A Synergistic Relationship between Polycaprolactone and Natural Polymers Enhances the Physical Properties and Biological Activity of Scaffolds.

Biomaterials for tissue engineering include natural and synthetic polymers, but their clinical application is still limited due to various disadvantages associated with the use of these polymers. This uncertainty of the polymeric approach in tissue engineering launches an opportunity to address a key question: can we eliminate the disadvantages of both natural and synthetic polymers by combining them to form a synergistic relationship? To answer this question, we fabricated scaffolds from elastin, collagen, fibrin, and electrospun polycaprolactone (PCL) with different ratios. The material characterization of these scaffolds investigated degradation, water contact angle, angiogenesis by an ex ovo chorion allantoic membrane (CAM) assay, and mechanical and structural properties. Biological activity and specific differentiation pathways (MSC, adipogenic, osteogenic, myogenic, and chondrogenic) were studied by using human adipose-derived stem cells. Results indicated that all composite polymers degraded at a different rate, thus affecting their mechanical integrity. Cell-based assays demonstrated continual proliferative and viable properties of the cells on all seeded scaffolds with the particular initiation of a differentiation pathway among which the PCL/collagen/fibrin composite was the most angiogenic material with maximum vasculature. We were able to tailor the physical and biological properties of PCL-based composites to form a synergistic relationship for various tissue regeneration applications.

Hydrallantois in cows naturally poisoned by Sida carpinifolia in Brazil.

Sida carpinifolia is a small subshrub that is distributed throughout Brazil and is responsible for lysosomal storage disease and occasional reproductive problems in cattle, goats, equids, sheep, and deer. We describe herein the clinical, epidemiologic, and pathologic features of hydrallantois in 3 cows naturally poisoned by S. carpinifolia in Rio Grande do Sul State, Brazil. Clinically, all cows had marked abdominal distension and mild ataxia. After natural death or euthanasia, autopsies revealed that the abdominal distension in all 3 cases was caused by severe enlargement of the uterus, which contained 100-120 L of translucent fluid within the allantois, in addition to adventitial placentation. Microscopic evaluation of the placenta revealed marked diffuse edema, sometimes with a myxomatous appearance. Neurons in the cerebellum and obex were swollen, with mild-to-moderate cytoplasmic granular vacuolation. Histochemical examination with lectins ConA, WGA, and sWGA revealed mild-to-marked staining in the cytoplasm of neurons of the cerebellum and medulla at the level of the obex, indicating the occurrence of α-mannosidosis.

VEGF-mediated fusion in the generation of uniluminal vascular spheroids.

Embryonic mouse allantoic tissue (E8.5) was cultured in hanging drops to generate a three-dimensional vascular micro-tissue. The resulting tissue spheroids had an inner network of small diameter vessels expressing platelet endothelial cell adhesion molecule-1 (PECAM-1) and an outer layer of cells expressing SMalphaA, SM22-alpha, and SM-MHC. In a subsequent phase of culture, the fusion-promoting activity of vascular endothelial growth factor (VEGF) was used to transform the inner network of small diameter endothelial tubes into a contiguous layer of cells expressing PECAM-1, CD34, and VE-cadherin that circumscribed a central lumen-like cavity. The blood vessel-like character of the VEGF-treated spheroids was further demonstrated by their physiologically relevant vasodilatory and contractile responses, including contraction induced by KCl and relaxation stimulated by high-density lipoproteins and acetylcholine-induced nitric oxide production.

IB05204, a dichloropyridodithienotriazine, inhibits angiogenesis in vitro and in vivo.

In the course of a blind screening program for inhibitors of angiogenesis, IB05204 (4,8-dichloro-12-phenylpyrido[5',6':4'',5'';3',2':4,5]dithieno[3'',2''-d':3,2-d]-1,2,3-ditriazine) was selected for its ability to inhibit endothelial tubule-like network formation on Matrigel. IB05204 inhibits the in vivo angiogenesis in the chorioallantoic membrane (CAM) and the mouse Matrigel plug assays. Antiangiogenic activity seems to be highly dependent on the chloro substituents because their removal results in a complete loss of the in vitro inhibitory activity of endothelial differentiation and in vivo antiangiogenic activity in CAM assay. Although IB05204 inhibits the growth of endothelial and tumor cells in culture, its antiangiogenic activity seems to be mainly dependent on the prevention of endothelial capillary-like tube formation and inhibition of endothelial migration because these effects are recorded at lower concentrations. IB05204 treatment inhibits matrix metalloproteinase-2 (MMP-2) production in endothelial and tumor cells, down-regulates endothelial cyclooxygenase-2 expression, and represses phosphorylation of endothelial Akt in response to serum stimulation, suggesting that IB05204 interferes with molecular mechanisms of cell migration and survival. IB05204 induces apoptosis in endothelial cells through cytochrome c release and caspase activation. Data here shown altogether indicate that IB05204 is a compound that interferes with several key steps of angiogenesis, making it a promising drug for further evaluation in the treatment of angiogenesis-related pathologies.

Antiproliferation in human EA.hy926 endothelial cells and inhibition of VEGF expression in PC-3 cells by topotecan.

Protracted administration of topotecan (TPT), a topoisomerase I inhibitor, exhibited high anticancer efficacy both in animal models and human cancers. This phenomenon is related to the TPT-induced inhibition of angiogenesis in tumor, but the potential mechanism remains largely unknown. In the present study, we reported that TPT (1-10 microM) could inhibit angiogenesis in a dose-dependent manner in Chick embryo chorioallantoic membrane (CAM) assay. TPT showed strong inhibitory activity against proliferation on human EA.hy926 endothelial cells with an IC50 value of 0.13 microM (MTT assay), lower than that of most sensitive cancer cell lines (IC50 range, 0.17 microM to 5.1 microM). TPT could induce EA.hy926 cells undergoing apoptosis, and the percentage of apoptotic cells induced by TPT (0.05 microM-5.0 microM) were 17.9%-52.3%. The similar results were observed with AO/EB staining. Flow cytometry assay also revealed that various concentrations of TPT induced cell cycle disturbance in EA.hy926 cells. Western blotting results showed that TPT caused an obvious increase of p53 expression and a decline of ERK expression in EA.hy926 cells. In addition, the VEGF expression of PC-3 cells is inhibited by TPT in hypoxia. Altogether, inhibiting proliferation of endothelial cells and down-regulating VEGF expression in cancer cells may involve in the antiangiogenesis mechanism of TPT.

Antiangiogenic activity of TZT-1027 (soblidotin) on chick chorioallantoic membrane and human umbilical vein endothelial cells.

BACKGROUND: TZT-1027 (Soblidotin), a microtubule-depolymerizing agent, has antivascular activity which disrupts newly formed tumor vasculature. In this study, it was investigated whether TZT-1027 has also antiangiogenic activity preventing neovascularization. MATERIALS AND METHODS: Antiangiogenic activities were evaluated in vivo in a chick embryo chorioallantoic membrane (CAM) assay and in vitro in a tube formation assay on human umbilical vein endothelial cells (HUVEC). RT-PCR and skimmed milk zymography analyses were performed to clarify the involvement of angiogenesis-related proteolytic enzymes and transcription factors. RESULTS: TZT-1027 at doses of 0.01 and 0.06 microg/egg showed potent antiangiogenic activities in the CAM assay (80% and 100% inhibition, respectively), with no lethal toxicity to the chick embryo. TZT-1027 at doses of 0.01-10 ng/mL prevented tube formation, while 1-100 ng/mL disrupted the preformed vascular tube. However, mRNA and protein expression were unchanged. CONCLUSION: TZT-1027 showed antiangiogenic activity at lower doses than it exhibited its antivascular activity. We believe it would exert its antiangiogenic activity, even if kept in a tumor at reduced concentrations to keep its antivascular activity to a minimum.

Anti-angiogenic properties of myo-inositol trispyrophosphate in ovo and growth reduction of implanted glioma.

We investigate here the anti-angiogenic properties of the synthetic compound myo-inositol trispyrophosphate (ITPP). By increasing oxy-haemoglobin dissociation, ITPP has the potential to counteract the effects of hypoxia, a critical regulator of angiogenesis and cancer progression. ITPP inhibited angiogenesis of the chorioallantoic membrane (CAM), as analyzed with an original program dedicated to automated quantification of angiogenesis in this model. ITPP also markedly reduced tumor progression and angiogenesis in an experimental model of U87 glioma cell nodules grafted onto the CAM. These results point out the potential of ITPP for the development of a new class of anti-angiogenic and anti-cancer compounds.

An enediyne-energized single-domain antibody-containing fusion protein shows potent antitumor activity.

Single-domain antibodies are attractive as tumor-targeting vehicles because of their much smaller size than intact antibody molecules. Lidamycin is a macromolecular antitumor antibiotic, which consists of a labile enediyne chromophore (AE) and a noncovalently bound apoprotein (LDP). An enediyne-energized fusion protein VH-LDP-AE composed of single-domain antibody directed against type IV collagenase and lidamycin was prepared by a novel two-step method including DNA recombination and molecular reconstitution. VH-LDP-AE demonstrated extremely potent cytotoxicity to cancer cells and marked antiangiogenic activity in vitro. In the mouse hepatoma 22 model, drugs were administered intravenously as a single dose on day 1 with maximal tolerated doses. VH-LDP-AE (0.25 mg/kg) suppressed the tumor growth by 95.9%, whereas lidamycin (0.05 mg/kg) and mitomycin (1 mg/kg) by 79.6 and 51.1%, respectively. In the HT-1080 xenograft model in nude mice, drugs were given intravenously as a single dose on day 4 after tumor implantation. VH-LDP-AE at 0.25 mg/kg suppressed tumor growth by 76% (P<0.05) compared with that of lidamycin at 0.05 mg/kg (53%) on day 18. No obvious toxic effects were observed in all groups during treatments. The results showed that energized fusion protein VH-LDP-AE was more effective than lidamycin and mitomycin. These properties, together with its much smaller size than conventional antibody-based agents, suggested that VH-LDP-AE would be a promising candidate for cancer-targeting therapy. In addition, the two-step approach could serve as a new technology platform for making a series of highly potent engineered antibody-based drugs for a variety of cancers.

Oligomannurarate sulfate, a novel heparanase inhibitor simultaneously targeting basic fibroblast growth factor, combats tumor angiogenesis and metastasis.

Inhibitors of tumor angiogenesis and metastasis are increasingly emerging as promising agents for cancer therapy. Recently, heparanase inhibitors have offered a new avenue for such work because heparanase is thought to be critically involved in the metastatic and angiogenic potentials of tumor cells. Here, we report that oligomannurarate sulfate (JG3), a novel marine-derived oligosaccharide, acts as a heparanase inhibitor. Our results revealed that JG3 significantly inhibited tumor angiogenesis and metastasis, both in vitro and in vivo, by combating heparanase activity via binding to the KKDC and QPLK domains of the heparanase molecule. The JG3-heparanase interaction was competitively inhibited by low molecular weight heparin (4,000 Da) but not by other glycosaminoglycans. In addition, JG3 abolished heparanase-driven invasion, inhibited the release of heparan sulfate-sequestered basic fibroblast growth factor (bFGF) from the extracellular matrix, and repressed subsequent angiogenesis. Moreover, JG3 inactivated bFGF-induced bFGF receptor and extracellular signal-regulated kinase 1/2 phosphorylation and blocked bFGF-triggered angiogenic events by directly binding to bFGF. Thus, JG3 seems to inhibit both major heparanase activities by simultaneously acting as a substrate mimetic and as a competitive inhibitor of heparan sulfate. These findings suggest that JG3 should be considered as a promising candidate agent for cancer therapy.

An oriental herbal cocktail, ka-mi-kae-kyuk-tang, exerts anti-cancer activities by targeting angiogenesis, apoptosis and metastasis.

Rigorous and systematic pre-clinical studies are necessary and essential to establish the efficacy and safety of Oriental herbs and formulas in order to transform traditional herbal practices into evidence-based medicine. Here we evaluated the anti-cancer activities of the ethanol extract of Ka-mi-kae-kyuk-tang (KMKKT), a formula of ten Oriental herbs, with a battery of in vitro and in vivo mechanism-based biomarkers involving angiogenesis, apoptosis and metastasis. The results show that KMKKT suppressed the vascular endothelial responses by inhibiting basic fibroblast growth factor (bFGF)-induced ERK1/2 phosphorylation, cell migration as well as tube formation in the human umbilical vein endothelial cell model, and decreased the hypoxia-induced HIF1alpha and vascular epithelial growth factor (VEGF) expression in the mouse Lewis lung carcinoma (LLC) cells in vitro, and inhibited the bFGF-induced angiogenesis in chick chorioallantoic membrane model, and in the Matrigel plugs in mice. Intraperitoneal delivery of KMKKT potently inhibited the growth of the subcutaneously inoculated LLC cells in syngenic mice. In addition, KMKKT inhibited the invasion ability of the mouse colon 26-L5 cancer cells in vitro and decreased their formation of liver metastasis when intraportally inoculated in syngenic mice. Furthermore, KMKKT suppressed the growth of the human PC-3 prostate cancer xenografts in athymic nude mice and averted the cancer-related body weight loss. The in vivo cancer growth suppression was associated with a decreased microvessel density and VEGF abundance as well as an increased PARP cleavage and the TUNEL-positive apoptosis. Together, our data support broad-spectra in vivo anti-cancer activities of KMKKT targeting angiogenesis, apoptosis and metastasis without any adverse effect on the body weight. This formula merits serious consideration for further evaluation for the chemoprevention and treatment of cancers of multiple organ sites.

Soluble multimer of recombinant endostatin expressed in E. coli has anti-angiogenesis activity.

The bioactivity, refolding, and multimer formation of endostatin, particularly of recombinant endostatin produced from bacteria, are proved challenging for clinical application. In order to determine the biological activity of recombinant endostatin multimer, first, we expressed endostatin in Escherichia coli and purified it with ion-exchange chromatography. The purified active protein could elicit multimer formation spontaneously, but still has comparable activity. Aim to determine the anti-angiogenic activity of multimer endostatin, by use of RP-HPLC, we then successfully separated endostatin monomer and multimer for subjecting to anti-angiogenesis assay. The results from CAM (chorioallantoic membrane) inhibition assay showed that both monomer and multimer suppressed CAM vascularization significantly. At the dosage of 0.8 microg, inhibition rates of multimeric and monomeric proteins were about 58% and 38%, respectively. Multimeric endostatin exerted a higher activity than monomeric endostatin (p < 0.05). However, when the protein dosage is less than 0.4 microg/ml, there is no significance between their inhibition rates (p > 0.05), although both of them show a high inhibition effect in contrast to control. The results from HUVEC proliferation assay also showed similar effects at dosages of 0.6 and 1.6 microg/ml, multimer exerted a higher activity on inhibition of HUVEC proliferation comparing with monomer (p < 0.05). In conclusion, our results suggest that endostatin multimer has a comparable or higher bioactivity and multimerization will not affect its bioactivity, implying that endostatin activity is insensitive to structure conformation contributed by disulfide bonds.

Lebestatin, a disintegrin from Macrovipera venom, inhibits integrin-mediated cell adhesion, migration and angiogenesis.

Lebestatin, a new member of the lysine-threonine-serine (KTS)-disintegrin family, was purified to homogeneity from Tunisian snake (Macrovipera lebetina) venom. It is a single-chain polypeptide composed of 41 amino acids. The amino-acid sequence of lebestatin shows that it displays a pattern of cysteines similar to other short disintegrins, but contains the sequence KTS rather than RGD in its integrin-binding loop. Lebestatin presents a high homology with obtustatin and viperistatin. Lebestatin interacts specifically with the alpha1beta1 integrin. It was thus able to inhibit both adhesion and migration of PC12 and alpha1beta1 integrin-expressing CHO cells (CHO-alpha1) to type I and IV collagens. This disintegrin also affected adhesion and migration of endothelial cells and exhibited an anti-angiogenic effect in vivo when using the 8-day-old embryo chick chorioallantoic membrane model.

Osteocalcin is angiogenic in vivo.

The exact function of osteocalcin (OC), a protein synthesized by osteoblasts during the matrix mineralization phase, is still unknown. In this study we investigated the capacity of OC to promote vasoproliferation in chick embryo chorioallantoic membrane (CAM), a well established in vivo assay for angiogenesis and anti-angiogenesis. The results showed that OC stimulates angiogenesis and that the response is similar to that obtained with FGF-2, a well-known angiogenic cytokine. It has previously been demonstrated that OC is involved in bone repair, so the angiogenic activity reported here might also play a crucial role in bone formation.

Angiogenesis assays in the chick CAM.

The growth of new blood vessels from pre-existing vascular elements, or angiogenesis, involves coordinated signals to the adhesion, migration, and survival machinery within the target endothelial cell. Agents that interfere with any of these processes may therefore influence angiogenesis. Here, we describe the angiogenesis assay in the chick chorioallantoic membrane (CAM). The CAM is a useful tool to studying angiogenesis because 1) it is amenable to both intravascular and topical administration of study agents, 2) it is a relatively rapid assay, and 3) it can be adapted very easily to study angiogenesis-dependent processes, such as tumor growth. Importantly, the CAM provides a physiological setting that permits investigation of pro- and anti-angiogenic agent interactions in vivo.

Eye irritation of low-irritant cosmetic formulations: correlation of in vitro results with clinical data and product composition.

Alternative methods to the Draize eye irritation test, such as the hen's egg test-chorioallantoic membrane (HET-CAM) or the bovine corneal opacity and permeability (BCOP) tests, are currently used to evaluate the irritant potential of cosmetic or consumer products. Although, for strong irritants, the results of these tests correlate well with those of the Draize test, they appear to be less suited to identify mild irritants. In order to improve the sensitivity of alternative eye irritation tests, we developed a novel method that uses a human corneal epithelial cell line (CEPI), and the endpoints of cytotoxicity and IL-8 release. Twelve make-up removers were assessed by the HET-CAM, BCOP and CEPI tests, as well as in a clinical in-use test under ophthalmological control after their application to the external eye lid. In addition, we investigated the impact of osmolality and raw material composition on in vitro and clinical results and compared the in vitro results with those of clinical studies. Overall, although HET-CAM results were unrelated to eye discomfort and adverse clinical signs, they correlated mainly with the presence and concentration of surfactants in the test articles. BCOP scores were unrelated to clinical signs, but related mainly to glycol and sodium lactate content and concentration in the test articles. Cytotoxicity in CEPI mainly correlated with presence and concentrations of surfactants, and IL-8 release to clinical signs and/or glycol and sodium lactate concentrations. Overall, IL-8 release appeared to be the most sensitive and reliable endpoint to predict human eye tolerance to mildly irritant products. Although our results suggest that the IL-8 assay appears to be a promising screen for borderline-irritant formulations, further experiments are required to confirm and validate these preliminary results.

The effect of dietary supplementation with linoleic acid to late gestation ewes on the fatty acid composition of maternal and fetal plasma and tissues and the synthetic capacity of the placenta for 2-series prostaglandins.

Linoleic acid (18:2n-6) is metabolised to arachidonic acid (20:4n-6), the precursor for 2-series prostaglandins (PGs). Increased consumption of 18:2n-6 during pregnancy may thus modify PG synthesis during labour. We have investigated whether increased 18:2n-6 composition during gestation altered the fatty acid consumption and PG synthesis of maternal and fetal tissues in the sheep. Ewes were fed a control diet or a diet providing 40% more 18:2n-6 from 96 days gestation. Half of each group received dexamethasone on day 136 to up-regulate the PG synthetic pathways promoting parturition. Maternal and fetal tissues were collected at 138 days. The 18:2n-6 diet significantly increased the 20:4n-6 content of maternal plasma, fetal plasma and allantochorion (51-81%) phosphatidylcholine, and fetal liver (40%) and maternal caruncular endometrium (57%) phosphatidylethanolamine. Increased 18:2n-6 intake increased production of PGF(2alpha) and PGE(2) in all placental tissues (maternal caruncular and intercaruncular endometrium and fetal allantochorion) by 23-98%, whereas dexamethasone increased it by 32-142%. This suggests that consumption of an 18:2n-6-enriched diet in late pregnancy enhanced placental PG production by increasing the supply of 20:4n-6. Variations in the extent to which the diet altered the polyunsaturated fatty acid (PUFA) content of the different tissues indicated complex interactions between nutrient availability and metabolic adaptation.

0.2 T magnetic field inhibits angiogenesis in chick embryo chorioallantoic membrane.

Inhibition of angiogenesis is a major target in the fight against cancer and other diseases. Although the effects of static magnetic fields on cancer development and cell growth have been investigated, effects on angiogenesis have received no attention so far. In this study we report the effects on angiogenesis of exposure to 0.2 T static magnetic field. Angiogenesis was analyzed using the chick embryo chorioallantoic membrane assay. Exposure to 0.2 T static magnetic field was achieved by placing the eggs for 3 hr in the isocentre of the magnet of a sectorial magnetic resonance tomograph used in clinical practice. In sham exposed specimens treated with phosphate buffered saline (negative control), no significant vascular reaction was detectable; 3 hr exposure to 0.2 T static magnetic field did not affect the basal pattern of vascularization or chick embryo viability. Prostaglandin E1 and fetal calf serum elicited a strong angiogenic response in sham exposed eggs. This angiogenic response was significantly inhibited by 3 hr exposure to 0.2 T static magnetic field. These findings point to possible use of static magnetic field in inhibiting angiogenesis; this effect could be exploited for treatment of cancer and other diseases where excessive angiogenesis is involved.

Matrix-mediated canal formation in primmorphs from the sponge Suberites domuncula involves the expression of a CD36 receptor-ligand system.

Sponges (Porifera), represent the phylogenetically oldest metazoan phylum still extant today. Recently, molecular biological studies provided compelling evidence that these animals share basic receptor/ligand systems, especially those involved in bodyplan formation and in immune recognition, with the higher metazoan phyla. An in vitro cell/organ-like culture system, the primmorphs, has been established that consists of proliferating and differentiating cells, but no canals of the aquiferous system. We show that after the transfer of primmorphs from the demosponge Suberites domuncula to a homologous matrix (galectin), canal-like structures are formed in these 3D-cell aggregates. In parallel with the formation of these structures a gene is expressed whose deduced protein falls into the CD36/LIMPII receptor family. The receptor was cloned and found to be strongly expressed after adhesion to the galectin matrix. This process was suppressed if primmorphs were co-incubated with a homologous polypeptide containing the CSVTCG domain, as found in thrombospondin-1 (and related) molecules of vertebrates. In situ hybridization studies revealed that the S. domuncula CD36/LIMPII receptor is localized in the pinacocytes that surround the canals of the sponge. Furthermore, a secondary metabolite from a sponge-associated bacterium was isolated and characterized, the 2-methylthio-1,4-naphthoquinone (MTN). MTN causes inhibition of cell proliferation of vertebrate tumor cells at concentrations of >80 ng/ml. However, doses of only 2 ng are required to potently inhibit angiogenesis in the chick chorio-allantoic membrane assay. At concentrations of 10 ng/ml this compound was also found to suppress the expression of the S. domuncula CD36/LIMPII; this result is a first indication that this secondary metabolite has a conserved functional activity: the suppression of the formation of the circulation system, from sponges to vertebrates.

Cell-demanded liberation of VEGF121 from fibrin implants induces local and controlled blood vessel growth.

Although vascular endothelial growth factor (VEGF) has been described as a potent angiogenic stimulus, its application in therapy remains difficult: blood vessels formed by exposure to VEGF tend to be malformed and leaky. In nature, the principal form of VEGF possesses a binding site for ECM components that maintain it in the immobilized state until released by local cellular enzymatic activity. In this study, we present an engineered variant form of VEGF, alpha2PI1-8-VEGF121, that mimics this concept of matrix-binding and cell-mediated release by local cell-associated enzymatic activity, working in the surgically-relevant biological matrix fibrin. We show that matrix-conjugated alpha2PI1-8-VEGF121 is protected from clearance, contrary to native VEGF121 mixed into fibrin, which was completely released as a passive diffusive burst. Grafting studies on the embryonic chicken chorioallantoic membrane (CAM) and in adult mice were performed to assess and compare the quantity and quality of neovasculature induced in response to fibrin implants formulated with matrix-bound alpha2PI1-8-VEGF121 or native diffusible VEGF121. Our CAM measurements demonstrated that cell-demanded release of alpha2PI1-8-VEGF121 increases the formation of new arterial and venous branches, whereas exposure to passively released wild-type VEGF121 primarily induced chaotic changes within the capillary plexus. Specifically, our analyses at several levels, from endothelial cell morphology and endothelial interactions with periendothelial cells, to vessel branching and network organization, revealed that alpha2PI1-8-VEGF121 induces vessel formation more potently than native VEGF121 and that those vessels possess more normal morphologies at the light microscopic and ultrastructural level. Permeability studies in mice validated that vessels induced by alpha2PI1-8-VEGF121 do not leak. In conclusion, cell-demanded release of engineered VEGF121 from fibrin implants may present a therapeutically safe and practical modality to induce local angiogenesis.

Effects of paclitaxel in combination with ionizing radiation on angiogenesis in the chick embryo chorioallantoic membrane. A radiobiological study.

PURPOSE: To investigate the combined effects of paclitaxel and single or fractionated doses of ionizing radiation on the angiogenesis process, using as a model the chick embryo choriallantoic membrane (CAM). MATERIAL AND METHODS: Experiments were performed on 9-day CAM, when membranes were irradiated with various single or fractionated doses of X-rays, either alone or in combination with paclitaxel (6.4 micro g/disk). RESULTS: Single doses of irradiation (5, 10, or 15 Gy) produced a significant antiangiogenic effect, which was not dose-dependent. Fractionated doses of X-rays (two doses of 2.5, 5, or 7.5 Gy, each 12 h apart) exerted a dose-dependent reduction of the vascular density index. Paclitaxel was not shown to provoke radiosensitization in this model, i. e., to inhibit angiogenesis of the 9-day CAM. CONCLUSION: These data confirm that the CAM system can be conveniently and properly used for radiobiological studies and indicate that paclitaxel in combination with ionizing radiation does not inhibit further angiogenesis in the system used.