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Laminins are essential in basement membrane architecture and critical in re-epithelialization and angiogenesis. These processes and collagen deposition are vital in skin wound healing. The role of angiogenic peptides in accelerating the wound-healing process has been known. The bioactive peptides could be a potential approach due to their similar effects as growth factors and inherent biocompatible and biodegradable nature with lower cost. They can also recognize ligand-receptor interaction and mimic the extracellular matrix. Here, we report novel angiogenic DYVRLAI, CDYVRLAI, angiogenic-collagen PGPIKVAV, and Ac-PGPIKVAV peptides conjugated sodium carboxymethyl cellulose hydrogel, which was designed from laminin. The designed peptide exhibits a better binding with the α 3 β 1 , α v β 3 , and α 5 β 1 integrins and CXCR2 receptor, indicating their angiogenic and collagen binding efficiency. The peptides were evaluated to stimulate wound healing in full-thickness excision wounds in normal and diabetic mice (type II). They demonstrated their efficacy in terms of angiogenesis (CD31), re-epithelialization through regeneration of the epidermis (H&E), and collagen deposition (MT). The synthesized peptide hydrogel (DYVRLAI and CDYVRLAI) showed enhanced wound contraction up to 10.1 % and 12.3 % on day 7 th compared to standard becaplermin gel (49 %) in a normal wound model. The encouraging results were also observed with the diabetic model, where these peptides showed a significant decrease of 5.20 and 5.17 % in wound size on day 10 th compared to the commercial gel (9.27 %). These outcomes signify that the modified angiogenic peptide is a cost effective, novel peptide motif to promote dermal wound healing in both models., Competing Interests: Declaration of competing interest The author declares no conflict of interest., (Copyright © 2024. Published by Elsevier B.V.)

Background: Breast cancer is currently the world's most predominant malignancy. In cancer progression, angiogenesis is a requirement for tumor growth and metastasis.Alpinumisoflavone (AIF), a bioactive isoflavonoid, exhibited good binding affinity with the angiogenesis pathway's druggable target through molecular docking., Objectives: To confirm AIF's angiogenesis inhibitory activity, cytotoxic potential toward breast cancer cells, and druggability., Methods: Antiangiogenic activity was evaluated in six pro-angiogenic proteins in vitro, duck chorioallantoic membrane (CAM) in ovo, molecular docking and druggability in silico., Results: Findings showed that AIF significantly inhibited (p =  < 0.001) the HER2(IC 50  = 2.96 µM), VEGFR-2(IC 50  = 4.80 µM), MMP-9(IC 50  = 23.00 µM), FGFR4(IC 50  = 57.65 µM), EGFR(IC 50  = 92.06 µM) and RET(IC 50  =  > 200 µM) activity in vitro.AIF at 25 µM-200 µM significantly inhibited (p =  < 0.001) the total number of branch points (IC 50  = 14.25 μM) and mean length of tubule complexes (IC 50  = 3.52 μM) of duck CAM comparable (p =  > 0.001) with the positive control 200 µM celecoxib on both parameters.AIF inhibited the growth of the estrogen-receptor-positive (ER +) human breast cancer cells (MCF-7) by 44.92 ± 1.79% at 100 µM while presenting less toxicity to human dermal fibroblast neonatal (HDFn) normal cells.The positive control 100 µM doxorubicin showed 86.66 ± 0.93% and 92.97 ± 1.27% inhibition with MCF-7 (IC 50  = 3.62 μM) and HDFn, (IC 50  = 27.16 μM) respectively.In docking, AIF has the greatest in silico binding affinity on HER2 (-10.9 kcal/mol) among the key angiogenic molecules tested. In silico rat oral LD 50 calculation indicates that AIF is moderate to slightly toxic at 146.4 mg/kg with 1.1 g/kg and 20.1 mg/kg upper and lower 95% confidence limits. Lastly, it sufficiently complies with Lipinski's, Veber's, Egan's, Ghose's, and Muegge's Rule, supporting its oral drug-like property., Conclusion: This study revealed that AIF possesses characteristics of a phytoestrogen compound with significant binding affinity, inhibitory activity against pro-angiogenic proteins, and cytotoxic potential against ER + breast cancer cells.The acceptable and considerable safety and drug-likeness profiles of AIF are worthy of further confirmation in vivo and advanced pre-clinical studies so that AIF can be elevated as a promising molecule for breast cancer therapy., (© 2022. The Author(s), under exclusive licence to Tehran University of Medical Sciences.)

Objective: Angiogenic factor AGGF1 (angiogenic factor with G-patch and FHA [Forkhead-associated] domain 1) promotes angiogenesis as potently as VEGFA (vascular endothelial growth factor A) and regulates endothelial cell (EC) proliferation, migration, specification of multipotent hemangioblasts and venous ECs, hematopoiesis, and vascular development and causes vascular disease Klippel-Trenaunay syndrome when mutated. However, the receptor for AGGF1 and the underlying molecular mechanisms remain to be defined., Approach and Results: Using functional blocking studies with neutralizing antibodies, we identified [alpha]5[beta]1 as the receptor for AGGF1 on ECs. AGGF1 interacts with [alpha]5[beta]1 and activates FAK (focal adhesion kinase), Src (proto-oncogene tyrosine-protein kinase), and AKT (protein kinase B). Functional analysis of 12 serial N-terminal deletions and 13 C-terminal deletions by every 50 amino acids mapped the angiogenic domain of AGGF1 to a domain between amino acids 604-613 (FQRDDAPAS). The angiogenic domain is required for EC adhesion and migration, capillary tube formation, and AKT activation. The deletion of the angiogenic domain eliminated the effects of AGGF1 on therapeutic angiogenesis and increased blood flow in a mouse model for peripheral artery disease. A 40-mer or 15-mer peptide containing the angiogenic domain blocks AGGF1 function, however, a 15-mer peptide containing a single amino acid mutation from -RDD- to -RGD- (a classical RGD integrin-binding motif) failed to block AGGF1 function., Conclusions: We have identified integrin [alpha]5[beta]1 as an EC receptor for AGGF1 and a novel AGGF1-mediated signaling pathway of [alpha]5[beta]1-FAK-Src-AKT for angiogenesis. Our results identify an FQRDDAPAS angiogenic domain of AGGF1 crucial for its interaction with [alpha]5[beta]1 and signaling.

Background: Pathological angiogenesis is the hallmark of many vision-threatening diseases. Anti-VEGF is a primary treatment with substantial beneficial effects. However, such agents require frequent intravitreal injections. Our previous work established a method for effectively modifying exosomes (EXOs) for loading therapeutic peptides. Here, we used this system to load the anti-angiogenic peptide KV11, aiming to establish an EXO-based therapy strategy to suppress neovascularization in the retina. Methods: Using an anchoring peptide, CP05, we linked KV11 to endothelial cell (EC) derived EXOs, yielding EXO KV11 . We tested the delivery efficiency of EXO KV11 via two commonly used ocular injection methods: retro-orbital injection and intravitreal injection. Deploying an oxygen-induced retinopathy (OIR) model and a VEGF injection model, we tested the effects of EXO KV11 on neovascular formation, EC proliferation, and vascular permeability. In vitro experiments were used to test the mechanism and to analyze the effects of EXO KV11 on EC proliferation, migration, and sprouting. Results : By using the EXO loading system, KV11 was more efficiently delivered to the blood vessels of the mouse retina via retro-orbital injection. In both OIR model and VEGF injection model, EXO KV11 was more effective than KV11 alone in inhibiting neovascularization and vessel leakage. The therapeutic effect of retro-orbital injection of EXO KV11 was comparable to the intravitreal injection of VEGF-trap. Mechanistically, KV11 alone inhibited VEGF-downstream signaling, while EXO KV11 showed a stronger effect. Conclusions: We used EXOs as a carrier for intraocular delivery of KV11. We showed that KV11 itself has an anti-angiogenic effect through retro-orbital injection, but that this effect was greatly enhanced when delivered with EXOs. Thus, this system has the potential to treat proliferative retinopathy via retro-orbital injection which is a less invasive manner compared with intravitreal injection., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Objective: We sought to identify and investigate the functional role of the major endothelial cell (EC)-derived factors that control pericyte recruitment to EC tubes and pericyte-induced tube maturation during capillary network formation. Approach and Results: We identify PDGF (platelet-derived growth factor)-BB, PDGF-DD, ET (endothelin)-1, TGF (transforming growth factor)-β, and HB-EGF (heparin-binding epidermal growth factor), as the key individual and combined regulators of pericyte assembly around EC tubes. Using novel pericyte only assays, we demonstrate that PDGF-BB, PDGF-DD, and ET-1 are the primary direct drivers of pericyte invasion. Their addition to pericytes induces invasion as if ECs were present. In contrast, TGF-β and HB-EGF have minimal ability to directly stimulate pericyte invasion. In contrast, TGF-β1 can act as an upstream pericyte primer to stimulate invasion in response to PDGFs and ET-1. HB-EGF stimulates pericyte proliferation along with PDGFs and ET-1. Using EC-pericyte cocultures, individual, or combined blockade of these EC-derived factors, or their pericyte receptors, using neutralizing antibodies or chemical inhibitors, respectively, interferes with pericyte recruitment and proliferation. As individual factors, PDGF-BB and ET-1 have the strongest impact on these events. However, when the blocking reagents are combined to interfere with each of the above factors or their receptors, more dramatic and profound blockade of pericyte recruitment, proliferation, and pericyte-induced basement membrane deposition occurs. Under these conditions, ECs form tubes that become much wider and less elongated as if pericytes were absent., Conclusions: Overall, these new studies define and characterize a functional role for key EC-derived factors controlling pericyte recruitment, proliferation, and pericyte-induced basement membrane deposition during capillary network assembly.

Background: Vasohibins (VASH), which are angiogenesis regulators, consist of Vasohibin-1 (VASH1) and Vasohibin-2 (VASH2). VASH1 is an angiogenesis inhibitor, while VASH2 is a proangiogenic factor. Patients with esophageal squamous cell carcinoma (ESCC) with high tumor expression levels of VASH1 and VASH2 have been reported to show a poor prognosis. The clinical significance of VASH concentrations in the blood of patients with ESCC has not yet been investigated., Methods: Plasma samples from 89 patients with ESCC were analyzed, and the relationships between the plasma VASH concentrations and the clinicopathological factors of the patients were evaluated. Immunohistochemical examination (IHC) of the resected tumor specimens for VASH was performed in 56 patients, and the correlation between the plasma VASH concentrations and tumor expression levels of VASH was analyzed., Results: The patient group with high plasma concentrations of VASH1 showed a higher frequency of lymph node metastasis (P = 0.01) and an invasive growth pattern (P = 0.05). Furthermore, poorly differentiated cancer occurred at a higher frequency in the patient group with high plasma concentrations of VASH2 (P < 0.01). High tumor expression levels of VASH1 were encountered more frequently in the patient group with high plasma concentrations of VASH1 (P = 0.03), and high tumor expression levels of VASH2 were encountered more frequently in the patient group with high plasma concentrations of VASH2 (P = 0.04)., Conclusions: In patients with ESCC, high plasma concentrations were associated with poor clinical outcomes for both VASH1 and VASH2. We propose that results indicate that plasma VASH1 and VASH2 are useful biomarkers in patients with ESCC.

Angiogenesis plays a pivotal role in tissue regeneration following bone-grafting procedures; however, nonautogenous graft materials typically lack critical angiogenic growth factors. While much research has focused on modifying grafts with angiogenic factors, controlled delivery of these molecules remains a challenge. The current study describes a method for sustained delivery of an angiogenic peptide from hydroxyapatite (HA), a common alloplast material. Specifically, VEGF-derived "QK" peptides were synthesized with polyglutamate domains containing varying numbers of glutamates. The rate of peptide release from HA inversely correlated with glutamate number, with diglutamate-QK (E2-QK) released first, followed by tetraglutamate-QK (E4-QK), and finally, heptaglutamate-QK (E7-QK). By coating HA with a mixture of these peptides, termed, PGM-QK (polyglutamate-modified mixture), sequential peptide release was achieved, enabling gradient QK delivery. To evaluate bioactivity, HA disks were coated with PGM-QK and then placed in fresh media for 6 days. Media containing the released peptides was collected at varying time intervals and placed on human umbilical vein endothelial cells (HUVECs). Cells were evaluated for activation of angiogenic signaling pathways (ERK and Akt) and cell migration. Results showed that QK peptides were continuously released over the 6-day interval, and maintained their capacity to activate HUVECs. These findings point to a new approach for gradient delivery of an angiogenic stimulus., (© 2019 Wiley Periodicals, Inc.)

Cancer remains one of the major causes of death worldwide. Angiogenesis is crucial for the pathogenesis of various human diseases, especially solid tumors. The discovery of anti-angiogenic peptides is a promising therapeutic route for cancer treatment. Thus, reliably identifying anti-angiogenic peptides is extremely important for understanding their biophysical and biochemical properties that serve as the basis for the discovery of new anti-cancer drugs. This study aims to develop an efficient and interpretable computational model called TargetAntiAngio for predicting and characterizing anti-angiogenic peptides. TargetAntiAngio was developed using the random forest classifier in conjunction with various classes of peptide features. It was observed via an independent validation test that TargetAntiAngio can identify anti-angiogenic peptides with an average accuracy of 77.50% on an objective benchmark dataset. Comparisons demonstrated that TargetAntiAngio is superior to other existing methods. In addition, results revealed the following important characteristics of anti-angiogenic peptides: (i) disulfide bond forming Cys residues play an important role for inhibiting blood vessel proliferation; (ii) Cys located at the C-terminal domain can decrease endothelial formatting activity and suppress tumor growth; and (iii) Cyclic disulfide-rich peptides contribute to the inhibition of angiogenesis and cell migration, selectivity and stability. Finally, for the convenience of experimental scientists, the TargetAntiAngio web server was established and made freely available online.

In this study, we hydrolyzed rice endosperm protein (REP) with pepsin and generated 20 fractions containing multifunctional cationic peptides with varying isoelectric point (pI) values using ampholyte-free isoelectric focusing (autofocusing). Subsequently, we determined antimicrobial activities of each fraction against the pathogens Prophyromonas gingivalis, Propionibacterium acnes, Streptocossus mutans, and Candida albicans. Fractions 18, 19, and 20 had pI values greater than 12 and exhibited antimicrobial activity against P. gingivalis, P. acnes, and C. albicans, but not against S. mutans. In further experiments, we purified and identified cationic peptides from fractions 18, 19, and 20 using reversed-phase high-performance liquid chromatography and matrix-assisted laser/desorption ionization-time-of-flight mass spectroscopy. We also chemically synthesized five identified peptides (RSVSKSR, RRVIEPR, ERFQPMFRRPG, RVRQNIDNPNRADTYNPRAG, and VVRRVIEPRGLL) with pI values greater than 10.5 and evaluated antimicrobial, lipopolysaccharide (LPS)-neutralizing, and angiogenic activities. Among these synthetic peptides, only VVRRVIEPRGLL exhibited antimicrobial activity against P. gingivalis, with an IC 50 value of 87μM. However, all five cationic peptides exhibited LPS-neutralizing and angiogenic activities with little or no hemolytic activity against mammalian red blood cells at functional concentrations. These present data show dual or multiple functions of the five identified cationic peptides with little or no hemolytic activity. Therefore, fractions containing cationic peptides from REP hydrolysates have the potential to be used as dietary supplements and functional ingredients in food products., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: The therapeutic potential of mesenchymal stem cells (MSCs) may be attributed partly to humoral factors such as growth factors, cytokines, and chemokines. Human term placental tissue-derived MSCs (PlaMSCs), or conditioned medium left over from cultures of these cells, have been reported to enhance angiogenesis. Recently, the exosome, which can transport a diverse suite of macromolecules, has gained attention as a novel intercellular communication tool. However, the potential role of the exosome in PlaMSC therapeutic action is not well understood. The purpose of this study was to evaluate PlaMSC-derived exosome angiogenesis promotion in vitro and in vivo., Methods: MSCs were isolated from human term placental tissue by enzymatic digestion. Conditioned medium was collected after 48-h incubation in serum-free medium (PlaMSC-CM). Angiogenic factors present in PlaMSC-CM were screened by a growth factor array. Exosomes were prepared by ultracentrifugation of PlaMSC-CM, and confirmed by transmission electron microscopy, dynamic light scattering, and western blot analyses. The proangiogenic activity of PlaMSC-derived exosomes (PlaMSC-exo) was assessed using an endothelial tube formation assay, a cell migration assay, and reverse transcription-PCR analysis. The in-vivo angiogenic activity of PlaMSC-exo was evaluated using a murine auricle ischemic injury model., Results: PlaMSC-CM contained both angiogenic and angiostatic factors, which enhanced endothelial tube formation. PlaMSC-exo were incorporated into endothelial cells; these exosomes stimulated both endothelial tube formation and migration, and enhanced angiogenesis-related gene expression. Laser Doppler blood flow analysis showed that PlaMSC-exo infusion also enhanced angiogenesis in an in-vivo murine auricle ischemic injury model., Conclusions: PlaMSC-exo enhanced angiogenesis in vitro and in vivo, suggesting that exosomes play a role in the proangiogenic activity of PlaMSCs. PlaMSC-exo may be a novel therapeutic approach for treating ischemic diseases.

Background: The main goal of bone tissue engineering has been the generation of healthy bone in order to replace affected tissue. Therefore, optimized biomaterials are needed which allow the survival and growth of mesenchymal stem cells. Until now the key challenge in the clinical application of cell-based tissue engineering bone implants was poor diffusion of oxygen into the tissue, making functional blood vessel networks a necessity. With their ability to evolve into different cell types, to expand extensively in vitro, and to release paracrine soluble factors, bone marrow stromal cells (BMSC) are highly attractive for tissue engineering. During the last years hypoxia became a proven method to control proliferation, differentiation, and pluripotency of BMSC. Here we applied different methods to characterize metabolically conditioned media (MCM) in comparison to hypoxia conditioned media (HCM) and evaluated their ability to attract BMSC in 2-D migration assays., Methods: BMSC and fibroblasts of human origin were isolated and cultivated to obtain HCM and MCM. Both media were characterized by angiogenesis arrays, cytokine arrays, and ELISA for selected factors. 2-D migration tests were performed with Corning Transwell®-96 permeable support chambers with porous polyester membranes with a pore size of 8.0 μm., Results: Characterization of HCM and MCM revealed that the concentration of angiogenic factors was higher in MCM than in HCM. However, the chemoattractive capacity of MCM for BMSC was equivalent to that of HCM. HCM and MCM produced by human skin fibroblasts attracted human BMSC as efficiently as HCM and MCM produced by human BMSC., Conclusions: HCM and MCM have a high chemoattractive capacity for BMSC. Both conditioned media harbor high concentrations of angiogenic factors which are important for angiogenesis and cell migration. Both chemoattracting conditioned media can also be derived from skin fibroblasts which can easily be obtained from patients in individualized therapy approaches.

We investigated the influence of vascular peptide bioregulator on microcirculation in the brain cortex of spontaneously hypertensive rats of different ages and figured out whether there is functional cumulation during two-time application of the drug «Slavinorm» by above-mentioned animals. It was shown that a single course treatment with vascular peptide bioregulator had increased the density of microvascular network of the pia mater in young animals ca. 1,2-fold and had not affected the perfusion and oxygen saturation of sensorimotor cortex. The second course treatment with «Slavinorm» was provided in a 6 months. Functional cumulation was revealed in 12 month-aged rats which had 2 course treatments with vascular peptide bioregulation: the density of microvascular network of the pia mater was increased ca. 1,6-fold; level of perfusion was increased ca. 15% in comparison with intact animals of the same age. These animals were more tolerant to cerebral vasospasm (the application of vasoconstrictor on the surface of the brain): the highest level of tissue oxygen saturation was remained at fairly constant perfusion in comparison with other animals.

Introduction: Although liposomes hold promise for cancer therapy, the effectiveness of treating myocardial ischemia by promoting angiogenesis has yet to be proved. Nanoliposomes loaded with therapeutic agents can effectively target ischemic myocardium via enhanced permeability and retention. Surface polyethylene glycol (PEG) modification can further facilitate effective targeting by prolonging liposomal circulation. This study aimed to determine whether PEGylated nanoliposomes are effective in facilitating targeted drug delivery and treating myocardial ischemia., Methods: Rats subjected to 30min of myocardial ischemia were given (99m)Tc-hexamethylpropyleneamine oxime- or (99m)Tc-diethylenetriamine pentaacetate-labeled liposomes with mean diameters of ~100nm or ~600nm with or without PEG modifications to determine the extent of myocardial uptake in the different conditions. Therapeutic effectiveness was assessed by studying changes in myocardial perfusion defects with (99m)Tc-tetrofosmin autoradiography and vascular density with immunohistochemistry at 7days post-treatment., Results: The liver and spleen showed the largest capacity for liposome uptake. Uptake by the liver and spleen was more pronounced when the liposomes were larger. Conversely, myocardial liposome uptake was significantly greater when the liposomes were ~100nm rather than ~600nm in diameter. Surface modification with PEG significantly augmented myocardial uptake of ~100nm liposomes. PEG modification did not affect the size dependence. To investigate therapeutic efficacy, hearts subjected to ischemia received PEGylated nanoliposomes encapsulated with angiogenic peptides. Our data demonstrated that PEGylated nanoliposomes loaded with angiogenic peptides improved myocardial perfusion defects and increased vascular density. A 10-fold increase in liposomal concentration did not further benefit myocardial ischemia., Conclusions: Liposomal angiogenic formulation with size control and PEG modification may be effective treatment strategy for myocardial ischemia. Increasing the concentration of liposomes does not necessarily benefit myocardial ischemia., (Copyright © 2016 Elsevier Inc. All rights reserved.)

AGGF1 is an angiogenic factor with therapeutic potential to treat coronary artery disease (CAD) and myocardial infarction (MI). However, the underlying mechanism for AGGF1-mediated therapeutic angiogenesis is unknown. Here, we show for the first time that AGGF1 activates autophagy, a housekeeping catabolic cellular process, in endothelial cells (ECs), HL1, H9C2, and vascular smooth muscle cells. Studies with Atg5 small interfering RNA (siRNA) and the autophagy inhibitors bafilomycin A1 (Baf) and chloroquine demonstrate that autophagy is required for AGGF1-mediated EC proliferation, migration, capillary tube formation, and aortic ring-based angiogenesis. Aggf1+/- knockout (KO) mice show reduced autophagy, which was associated with inhibition of angiogenesis, larger infarct areas, and contractile dysfunction after MI. Protein therapy with AGGF1 leads to robust recovery of myocardial function and contraction with increased survival, increased ejection fraction, reduction of infarct areas, and inhibition of cardiac apoptosis and fibrosis by promoting therapeutic angiogenesis in mice with MI. Inhibition of autophagy in mice by bafilomycin A1 or in Becn1+/- and Atg5 KO mice eliminates AGGF1-mediated angiogenesis and therapeutic actions, indicating that autophagy acts upstream of and is essential for angiogenesis. Mechanistically, AGGF1 initiates autophagy by activating JNK, which leads to activation of Vps34 lipid kinase and the assembly of Becn1-Vps34-Atg14 complex involved in the initiation of autophagy. Our data demonstrate that (1) autophagy is essential for effective therapeutic angiogenesis to treat CAD and MI; (2) AGGF1 is critical to induction of autophagy; and (3) AGGF1 is a novel agent for treatment of CAD and MI. Our data suggest that maintaining or increasing autophagy is a highly innovative strategy to robustly boost the efficacy of therapeutic angiogenesis.

Using a TV device to study brain microcirculation, we found that after a course of vascular peptide bioregulator the density of microvascular network of pia matter of old rats (22-24 months) sensomotor cortex increased about 2,5-2,8 times compared to control old rates; and noradrenaline-induced constriction reactions and acetylcholine-induced dilative reactions of the pial arterioles increased significantly. This perfusion in the tissue of the cerebral cortex is not increased, but the degree of blood oxygen saturation in the microvasculature of this tissue region raised.

Therapeutic angiogenesis holds great potential for a myriad of tissue engineering and regenerative medicine approaches. While a number of peptides have been identified with pro-angiogenic behaviors, therapeutic efficacy is limited by poor tissue localization and persistence. Therefore, poly(ethylene glycol) hydrogels providing sustained, enzymatically-responsive peptide release were exploited for peptide delivery. Two pro-angiogenic peptide drugs, SPARC113 and SPARC118, from the Secreted Protein Acidic and Rich in Cysteine, were incorporated into hydrogels as crosslinking peptides flanked by matrix metalloproteinase (MMP) degradable substrates. In vitro testing confirmed peptide drug bioactivity requires sustained delivery. Furthermore, peptides retain bioactivity with residual MMP substrates present after hydrogel release. Incorporation into hydrogels achieved enzymatically-responsive bulk degradation, with peptide release in close agreement with hydrogel mass loss and released peptides retaining bioactivity. Interestingly, SPARC113 and SPARC118-releasing hydrogels had significantly different degradation time constants in vitro (1.16 and 8.77×10(-2) h(-1), respectively), despite identical MMP degradable substrates. However, upon subcutaneous implantation, both SPARC113 and SPARC118 hydrogels exhibited similar degradation constants of ~1.45×10(-2) h(-1), and resulted in significant ~1.65-fold increases in angiogenesis in vivo compared to controls. Thus, these hydrogels represent a promising pro-angiogenic approach for applications such as tissue engineering and ischemic tissue disorders., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The injured skin produces a number of mediators that directly or indirectly modulate cell chemotaxis, migration, proliferation, and angiogenesis. Components of the kinin pathway including the kinin B1 receptor (B1R) have been found to occur in the human skin, but information about its role on keratinocyte biology is still scarce. Our aim was to determine whether stimulation of B1R causes the secretion of IL-4 and/or VEGF from human keratinocytes and to evaluate the role of the B1R agonist Lys-des[Arg(9)]bradykinin and IL-4 on various stages of angiogenesis, such as cell migration, proliferation, and release of metalloproteases. By using ELISA and Western blotting, we showed that HaCaT keratinocytes stimulated with the B1R agonist release IL-4 and VEGF. Stimulation of B1R also caused transient c-JunN-terminal kinase phosphorylation and JunB nuclear translocation, transcription factor that regulates IL-4 expression. The 3D-angiogenesis assay, performed on spheroids of EA.hy923 endothelial cells embedded in a collagen matrix, showed that their cumulative sprout area increased significantly following stimulation with either IL-4 or B1R agonist. Furthermore, these ligands produced significant endothelial cell migration and release of metalloproteases 2 and 9, but did not increase endothelial cell proliferation as measured by 5-bromo-2'-deoxyuridine incorporation. Our results provide experimental evidence that establishes IL-4 and B1R agonist as important angiogenic factors of relevance for skin repair.

Background: Rapid wound healing of oral soft tissue may reduce the opportunity of infection and discomfort of patients. Previous studies have demonstrated that enhancement of angiogenesis is an effective way to accelerate wound repair. In this study, to enhance angiogenesis and healing of palatal wounds, dimethyloxalylglycine (DMOG) was applied to a rat palatal wound model. DMOG is known to inhibit oxygen-dependent degradation of hypoxia inducible factor-1 alpha (HIF-1α), which can lead to up-regulation of angiogenesis markers, favoring wound repair. We also evaluated the effects of DMOG on cell migration and HIF-1α expression of rat palatal (RP) cells. Furthermore, mRNA and protein expression of vascular endothelial growth factor (VEGF) were analyzed in DMOG-treated RP cells., Methods: Primary cultures of rat palatal (RP) cells were obtained from Sprague-Dawley (SD) rats. Effects of DMOG on cell viability and migration of RP cells were evaluated by using a formazan and culture insert, respectively. VEGF mRNA was observed by real-time PCR, and VEGF and HIF-1α proteins were detected by Western blotting. For the animal study, excisional wounds, 3 mm in diameter, were made at the central part of the palate of SD rats. DMOG with hyaluronic acid ointment was topically applied three times during 1 week, and then wound closures were quantitated photographically and histologically., Results: DMOG was cytotoxic to RP cells at concentrations higher than 2 mM and did not affect cell migration at non-cytotoxic concentrations. mRNA and protein expression of VEGF were significantly stimulated by DMOG treatment. The protein level of HIF-1α was also stabilized in RP cells by DMOG. In the animal study, groups treated with 1 mg/ml DMOG showed an increase of rat palatal wound contractures., Conclusions: DMOG enhanced wound healing of rat palatal mucosa, which was likely due to the angiogenic effect of the agent.

Ulcers in the stomach, duodenum, ileum/jejunum and colon may look alike grossly and microscopically, but they have very different etiologies and pathogenesis. Unfortunately, there is virtually no etiologic treatment for any of these lesions which are also accompanied by limited or extensive inflammation. This article reviews four groups of new antiulcer drugs discovered and patented in our lab in Boston and Long Beach/Irvine (Table 1). Actually, the first group, pyrazole and its derivatives can be used for prevention, i.e., long lasting protection of gastric mucosa against alcohol- or NSAID-induced erosions. Dopamine seems to be a new etiologic treatment for both upper and lower GI tract ulcers. Angiogenic growth factors like bFGF or PDGF (daily administration as peptides orally or by rectal enemas, or as single or double-dose of gene therapy) accelerated the healing of gastroduodenal ulcers and UC, while VEGF seems to be effective only for upper GI tract ulcers. Last but not least, a novel group of angiogenic steroids which not only stimulate new blood vessel formation and granulation tissue production (essential elements of healing of ulcer types) but may also exert mild or prominent antiinflammatory action and seem to be ideal drugs for the treatment of IBD.

The subcutaneous matrigel plug assay in mice is a method of choice for the in vivo evaluation of pro- and anti-angiogenic factors. In this method, desired factors are introduced into cold-liquid ECM-mimic gel which, after subcutaneous injection, solidifies to form an environment mimicking the cancer milieu. This matrix permits the penetration of host cells, such as endothelial cells, and therefore, the formation of vasculature. Herein we propose a new modified matrigel plug assay, which can be exploited to illustrate the angiogenic potential of a pool of factors secreted by cancer cells, as opposed to a specific factor (e.g., bFGF and VEGF) or agent. The plug containing ECM-mimic gel is utilized to introduce the host (i.e., mouse) with a pool of factors secreted to the C.M. of fast-growing tumor-generating glioblastoma cells. We have previously described an extensive comparison of the angiogenic potential of U-87 MG human glioblastoma and its dormant-derived clone, in this system model, showing induced angiogenesis in the U-87 MG parental cells. The C.M. is prepared by filtering collected media from confluent tissue culture plates of either cell line following 48 hr incubation. Hence, it contains only factors secreted by the cells, without the cells themselves. Described here is the combination of two imaging modalities, microbubbles contrast-enhanced ultrasound imaging and intravital fibered-confocal endomicroscopy, for an accurate, real-time characterization of the extent, morphology and functionality of newly-formed blood vessels within the plugs.

Introduction: Prostacyclin (PGI2), a member of the prostaglandin family, can promote angiogenesis and cell proliferation., Methods: In this study, the effect of the application of a PGI2 analog (iloprost) on dentin repair was examined in vitro and in vivo., Results: Iloprost significantly stimulated the expression of vascular endothelial growth factor and osteo-/odontogenic marker messenger RNA in human dental pulp cells (HDPCs) under osteoinductive conditions in vitro. In addition, iloprost enhanced HDPC alkaline phosphatase enzymatic activity and mineral deposition. An in vivo study was performed using a rat molar mechanical pulp exposure model. After 30 days, histologic analysis revealed that there was a dramatic tertiary dentin formation in the iloprost-treated group compared with the calcium hydroxide and the untreated control groups. Furthermore, vascular endothelial growth factor protein expression in dental pulp tissue was increased in the iloprost-treated group as determined by immunohistochemical staining., Conclusions: Taken together, the present study, for the first time, shows that iloprost induces the expression of osteo-/odontogenic markers in vitro and promotes angiogenic factor expression and enhances tertiary dentin formation in vivo. This implies the potential clinical usefulness of iloprost in vital pulp therapy., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Angiogenic factor with G patch and FHA domains 1 (AGGF1) is a newly identified proangiogenic protein, which plays an important role in vascular disease and angiogenesis. However, its role in myocardial ischemia/reperfusion (I/R) injury remains unknown. This study investigated whether AGGF1 is involved in the pathogenesis of mouse myocardial I/R injury and the underlying mechanisms. Wild-type (WT) C57BL/6 J mice were treated at 30 min prior to I/R injury with anti-AGGF1 neutralizing antibody (3 mg/kg) or recombinant human AGGF1 (rhAGGF1, 0.25 mg/kg). After I/R injury, the infarct size, the number of TUNEL-positive cardiomyocytes, Bax/Bcl2 ratio, inflammatory cytokine expression and angiogenesis were markedly increased as compared with sham control. Treatment of WT mice with anti-AGGF1 neutralizing antibody resulted in exaggeration of myocardial I/R injury but reducing angiogenesis. In contrast, administration of rhAGGF1 markedly reversed these effects. Furthermore, anti-AGGF1- or rhAGGF1-mediated effects on I/R-induced cardiac apoptosis, inflammation and angiogenesis were dose dependent. In addition, the protective effects of AGGF1 on cardiomyocyte apoptosis and inflammation were confirmed in cultured cardiomyocytes after I/R. Finally, these effects were associated with activation of ERK1/2, Stat3 and HIF-1α/VEGF pathways and inhibition of activation of NF-κB, p53 and JNK1/2 pathways. In conclusion, we report the first in vivo and in vitro evidence that AGGF1 reduces myocardial apoptosis and inflammation and enhances angiogenesis, leading to decreased infarct size after I/R injury. These results may provide a novel therapeutic approach for ischemic heart diseases.

Peptide mimics of growth factors represent an emerging class of therapeutic drugs due to high biological specificity and relative ease of synthesis. However, maintaining efficacious therapeutic dosage at the therapy site has proven challenging owing to poor intestinal permeability and short circulating half-lives in the blood stream. In this work, we present the affinity immobilization and controlled release of QK, a vascular endothelial growth factor (VEGF) mimetic peptide, from an injectable mixing-induced two-component hydrogel (MITCH). The MITCH system is crosslinked by reversible interactions between WW domains and complementary proline-rich peptide modules. Fusion of the QK peptide to either one or two units of the proline-rich sequence creates bifunctional peptide conjugates capable of specific binding to MITCH while preserving their angiogenic bioactivity. Presenting two repeats of the proline-rich sequence increases the binding enthalpy 2.5 times due to avidity effects. Mixing of the drug conjugates with MITCH components results in drug encapsulation and extended release at rates consistent with the affinity immobilization strength. Human umbilical vein endothelial cells (HUVECs) treated with the soluble drug conjugates exhibit morphogenetic events of VEGF receptor 2 signal transduction followed by cell migration and organization into networks characteristic of early angiogenesis. In a three-dimensional model where HUVECs were cultured as spheroids in a matrix of collagen and fibronectin, injection of drug-releasing MITCH resulted in significantly more cell outgrowth than drugs injected in saline. This ability to sustain local drug availability is ideal for therapeutic angiogenesis applications, where spatiotemporal control over drug distribution is a key requirement for clinical success.

Objective: Vascular lineage differentiation of stem/progenitor cells can contribute to both tissue repair and exacerbation of vascular diseases such as in vein grafts. The role of macrophages in controlling vascular progenitor differentiation is largely unknown and may play an important role in graft development. This study aims to identify the role of macrophages in vascular stem/progenitor cell differentiation and thereafter elucidate the mechanisms that are involved in the macrophage- mediated process., Approach and Results: We provide in vitro evidence that macrophages can induce endothelial cell (EC) differentiation of the stem/progenitor cells while simultaneously inhibiting their smooth muscle cell differentiation. Mechanistically, both effects were mediated by macrophage-derived tumor necrosis factor-α (TNF-α) via TNF-α receptor 1 and canonical nuclear factor-κB activation. Although the overexpression of p65 enhanced EC (or attenuated smooth muscle cell) differentiation, p65 or TNF-α receptor 1 knockdown using lentiviral short hairpin RNA inhibited EC (or rescued smooth muscle cell) differentiation in response to TNF-α. Furthermore, TNF-α-mediated EC differentiation was driven by direct binding of nuclear factor-κB (p65) to specific VE-cadherin promoter sequences. Subsequent experiments using an ex vivo decellularized vessel scaffold confirmed an increase in the number of ECs and reduction in smooth muscle cell marker expression in the presence of TNF-α. The lack of TNF-α in a knockout mouse model of vein graft decreased endothelialization and significantly increased thrombosis formation., Conclusions: Our study highlights the role of macrophages in directing vascular stem/progenitor cell lineage commitment through TNF-α-mediated TNF-α receptor 1 and nuclear factor-κB activation that is likely required for endothelial repair in vascular diseases such as vein graft.

Present report shows for the first time on the induction of in vitro angiogenesis by a 3.9 kDa novel peptide (RVVAP) purified from Russell's viper venom. Secondary structure of RVVAP is made up of 36.8% α-helix, 33.3% β pleated sheets and 29.9% turns. Optimum angiogenesis and significant elevation in endothelial migration were observed at 50 ng/ml of RVVAP treatment; above this concentration, progressive decrease in wound healing was noted. RVVAP (1.0 μg/ml) was non-cytotoxic to U87-MG, HeLa and HT-29 cells; however, increasing the RVVAP concentration above 500 ng/ml resulted in induction of chromosomal aberrations and delay in cell cycle kinetics of Chinese hamster ovary cells., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Loss of glomerular function associated with the presence of tubulointerstitial lesions, which are characterized by peritubular capillary loss, is a common finding in progressive renal disorders. Dysregulated expression of angiogenic factors (such as vascular endothelial growth factor [VEGF] and angiopoietins) and endogenous angiogenic inhibitors (such as thrombospondin-1, angiostatin and endostatin) underlie these conditions and negatively influence the balance between capillary formation and regression, resulting in capillary rarefaction. Recent studies have provided unequivocal evidence for a pathogenic role of tubulointerstitial hypoxia and the involvement of hypoxia-inducible transcription factors in the advanced stages of chronic kidney disease. The mainstay of potential angiogenic therapies is the application of angiogenic factors with the primary aim of ameliorating reduced oxygenation in the ischaemic tubulointerstitium. However, this strategy is strongly associated with inflammation and changes in vascular permeability. For example, supraphysiological expression of VEGF results in glomerular expansion and proteinuria, whereas VEGF blockade using neutralizing antibodies can cause hypertension and thrombotic microangiopathy. These effects highlight the importance of tight regulation of angiogenic factors and inhibitors. Novel therapeutic approaches that target vascular maturation and normalization are now being developed to protect kidneys from capillary rarefaction and hypoxic injury.

We previously identified a novel angiogenic peptide, AG30, with antibacterial effects that could serve as a foundation molecule for the design of wound-healing drugs. Toward clinical application, in this study we have developed a modified version of the AG30 peptide characterized by improved antibacterial and angiogenic action, thus establishing a lead compound for a feasibility study. Because AG30 has an α-helix structure with a number of hydrophobic and cationic amino acids, we designed a modified AG30 peptide by replacing several of the amino acids. The replacement of cationic amino acids (yielding a new molecule, AG30/5C), but not hydrophobic amino acids, increased both the angiogenic and the antimicrobial properties of the peptide. AG30/5C was also effective against methicillin-resistant Staphylococcus aureus (MRSA) and antibiotic-resistant Pseudomonas aeruginosa. In a diabetic mouse wound-healing model, the topical application of AG30/5C accelerated wound healing with increased angiogenesis and attenuated MRSA infection. To facilitate the eventual clinical investigation/application of these compounds, we developed a large-scale procedure for the synthesis of AG30/5C that employed the conventional solution method and met Good Manufacturing Practice guidelines. In the evaluation of stability of this peptide in saline solution, RP-HPLC analysis revealed that AG30/5C was fairly stable under 5°C for 12 months. Therefore, we propose the use of AG30/5C as a wound-healing drug with antibacterial and angiogenic actions., (© 2011 The Authors Journal of Cellular and Molecular Medicine © 2011 Foundation for Cellular and Molecular Medicine/Blackwell Publishing Ltd.)

Structure-activity relationship (SAR) studies are essential in the generation of peptides with enhanced activity and efficacy as therapeutic agents. In this study, we report a Structure-activity relationship study for a family of mimetic peptides derived from type IV collagen with potent anti-angiogenic properties. The Structure-activity relationship study was conducted using a number of validated in vitro assays including cell proliferation, adhesion, migration, and tubule formation. We report a critical sequence (NINNV) within this peptide series, which is required for the potent anti-angiogenic activity. Detailed amino acid substitutions resulted in peptides with superior efficacy. Specifically, substitutions with isoleucine at positions 12 and 18 along with the substitution of the methionine at position 10 with the non-natural amino acid D-alanine led to an increase in potency by two orders of magnitude over the parent peptide. Several mimetic peptides in this series exhibit a significant improvement of activity over the parent peptide. This improved in vitro activity is expected to correlate with an increase in in vivo activity leading to effective peptides for anti-angiogenic therapy for different disease applications including cancer and age-related macular degeneration., (© 2012 John Wiley & Sons A/S.)

Background: In sites with diminished bone volume, the osseointegration of dental implants can be compromised. Innovative biomaterials have been developed to aid successful osseointegration outcomes., Purpose: The aim of this study was to evaluate the osteogenic potential of angiogenic latex proteins for improved bone formation and osseointegration of dental implants., Materials and Methods: Ten dogs were submitted to bilateral circumferential defects (5.0 × 6.3 mm) in the mandible. Dental implant (3.3 × 10.0 mm, TiUnite MK3™, Nobel Biocare AB, Göteborg, Sweden) was installed in the center of the defects. The gap was filled either with coagulum (Cg), autogenous bone graft (BG), or latex angiogenic proteins pool (LPP). Five animals were sacrificed after 4 weeks and 12 weeks, respectively. Implant stability was evaluated using resonance frequency analysis (Osstell Mentor, Osstell AB, Göteborg, Sweden), and bone formation was analyzed by histological and histometric analysis., Results: LPP showed bone regeneration similar to BG and Cg at 4 weeks and 12 weeks, respectively (p ≥ .05). Bone formation, osseointegration, and implant stability improved significantly from 4 to 12 weeks (p ≤ .05)., Conclusion: Based on methodological limitations of this study, Cg alone delivers higher bone formation in the defect as compared with BG at 12 weeks; compared with Cg and BG, the treatment with LPP exhibits no advantage in terms of osteogenic potential in this experimental model, although overall osseointegration was not affected by the treatments employed in this study., (© 2009 Wiley Periodicals, Inc.)

Fragments from the extracellular matrix proteins laminin and osteopontin and a sequence from VEGF have potent proangiogenic activity despite their small size (< 10 residues). However, these linear peptides have limited potential as drug candidates for therapeutic angiogenesis because of their poor stability. In the present study, we show that the therapeutic potential of these peptides can be significantly improved by "grafting" them into cyclic peptide scaffolds. Momordica cochinchinensis trypsin inhibitor-II (MCoTI-II) and sunflower trypsin inhibitor-1 (SFTI-1), naturally occurring, plant-derived cyclic peptides of 34 and 14 residues, respectively, were used as scaffolds in this study. Using this approach, we have designed a peptide that, in contrast to the small peptide fragments, is stable in human serum and at nanomolar concentration induces angiogenesis in vivo. This is the first report of using these scaffolds to improve the activity and stability of angiogenic peptide sequences and is a promising approach for promoting angiogenesis for therapeutic uses.

Background: Experimentally, exogenous administration of recombinant stromal cell-derived factor-1α (SDF) enhances neovasculogenesis and cardiac function after myocardial infarction. Smaller analogs of SDF may provide translational advantages including enhanced stability and function, ease of synthesis, lower cost, and potential modulated delivery via engineered biomaterials. In this study, computational protein design was used to create a more efficient evolution of the native SDF protein., Methods and Results: Protein structure modeling was used to engineer an SDF polypeptide analog (engineered SDF analog [ESA]) that splices the N-terminus (activation and binding) and C-terminus (extracellular stabilization) with a diproline segment designed to limit the conformational flexibility of the peptide backbone and retain the relative orientation of these segments observed in the native structure of SDF. Endothelial progenitor cells (EPCs) in ESA gradient, assayed by Boyden chamber, showed significantly increased migration compared with both SDF and control gradients. EPC receptor activation was evaluated by quantification of phosphorylated AKT, and cells treated with ESA yielded significantly greater phosphorylated AKT levels than SDF and control cells. Angiogenic growth factor assays revealed a distinct increase in angiopoietin-1 expression in the ESA- and SDF-treated hearts. In addition, CD-1 mice (n=30) underwent ligation of the left anterior descending coronary artery and peri-infarct intramyocardial injection of ESA, SDF-1α, or saline. At 2 weeks, echocardiography demonstrated a significant gain in ejection fraction, cardiac output, stroke volume, and fractional area change in mice treated with ESA compared with controls., Conclusions: Compared with native SDF, a novel engineered SDF polypeptide analog (ESA) more efficiently induces EPC migration and improves post-myocardial infarction cardiac function and thus offers a more clinically translatable neovasculogenic therapy.

Background: Granulocyte colony-stimulating factor (G-CSF) mobilizes hematopoietic bone marrow cells into systemic circulation and has been used clinically to treat chemotherapy-induced neutropenia. Recently, G-CSF was shown to have neuroprotective and angiogenetic effects in acute cerebral infarction., Objective: To evaluate the effects of G-CSF for angiogenesis after indirect bypass surgery., Methods: : Chronic cerebral hypoperfusions were induced in male Wistar rats by permanent bilateral internal carotid artery occlusion (BICAO). After BICAO, unilateral indirect bypass and encephalogaleosynangiosis (EGS) were performed, and human recombinant G-CSF (10 μg/kg) or saline was injected intramuscularly for 5 consecutive days. We measured regional cerebral blood flow (rCBF) by laser Doppler flowmetry and performed immunohistochemical analysis 21 days after BICAO., Results: BICAO decreased rCBF to 62.52% ± 5.8% of control (P < .01). The rCBF increased significantly 21 days after BICAO in all treatment groups (n = 10; P < .05) except the G-E- group. The rCBF increase observed in the G+E+ group was significantly higher than that observed in other groups. Both G-CSF and EGS treatments significantly increased the number of small vessels (P < .01), and G-CSF and EGS showed additive effect in increasing the number of small vessels., Conclusion: Combined use of G-CSF and indirect bypass surgery induces an increase in rCBF and angiogenesis under conditions of cerebral chronic hypoperfusion. This is the first report to demonstrate that G-CSF can enhance angiogenesis induced by indirect bypass surgery, and that this combined therapy is a safe and easy method of treatment.

Functional vascularization is a key requirement for the development and function of most tissues, and most critically cardiac muscle. Rapid and irreversible loss of cardiomyocytes during cardiac infarction directly results from the lack of blood supply. Contractile cardiac grafts, engineered using cardiovascular cells in conjunction with biomaterial scaffolds, are an actively studied method for cardiac repair. In this article, we focus on biomaterial scaffolds designed to mediate the development and maturation of vascular networks, by immobilized growth factors. The interactive effects of multiple vasculogenic factors are discussed in the context of cardiac tissue engineering.

Alginate microcapsules coated with a permselective poly-L-ornithine (PLO) membrane have been investigated for the encapsulation and transplantation of islets as a treatment for type 1 diabetes. The therapeutic potential of this approach could be improved through local stimulation of microvascular networks to meet mass transport demands of the encapsulated cells. Fibroblast growth factor-1 (FGF-1) is a potent angiogenic factor with optimal effect occurring when it is delivered in a sustained manner. In this article, a technique is described for the generation of multilayered alginate microcapsules with an outer alginate layer that can be used for the delivery of FGF-1. The influence of alginate concentration and composition (high mannuronic acid (M) or guluronic acid (G) content) on outer layer size and stability, protein encapsulation efficiency, and release kinetics was investigated. The technique results in a stable outer layer of alginate with a mean thickness between 113 and 164 μm, increasing with alginate concentration and G-content. The outer layer was able to encapsulate and release FGF-1 for up to 30 days, with 1.25% of high G alginate displaying the most sustained release. The released FGF-1 retained its biologic activity in the presence of heparin, and the addition of the outer layer did not alter the permselectivity of the PLO coat. This technique could be used to generate encapsulation systems that deliver proteins to stimulate local neovascularization around encapsulated islets.

We showed previously in a mouse model of lung ischemia-induced angiogenesis, enhanced expression of the three ELR+ CXC chemokines (KC, LIX, and MIP-2) and that blockade of the ligand receptor CXCR(2) limited neovascularization. The present study was undertaken to determine the relative abundance and angiogenic potential of the three CXC chemokines and whether RhoA activation explained the measured differences in potencies. We found that LIX showed the greatest absolute amount in the in vivo model 4 h after left pulmonary artery obstruction (LIX>KC>MIP-2; p<0.05). In vitro, LIX induced the greatest degree of arterial endothelial cell chemotaxis and KC was without effect. A significant increase (approximately 40%) in active RhoA was observed with both LIX and MIP-2 compared with vehicle control (p<0.05). On average, LIX induced the greatest amount of tube formation within pleural tissue in culture. Thus, the results of the present study suggest that among the three ELR+ CXC chemokines, LIX predominates in eliciting a pro-angiogenic phenotype., (Copyright 2010 Elsevier Inc. All rights reserved.)

Objective: To investigate the novel hypothesis that neurotrophin-3 (NT-3), an established neurotrophic factor that participates in embryonic heart development, promotes blood vessel growth., Methods and Results: We evaluated the proangiogenic capacity of recombinant NT-3 in vitro and of NT-3 gene transfer in vivo (rat mesenteric angiogenesis assay and mouse normoperfused adductor muscle). Then, we studied whether either transgenic or endogenous NT-3 mediates postischemic neovascularization in a mouse model of limb ischemia. In vitro, NT-3 stimulated endothelial cell survival, proliferation, migration, and network formation on the basement membrane matrix Matrigel. In the mesenteric assay, NT-3 increased the number and size of functional vessels, including vessels covered with mural cells. Consistently, NT-3 overexpression increased muscular capillary and arteriolar densities in either the absence or the presence of ischemia and improved postischemic blood flow recovery in mouse hind limbs. NT-3-induced microvascular responses were accompanied by tropomyosin receptor kinase C (an NT-3 high-affinity receptor) phosphorylation and involved the phosphatidylinositol 3-kinase-Akt kinase-endothelial nitric oxide synthase pathway. Finally, endogenous NT-3 was shown to be essential in native postischemic neovascularization, as demonstrated by using a soluble tropomyosin receptor kinase C receptor domain that neutralizes NT-3., Conclusions: Our results provide the first insight into the proangiogenic capacity of NT-3 and propose NT-3 as a novel potential agent for the treatment of ischemic disease.

Purpose: Modulators of angiogenesis typically work in an orchestrated manner. The authors examined the interaction between insulinlike growth factor (IGF)-1, vascular endothelial growth factor (VEGF), and stromal derived factor (SDF)-1 in vivo and in vitro using angiogenesis models., Methods: The angiogenic effect of SDF-1, alone or in combination with IGF-1 and VEGF, was assessed in human lung microvascular endothelial cells using capillary tube formation and thymidine incorporation. Immunohistochemical analysis for CD31, SDF-1, and CXCR4 was performed on mouse eyes 2 weeks after the initiation of laser rupture of Bruch's membrane, a choroidal neovascularization (CNV) model. CXCR4 antagonist and CXCR4 blocking antibody were tested on inhibition of CNV lesion size in this model. Real-time PCR was used to determine mRNA levels for SDF-1, VEGF, IGF-1, and their cognate receptors in the retinal pigment epithelium/choroid complex of mice that underwent this CNV model., Results: IGF-1 and VEGF demonstrated an additive effect on SDF-1-induced in vitro angiogenesis. CXCR4 immunoreactivity was present in both normal and laser-injured mice at the laser burn site and at the ganglion cell layer, the anterior portion of the inner nuclear layer, photoreceptors, and choroidal stroma. SDF-1 was observed in identical locations but was not seen in photoreceptors. mRNA levels for SDF-1, VEGF, and IGF-1 and their receptors were increased after laser injury. CXCR4-neutralizing antibody reduced neovascularization when injected subretinally but not intraperitoneally or intravitreally., Conclusions: The potent proangiogenic factors IGF-1 and VEGF both stimulate SDF-1-induced angiogenesis. Local inhibition of CXCR4 is required for an antiangiogenic effect in CNV lesions.

Brain angiogenesis inhibitor 1 (BAI1) is a transmembrane protein expressed on glial cells within the brain. Its expression is dramatically down-regulated in many glioblastomas, consistent with its functional ability to inhibit angiogenesis and tumor growth in vivo. We have shown that the soluble anti-angiogenic domain of BAI1 (termed Vstat120) requires CD36, a cell surface glycoprotein expressed on microvascular endothelial cells (MVECs), for it to elicit an anti-angiogenic response. We now report that Vstat120 binding to CD36 on MVECs activates a caspase-mediated pro-apoptotic pathway, and this effect is abrogated by histidine-rich glycoprotein (HRGP). HRGP is a circulating glycoprotein previously shown to function as a CD36 decoy to promote angiogenesis in the presence of thrombospondin-1 or -2. Data here show that Vstat120 specifically binds HRGP. Under favorable MVEC growth conditions this interaction allows chemotactic-directed migration as well as endothelial tube formation to persist in in vitro cellular systems, and increased tumor growth in vivo as demonstrated in both subcutaneous and orthotopic brain tumor models, concomitant with an increase in tumor vascularity. Finally, we show that HRGP expression is increased in human brain cancers, with the protein heavily localized to the basement membrane of the tumors. These data help define a novel angiogenic axis that could be exploited for the treatment of human cancers and other diseases where excess angiogenesis occurs.

Histidine-rich glycoprotein (HRG) is a heparin-binding glycoprotein present in plasma at 100microg/ml. A recent study revealed that HRG suppressed heparin-dependent basic fibroblast growth factor (bFGF)-induced angiogenesis. Additionally, we reported that high mobility group box 1 (HMGB1) in complex with heparin induces angiogenesis; therefore, we examined the effect of HRG on heparin-dependent HMGB1-induced angiogenesis in the present study. HRG completely inhibited angiogenesis induced by HMGB1 in complex with heparin. HRG inhibited the diffusion of a complex of HMGB1 with heparin from matrigel into surrounding tissue. HRG also competed with HMGB1 for heparin binding in vitro. Moreover, HRG inhibited heparin-dependent vascular endothelial growth factor-A(165) (VEGF-A(165))-induced angiogenesis. These results strongly suggested that HRG might be an inhibitor of angiogenesis induced by growth factors with heparin binding activity and that HRG may be a potential drug for angiogenic diseases, including tumor growth.

Angiogenesis, the sprouting of blood vessels from preexisting vasculature is associated with both natural and pathological processes. Various angiogenesis assays involve the study of individual endothelial cells in culture conditions (1). The aortic ring assay is an angiogenesis model that is based on organ culture. In this assay, angiogenic vessels grow from a segment of the aorta (modified from (2)). Briefly, mouse thoracic aorta is excised, the fat layer and adventitia are removed, and rings approximately 1 mm in length are prepared. Individual rings are then embedded in a small solid dome of basement matrix extract (BME), cast inside individual wells of a 48-well plate. Angiogenic factors and inhibitors of angiogenesis can be directly added to the rings, and a mixed co-culture of aortic rings and other cell types can be employed for the study of paracrine angiogenic effects. Sprouting is observed by inspection under a stereomicroscope over a period of 6-12 days. Due to the large variation caused by the irregularities in the aortic segments, experimentation in 6-plicates is strongly advised. Neovessel outgrowth is monitored throughout the experiment and imaged using phase microscopy, and supernatants are collected for measurement of relevant angiogenic and anti-angiogenic factors, cell death markers and nitrite.

The long-term outcome of replanted avulsed permanent teeth is frequently compromised by lack of revascularization, resulting in pulp necrosis. The purpose of this study was to evaluate the effects of vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF-2) on the revascularization of severed human dental pulps. Tooth slices were prepared from non-carious human molars and treated with 0-50 ng/mL rhVEGF(165) or rhFGF-2 for 7 days in vitro. Both angiogenic factors enhanced pulp microvessel density compared with untreated controls (p < 0.05). Tooth slices were also treated with 0 or 50 ng/mL rhVEGF(165) for one hour prior to implantation into the subcutaneous space of immunodeficient mice. Treatment with rhVEGF(165) increased pulp microvessel density in vivo (p < 0.05). These results demonstrate that rhVEGF(165) enhanced neovascularization of severed human dental pulps and suggest that topical application of an angiogenic factor prior to replantation might be beneficial for the treatment of avulsed teeth.

Aims: The present study investigated the detailed mechanism by which fractalkine (Fkn), a CX3C chemokine, induces angiogenesis and its functional implication in alleviating ischaemia in vivo., Methods and Results: Fkn induced new vessel formation on the excised rat aorta and chick chorioallantoic membrane (CAM) through CX3CR1 activation. Immunoblotting analysis, promoter assay and electrophoretic mobility shift assay showed that Fkn upregulated hypoxia-inducible factor-1 alpha (HIF-1alpha) by cultured human aortic endothelial cells (ECs), which in turn induced mRNA and protein levels of vascular endothelial growth factor (VEGF)-A through a p42/44 mitogen-activated protein kinase pathway. In vivo Fkn-induced angiogenesis on CAM was completely blocked by functional inhibition of VEGF receptor 2 kinase insert domain-containing receptor (KDR) and Rho GTPase. C57/BL6 mice with CX3CR1(-/-) bone marrow-derived cells developed angiogenesis in the implanted Fkn-mixed Matrigel plug, suggesting CX3CR1 activation in vascular ECs is sufficient for Fkn-induced angiogenesis in vivo. The condition of rat hindlimb ischaemia, which rapidly stimulated mRNA expression of both Fkn and VEGF-A, was significantly alleviated by the injection of whole-length Fkn protein., Conclusion: Fkn-induced activation of CX3CR1 by ECs leads to in vivo angiogenesis through two sequential steps: the induction of HIF-1alpha and VEGF-A gene expression by CX3CR1 activation and the subsequent VEGF-A/KDR-induced angiogenesis. The potent induction of angiogenesis by Fkn can be used as a therapeutic strategy for alleviating peripheral ischaemia.

Kallikrein, a serine proteinase, has been identified as an angiogenic growth factor recently. We investigated whether delayed treatment with exogenous kallikrein enhances neurogenesis and angiogenesis after focal cortical infarction in stroke-prone renovascular hypertensive rats. Human tissue kallikrein (1.6 x 10(-2) PNAU/kg) or vehicle was given through a tail vein daily for 6 consecutive days starting 24 h after distal middle cerebral artery occlusion (MCAO). Cell proliferation was examined by using 5'-bromo-2'-deoxyuridine (BrdU, 50 mg/kg). Rats were sacrificed at 3, 7, 14 or 28 d after MCAO, respectively. Treatment with kallikrein significantly increased the number of BrdU(+) cells in the subventricular zone (SVZ) and the peri-infarction region initiating 3 d after MCAO compared with the vehicle group (all p<0.05). Kallikrein significantly increased the number of BrdU(+)/DCX(+) cells and BrdU(+)/nestin(+) cells in the SVZ as well as vascular density in the peri-infarction region compared with the vehicle group (all p<0.05), which increased at 3 d, peaked at 7-14 d after MCAO, and then gradually decreased. Kallikrein markedly increased the number of BrdU(+)/NeuN(+) cells in the peri-infarction region compared with the vehicle group at 14 d and 28 d after MCAO (all p<0.05). The kallikrein group showed better functional improvement after stroke (all p<0.05). Our study demonstrates that delayed administration of kallikrein at 24 h after cortical infarction promotes the SVZ neuroblasts proliferation, migration, and selective differentiation. Moreover, kallikrein enhanced endogenous neurogenesis is associated with angiogenesis, both attributing to functional improvement after stroke. Therefore, kallikrein may have a potential therapeutic perspective on ischemic stroke.

Vascular endothelial growth factor receptor-1 (VEGFR-1) is a tyrosine kinase receptor for growth factors of the VEGF family. Endothelial cells express a membrane-bound and a soluble variant of this protein, the latter being mainly considered as a negative regulator of VEGF-A signaling. We previously reported that the soluble form is deposited in the extracellular matrix produced by endothelial cells in culture and is able to promote cell adhesion and migration through binding to alpha5beta1 integrin. In this study, we demonstrate that the Ig-like domain II of VEGFR-1, which contains the binding determinants for the growth factors, is involved in the interaction with alpha5beta1 integrin. To identify domain regions involved in integrin binding, we designed 12 peptides putatively mimicking the domain II surface and tested their ability to inhibit alpha5beta1-mediated endothelial cell adhesion to soluble VEGFR-1 and directly support cell adhesion. One peptide endowed with both these properties was identified and shown to inhibit endothelial cell migration toward soluble VEGFR-1 as well. This peptide directly binds alpha5beta1 integrin, but not VEGF-A, inducing endothelial cell tubule formation in vitro and neoangiogenesis in vivo. Alanine scanning mutagenesis of the peptide defined which residues were responsible for its biologic activity and integrin binding.

Tissue factor pathway inhibitor (TFPI) is a plasma Kunitz-type serine protease inhibitor that is mainly known for its inhibition of tissue factor-mediated coagulation. In addition to its anticoagulant properties, emerging data show that TFPI may also regulate endothelial cell functions via a non-haemostatic pathway. In this work we demonstrate that at concentrations within the physiological range, TFPI inhibits both endothelial cell migration and their differentiation into capillary-like structures in vitro. These effects were specific to endothelial cells since no inhibitory effect was observed on the migration of tumor (glioblastoma) cells. Inhibition of endothelial cell migration was correlated with a concomitant loss in cell adhesion, suggesting an alteration of focal adhesion complex integrity. Accordingly, we observed that TFPI inhibited the phosphorylation of focal adhesion kinase and paxillin, two key proteins involved in the scaffolding of these complexes, and that this effect was specific to endothelial cells. These results suggest that TFPI influences the angiogenic process via a non-haemostatic pathway, by downregulating the migratory mechanisms of endothelial cells.

Background: Leptin is a potent direct angiogenic factor that stimulates endothelial cell migration and activation in vitro and angiogenesis in vivo. In addition, leptin has been discussed to play an important role in angiogenesis, as it promotes the formation of new blood vessels., Purpose: The effect of exogenously administered leptin on the healing process of a full tissue burn wound model., Methods: Sixty-three Sprague-Dawley male rats were used. Full tissue burn wound was created by electrocautery. The width of the pin was 0.3 cm; its length was 2 cm and was used at the "cut" modulation. Rats were divided into seven groups of nine animals each. Burn wounds were injected with murine recombinant leptin and the rats were sacrificed 3, 7 and 9 days after surgery. Every group had obtained three animals for the three different days of sacrifice. Three different leptin doses of 250 pg/ml, 500 pg/ml and 1000 pg/ml were used in different animal groups (A, B and C). For every one of the three leptin doses used, another animal group was evaluated by using the combined injection of leptin and antileptin (A1, B1, and C1), in order to study the inhibitory effect to the leptin factor. Nine rats were served as controls. These were injected with 0.3 ml water for injection solution and sacrificed at the same time intervals. After sacrifice of the animals, the skin was grossly determined by its appearance, colour and texture. Full thickness burn wounds were dissected for histological examination. A qualitative analysis of angiogenesis in the burn wound was conducted following a standard hematoxylin and eosin stain. The wound tissue samples from each experimental group underwent immunohistochemical evaluation of microvessel density by endothelial cell staining with mouse anti-rat CD 34 monoclonal antibody., Results: The most impressive growth of new blood vessels appeared seven and nine days after treatment with the highest leptin doses. There were no significant differences in microvessel density between the seventh and the ninth postoperative day among different groups treated with leptin. All wounds from the control group, as well as those from animal groups treated with the combined injection of leptin and antileptin did not develop any new vessels., Conclusion: Exogenous administration of recombinant leptin increases early tissue angiogenesis in the burn wound level of an experimental animal model.

Tumor neo-vascularization is critical for tumor growth, invasion and metastasis, which has been considered to be mediated by a mechanism of angiogenesis. However, histopathological studies have suggested that tumor cells might be the progenitor for tumor vasculature. Recently, we have reported that the precancerous stem cells (pCSCs) representing the early stage of developing cancer stem cells (CSCs), have the potential for both benign and malignant differentiation. Therefore, we investigated whether pCSCs serve as progenitors for tumor vasculogenesis. Herein, we report that in the pCSC-derived tumors, most blood vessels were derived from pCSCs. Some pCSCs constitutively expressed vasculogenic receptor VEGFR-2, which can be up-regulated by hypoxia and angiogenesis-promoting cytokines, such as GM-CSF, Flt3 ligand, and IL-13. The pCSCs are much more potent in tumor vasculogenesis than the differentiated tumor monocytic cells (TMCs) from the same tumor, which had comparable or even higher capacity to produce some vascular growth factors, suggesting that the potent tumor vasculogenesis of pCSCs is associated with their intrinsic stem-like property. Consistently tumor vasculogenesis was also observed in human cancers such as cervical cancer and breast cancer and xenograft lymphoma. Our studies indicate that pCSCs can serve as tumor vasculogenic stem/progenitor cells (TVPCs), and may explain why anti-angiogenic cancer therapy trials are facing challenge.

Understanding mechanisms of formation of vascular networks under different experimental conditions is essential for improving treatment of angiogenesis-dependent diseases. To this end, we investigated the dose response of angiogenesis to basic fibroblast growth factor (bFGF) using the rat corneal pocket assay. The response was quantified, in terms of (i) the migration distance of vascular networks, (ii) the total vessel length, (iii) the distribution of the projected width of vessels, (iv) the distribution of the number of vessels, and (v) the distribution of vessel diameters. The quantification was based on new image analysis methods developed in the study. It was observed that the migration distance and the total vessel length increased by 82% and 199%, respectively, when the dose of bFGF was increased from 5 ng to 50 ng. The number and the diameter of vessels increased with the dose of bFGF as well. However, the last two parameters at a given dose of bFGF were approximately independent of the location in the middle region between the pellet and the limbus. These results provided useful information for understanding mechanisms of angiogenesis induced by bFGF and important data for validating a mathematical model of angiogenesis described in the second part of the study.

Acceleration of the wound healing process by using angiogenic peptides has been demonstrated previously. Here we used select laminin-111 peptides, A13 and C16, from the laminin alpha1 and gamma1 chain, respectively, to test whether they are able to stimulate wound healing in a rat full thickness wound model. The 12-mer peptides C16 and A13 are highly angiogenic and bind to integrins alphavbeta3 and alpha5beta1. We show that A13 increases wound re-epithelialization as much as 17% over controls by day 4 and C16 increases coverage by 11%. Contraction of the treated wounds was increased as much as 11% for A13 and 8% for C16 at day 4. No differences were observed at day 7 with either peptide. The peptides also stimulated fibroblast migration in Boyden chamber assays. A13 increased cell migration as much as 2.4-fold on uncoated filters and as much as 16-fold on collagen type IV-coated filters over negative controls. Similarly, C16 also stimulated migration 1.8-fold on uncoated filters and as much as 12-fold on collagen-coated filters. A13 and C16 significantly decreased expression of the pro and active forms of matrix metalloproteinase 2 in foreskin fibroblasts indicating their role in collagen accumulation. We conclude that small bioactive angiogenic peptides can promote dermal wound healing and may offer a new class of stable and chemically manipulable therapeutics for wound healing.

Angiogenesis involves interactions among various molecules and cells. To understand the complexity of interactions, we developed a mathematical model to numerically simulate angiogenesis induced by basic fibroblast growth factor (bFGF) in the corneal pocket assay. The model considered interstitial transport of bFGF, cellular uptake of bFGF, and dynamics of vessel growth. The model was validated by comparing simulated vascular networks, induced by bFGF at three different doses: 5 ng, 15 ng, and 50 ng, with experimental data obtained in the first part of the study, in terms of migration distance of vascular network, total vessel length, and number of vessels. The model was also used to simulate growth dynamics of vascular networks as well as spatial and temporal distribution of bFGF, which could not be measured experimentally. Taken together, results of the study suggested that the coupling between diffusion and cellular uptake of bFGF was critical for determining structures of vascular networks and that the mathematical model was appropriate for simulation of angiogenesis in the cornea.