Endogenous and exogenous fibroblast growth factor-2 modulate wound healing in the chick embryo chorioallantoic membrane

The potential effect of leptin co-administration on photodynamic damage using quail chorioallantoic membrane model

BACKGROUND

The chorioallantoic membrane (CAM) of the Japanese quail is an excellent model for studying photodynamic therapy (PDT) due to its rich vascularization. PDT is used not only in oncological treatment but also in infectious diseases, or psoriasis, where it yields significant advantages. This treatment also has its limitations, such as burning, itching, erythema, redness, swelling, and delayed wound healing. The aim of this study was to analyse the potentially protective properties of the tissue hormone leptin during PDT.

METHODS

Japanese quail embryos incubated ex ovo were used in this experiment. On the 9th day of embryonic development, leptin (5 μg) and photosensitiser hypericin (79 μM) were topically applied, followed by irradiation. The effect of leptin co-administration was evaluated from CAM images and histological structure analysis, histological samples, and qPCR, where the expression of genes involved in angiogenesis, apoptosis, and oxidative stress was monitored.

RESULTS

We observed vascular damage in all experimental groups, the highest damage was found after the application of hypericin without leptin coadministration. Histological analysis confirmed the protective effect of leptin. qPCR analysis presented differences in FREK gene expression, but also in genes involved in oxidative stress like SOD, NRF-1, NRF-2, and GPX7. The application of leptin significantly reduced the expression of apoptosis regulatory proteins CASP3, cytochrome C, and APAF1.

CONCLUSIONS

Our results in the CAM model suggest a possible protective effect of leptin to prevent PDT damage and aid in the subsequent regeneration of target tissues after antimicrobial PDT.

Chorioallantoic Membrane Assay at the Cross-Roads of Adipose-Tissue-Derived Stem Cell Research

With a history of more than 100 years of different applications in various scientific fields, the chicken chorioallantoic membrane (CAM) assay has proven itself to be an exceptional scientific model that meets the requirements of the replacement, reduction, and refinement principle (3R principle). As one of three extraembryonic avian membranes, the CAM is responsible for fetal respiration, metabolism, and protection. The model provides a unique constellation of immunological, vascular, and extracellular properties while being affordable and reliable at the same time. It can be utilized for research purposes in cancer biology, angiogenesis, virology, and toxicology and has recently been used for biochemistry, pharmaceutical research, and stem cell biology. Stem cells and, in particular, mesenchymal stem cells derived from adipose tissue (ADSCs) are emerging subjects for novel therapeutic strategies in the fields of tissue regeneration and personalized medicine. Because of their easy accessibility, differentiation profile, immunomodulatory properties, and cytokine repertoire, ADSCs have already been established for different preclinical applications in the files mentioned above. In this review, we aim to highlight and identify some of the cross-sections for the potential utilization of the CAM model for ADSC studies with a focus on wound healing and tissue engineering, as well as oncological research, e.g., sarcomas. Hereby, the focus lies on the combination of existing evidence and experience of such intersections with a potential utilization of the CAM model for further research on ADSCs.

Biomaterials-Based Regenerative Strategies for Skin Tissue Wound Healing

Skin tissue wound healing proceeds through four major stages, including hematoma formation, inflammation, and neo-tissue formation, and culminates with tissue remodeling. These four steps significantly overlap with each other and are aided by various factors such as cells, cytokines (both anti- and pro-inflammatory), and growth factors that aid in the neo-tissue formation. In all these stages, advanced biomaterials provide several functional advantages, such as removing wound exudates, providing cover, transporting oxygen to the wound site, and preventing infection from microbes. In addition, advanced biomaterials serve as vehicles to carry proteins/drug molecules/growth factors and/or antimicrobial agents to the target wound site. In this review, we report recent advancements in biomaterials-based regenerative strategies that augment the skin tissue wound healing process. In conjunction with other medical sciences, designing nanoengineered biomaterials is gaining significant attention for providing numerous functionalities to trigger wound repair. In this regard, we highlight the advent of nanomaterial-based constructs for wound healing, especially those that are being evaluated in clinical settings. Herein, we also emphasize the competence and versatility of the three-dimensional (3D) bioprinting technique for advanced wound management. Finally, we discuss the challenges and clinical perspective of various biomaterial-based wound dressings, along with prospective future directions. With regenerative strategies that utilize a cocktail of cell sources, antimicrobial agents, drugs, and/or growth factors, it is expected that significant patient-specific strategies will be developed in the near future, resulting in complete wound healing with no scar tissue formation.

Cellular Mechanisms of FGF-Stimulated Tissue Repair

Growth factors belonging to the FGF family play important roles in tissue and organ repair after trauma. In this review, I discuss the regulation by FGFs of the aspects of cellular behavior important for reparative processes. In particular, I focus on the FGF-dependent regulation of cell proliferation, cell stemness, de-differentiation, inflammation, angiogenesis, cell senescence, cell death, and the production of proteases. In addition, I review the available literature on the enhancement of FGF expression and secretion in damaged tissues resulting in the increased FGF supply required for tissue repair.

Expression Analysis of FGF/FGFR and FOX Family Proteins in Mucosal Tissue Obtained from Orofacial Cleft-Affected Children

Orofacial clefts affect hundreds of thousands of children worldwide annually and are usually corrected by a series of surgeries extending to childhood. The underlying mechanisms that lead to clefts are still unknown, mainly because of the multifactorial etiology and the myriad of interactions between genes and environmental factors. In the present study, we investigated the role and expression of candidate genes belonging to the FGF/FGFR signaling pathway and FOX family in tissue material obtained from 12 pediatric patients undergoing cleft correction surgery. The expression was investigated using immunohistochemistry (IHC) and chromogenic in-situ hybridization (CISH) in three cell/tissue types-epithelial cells, connective tissue, and endothelial cells. We found elevated expression of FGFR1 in epithelial cells while no expression was observed in endothelial cells. Further, our results elucidate the potential pathogenetic role of FGFR1 in cellular proliferation, local site inflammation, and fibrosis in cleft patients. Along with bFGF (also called FGF2), FGFR1 could play a pro-inflammatory role in clefts. Over-amplification of FGFR2 in some patients, along with bFGF, could potentially suggest roles for these genes in angiogenesis. Additionally, increased expression of FOXE1 (also called TTF2) contributes to local site inflammation. Finally, zero to low amplification of FOXO1 could suggest its potential role in inducing oxidative stress in the endothelium along with reduced epithelial apoptosis.

Utilisation of Chick Embryo Chorioallantoic Membrane as a Model Platform for Imaging-Navigated Biomedical Research

The fertilised chick egg and particularly its chorioallantoic membrane (CAM) have drawn continuing interest in biomedicine and bioengineering fields, especially for research on vascular study, cancer, drug screening and development, cell factors, stem cells, etc. This literature review systemically introduces the CAM's structural evolution, functions, vascular features and the circulation system, and cell regulatory factors. It also presents the major and updated applications of the CAM in assays for pharmacokinetics and biodistribution, drug efficacy and toxicology testing/screening in preclinical pharmacological research. The time course of CAM applications for different assays and their advantages and limitations are summarised. Among these applications, two aspects are emphasised: (1) potential utility of the CAM for preclinical studies on vascular-disrupting agents (VDAs), promising for anti-cancer vascular-targeted therapy, and (2) modern imaging technologies, including modalities and their applications for real-time visualisation, monitoring and evaluation of the changes in CAM vasculature as well as the interactions occurring after introducing the tested medical, pharmaceutical and biological agents into the system. The aim of this article is to help those working in the biomedical field to familiarise themselves with the chick embryo CAM as an alternative platform and to utilise it to design and optimise experimental settings for their specific research topics.

Angiogenesis-Inflammation Cross Talk in Diabetic Retinopathy: Novel Insights From the Chick Embryo Chorioallantoic Membrane/Human Vitreous Platform

Pathological angiogenesis of the retina is a key component of irreversible causes of blindness, as observed in proliferative diabetic retinopathy (PDR). The pathogenesis of PDR is complex and involves vascular, inflammatory, and neuronal mechanisms. Several structural and molecular alterations associated to PDR are related to the presence of inflammation that appears to play a non-redundant role in the neovascular response that characterizes the retina of PDR patients. Vascular endothelial growth factor (VEGF) blockers have evolved over time for the treatment of retinal neovascularization. However, several limitations to anti-VEGF interventions exist. Indeed, the production of other angiogenic factors and pro-inflammatory mediators may nullify and/or cause resistance to anti-VEGF therapies. Thus, appropriate experimental models are crucial for dissecting the mechanisms leading to retinal neovascularization and for the discovery of more efficacious anti-angiogenic/anti-inflammatory therapies for PDR patients. This review focuses on the tight cross talk between angiogenesis and inflammation during PDR and describe how the chick embryo chorioallantoic membrane (CAM) assay may represent a cost-effective and rapid in vivo tool for the study of the relationship between neovascular and inflammatory responses elicited by the vitreous humor of PDR patients and for the screening of novel therapeutic agents.

Basic Fibroblast Growth Factor Induces Angiogenic Properties of Fibrocytes to Stimulate Vascular Formation during Wound Healing

The role of fibrocytes in wound angiogenesis remains unclear. We therefore demonstrated the specific changes in fibrocyte accumulation for angiogesis in basic fibroblast growth factor (bFGF)-treated wounds. bFGF-treated wounds exhibited marked formation of arterioles and inhibition of podoplanin⁺ lymph vessels that were lacking in vascular endothelial growth factor-A-treated wounds. Real-time PCR in bFGF-treated wounds manifested enhanced expression of CD34, CD31, and bFGF mRNA and reduced expression of podoplanin and collagen type I, III, and IV mRNA. Double immunofluorescence staining focusing on fibrocyte detection in bFGF-treated wounds showed increased formation of capillary-like structures composed of CD34⁺/procollagen I⁺ fibrocytes, with a lack of capillary-like structures formed by CD45⁺/procollagen I⁺ or CD11b⁺/procollagen I⁺ fibrocytes. However, vascular endothelial growth factor-A-treated wounds lacked capillary-like structures composed of CD34⁺/procollagen I⁺ fibrocytes, with increased numbers of CD34⁺/fetal liver kinase-1⁺ endothelial progenitor cells. Furthermore, fibroblast growth factor receptor 1 siRNA injection into wounds, followed by bFGF, inhibited the formation of capillary-like structures composed of CD34⁺/procollagen I⁺ fibrocytes, together with inhibited mRNA expression of CD34 and CD31 and enhanced mRNA expression of collagen type I, indicating the requirements of bFGF/fibroblast growth factor receptor 1 system for capillary structure formation. This study highlights the angiogenic properties of CD34⁺/procollagen I⁺ fibrocytes specifically induced by bFGF, providing new insight into the active contribution of fibrocytes for vascular formation during wound healing.

Fibroblast growth factor-2 promotes in vitro mitral valve interstitial cell repair through transforming growth factor-β/Smad signaling

Transforming growth factor (TGF)-β and fibroblast growth factor (FGF)-2 both promote repair in valve interstitial cell (VIC) injury models; however, the relationship between TGF-β and FGF-2 in wound repair are not well understood. VIC confluent monolayers were wounded by mechanical injury and incubated separately or in combination with FGF-2, neutralizing antibody to FGF-2, neutralizing antibody to TGF-β, and betaglycan antibody for 24 hours after wounding. Phosphorylated Smad2/3 (pSmad2/3) was localized at the wound edge (WE) and at the monolayer away from the WE. Down-regulation of pSmad2/3 protein expression via small-interfering RNA transfection was performed. The extent of wound closure was monitored for up to 96 hours. FGF-2 incubation resulted in a significant increase in nuclear pSmad2/3 staining at the WE. Neutralizing antibody to TGF-β alone or with FGF-2 present resulted in a similar significant decrease in pSmad2/3. Neutralizing antibody to FGF-2 alone or with FGF-2 present showed a similar significant decrease in pSmad2/3; however, significantly more staining was observed than treatment with neutralizing antibody to TGF-β. Incubation with betaglycan antibody inhibited FGF-2-mediated pSmad2/3 signaling. Wound closure corresponded with pSmad2/3 staining at the WE. Down-regulation of pSmad2/3 via small-interfering RNA transfection significantly reduced the extent to which FGF-2 promoted wound closure. Fibroblast growth factor-2 promotes in vitro VIC wound repair, at least in part, through the TGF-β/Smad2/3 signaling pathway.

A pro-inflammatory signature mediates FGF2-induced angiogenesis

Fibroblast growth factor-2 (FGF2) is a potent angiogenic growth factor. Here, gene expression profiling of FGF2-stimulated microvascular endothelial cells revealed, together with a prominent pro-angiogenic profile, a pro-inflammatory signature characterized by the upregulation of pro-inflammatory cytokine/chemokines and their receptors, endothelial cell adhesion molecules and members of the eicosanoid pathway. Real-time quantitative PCR demonstrated early induction of most of the FGF2-induced, inflammation-related genes. Accordingly, chick embryo chorioallantoic membrane (CAM) and murine Matrigel plug angiogenesis assays demonstrated a significant monocyte/macrophage infiltrate in the areas of FGF2-driven neovascularization. Similar results were obtained when the conditioned medium (CM) of FGF2-stimulated endothelial cells was delivered onto the CAM, suggesting that FGF2-upregulated chemoattractants mediate the inflammatory response. Importantly, FGF2-triggered new blood vessel formation was significantly reduced in phosphatidylinositol 3-kinase-gamma null mice exhibiting defective leucocyte migration or in clodronate liposome-treated, macrophage-depleted mice. Furthermore, the viral pan-chemokine antagonist M3 inhibited the angiogenic and inflammatory responses induced by the CM of FGF2-stimulated endothelial cells and impaired FGF2-driven neovascularization in the CAM assay. These findings point to inflammatory chemokines as early mediators of FGF2-driven angiogenesis and indicate a non-redundant role for inflammatory cells in the neovascularization process elicited by the growth factor.

VEGF and pleiotrophin modulate the immune profile of breast cancer

Angiogenesis, the sprouting of the existing vascular network to form new vessels, is required for the growth of solid tumors. For this reason, the primary stimulant of angiogenesis, vascular endothelial growth factor-A (VEGF), is an attractive target for tumor therapy. In fact, there are currently numerous anti-VEGF therapies in clinical development for the treatment of various cancers, including breast cancer. VEGF signals through two primary VEGF receptors, VEGFR1 and VEGFR2. VEGFR2 is the primary angiogenic receptor, and VEGFR1 has been implicated in macrophage chemotaxis and tumor cell survival and invasion. It has only been appreciated recently that the VEGFRs are expressed not only on endothelial cells and tumor cells but also on many host immune cells. Therefore, to better understand the effects of anti-VEGF therapy it is important to consider the effects of VEGF on all cells in the tumor microenvironment, including immune cells. Bevacizumab (Avastin^®, Genetech), which binds VEGF and inhibits interaction with VEGFR1 and VEGFR2, was approved for the treatment of metastatic HER2/NEU-negative breast cancer in 2008, however, the majority of human mammary tumors are either innately resistant or will acquire resistance to anti-VEGF therapy. This suggests that these tumors activate alternate angiogenesis pathways. Pleiotrophin (PTN) is an important angiogenic cytokine in breast cancer and is expressed at high levels in approximately 60% of human breast tumors. PTN functions as an angiogenic factor and promotes remodeling of the tumor microenvironment as well as epithelial-mesenchymal transition (EMT). In addition, PTN can have profound effects on macrophage phenotype. The present review focuses on the functions of VEGF and PTN on immune cell infiltration and function in breast cancer. Furthermore, we will discuss how anti-VEGF therapy modulates the immune cell profile.

Mathematical modelling of tissue-engineered angiogenesis

We present a mathematical model for the vascularisation of a porous scaffold following implantation in vivo. The model is given as a set of coupled non-linear ordinary differential equations (ODEs) which describe the evolution in time of the amounts of the different tissue constituents inside the scaffold. Bifurcation analyses reveal how the extent of scaffold vascularisation changes as a function of the parameter values. For example, it is shown how the loss of seeded cells arising from slow infiltration of vascular tissue can be overcome using a prevascularisation strategy consisting of seeding the scaffold with vascular cells. Using certain assumptions it is shown how the system can be simplified to one which is partially tractable and for which some analysis is given. Limited comparison is also given of the model solutions with experimental data from the chick chorioallantoic membrane (CAM) assay.

Chick chorioallantoic membrane as an in situ biological membrane for pharmaceutical formulation development: a review

The use of animals in research has always been a debatable issue. Over the past few decades, efforts have been made to reduce, replace, and refine experiments for ethical use of experimental animals. The use of chick chorioallantoic membrane (CAM) was one of the proposed alternatives to the Draize rabbit ocular irritation test with several advantages including simplicity, rapidity, sensitivity, ease of performance, and cost-effectiveness. The recent use of CAM in the development of pharmaceuticals and testing models to mimic human tissue, including drug transport across CAM, will be discussed in this review.

Effects of bFGF on suppression of collagen type I accumulation and scar tissue formation during wound healing after mucoperiosteal denudation of rat palate

OBJECTIVE

The purpose of this study was to evaluate the effect of basic fibroblast growth factor (bFGF) on collagen changes after mucoperiosteal denudation of rat palate.

MATERIAL AND METHODS

A total of 36 male Wistar rats were divided into control, scar, sham, and bFGF groups. In the scar, sham, and bFGF groups, lateral palatal mucoperiosteum was excised to form scar tissue on the palate. In the bFGF group, bFGF solution was injected into the operated area 1 week postoperatively. At 6 weeks postoperatively, the distribution of collagen type I and the 3-dimensional structure of collagen fibers were investigated under immunofluorescent and scanning electron microscopy.

RESULT

In the bFGF group, weakly immunostained submucosa was clearly distinguishable from the strongly immunostained cervical periodontal ligament and gingiva. Collagen fibers running from submucosal tissue into the surface of underlying palatal bone comprised loosely arranged collagen fibrils. Lumen structures in collagen fibers resembled those in the control group.

CONCLUSION

Administration of bFGF for suppression of collagen type I generation could suppress scar tissue formation and reduce connective strength with adjacent teeth and palatal bone.

Effects of Basic Fibroblast Growth Factor Administration on Vascular Changes in Wound Healing of Rat Palates

Objective:

The purpose of this study was to investigate the vascular changes induced by mucoperiosteal denudation of rat palate and to elucidate the effects of basic fibroblast growth factor (bFGF) administration on the palatal vascular network in wound healing.

Methods:

A total of 117 male Wistar rats were used for the study on their 20th postnatal day. The animals were divided into three groups: a scar formation group, a basic fibroblast growth factor group, and a control group. The scar formation and basic fibroblast growth factor groups had lateral mucoperiosteum excised from the palate. In the basic fibroblast growth factor group, a solution of basic fibroblast growth factor was injected into the operated area 1 week after excision. At 6, 8, and 10 weeks postoperatively, palatal vascular changes were investigated by immunohistochemical staining and corrosion cast techniques.

Results:

Throughout the experimental period, there were significantly fewer vessels in the scar formation group than in the control and basic fibroblast growth factor groups. In the basic fibroblast growth factor group, the elongation of new vessels and capillary proliferation proceeded, and after 10 weeks a highly organized vascular network was established. The scar formation group showed few Volkmann's canals that were shrunken or closed, whereas the basic fibroblast growth factor group evidenced Volkmann's canals with arterioles or venules, as seen in the control.

Conclusions:

The results suggested that injection of basic fibroblast growth factor into palatal wounds improves the vascular supply to the operated mucosa and underlying bone during and after palatal wound healing, which may contribute to tissue remodeling of the palate during growth.

Pharmacological modulation of wound healing in experimental burns

Factors involved in wound healing and their interdependence are not yet fully understood; nevertheless, new prospects for therapy to favor speedy and optimal healing are emerging. Reports about wound healing modulation by local application of simple and natural agents abound even in the recent literature, however, most are anecdotal and lack solid scientific evidence. We describe the effect of silver sulfadiazine and moist exposed burn ointment (MEBO), a recently described burn ointment of herbal origin, on mast cells and several wound healing cytokines (bFGF, IL-1, TGF-beta, and NGF) in the rabbit experimental burn model. The results demonstrate that various inflammatory cells, growth factors and cytokines present in the wound bed may be modulated by application of local agents with drastic effects on their expression dynamics with characteristic temporal and spatial regulation and changes in the expression pattern. Such data are likely to be important for the development of novel strategies for wound healing since they shed some light on the potential formulations of temporally and combinatory optimized therapeutic regimens.

Modifications of the fibroblast growth factor-2 gene led to a marked enhancement in secretion and stability of the recombinant fibroblast growth factor-2 protein

Progress in FGF-2 gene therapy has been hampered by the difficulty in achieving therapeutic levels of FGF-2 secretion. This study tested whether the addition of BMP2/4 hybrid secretion signal to the FGF-2 gene and mutation of cys-70 and cys-88 to serine and asparagine, respectively, would increase the stability and secretion of active FGF-2 protein in mammalian cells using MLV-based vectors. Single or double mutations of cys-70 and cys-88 to ser-70 and asp-88, respectively, markedly increased the amounts of FGF-2 protein in conditioned media and cell lysates, which may be due to glycosylation, particularly at the mutated asp-88 residue. Addition of BMP2/4 secretion signal increased FGF-2 secretion, but also suppressed FGF-2 biosynthesis. The combination of BMP2/4 secretion signal and double cys-70 and cys-88 mutations increased the total amount of secreted FGF-2 protein >60-fold. The modifications did not alter its ability to stimulate cell proliferation and Erk1/2 phosphorylation in marrow stromal cells or its ability to bind heparin in vitro, suggesting that the modified FGF-2 protein was functionally as effective as the unmodified FGF-2. An ex vivo application of rat skin fibroblasts (RSF) transduced with the modified FGF-2 vector in a subcutaneous implant model showed that rats with implants containing cells transduced with the modified FGF-2 vector increased serum FGF-2 level >15-fold, increased growth of the implant, and increased vascularization within the implant, compared to rats that received implants containing beta-galactosidase- or wild-type FGF-2-transduced control cells. This modified vector may be useful in FGF-2 gene therapy investigations.

Transport of hypericin across chick chorioallantoic membrane and photodynamic therapy vasculature assessment

This study examined the transport of a photosensitizer (hypericin, HY) using the chick chorioallantoic membrane (CAM) as a model of transport after topical administration. The model correlates both the photosensitizer uptake and anti-vasculature effects after photodynamic therapy (PDT). HY formulations were prepared using N-methyl pyrrolidone (NMP) as a solvent and penetration enhancer. Fertilized chicken eggs were disinfected and incubated at 37.4 degrees C and 60% humidity. Formulations were applied on CAM and incubated for 30 min in the dark. Subsequently, the solutions were removed from the CAM surface and the HY concentration was determined. The CAM was exposed to a fixed light dose of 10 J/cm2 at 50 mW/cm2. The vascular damage induced by the light was quantitatively measured using image-processing techniques. The uptake ratio of HY in 4.8% NMP (HD group) to that of 0.6% NMP (LD group) was found to be 1.96. This ratio is correlated with the vascular damage caused by the PDT effect of HY. The HD treated CAM showed a vessel regression that was 2.37 times higher than that of LD treated CAM. This paper reports the first attempt to develop a quantitative transport study for HY using CAM and to explore the relationship between the vascular regression and amount of drug of uptake. The model has potential for other similar transport studies.

Arnebia root oil promotes wound healing and expression of basic fibroblast growth factor on the wound surface in rabbits

OBJECTIVE

To observe the promoting effect of arnebia root oils on expression of basic fibroblast growth factor (bFGF) in skin wound of rabbits and the histomorphological changes in the wound surface, and to discuss its mechanism.

METHODS

Bilateral round skin wounds were made on the back of 15 rabbits. The three wounds on one side of the back of each rabbit were treated with arnebia root oils, while the three wounds on the other side were treated with vaseline in order to promote the wound healing. The histomorphology and ultrastructure under electron microscopy of the wounds, and the rate of wound healing were examined at different time. Western blotting assay was used to detect the expression of bFGF in the wound surface.

RESULTS

The healing rate of the arnebia root oils-treated wounds was evidently higher than that of the vaseline-treated wounds (P<0.05). The quantities of fibroblast, collagen and capillary in the arnebia root oils-treated wounds were much more than those in the vaseline-treated wounds, and the expression of endogenous bFGF in the arnebia root oils-treated wounds was enhanced obviously as compared with that in the vaseline-treated wounds in different period of wound healing. There existed a parallel correlation between the expression level of bFGF and the rate of wound healing.

CONCLUSION

The promoting effect of arnebia root oils on wound healing may be related to increasing the expression level of basic fibroblast growth factor in the skin wound.

Role of AKT/PKB signaling in fibroblast growth factor-1 (FGF-1)-induced angiogenesis in the chicken chorioallantoic membrane (CAM)

Transfection of chicken chorioallantoic membranes (CAMs) with a chimeric secreted version of fibroblast growth factor-1 (sp-FGF-1) gene construct leads to a significant increase in vascularization. Though FGF-stimulated angiogenesis has been extensively studied, the molecular mechanisms regulating FGF-1-induced angiogenesis are poorly understood in vivo. This study was designed to investigate the role of the AKT (PKB) kinase signaling pathway in mediating sp-FGF-1-induced angiogenesis in the chicken CAM. The involvement of the AKT pathway was demonstrated by up-regulation of AKT1 mRNA expression in sp-FGF-1 compared to vector alone control transfected CAMs as demonstrated by real-time RT-PCR. Western analysis using an antibody specific to the activated AKT (phosphorylated AKT), demonstrated an increase in AKT activity in sp-FGF-1 compared to vector control transfected CAMs. More importantly, the AKT inhibitor ML-9 significantly reduced sp-FGF-1-induced angiogenesis in CAMs. These results indicate that AKT signaling plays a role in FGF-1-stimulated angiogenesis in vivo and the AKT pathway may serve as a therapeutic target for angiogenesis-associated diseases.

Uncaria rhynchophylla Induces Angiogenesis in Vitro and in Vivo

Angiogenesis consists of the proliferation, migration, and differentiation of endothelial cells, and angiogenic factors and matrix protein interactions modulate this process. The aim of this study was to determine the angiogenic properties of Uncaria rhynchophylla. Uncaria rhynchophylla significantly enhanced human umbilical vein endothelial cells (HUVECs) proliferation in a dose-dependent manner. Neutralization of vascular endothelial growth factor (VEGF) or basic fibroblast growth factor (bFGF) by monoclonal antibody suppressed the Uncaria rhynchophylla stimulatory effect on proliferation. In addition, Uncaria rhynchophylla significantly increased chemotactic-migration on gelatin and tubular structures on Matrigel of HUVECs in a dose-dependent manner. Interestingly, Uncaria rhynchophylla dose-dependently increased VEGF, and bFGF gene expression and protein secretion of HUVEC. The angiogenic activity of Uncaria rhynchophylla was confirmed using an in vivo Matrigel angiogenesis model, showing promotion of blood vessel formation. These results suggest that Uncaria rhynchophylla could potentially used to accelerate vascular wound healing or to promote the growth of collateral blood vessel in ischemic tissues.