Enhanced formation of fibrosis in a rabbit aneurysm by gelatin hydrogel incorporating basic fibroblast growth factor

OBJECTIVE: This study was undertaken to analyze whether the controlled release of basic fibroblast growth factor (bFGF) can promote intrasaccular thrombosis in an experimental aneurysmal model. METHODS: Carotid aneurysms were constructed in 80 rabbits with venous pouches and treated by placing gelatin hydrogels into each aneurysm incorporating 0, 25, 50, or 100 microg of bFGF or incorporating 100 microg of bFGF with different water contents. In the controls, the venous pouches either were not treated or were treated with gauze alone. Gelatin hydrogel was used for the controlled release of bFGF into the aneurysms. The formation of fibrosis in the aneurysms was histologically viewed to assess the area occupied by the fibrous tissues at 3 and 6 weeks after the hydrogel application. The effect of the bFGF dose and water content on obliterating the aneurysm by the hydrogels incorporating bFGF was also investigated. RESULTS: Six weeks after the application of gelatin hydrogels with a water content of 95 wt% incorporating 100 microg of bFGF, the lateral pouch orifice was completely closed, obliterating the aneurysm at the level of tissue appearance, in contrast to hydrogels incorporating lower doses of bFGF and other control agents. The venous pouch aneurysm was histologically occupied with the newly formed fibrous tissue, and the fibrous tissue area and percentage of the aneurysmal lumen occupied by the fibrosis-gauze complex were significantly larger than those of other hydrogel applications (P < 0.05). The neointima tissue was homogeneously covered with a monolayer of Factor VIII-positive cells. The fact that there was no difference in the water content in the fibrosis formation induced by the bFGF-incorporated gelatin hydrogels indicated that the hydrogel biodegradability did not affect the obliteration of the aneurysm. CONCLUSION: Local controlled release of bFGF stimulated the formation of in vivo fibrosis, resulting in obliteration of the aneurysm. The long-term results of the fibrous organization remain speculative.     

碱性成纤维细胞生长因子对组织工程化外周神经的影响

目的　研究碱性成纤维细胞生长因子 (bFGF)和肝素与乳兔许旺细胞、去细胞基膜管、构成的复合型组织工程化外周神经桥接体修复兔正中神经缺损的效果。　方法　新西兰兔 48只 ,建立左侧上臂正中神经 3 0mm缺损模型 ,随机分为 4组 ,分别用去细胞基膜管种植许旺细胞并复合bFGF及肝素 (Hep)的桥接体 (A组 )、去细胞基膜管种植许旺细胞的桥接体 (B组 )、去细胞基膜管复合bFGF及Hep桥接体 (C组 )、自体神经 (D组 )修复神经缺损 ,于术后 1、3个月分别进行大体观察 ,Masson三色染色光镜观察神经再生、神经内胶原纤维形成及血管形成 ,3个月检测各组桥接体运动神经传导速度 ,并行透射电镜检查 ,称量指浅屈肌肌肉湿重 ,观察神经功能恢复。　结果　去细胞基膜管种植许旺细胞并复合bFGF及Hep的桥接体组 (A组 )神经再生及功能指标 (再生有髓神经纤维密度、平均髓鞘厚度、有髓纤维直径、运动神经传导速度、肌肉湿重恢复率 )与自体神经移植 (D组 )比较 ,差异无显著性 (P >0 .0 5 )。　结论　bFGF及肝素与许旺细胞、去细胞神经基膜管构成的复合型组织工程神经桥接体修复神经缺损能提高神经再生质量。     

Simultaneous application of basic fibroblast growth factor and hepatocyte growth factor to enhance the blood vessels formation

OBJECTIVE: The present study investigated whether the simultaneous application of basic fibroblast growth factor (bFGF) and hepatocyte growth factor (HGF) enhances blood vessel formation in murine ischemic hindlimb compared with bFGF or HGF applied alone. METHODS: Unilateral hindlimb ischemia was created in C57BL/6 mice. Hindlimb blood flow was evaluated by laser Doppler perfusion image index (LDPII) (ratio (%) of ischemic-to-normal-limb blood flow). The ischemic limbs were treated with bFGF and HGF separately, or bFGF and HGF together, and their therapeutic effects were assessed. Collagen microspheres (CM) were used as a sustained-release carrier for bFGF and HGF. RESULTS: A single intramuscular injection of 5 microg or less of bFGF-incorporated CM (bFGF/CM) into the ischemic limb did not significantly increase the LDPII compared with the control (no treatment) 4 weeks after the treatment. Similarly, 20 microg or less of HGF/CM did not increase LDPII. Based on these results, we compared the dual release of CM incorporating 5 microg of bFGF and 20 microg of HGF with either the single release of 5 mug of bFGF/CM alone or 20 microg of HGF/CM alone. The LDPII of the dual release (94.2% +/- 10.9%) was higher than either single release (51.2% +/- 5.8% or 52.5% +/- 8.0%, P < .01). Furthermore, the LDPII in the dual release (94.2% +/- 10.9%) was equivalent to that with 80 microg of bFGF/CM (95.1% +/- 7.6%) alone or 80 microg of HGF/CM (92.8% +/- 7.6%) alone. A histologic evaluation at 4 weeks showed capillary density in the dual release (868 +/- 173 vessels/mm(2)) was higher than that in either single release (204 +/- 68 vessels/mm(2) or 185 +/- 98 vessels/mm(2) , P < .01). The percentage of mature vessels assessed by alpha-smooth muscle actin staining was also higher in the dual release (43.8% +/- 7.8% vs 9.5% +/- 3.0% or 11.7% +/- 3.8%, respectively; P < .01). CONCLUSIONS: This study demonstrates that the sustained dual release of a lower dose of bFGF and HGF from a carrier matrix can achieve equivalent blood perfusion recovery and more mature vasculature in the ischemic limb than a higher dose of bFGF or HGF alone. This approach may be a highly promising strategy for the future treatment of peripheral vascular disease.     

Stimulation of bone formation by intraosseous injection of basic fibroblast growth factor in ovariectomised rats

Summary. The effect on intraosseous bone formation of a single local injection of recombinant human basic fibroblast growth factor into trabecular bones was examined in ovariectomised osteoporotic rats. Fibroblast growth factor (400 μg), or the vehicle alone, was injected into the ilium at 16 weeks after ovariectomy or a simulated operation. Bone mineral density in the ovariectomised rats increased to a level similar to the latter at 2 weeks and reached a maximum at 8 weeks. After 8 weeks, BMD decreased slowly and the value at 24 weeks was still higher than that in the ovariectomised rats. Fibroblast growth factor stimulated osteoid formation in the first 2 weeks, bone volume reaching a peak at 8 weeks. From 8 to 12 weeks, bone resorption increased, resulting in decreases in bone volume to the levels of the group with simulated operations at 24 weeks. Structural analysis at 8 and 24 weeks showed that ovariectomy decreased the continuity of trabeculae and the injection of fibroblast growth factor restored it to levels higher than, or equal to, those who had the simulated operation. The present study demonstrated that intraosseous fibroblast growth factor given to ovariectomised rats restored bone volume and quality to the levels of the rats who had a simulated operation only.

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Résumé. L’effet d’une unique injection locale dans les os trabeculaires de facteur de croissance de base de fibroblaste humain recombinant (bFGF) sur la formation intra-osseuse a été examiné sur des rats ostéoporotiques ovariectomisés. L’injection bFGF (400 μg) ou véhicule seul (V) a été pratiquée dans l’ilion 16 semaines après ovariectomie (OVX) ou pseudo-opération (Sham). A 2 semaines, la densité osseuse moyenne des OVX+bFGF avait augmenté jusqu’à un niveau similaire aux Sham+V pour atteindre son maximum à 8 semaines, soit 19% de plus que les Sham+V. Au-delà de 8 semaines, la densité moyenne a décliné lentement, conservant à 24 semaines une valeur supérieure aux OVX+V. Le bFGF a stimulé la formation ostéo? de des 2 premières semaines. Le volume d’os minéralisé a atteint son sommet à 8 semaines. Entre 8 et 12 semaines, la résorption osseuse a été facilitée, conduisant à des baisses du volume osseux jusqu’aux niveaux Sham+V 24 semaines. Les analyses structurelles à 8 et 24 semaines ont montré que l’injection bFGF ramène à des niveaux égaux ou supérieurs à Sham+V la connectivité des trabeculae réduite par l’OVX. La présente étude établit qu’une application intraosseuse de bFGF après ovariectomie ramène le volume et la qualité osseuse au niveau des rats pseudo-opérés.

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Accepted: 7 July 1997     

The prevention of incisional hernia formation using a delayed-release polymer of basic fibroblast growth factor

OBJECTIVE: We sought to reduce the high incidence of abdominal wall incisional hernias using sustained release growth factor therapy. SUMMARY BACKGROUND DATA: Incisional hernias complicate 11% of abdominal wall closures, resulting in 200,000 incisional hernia repairs in the United States each year. Mechanical improvements alone in mesh, suture material, and surgical technique have failed to reduce the high rate of fascial wound failure. METHODS: Sprague-Dawley rats underwent midline celiotomies that were closed with fast-absorbing suture to induce early biomechanical wound failure and incisional hernia formation. In primary wounds, fascial incisions were closed adjacent to a continuous release polygalactone polymer rod containing basic fibroblast growth factor (bFGF), no growth factor (control-rod), or without rods. In a second group, incisional hernias were repaired with either bFGF or control-rod therapy. Breaking strength was measured on postoperative day (POD) 7, and the incidence of incisional hernia formation was determined on POD 28. RESULTS: Treatment with bFGF rods significantly increased fascial wound breaking strength. In the "hernia-prevention" experiments, incisional hernias developed in 90% of untreated incisions, 60% of control-rod incisions, and only 30% of bFGF-rod incisions (P < 0.05). In the "hernia-treatment" experiments, recurrent incisional hernias developed in 86% of control-rod incisions compared with only 23% of bFGF-rod treated incisions (P < 0.05). Immunohistochemistry demonstrated increased angiogenesis and collagen protein production in bFGF treated incisions. CONCLUSION: The treatment of abdominal fascial incisions with a sustained-release bFGF polymer significantly lowered the incidence of incisional hernias and the recurrence rate after repair.     

The usefulness of basic fibroblast growth factor for radiation‐exposed tissue

A high dose of ionizing external radiation damage to the skin and soft tissue results in changes in function as well as in the general body condition. Once radiation surpasses the tissue safety or survival level, progressive alteration in the damaged tissue results in tissue loss and then flap loss. Local expression and action of stem cells or local growth factors in the irradiated tissue is mitigated, and external administration is sought to investigate the possibility of skin and soft tissue survival after an elevating flap. Basic fibroblast growth factor (bFGF) is primarily considered as a potent angiogenic growth factor. In burns, resurfacing with a dermal component is required, and bFGF stimulates wound healing and enhances human skin‐derived mesenchymal stem cells under serum‐free conditions in a dose‐dependent manner. Thirty‐five male, 4‐ to 8‐week‐old CLAWN miniature pigs received radiation exposure to assess the effectiveness of bFGF in terms of the progressive clinical course relevant to human skin and soft tissue. At 2 weeks following 10‐Gy irradiation, tissue was preserved in the group receiving subcutaneous placement of a round‐type tissue expander and bFGF. The expander plus bFGF group demonstrated significantly greater dermo‐epidermal proliferation than the radiation alone, radiation plus bFGF, or expander plus radiation plus vehicle‐solution groups, and new blood vessel formation was significantly increased in the expander tissue with bFGF after irradiation (p < 0.01). Electron microscopy revealed that tissue with expander and bFGF maintained more stable skin adnexae with preserved intact epidermis and dermis. Thus, bFGF improved and maintained the tissue viability after immediate irradiation in the skin and soft tissue.     

Recombinant basic fibroblast growth factor accelerates wound healing

Basic fibroblast growth factor (bFGF) stimulates extracellular matrix metabolism, growth, and movement of mesodermally derived cells. We have previously shown that collagen content in polyvinyl alcohol sponges increased after bFGF treatment. We hypothesized that bFGF-treated incisional wounds would heal more rapidly. After intraperitoneal pentobarbital anesthesia, male, 200- to 250-g, Sprague-Dawley rats (n = 27) each underwent two sets of paired, transverse, dorsal incisions closed with steel sutures. On Day 3 postwounding, 0.4 ml of bFGF (recombinant, 400 ng. Synergen) or normal saline was injected into one of each paired incisions. Animals were killed with ether on postwounding Days 5, 6, and 7 and their dorsal pelts were excised. Fresh or formalin-fixed wound strips were subjected to tensile strength measurements using a tensiometer. Breaking energy was calculated. Wound collagen content (hydroxyproline) was measured in wound-edge samples following hydrolysis using high-performance liquid chromatography. There was an overall significant increase in fresh wound tensile strength (13.7 +/- 1.06 vs 19.1 +/- 1.99 g/mm, P less than 0.01) and wound breaking energy (476 +/- 47 vs 747 +/- 76 mm2, P less than 0.001) in bFGF-treated incisions. There was an increase in wound collagen content which was not statistically significant and there was no difference in fixed incisional tensile strength. Histologic examination showed better organization and maturation in bFGF wounds. Recombinant bFGF accelerates normal rat wound healing. This may be due to earlier accumulation of collagen and fibroblasts and/or to greater collagen crosslinking in bFGF-treated wounds.     

Stimulation of bone formation by intraosseous application of recombinant basic fibroblast growth factor in normal and ovariectomized rabbits

The effect on intraosseous bone formation of a single local injection of recombinant human basic fibroblast growth factor into the distal femur was examined in normal and ovariectomized rabbits. In normal rabbits, basic fibroblast growth factor increased bone mineral density around the injected site in a dose-dependent manner at 4 weeks, with significant effects at concentrations of 400 μg and greater. Doses of 400 and 1,600 μg of basic fibroblast growth factor increased bone mineral density by 8 and 9%, respectively, compared with the opposite control femur. Histological examination showed that basic fibroblast growth factor (400 μg) induced the proliferation or recruitment of undifferentiated mesenchymal cells around the existing trabeculae at 3 days after the injection. For the first 2 weeks, osteoid formation was strongly stimulated, and this was followed by mineral apposition for another 2 weeks, at which time the femurs were harvested. Consequently, basic fibroblast growth factor stimulated intraosseous bone formation at 4 weeks. We speculate that the direct action of basic fibroblast growth factor on bone formation may be to stimulate proliferation or recruitment of minimally differentiated mesenchymal cells and to initiate the cascade of events in later stages of bone formation. In ovariectomized rabbits, basic fibroblast growth factor (400 μg) also increased bone mineral density, histomorphometrical bone formation markers, and trabecular connectivity to levels similar to those in rabbits who had received sham operations.     

胶原多聚物载体运载碱性成纤维细胞生长因子的研究

目的探讨以含有胶原的聚丙烯酸交酯（PGA）为载体，运载碱性成纤维细胞生长因子（bVgr），同时复合人骨髓基质干细胞（hBMSCs）进行体外构建的可行性。方法不含胶原的和含有20％胶原的PGA运载系统合成后负载bFGF，利用免疫组化的方法检测运载系统中bFGF的释放动力学，观察释放后的bFGF对增殖的影响，从而推测该运载系统可否固定bFGF；同时建立bFGF＋hBMSCs＋载体的复合体，对该构件进行体外培养，通过测定其中DNA总量和H^3胸腺嘧啶核苷的吸收情况，了解构件中细胞的增殖情况，证实其bFGF存在活性。结果不含有胶原的运载系统中，bFGF有明显的突发释放现象；而含20％胶原的运载系统中，bFGF的突发释放较弱。前种运载系统的释放液可以持续刺激细胞的增殖，而后者的释放液对细胞的增殖影响不明显。含有胶原＋bFGF的构件中细胞增殖较快，在体外培养2周后检测出较多的DNA含量。结论含有胶原的PGA运载系统可以用于固定和运载bFGF，并保持其活性。因子＋hBMSCs＋载体的模式为骨组织工程学提供了新的方法。     

Serum basic fibroblast growth factor as a marker of reflux nephropathy

Purpose

The authors investigated whether serum basic fibroblast growth factor (b-FGF) can be used as a noninvasive marker of renal parenchymal damage (scarring) in cases of vesicoureteric reflux (VUR).

Methods

Serum levels of b-FGF were measured in 120 children with known grade III to grade V VUR and 21 controls using a standard enzyme-linked immunosorbent assay technique.

Results

Sixty-five children had grade III VUR, 39 had grade IV, and 16 had grade V. Renal scarring was seen in 43 children on radionuclide scanning. There were no significant differences between serum b-FGF levels for different grades of VUR without scarring and controls. However, serum b-FGF levels were significantly higher in VUR patients with renal scarring than in patients with VUR without renal scarring (P < .001).

Conclusions

This report is the first to document serum b-FGF profiles in children with VUR and renal scarring. The authors recommend measuring it as a simple, noninvasive marker of renal scarring in cases of VUR.     

Alginate microparticles loaded with basic fibroblast growth factor induce tissue coverage in a rat model of myelomeningocele

Background/Purpose

We sought to develop a minimally invasive intra-amniotic therapy for prenatal treatment of myelomeningocele (MMC) in an established rat model.

Increased gene expression of scatter factor—hepatocyte growth factor and basic fibroblast growth factor in granulation tissue in the rat

Scatter factor-hepatocyte growth factor is a protein secreted by fibroblasts which disperses colonies of epithelial cells and keratinocytes in culture. The factor is also a patent mitogen for hepatocytes, synthesized in the liver. Basic fibroblast growth factor, another heparin-binding factor, is most abundant in the brain but also plays a role in wound healing. Using a solution hybridization/RNAase protection assay, we have measured the abundance of messenger RNA for scatter factor-hepatocyte growth factor and basic fibroblast growth factor in granulation tissue obtained from subcutaneously Hunt-Schilling wound cylinders. The levels of scatter factor-hepatocyte growth factor messenger RNA increased after weeks 2 through 4 to a twofold higher level in weeks 5 through 7 after implantation of the cylinders, whereas no changes in basic fibroblast growth factor messenger RNA levels were noticed. At week 3 after implantation of the cylinders, scatter factor-hepatocyte growth factor messenger RNA levels in granulation tissue were more than threefold higher than in skin dermis fibroblasts but markedly lower than in the liver. The abundance of basic fibroblast growth factor messenger RNA was also significantly increased in granulation tissue compared with dermis but, as expected, markedly lower than in the brain. In conclusion, the gene expression of the scatter factor-hepatocyte growth factor, as well as basic fibroblast growth factor, is increased in granulation tissue. Because there was a time-dependent increase in the expression of scatter factor-hepatocyte growth factor, it is hypothesized that scatter factor-hepatocyte growth factor acts as a signal from fully developed granulation tissue to stimulate skin epithelial cells to scatter over the wound.     

bFGF调节PDGF对人成骨细胞的促增殖作用

目的 探讨碱性成纤维细胞生长因子（ｂＦＧＦ）对血小板衍生生长因子（ＰＤＧＦ）促成骨细胞增殖作用的影响及其机制。方法 分离培养人成骨细胞;以ＰＤＧＦ－ＡＢ（１００ｎｇ／ｍｌ）单独培养、ｂＦＧＦ（１０ｎｇ／ｍｌ）与ＰＤＧＦ－ＡＢ（１００ｎｇ／ｍｌ）混合培养、不加生长因子等３种方式培养细胞,绘制细胞生长曲线;ｂＦＧＦ（１０ｎｇ／ｍｌ）与ＰＤＧＦ－ＡＡ或ＰＤＧＦ－ＢＢ（浓度均为４０ｎｇ／ｍｌ）以不同方式联     

Expression of basic fibroblast growth factor in thyroid disorders

Morphologic and biologic studies were undertaken to clarify the biologic significance of basic fibroblast growth factor (bFGF) in human thyroid neoplasms. A total of 71 malignant tumors (50 papillary carcinomas, 14 follicular carcinomas, 7 anaplastic carcinomas), 11 follicular adenomas, 6 adenomatous goiters, and 6 Graves' disease tissues were examined employing immunohistochemical methods (avidin-biotin-peroxidase complex technique). An affinity-purified polyclonal rabbit antiserum to human bFGF was used as a primary antibody. The eluate of malignant thyroid tumor tissues from the heparin-Sepharose column was examined by Western blot analysis to elucidate the molecular weight form. With immunohistochemical staining, bFGF was frequently detected in the cytoplasm of malignant thyroid tumors compared to tissues of the benign diseases and normal controls. With anaplastic carcinoma, immunoreactivity of the tumor cells was particularly strong. In the correlative analyses between UICC TNM classification and bFGF staining in papillary carcinoma, there were significant differences when relating positive staining to the grade of nodal metastases. By Western blot analysis, the bFGF immunoreactivity was specifically detected in the two forms, with molecular weights of 18 and 33 kDa. The high-molecular-weight form was detected in only anaplastic carcinoma. The present investigations demonstrated a close correlation between the expression of bFGF and the degree of malignancy. bFGF might play an important role in promoting lymph node metastases. Moreover, the high-molecular-weight form of bFGF might have an intense influence on tumor growth.

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Resumen Se emprendió un estudio morfológico y biológico, con el propósito de clarificar la significación biológica del factor básico de crecimiento de fibroblastos (FBCF) en los neoplasmas de la glándula tiroides humana.Setenta y un tumores malignos (50 carcinomas papilares, 14 carcinomas foliculares y 7 carcinomas anaplásico), 11 adenomas foliculares, 6 bocios adenomatosos y 6 tejidos de glándula con enfermedad de Graves fueron examinados mediante métodos inmunohistoquímicos (técnica del complejo avidina-biotinaperoxidasa); se utilizó un antisuero policlonal purificado contra el FBCF humano, como anticuerpo primario. Además, se utilizó el análisis de Western blot para elucidar la forma de peso molecular.Con la coloración inmunohistoquímica, el FBCF fue detectado con frecuencia en el citoplasma de los tumores malignos de la tiroides, en comparación con lo observado en la enfermedad benigna y en los controles normales. La inmunorreactividad tumoral fue particulamente fuerte en el carcinoma anaplásico. En el análisis correlativo entre la clasificiación TNM UICC y la coloración del FBCF en el carcinoma papilar, se hallaron diferencias significativas relativas a la coloración positiva y al grado de la metástasis ganglionares.En el análisis Western blot, la inmunorreactividad FBCF fue específicamente detectada en las dos formas diferentes con pesos moleculares de 18 K y 33 K. La forma de alto peso molecular fue detectada sólamante en el carcinoma anaplásico.La presente investigación demuestra una estrecha correlación entre la expresión de FBCF y el grado de malignidad. El FBCF puede jugar un papel importante en promover las metástasis ganglionares. Además, la forma de alto peso molecular del FBCF puede tener una influencia más intensa sobre el crecimiento del tumor.

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Résumé Une étude morphologique et biologique a été effectuée pour clarifier la signification du facteur de croissance des fibroblastes de base (bFGF) dans les tumeurs de la thyroïde chez l'homme. On a étudié 71 tumeurs de la thyroïde (50 cancers papillaires, 14 cancers folliculaires, 6 adénomes solitaires, et 7 cancers anaplasiques, 11 adénomes folliculaires, 6 goitres adénomateux et 6 Maladies de Basedow) en utilisant des méthodes immunohistochimiques et notamment la technique du complexe avidinebiotine-peroxydase. On a employé un anticorps primaire fabriqué à partir d'un antisérum polyclonal de lapin purifié dirigé contre le bFGF humain. L'éluat des tissus thyroïdiens malins provenant de la colonne héparine-sepharose a été examiné selon la technique Western Blot pour déterminer son poids moléculaire. Le bFGF a été détecté plus fréquemment dans le cytoplasme des tumeurs thyroïdiennes malignes que dans les maladies bénignes et les contrôles. Dans le cancer anaplasique, l'immunoréactivité des cellules cancéreuses a été particulièrement forte. En ce qui concerne la corrélation entre la classification TNM de l'Union Internationale contre le Cancer et la coloration bFGF des cancers papillaires, il y avait des différences significatives correspondant au degré d'envahissement des ganglions lymphatiques. Dans l'analyse selon la technique du Western blot, l'immunoréactivité bFGF a été détectée spécifiquement sous les deux formes de bFGF ayant des poids moléculaires de 18 et de 33 K, respectivement. Le poids moléculaire de 33K n'a été détecté que dans le cancer anaplasique. Cette étude démontre la corrélation étroite entre l'expression bFGF et le degré de malignité. Le bFGF peut probablement jouer un rôle important dans la survenue de métastase lymphatique. Le type à poids moléculaire élevé de bFGF pourrait influencer d'advantage la croissance tumorale.

     

Dose-dependent stimulation of bone induction by basic fibroblast growth factor in rats

Implantation of demineralized bone matrix in rodents elicits a series of cellular events leading to the formation of new bone inside and adjacent to the implant. This process is believed to be initiated by an inductive protein present in bone matrix, and local growth factors may further regulate the process. We have previously shown that local application of recombinant human basic fibroblast growth factor (bFGF) in a carboxymethyl cellulose gel to demineralized bone matrix implants increases the bone yield as measured by calcium content 3 weeks after implantation in rats. We now report that this increase was seen at 3 and 4 weeks, but not earlier or later. Further, the stimulatory effect was seen with doses from 3 to 75 ng per implant. A dose of 0.6 or 380 ng did not increase the bone yield, and 1,900 ng had a marked inhibitory effect. This narrow dosage optimum may reflect the complex actions of the growth factor.     

Tissue-specific regulation of basic fibroblast growth factor mRNA levels by diabetes.

Because basic fibroblast growth factor (bFGF) is recognized as an angiogenic factor and diabetes is characterized by multiple vascular complications, including diabetic microangiopathy, we examined the regulation of tissue bFGF mRNA levels by diabetes. Diabetes was induced in male Sprague-Dawley rats by injection of 125 mg/kg body wt i.v. streptozocin (STZ), with intensive insulin therapy initiated in half of the diabetic rats. Rats were killed 96 h postinjection of STZ. Tissue bFGF and insulinlike growth factor I (IGF-I) mRNA levels were measured simultaneously with a solution hybridization-RNase protection assay. bFGF mRNA levels increased from 1.7- to 2.7-fold in eye, heart, lung, and brain from diabetic compared with buffer-injected control rats. In skeletal muscle, bFGF mRNA levels decreased to 23% of control levels, whereas bFGF mRNA levels were unchanged in kidneys from diabetic versus control rats. Changes in tissue bFGF mRNA levels were partially reversed by insulin treatment in all tissues. In contrast, IGF-I mRNA levels were significantly decreased from 15 to 50% of control levels in all tissues studied except those in brain, which decreased to only 85% of control levels. These data demonstrate that bFGF mRNA levels are altered by diabetes in a tissue-specific fashion and are consistent with the hypothesis that increased production of bFGF may contribute to the development of diabetic microangiopathy in some tissues.     

Expression of basic fibroblast growth factor during distraction osteogenesis

Distraction osteogenesis is a process of tissue regeneration under an external mechanical stimulation. In the study, the spatial and temporal expression patterns of basic fibroblast growth factor in the newly formed osseous tissue during distraction osteogenesis in goats were studied using immunohistochemistry. During the distraction period, the expression of basic fibroblast growth factor was observed in the osteoblasts on the newly formed trabecular bone and the bone formation front. The cells of osteoblastic lineage and the mesenchymal cells in the distraction callus also expressed basic fibroblast growth factor. The expression of basic fibroblast growth factor in the distraction period was stronger than that during the latency and consolidation periods. However, some osteoblasts still were expressing basic fibroblast growth factor in the consolidation periods. According to these results, basic fibroblast growth factor may have a local regulatory role during distraction osteogenesis. The tensile force may stimulate the expression of basic fibroblast growth factor in osteoblasts and other cell types.     

A growth factor in bovine and human testes structurally related to basic fibroblast growth factor

Homogenates of human testes, epididymides and prostate, and calf testes and epididymides are mitogenic for cultured human foreskin fibroblasts. The growth factors appear similar in that they are inactivated by boiling and acid, but not by treatment with reducing agent. The growth factor in human and bovine testes was partially purified from tissue homogenates, prepared in high ionic strength buffer (pH 7.6) containing protease inhibitors, by ammonium sulfate precipitation and two cycles of heparin-Sepharose chromatography. The growth factor in calf testes was also partially purified from tissue extracted in ammonium sulfate without protease inhibitors, acidified to pH 4.5, and precipitated by ammonium sulfate followed by two cycles of heparin-affinity chromatography. A predominant 17,500 molecular weight (MW) growth factor was identified from alkaline homogenates of human and calf testes by its reactivity with antisera prepared against synthetic peptides whose sequences corresponded to residues 1-12 (amino-terminal), 33-43 (internal) and 136-145 (carboxy-terminal) of bovine basic fibroblast growth factor (bFGF). A slightly smaller 16,600 MW peptide from acidic extracts of calf testes also reacted with antisera to the three synthetic peptides. A 15,500 MW peptide, lacking immunoreactivity with antiserum to the amino-terminal synthetic peptide, was also seen. These findings suggest that a growth factor is present in human and calf testes that is structurally related to bFGF. The structure of the growth factors appears to be altered during the isolation procedure.