Elevated levels of basic fibroblast growth factor in patients with limb ischemia

Basic fibroblast growth factor (bFGF), a prototypic member of a family of heparin-binding growth factors, is angiogenic both in vitro and in vivo. Increased levels and activity of bFGF have been documented in a variety of diseases, including tumors. We sought to determine whether bFGF might be similarly elevated in patients with clinical evidence of limb ischemia. Serum was obtained at the time of percutaneous revascularization from patients with symptomatic peripheral vascular disease (46 procedures were performed on 40 patients). An enzyme-linked immunoassay specific for bFGF was used (limit of detection, 1 pg/ml; range in normal subjects, 0 to 5 pg/ml). Among the 40 patients (28 men, 12 women, mean age 70 years) studied, elevated circulating bFGF (> or = 10 pg/ml) was detected in 36 samples (78%); levels ranged from 10 to 310 pg/ml (mean +/- SEM = 62 +/- 12). In 16 (89%) of 18 patients with both rest pain and nonhealing ischemic ulcers, serum bFGF levels were elevated up to 30 times normal values. In conclusion, circulating levels of bFGF are elevated in patients with vascular insufficiency and may reflect a physiologic response to limb ischemia.     

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.     

Complexation of basic fibroblast growth factor with gelatin

Polyion complexation between basic fibroblast growth factor (bFGF) and gelatin was studied by the turbidity change of mixed solution, heparin high performance liquid affinity chromatography (HPLAC), and isoelectric electrophoresis. When an aqueous solution of acidic gelatin with an isoelectric point (IEP) of 5.0 was mixed with that of bFGF, the turbidity of the mixed solution increased with time, whereas basic gelatin with and IEP of 9.0 did not cause any solution turbidity. A maximum turbidity of the mixed bFGF and acidic gelatin solution was observed around a bFGF/gelatin molar ratio of 1.0, irrespective of the gelatin concentration and solution temperature. The solution turbidity decreased with an increase in the ionic strength of the mixed solution. Complexation of bFGF with acidic gelatin was slower than that with poly(acrylic acid) probably because of the lower density of gelatin negative charge than that of poly(acrylic acid). HPLAC study revealed that complexation of bFGF with the acidic gelatin reduced the affinity of bFGF for heparin, in contrast to the basic gelatin, although the extent became smaller with the increasing ionic strength of the solution. An electrophoretic experiment showed that the IEP of bFGF shifted to a lower value after its gelatin complexation. These findings indicate that an electrostatic interaction is the main driving force for the complexation between acidic gelatin and basic bFGF.     

Immunolocalization of basic fibroblast growth factor and fibroblast growth factor receptor-1 and receptor-2 in rat cranial sutures

Craniosynostosis is a common disorder with an unknown etiology. Recent genetic mapping studies have demonstrated a strong linkage between several familial craniosynostotic syndromes and mutations in fibroblast growth factor receptor 1 (FGF-R1) and 2 (FGF-R2). The purpose of this experiment was to investigate by immunohistochemistry the protein production of these receptors as well as of their most prevalent ligand, basic fibroblast growth factor (bFGF), before, during, and after sutural fusion in rat cranial sutures. The posterior frontal (normally fuses between postnatal days 12 and 22) and sagittal (remains patent) sutures of embryonic day 20 and neonatal days 6, 12, 17, 22, and 62 (n = 3 per group) were harvested, fixed, and decalcified. Five-micrometer sections were stained with polyclonal antibodies against bFGF, FGF-R1, and FGF-R2, and patterns of immunohistochemical staining were assessed by independent reviewers. Our results indicate that increased bFGF production correlates temporally with suture fusion, with increased staining of the dura underneath the fusing suture prior to fusion followed by increased staining within osteoblasts and sutural cells during fusion. FGF-R1 and, to a lesser extent FGF-R2 immunostaining revealed a different pattern of localization with increased immunostaining within the patent sagittal suture at these time points. These results implicate bFGF in the regulation of sutural fusion and may imply autoregulatory mechanisms in fibroblast growth factor receptor expression.     

Effects of modulation of basic fibroblast growth factor on tumor growth in vivo

BACKGROUND: Recombinant human basic fibroblast growth factor (rHu-bFGF) is known to stimulate proliferation in some tumor cells and to modulate tumor vascularization. PURPOSE: The purpose of this study was to examine the possible role of this agent in the development of tumors. The study was designed to determine the effects of modulating bFGF activity in vivo in tumor models from cell lines with different responses to bFGF and with different content and receptor levels of bFGF. METHODS: Two tumor cell lines (human DLD-2 colon carcinoma and rat C6 glioma) were characterized for bFGF content and bFGF receptor levels by Western blot analysis in cultured cells and by studies of [125I]rHu-bFGF binding to sections from xenografts grown in nude mice. Tumor cell proliferation was monitored after treatment with rHu-bFGF or the DG2 or DE6 IgG monoclonal antibody to rHu-bFGF in culture and in vivo. RESULTS: C6 cells exhibited 7800 high-affinity receptors for rHu-bFGF per cell (dissociation constant [Kd] = 46 pM), while DLD-2 cells lacked high-affinity receptors. rHu-bFGF stimulated [3H]thymidine uptake by C6 cells, but the addition of DG2 IgG prevented this stimulation; rHu-bFGF had no effect on [3H]thymidine incorporation by DLD-2 cells. C6 cells had higher levels of immunoreactive bFGF than did DLD-2 cells. The xenografts from both cell lines exhibited high-affinity [125I]rHu-bFGF binding that was concentrated on vascular-like structures. rHu-bFGF at a dosage of 0.25 mg/kg given intraperitoneally daily for 18 days caused a twofold increase in DLD-2 tumor weight but had little effect on the growth of C6 xenografts. In contrast, daily intravenous injections of DG2 IgG given to mice had no effect on DLD-2 tumor growth but reduced growth of C6 tumors by approximately 30%--a statistically significant difference. CONCLUSIONS: The addition of exogenous rHu-bFGF or of a neutralizing antibody resulted in significant alterations in tumor growth in vivo, which were specific for tumor type and bFGF characteristics. While some of these effects may be mediated by the bFGF-responsive endothelial cells of the tumor vasculature (DLD-2 colon carcinoma), others may result from inhibition of bFGF-dependent tumor cell proliferation (C6 glioma). IMPLICATIONS: Studies that measure tumor blood flow are necessary to confirm that these effects are mediated by changes in tumor vasculature.     

Binding of basic fibroblast growth factor to fibrinogen and fibrin

Fibrin is formed at sites of tissue injury and provides the temporary matrix needed to support the initial endothelial cell responses needed for vessel repair. Basic fibroblast growth factor (bFGF) also acts at sites of injury and stimulates similar vascular cell responses. We have, therefore, investigated whether there are specific interactions between bFGF and fibrinogen and fibrin that could play a role in coordinating these actions. Binding studies were performed using bFGF immobilized on Sepharose beads and soluble 125I-labeled fibrinogen and also using Sepharose-immobilized fibrinogen and soluble 125I-bFGF. Both systems demonstrated specific and saturable binding. Scatchard analysis indicated two classes of binding sites for each with Kd values of 1.3 and 260 nM using immobilized bFGF; and Kd values of 0.9 and 70 nM using immobilized fibrinogen. After conversion of Sepharose-immobilized fibrinogen to fibrin by treatment with thrombin, bFGF also demonstrated specific and saturable binding with two classes of binding sites having Kd values of 0.13 and 83 nM. Fibrin binding was also investigated by clotting a solution of bFGF and fibrinogen, and two classes of binding sites were demonstrated using this system with Kd values of 0.8 and 261 nM. The maximum molar binding ratios of bFGF to fibrinogen were between 2.0 and 4.0 with the four binding systems. We conclude that bFGF binds specifically and saturably to fibrinogen and fibrin with high affinity, and this may have implications regarding the localization of its effect at sites of tissue injury.     

Glucocorticoids differentially increase nerve growth factor and basic fibroblast growth factor expression in the rat brain

Adrenocorticotropin hormone (ACTH) and adrenal steroids may influence trophic processes operative in neuronal plasticity. Because nerve growth factor (NGF) and basic fibroblast growth factor (bFGF) participate in neuronal trophism, we have investigated whether adrenal steroids induce the expression of these two trophic factors in the rat brain. The systemic administration of dexamethasone (DEX) elicited a rapid (within 3 hr) and sustained accumulation of bFGF and NGF mRNA in the cerebral cortex and hippocampus. Regional studies showed that DEX increases bFGF but not NGF mRNA in the cerebellum, striatum, and hypothalamus. In situ hybridization studies revealed that DEX increases NGF mRNA in superficial layers of the cerebral cortex and in the dentate gyrus of the hippocampus, and bFGF mRNA throughout the brain, suggesting that DEX induces NGF mRNA in neurons and bFGF in glial cells. ACTH administered systemically elicited a temporal and regional induction in NGF and bFGF mRNA similar to that obtained with DEX. Increases in NGF and bFGF mRNAs were also observed after administration of corticosterone and, albeit to a lesser extent, aldosterone, suggesting that the pituitary-adrenocortical axis plays an important role in the regulation of NGF and bFGF expression in the brain. Our data suggest that NGF and bFGF represent a link by which the adrenal cortical system can exert trophic action on the CNS.     

Accelerated healing of laser-injured rabbit retina by basic fibroblast growth factor

PURPOSE: To improve the outcome of injured retina, human recombinant basic fibroblast growth factor (bFGF) was examined for its ability to accelerate healing in laser-injured New Zealand Red rabbits. METHODS: A multi-line argon laser (454 to 514 nm) was used to produce lesions near subretinal hemorrhaging levels. Within 30 minutes after irradiation, eyes were intravitreally injected directly above the lesions with 10 microliters vehicle or 10 micrograms of bFGF in 10 microliters of vehicle. Lesions were evaluated by funduscopy and fluorescein angiography. After 4 days of treatment, animals were killed and eyes examined histologically. RESULTS: On subsequent days, bFGF-treated lesions were less opaque, smaller in diameter, and less leaky to fluorescein than lesions in the control eyes. Eyes treated with bFGF exhibited reduction in lesion diameter (P < or = 0.001) and in the lesion periphery, decreased loss of photoreceptors (P < or = 0.001), and greater numbers of pigmented epithelial cells, compared to controls. By bromodeoxyuridine incorporation, increased proliferation occurred in fibroblasts, retinal pigmented epithelial cells, and inner retinal glial cells. CONCLUSIONS: These results indicate that bFGF both accelerated ocular tissue repair and also prevented photoreceptor loss. The rescue of photoreceptors by bFGF may occur through direct action on the photoreceptors, or indirectly through effects on other cells in the retina.     

Adenovirally expressed basic fibroblast growth factor rescues photoreceptor cells in RCS rats

OBJECTIVE: To examine the efficacy of an antileukocyte adhesion antibody (anti-CD18) as an adjuvant for delayed (2 hours and 4 hours) thrombolytic therapy (recombinant human tissue plasminogen activator [rt-PA]) in middle cerebral artery occlusion (MCAO) in rats. BACKGROUND: Thrombolytic therapy with rt-PA is limited in its application by a short therapeutic window. METHODS: Male Wistar rats were subjected to MCAO by a single fibrin-rich clot. The rats were assigned to the following experimental groups: Experiment 1 (treatment 2 hours after embolization), 1) rt-PA, 2) anti-CD18 antibody, 3) rt-PA and anti-CD18 antibody, 4) immunoglobulin (Ig) G, and 5) vehicle; Experiment 2 (treatment 4 hours after occlusion), 1) rt-PA alone, 2) rt-PA and anti-CD18 antibody, and 3) nontreated control group. Neurologic deficits, infarction volume, hemorrhage, and brain myeloperoxidase (MPO) immunoreactivity were measured. Results: Administration of rt-PA and anti-CD18 antibody 2 hours later reduced significantly (p < 0.05) the infarct volume and improved neurologic deficits compared with the vehicle-treated group. Treatment with rt-PA alone improved neurologic deficits significantly and reduced mean infarct volume compared with the vehicle-treated group. However, treatment with anti-CD18 antibody neither reduced infarct volume nor improved neurologic deficits compared with the IgG-treated group. The combination of rt-PA and anti-CD18 antibody treatment at 4 hours reduced significantly the infarct volume and MPO immunoreactive cells compared with rt-PA treatment alone at 4 hours, and reduced neurologic deficits compared with rt-PA treatment alone and compared with the nontreated animals. CONCLUSIONS: The combination of antileukocyte adhesion antibody and thrombolytic therapy may increase the therapeutic window for the treatment of stroke.     

Bone regeneration by basic fibroblast growth factor complexed with biodegradable hydrogels

The objective of this study is to enhance the bone induction activity of basic fibroblast growth factor (bFGF) for reconstruction of skull bone defects which has been clinically recognized as almost impossible. For this purpose, we prepared biodegradable hydrogels from gelatin with an isoelectric point of 4.9 which is capable of polyionic complexing with basic bFGF. When implanted in rabbit skull defects of 6 mm in diameter (6 defects per experimental group), the gelatin hydrogels incorporating 100 microg of bFGF promoted bone regeneration at the defect in marked contrast to free bFGF of the same dose, finally closing the bone defects after 12 weeks of implantation as is apparent from histological examination. In dual energy X-ray absorptometry analysis, the bone mineral density at the skull defects enhanced by the hydrogels was significantly higher than that by free bFGF at doses ranging from 2 to 200 microg/defect (P < 0.05). The extent of bone regeneration induced by gelatin hydrogels incorporating 100 microg of bFGF increased with a decrease in their water content. Histological examination indicated that more slowly degrading hydrogels of lower water content prolonged the retention period of osteoblasts in the bone defects. This led to enhanced bone regeneration compared with faster degrading hydrogels of higher water content. It was concluded that this biodegradable hydrogel system was a promising surgical tool to assist self-reconstruction of the skull bone.     

Differential induction of nerve growth factor and basic fibroblast growth factor mRNA in neonatal and aged rat brain

Stimulation of glucocorticoid or beta-adrenergic receptors (BAR) has been shown to increase nerve growth factor (NGF) biosynthesis in adult rat brain. Little is known about the role of these receptors in the regulation of NGF expression in neonatal and aged brain. We have examined the effect of the synthetic glucocorticoid dexamethasone (DEX) and the BAR agonist clenbuterol (CLE) on the levels of NGF mRNA in neonatal (8 day old), adult (3 month old) and aged (24 month old) rats. By 3 h, DEX (0.5 mg/kg, s.c.) evoked a comparable increase in NGF mRNA in the cerebral cortex and hippocampus in both 8-day and 3-month-old rats. In contrast, CLE (10 mg/kg, i.p.) failed to change NGF mRNA levels in neonatal rats, while increasing (2-3-fold) NGF mRNA levels in the cerebral cortex of adult rats. In 24-month-old rats, both DEX and CLE elicited only a modest increase in NGF mRNA. This increase was, however, anatomically and temporally similar to that observed in adult animals. The weak effect of DEX or CLE was not related to a down-regulation of receptor function because both DEX and CLE were able to elicit a comparable increase in the mRNA levels for basic fibroblast growth factor (FGF2) in neonatal, adult and aged rat brain. Our data demonstrate that induction of NGF expression by neurotransmitter/hormone receptor activation varies throughout life and suggest that pharmacological agents might be useful tools to enhance trophic support in aging.     

Endothelial and fibroblast cell-derived heparan sulphate bind with differing affinity to basic fibroblast growth factor

Heparan sulphate from endothelial cells (ECHS) has been shown to bind to bFGF with a lower affinity than that seen for 3T3 fibroblast HS (FHS). To investigate the structural reasons for the low affinity binding of ECHS to bFGF, enzymatic degradation of intact ECHS and FHS chains was undertaken. Filter binding assays showed ECHS heparinase III-resistant fragments 6-7 disaccharides in length and had affinity for bFGF equivalent to that of the intact ECHS chains. The largest resistant fragments from FHS, again 6-7 disaccharides in length, bound to bFGF with a similar affinity to the largest ECHS oligosaccharides, and they therefore have considerably lower affinity than seen for the intact FHS chains. Disaccharide compositional analysis of both ECHS and FHS oligosaccharides showed them to contain similar amounts of 2-O-, 6-O-, and N-sulphated disaccharides. These results suggest that the sulphation pattern within sulphated HS domains and their overall length are not the sole contributors to the binding of intact HS chains to bFGF. It is suggested that domain organisation and frequency of occurrence of large heparinase III-resistant oligosaccharides within intact chains play an important role not only in governing the maximum observed binding affinity of intact chains in the assay system used, but also in the regulation of other biological properties of HS.     

Diagnostic and prognostic role of basic fibroblast growth factor in Wilms' tumor patients

Basic fibroblast growth factor (bFGF) is a potent angiogenic peptide implicated in the growth and metastasis of solid tumors. Elevated concentrations of bFGF have been found in the urine of patients with bladder, prostate, and renal tumors. Furthermore, urinary bFGF levels have been shown to correlate with extent of disease. In order to test the utility of urinary bFGF as a Wilms' tumor marker, we measured bFGF levels in preoperative and postoperative urine samples from 97 patients with Wilms' tumor. Preoperative urine samples (n = 97), early postoperative samples obtained from 1 to 3 weeks after surgery (n = 43), and late postoperative samples obtained from 1 to 6 months after surgery (n = 66) were collected from Wilms' tumor patients at 30 institutions between 1989 and 1993. Urine samples from age-matched controls (n = 17) were also obtained. The bFGF levels were determined in duplicate by a competitive sandwich ELISA capable of measuring bFGF at the pg/ml level. Samples were normalized for creatinine content. Urinary bFGF was elevated in 42% of preoperative samples when compared to controls (>90th percentile of normal). Patients with stage III, IV, and V disease had significantly higher preoperative levels of urinary bFGF when compared to patients with stage I and II disease (P < 0.01). Patients with relapse or persistent disease had significantly elevated late postoperative bFGF levels when compared to disease-free patients and controls (P < 0.05). Thus, in patients with Wilms' tumor, elevated preoperative urinary bFGF levels raise the suspicion of aggressive disease while elevated postoperative levels may indicate recurrence or persistence of disease. These data suggest that bFGF is a biological marker for Wilms' tumor and may have a role in the evaluation of patients with this disease.     

Expression of basic fibroblast growth factor and its mRNA in advanced ovarian cancers

Seventeen patients with a mean age of 7.33 (range 2.7-12.7) years with Rett syndrome (a progressive neurological disorder that occurs mainly in females) were evaluated for oral manifestations and habits. The most frequent habits were digit/hand sucking and/or biting (17/17), bruxism (14/17), mouth breathing (7/17), drooling (5/17), and tongue thrusting (5/17). Gingivitis (13/17) was the most common alteration of soft tissues. Only 2.7% of tooth surfaces were decayed. Nonphysiological dental attrition was present in 71% (12/17) of the children. Palatal shelving could be observed in 53% (9/17) of the children, probably related to the digit/hand sucking and/or biting habits. A high prevalence of anterior open bite (9/17) was observed. No patients exhibited anomalies of tooth number, size, form, structure, or eruption.     

Effects of basic fibroblast growth factor on hippocampal neurons after axonal injury

OBJECTIVE: Axons of adult central nervous system neurons fail to regenerate after diffuse axonal injury in head trauma. Basic fibroblast growth factor (bFGF) has been reported to enhance neuritic extensions after neuronal injury in immature nerve cells. To investigate the effects of bFGF on adult neurons and axonal reoutgrowth, differentiated nerve cells were axonally transected and bFGF was applied. DESIGN: Cell culture study with primary rat hippocampal neurons. MATERIALS AND METHODS: After axotomy, hippocampal cultures were maintained untreated or in the presence of 0.5, 1, 10, or 20 ng/mL bFGF and evaluated over a 7-day period after injury. MEASUREMENTS AND MAIN RESULTS: Seven days after injury, axotomy decreased cell survival to 65%, increased [3H]arachidonic acid release 1.8-fold from prelabeled cells, and showed negligible effects on neuronal dendrites. bFGF reduced this neurodegeneration at all doses applied. bFGF at 10 ng/mL most efficiently increased live cells to 85% and decreased [3H]arachidonic acid release from prelabeled cells to control values (p < 0.01, vs. damaged cells). Furthermore, 10 ng/mL bFGF induced axonal branching and the longest axonal re-extensions from 60 +/- 8 to 377 +/- 10 microns 7 days after injury (p < 0.01, vs. damaged cells). CONCLUSIONS: bFGF increased cell survival and supported axonal re-elongations in adult hippocampal neurons in vitro when applied after axotomy. bFGF may play a role in new therapeutic concepts for the management of axonal injury after head trauma.     

Direct application of basic fibroblast growth factor improves tympanic membrane perforation healing

Topical application of basic fibroblast growth factor (b-FGF) on tympanic membrane (TM) perforations was studied in guinea pigs. One-millimeter simple round TM perforations or 2-mm TM perforations with medially flapped borders were performed. Either b-FGF or placebo was instilled in each ear on the day of surgery and daily thereafter. Treatment was applied either directly to the perforation or to a Gelfoam pledget over the defect. When no scaffolding material was interposed, b-FGF induced a faster healing response characterized by a hyperplastic but linear subepidermal connective tissue reaction compared to the control. When Gelfoam was interposed as a scaffold, a voluminous scar protruding into the middle ear cavity and involving the ossicles was observed in both b-FGF and control animals. Gelfoam-induced scars did not decrease after long-term observation, therefore discouraging its use.     

Hepatocyte growth factor and fibroblast growth factor 2 are overexpressed after cerulein-induced acute pancreatitis

Competency assessments are a growing function of the consultation-liaison (C-L) psychiatrist. Such consultation requests often mask a variety of psychosocial issues that are a source of frustration to the referring physician responding to the pressures of the changing health care delivery system in the acute care setting. This study identifies the issues and the outcome of psychiatric consultation in these patients. The implications of this burgeoning role for the C-L psychiatrist are also explored.     

Expression of the angiogenic factors, basic fibroblast growth factor and vascular endothelial growth factor, in the ovary

In adult tissues, vascular growth (angiogenesis) occurs normally during tissue repair, such as in the healing of wounds and fractures. Inappropriate vascular growth is associated with various pathological conditions. These conditions include tumor growth, retinopathies, hemangiomas, fibroses, and rheumatoid arthritis in the case of rampant vascular growth and nonhealing wounds and fractures in the case of inadequate vascular growth. The female reproductive organs exhibit dramatic, periodic growth and regression, accompanied by equally dramatic changes in their rates of blood flow. Thus, it is not surprising that they are some of the few adult tissues in which angiogenesis occurs as a normal process. Ovarian follicles and corpora lutea contain and produce angiogenic factors. These angiogenic factors bind heparin and seem to belong to the fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF) families of proteins. Based on our studies of the pattern of expression of FGF and its major receptors in bovine, ovine, and porcine corpora lutea, we have suggested that FGF may influence not only luteal cell proliferation but also cell death, thereby regulating cell turnover in the luteal vascular and nonvascular compartments. In addition, we recently have shown that luteal expression of VEGF is greatest during the early luteal phase, coincident with luteal vascularization. Moreover, VEGF is present exclusively in luteal connective tissue and perivascular (arteriolar smooth muscle and capillary pericyte) cells. In fact, the first thecal-derived cells to invade the granulosa-derived regions immediately after ovulation seem to be VEGF-containing pericytes. We have therefore hypothesized that ovarian pericytes play a key role in vascularization of developing follicles and corpora lutea. Further understanding of the specific physiological roles of these factors in follicular and luteal growth, development, and function will ultimately lead to improved methods of regulating fertility.