Overexpression of Twist1 in vascular endothelial cells promotes pathological retinal angiogenesis in mice

Retinal angiogenesis is a critical process for normal retinal function.However,uncontrolled angiogenesis can lead to pathological neovascularization(NV),which is closely related to most irreversible blindness-causing retinal diseases.Understanding the molecular basis behind pathological NV is important for the treatment of related diseases.Twist-related protein 1(TWIST1)is a well-known transcription factor and principal inducer of epithelial-mesenchymal transition(EMT)in many human cancers.Our previous study showed that Twist1 expression is elevated in pathological retinal NV.To date,however,the role of TWIST1 in retinal pathological angiogenesis remains to be elucidated.To study the role of TWIST1 in pathological retinal NV and identify specific molecular targets for antagonizing pathological NV,we generated an inducible vascular endothelial cell(EC)-specific Twist1 transgenic mouse model(Tg-Twist1iEC+).Whole-mount retinas from Tg-Twist1iEC+mice showed retarded vascular progression and increased vascular density in the front end of the growing retinal vasculature,as well as aneurysm-like pathological retinal NV.Furthermore,overexpression of Twist1 in the ECs promoted cell proliferation but disturbed cell polarity,thus leading to uncontrolled retinal angiogenesis.TWIST1 promoted pathological NV by activating the Wnt/β-catenin signaling pathway and inducing the expression of NV formation-related genes,thereby acting as a‘valve’in the regulation of pathological angiogenesis.This study identified the critical role of TWIST1 in retinal pathological NV,thus providing a potential therapeutic target for pathological NV.

Thrombospondin-1 expression correlates with angiogenesis in experimental cirrhosis

AIM:To investigate the significance of Thrombospondin-1 (TSP-1) expression and its relationship with angiogenesis during experimental fibrosis. METHODS:Cirrhosis was induced in male Wistar rats by intraperitoneal administration of diethyl nitrosamine (DEN). The serial sections from liver tissues were stained with anti-CD34 and anti-TSP-1 antibodies before being quantitated by light microscopy. RESULTS:Our results showed that of TSP-1 expression gradually increases according to the severity of fibrosis (GroupⅠvs group Ⅱ, Group Ⅲ and Group Ⅳ;Group Ⅱ vs group Ⅲ and group Ⅳ;group Ⅲ vs group Ⅳ, P < 0.05). Moreover, TSP-1 expression was found to be correlated with angiogenesis (P < 0.05). CONCLUSION:The correlative evidence of the link between TSP-1 and fibrosis or angiogenesis provided by this study suggests that besides its role as a strong promoter of transforming growth factor-β1 (TGF-β1), TSP-1 might have an additional role in liver fibrogenesis by stimulating angiogenesis and this protein could be a potential target to prevent fibrogenesis in chronic inflammatory diseases of the liver.

Inhibition of Pathological Angiogenesis of Chinese Medicine against Liver Fibrosis

Pathological angiogenesis of liver which includes liver sinusoidal capillarization due to lose of fenestraes of liver sinusoidal endothelial cells（LSECs） and formation of new vascular, is a crucial mechanism responsible for origination and development of liver fibrosis and closely involves in the development of cirrhosis and hepatic cancer. Anti-neovascularization medicine such as sorafenib can decrease portosystemic shunts, improve splanchnic hyperdynamic circulation, lower portal hypertension, while it can not be applied in clinic due to its serious toxic and side reactions. Chinese herbal formula can effectively inhibit pathological angiogenesis of liver, improve microcirculation of liver, and decrease the probability of gastrointestinal hemorrhage in cirrhotic patients. Different Chinese herbal formula are of different characteristics on inhibiting pathological angiogenesis in liver fibrosis, which partly explains synergistic effect of different compatibility of Chinese materia medica and opens up good vista for Chinese medicine against liver fibrosis through inhibiting angiogenesis.

Whole mount of adult ear skin as a model to study vascular malformations

Background:Genetic analysis in human patients has linked mutations in PIK3CA,the catalytic subunit of PI-3′Kinase,to sporadic incidences of vascular malformations.Methods:We have developed a mouse model with inducible and endothelial-specific expression of PIK3CA H1047R,resulting in the development of vascular malformations.Systemic induction of this mutation in adult mice results in rapid lethality,limiting our ability to track and study these lesions;therefore,we developed a topical and local induction protocol using the active metabolite of tamoxifen,4OH-T,on the ear skin of adults.Results:This approach allows us to successfully model the human disease in a mature and established vascular bed and track the development of vascular malformations.To validate the utility of this model,we applied a topical rapamycin ointment,as rapamycin is therapeutically beneficial to patients in clinical trials.We found that the induced ear lesions showed significant attenuation after treatment,which was easily quantified.Conclusions:These data collectively provide evidence of a new model to study vascular malformations in adult tissues,which should be particularly useful in environments lacking specialized small-animal imaging facilities.

Pleiotropic Effects of Herbs Characterized with Blood-Activating and Stasis-Resolving Functions on Angiogenesis

Accumulative evidences have underpinned the nature candidates from Chinese medicine （CM）, particularly CM served as blood activating and stasis resolving （BASR, Huoxue Huayu in Chinese） by targeting tumor-associated angiogenesis. However, recent experiment research on the therapeutic angiogenesis by BASR-CM attracts wide attention and discussion. This opinion review focused on the underlying link between two indications and anticipated that （1） BASR-CM might emphasize on a balanced multi-cytokines network interaction; （2） BASR-CM might address on the nature of diseases prior to differently affecting physiological and pathological angiogenesis; （3） BASR-CM might mainly act on perivascular cells, either promotes arteriogenesis by increasing arteriogenic factors in ischemic diseases, or simultaneously keep a quiescent vasculature to impede angiogenesis in tumor context.

Inhibitory activity of gold and silica nanospheres to vascular endothelial growth factor （VEGF）-mediated angiogenesis is determined by their sizes

Nanoparticles can be involved in biological activities such as apoptosis, angiogenesis, and oxidative stress by themselves. In particular, inorganic nanoparticles such as gold and silica nanoparticles are known to inhibit vascular endothelial growth factor （VEGF）-mediated pathological angiogenesis. In this study, we show that anti-angiogenic effect of inorganic nanospheres is determined by their sizes. We demonstrate that 20 nm size gold and silica nanospheres suppress VEGF-induced activation of VEGF receptor-2, in vitro angiogenesis, and in vivo pathological angiogenesis more efficiently than their 100 nm size counterparts. Our results suggest that modulation of the size of gold and silica nanospheres determines their inhibitory activity to VEGF-mediated angiogenesis.

Serum Soluble Vascular Endothelial Growth Factor Receptor 1 as a Potential Biomarker of Hepatopulmonary Syndrome

Background and Aims:The results of basic research implicate the vascular endothelial growth factor(VEGF)family as a potential target of hepatopulmonary syndrome(HPS).However,the negative results of anti-angiogenetic therapy in clinical studies have highlighted the need for markers for HPS.Therefore,we aimed to determine whether VEGF family members and their receptors can be potential biomarkers for HPS through clinical and experimental studies.Methods:Clinically,patients with chronic liver disease from two medical centers were enrolled and examined for HPS.Patients were divided into HPS,intrapulmonary vascular dilation[positive contrast-enhanced echocardiography(CEE)and normal oxygenation]and CEE-negative groups.Baseline information and perioperative clinical data were compared between HPS and non-HPS patients.Serum levels of VEGF family members and their receptors were measured.In parallel,HPS rats were established by common bile duct ligation.Liver,lung and serum samples were collected for the evaluation of pathophysiologic changes,as well as the expression levels of the above factors.Results:In HPS rats,all VEGF family members and their receptors underwent significant changes;however,only soluble VEGFR1(sFlt-1)and the sFlt-1/placental growth factor(PLGF)ratio were changed in almost the same manner as those in HPS patients.Furthermore,through feature selection and internal and external validation,sFlt-1 and the sFlt-1/PLGF ratio were identified as the most important variables to distinguish HPS from non-HPS patients.Conclusions:Our results from animal and human studies indicate that sFlt-1 and the sFlt-1/PLGF ratio in serum are potential markers for HPS.