGF, 2.8-fold at 5 ng/ml, and reached a peak of 4-fold at 10 ng/ml and 3.7-fold at 50 ng/ml. At 10 ng/ml of bFGF, induction of bFGF mRNA was observed as early as 2 hours (2-fold) after treatment. The bFGF mRNA level continued to increase to 3.7-fold by 4 hours, and reached a maximum of 4.4-fold by 8 hours. A slow decline of the bFGF mRNA level was observed after 8 hours of bFGF treatment (3.5-fold by 12 hours, and 3-fold by 24 hours). This induction of bFGF gene expression was blocked by PKC inhibitors H-7 (30 microM). The PKC activator PMA (0.1 microM) also upregulated bFGF gene expression, but the effects of bFGF and PMA were not additive. An adenylate cyclase inhibitor, SQ22536 (100 microM), did not inhibit bFGF-induced bFGF gene expression. Although forskolin (5 microM), an adenylate cyclase activator, also upregulated the level of bFGF mRNA, the effects of forskolin and bFGF were additive. In addition, no inhibitory effect on bFGF-induced expression of bFGF mRNA was found using H-89 (1 microM). Exogenous bFGF did not alter the mRNA levels of CNTF and BDNF. CONCLUSIONS: These results indicate that bFGF induces bFGF gene expression in cultured rat Müller cells through PKC activation. The authors' findings raise the possibility that Müller cells in vivo also respond to available bFGF (for example, that released from the endogenous reservoirs in the case of injury) or to exogenous bFGF by producing more bFGF, which could in turn promote photoreceptor survival.     

Basic fibroblast growth factor mRNA, bFGF peptide and FGF receptor in epiretinal membranes of intraocular proliferative disorders (PVR and PDR)

Basic fibroblast growth factor (bFGF) has been shown to be involved in epiretinal membrane formation in proliferative vitreoretinal disorders. However, up to now, little knowledge exists; as to the actual cellular source of this potent mitogen. We examined 20 epiretinal membranes from patients with proliferative diabetic retinopathy (PDR) (n = 12) and proliferative vitreoretinopathy (PVR) (n = 8) for the presence of bFGF peptide, fibroblast growth factor receptor-1 (FGFR-1) and bFGF messenger ribonucleic acid (mRNA). Using a specific antibody, we detected bFGF peptide in most (8/10) examined PDR membranes and in all (8/8) PVR membranes. Moreover, we found positive staining for the corresponding receptor. Local production of bFGF in epiretinal membranes was confirmed by nonisotopic in situ hybridisation for bFGF mRNA in some (4/7) examined PDR membranes and some (3/4) examined PVR membranes. All membranes which contained bFGF mRNA were also positive for bFGF peptide. In conclusion, bFGF is produced and stored in epiretinal membranes. Together with the corresponding receptor, bFGF may play a role in the auto- and paracrine control of the proliferative processes at the vitreoretinal interface.     

Basic fibroblast growth factor promotes the generation and differentiation of calretinin neurons in the rat cerebral cortex in vitro

Calretinin-expressing neurons are some of the earliest postmitotic cells to appear in the developing cerebral cortex. Lineage studies have shown that the expression of this calcium-binding protein in cortical neurons is not genetically programmed and is likely to be induced by external factors. A number of studies have clearly shown that basic fibroblast growth factor (bFGF) and a number of neurotrophins promote the proliferation and differentiation of cortical progenitor cells to a particular lineage. Here, using a culture system of dissociated rat cortical cells, we found that brain-derived neurotrophic factor and neurotrophin-3 promoted the morphological differentiation of one of the calretinin-containing neuronal subpopulations, the Cajal-Retzius cells. Another subpopulation of calretinin-expressing cells of smaller size and bipolar form was generated when cultures were treated with bFGF. The progenitors of these neurons were stimulated by bFGF to divide a number of times before initiating their differentiation programme. The number of calretinin-expressing neurons increased further when cultures were treated with a combination of bFGF and retinoic acid.     

Characterization of GH3 cells overexpressing basic fibroblast growth factor (FGF-2)

Basic fibroblast growth factor (FGF-2) is not only a potent mitogen for various cells but also a multifunctional factor with angiogenic and chemotactic activity, and the capacity to induce the synthesis of various proteinases and to modulate endocrine function. To clarify the role played by FGF-2 in the progression of pituitary tumor, we fused rat FGF-2 cDNA to the promoter SR alpha, consisting of the early promoter of SV40 and HTLV(I)-LTR, and we cotransfected GH3 cells with pSV2-neo by an electroporation method. After selection by G418, we obtained 7 neomycin-resistant clones. Southern blot analysis of genomic DNA revealed the presence of transfected rat FGF-2 cDNA in 4 of the 7 clones. To measure FGF-2 molecules, we established a new immuno-fluorometric assay system, using 3 monoclonal antibodies against different portions of human FGF-2. This assay had a minimum sensitivity of 10 pg/ml and cross-reacted neither with acidic fibroblast growth factor (FGF-1) nor insulin-like growth factor 1 (IGF-1), even at a concentration of 100 ng/ml. Although FGF-2 was undetectable in the culture medium of any of the clones, the cell homogenate contained a significant amount of FGF-2 (7.2 ng/mg protein) in 1 of the 4 FGF-2-transfected clones (GH3FGF(+)), whereas FGF-2 was not detected (< 5.2 pg/mg protein) in the cell homogenates of either the parent GH3 cells or the control cells transfected with pSV2-neo alone (GH3FGF(-)), GH3FGF(+) grew as adherent cells and formed epithelial sheets with a growth rate similar to that of control cells. The amount of prolactin(PRL) released by TRH was greater in GH3FGF(+) than that in GH3 or GH3FGF(-). On the other hand, the sensitivity to SRIF was increased in GH3FGF(+) compared with that in other clones. The findings of these in vitro studies indicate that FGF-2, if it is expressed in pituitary tumor cells, plays little if any role in cell growth but may modulate certain cell functions such as responsiveness to hormones.