Inhibition of hepatic stellate cell contraction during activation in vitro by vascular endothelial growth factor in association with upregulation of FLT tyrosine kinase receptor family, FLT-1.

Activated hepatic stellate cells produce vascular endothelial growth factor (VEGF). VEGF has been shown to act on mesenchymal cells as well. If hepatic stellate cells can express FLT tyrosine receptor family, flt-1 and KDR/flk-1, their function might be regulated by VEGF in an autocrine manner. This hypothesis was tested using hepatic stellate cells isolated from normal rats. Northern blot analysis and immunocytochemical study revealed that hepatic stellate cells cultured for 3 days on plastic dishes expressed both flt-1 and KDR/flk-1. When the culture was prolonged to 10 days, the flt-1 mRNA expression was increased, whereas both KDR/flk-1 mRNA and protein expressions diminished. DNA and collagen syntheses were minimal in the cells cultured for 3 days, but marked in those cultured for 10 days. Addition of recombinant human VEGF to the culture medium did not change both syntheses but attenuated an increase of smooth muscle alpha-actin expression in the cells during culture on plastic dishes and also contraction of collagen gels on which the cells were cultured. We conclude that VEGF may inhibit contraction of hepatic stellate cells appearing during activation by culture, probably through attenuation of smooth muscle alpha-actin expression via upregulated VEGF receptor, flt-1.     

Expression of vascular endothelial growth factor receptors in smooth muscle cells

Vascular Endothelial Growth Factor (VEGF) has been typically considered to be an endothelial-specific growth factor. However, it was recently demonstrated that VEGF can interact with non endothelial cells. In this study, we tested whether vascular smooth muscles cells (VSMCs) can express VEGF receptors, such as flk-1, flt-1, and neuropilin (NP)-1, and respond to VEGF in vitro. In cultured VSMCs, flk-1 and flt-1 expression was inversely related to cell density. The expression of flk-1 was down-regulated with increasing passage numbers. However, NP-1 levels were not affected by cell density or passage numbers. Flk-1, Flt-1, and NP-1 protein levels were confirmed by Western Blotting. Although the functional mature form of Flk-1 protein is expressed at low levels in VSMCs, phosphorylation of Flk-1 following VEGF(165) stimulation was still observed. SMCs migrated significantly in response to VEGF(165) and VEGF-E, whereas Placenta Growth Factor (PlGF) induced migration only at higher concentrations. Since VEGF-E is a specific activator of flk-1 while PlGF specifically activates only flt-1, SMC migration induced by VEGF(165) is likely to be mediated primarily through the flk-1 receptor. VSMCs did not significantly proliferate in response to VEGF(165), PlGF, and VEGF-E. In conclusion, our studies demonstrate the presence of VEGF receptors on VSMCs that are functional. These studies also indicate that in vivo, VEGF may play a role in modulating the response of VSMCs.     

Effects of Selenium Supplementation on Gene Expression Levels of Inflammatory Cytokines and Vascular Endothelial Growth Factor in Patients with Gestational Diabetes

Selenium is known to exert multiple beneficial effects including anti-inflammatory actions. The aim of the study was to evaluate the effects of selenium supplementation on gene expression levels of inflammatory cytokines and vascular endothelial growth factor (VEGF) in women with gestational diabetes (GDM). This randomized double-blind, placebo-controlled trial was carried out among 40 subjects diagnosed with GDM aged 18–40 years old. Subjects were randomly allocated into two groups to receive either 200 μg/day selenium supplements (n = 20) or placebo (n = 20) for 6 weeks. Gene expression of inflammatory cytokines and VEGF were assessed in lymphocytes of GDM women with RT-PCR method. Results of RT-PCR indicated that after the 6-week intervention, compared with the placebo, selenium supplementation downregulated gene expression of tumor necrosis factor alpha (TNF-α) (P = 0.02) and transforming growth factor beta (TGF-β) (P = 0.01), and upregulated gene expression of VEGF (P = 0.03) in lymphocytes of patients with GDM. There was no statistically significant change following supplementation with selenium on gene expression of interleukin (IL)-1β and IL-8 in lymphocytes of subjects with GDM. Selenium supplementation for 6 weeks in women with GDM significantly decreased gene expression of TNF-α and TGF-β, and significantly increased gene expression of VEGF, but did not affect gene expression of IL-1β and IL-8. Clinical trial registration number http://www.irct.ir: IRCT201612045623N95.     

Skeletal muscle capillarity and angiogenic mRNA levels after exercise training in normoxia and chronic hypoxia.

Gene expression of vascular endothelial growth factor (VEGF), and to a lesser extent of transforming growth factor-beta(1) (TGF-beta(1)) and basic fibroblast growth factor (bFGF), has been found to increase in rat skeletal muscle after a single exercise bout. In addition, acute hypoxia augments the VEGF mRNA response to exercise, which suggests that, if VEGF is important in muscle angiogenesis, hypoxic training might produce greater capillary growth than normoxic training. Therefore, we examined the effects of exercise training (treadmill running at the same absolute intensity) in normoxia and hypoxia (inspired O(2) fraction = 0.12) on rat skeletal muscle capillarity and on resting and postexercise gene expression of VEGF, its major receptors (flt-1 and flk-1), TGF-beta(1), and bFGF. Normoxic training did not alter basal or exercise-induced VEGF mRNA levels but produced a modest twofold increase in bFGF mRNA (P < 0.05). Rats trained in hypoxia exhibited an attenuated VEGF mRNA response to exercise (1.8-fold compared 3.4-fold with normoxic training; P < 0.05), absent TGF-beta(1) and flt-1 mRNA responses to exercise, and an approximately threefold (P < 0.05) decrease in bFGF mRNA levels. flk-1 mRNA levels were not significantly altered by either normoxic or hypoxic training. An increase in skeletal muscle capillarity was observed only in hypoxically trained rats. These data show that, whereas training in hypoxia potentiates the adaptive angiogenic response of skeletal muscle to a given absolute intensity of exercise, this was not evident in the gene expression of VEGF or its receptors when assessed at the end of training.     

Chronic hypoxia attenuates resting and exercise-induced VEGF, flt-1, and flk-1 mRNA levels in skeletal muscle.

Vascular endothelial growth factor (VEGF) is a hypoxia-inducible angiogenic mitogen. However, chronic hypoxia is generally not found to increase mammalian skeletal muscle capillarity. We sought to determine the effect of chronic hypoxia (8 wk, inspired O2 fraction = 0.12) on skeletal muscle gene expression of VEGF, its receptors (flt-1 and flk-1), basic fibroblast growth factor, and transforming growth factor-beta1. Wistar rats were exposed to chronic hypoxia (n = 12) or room air (n = 12). After the exposure period, six animals from each group were subjected to a single 1-h treadmill exercise bout (18 m/min on a 10 degrees incline) in room air while the remaining six animals served as rest controls. Morphological analysis revealed that chronic hypoxia did not increase skeletal muscle capillarity. Northern blot analyses showed that chronic hypoxia decreased resting VEGF, flt-1, and flk-1 mRNA by 23, 68, and 42%, respectively (P < 0.05). The VEGF mRNA response to exercise was also decreased (4.1- and 2.7-fold increase in room air and chronic hypoxia, respectively, P < 0.05). In contrast, neither transforming growth factor-beta1 nor basic fibroblast growth factor mRNA was significantly altered by chronic hypoxia. In conclusion, prolonged exposure to hypoxia attenuated gene expression of VEGF and its receptors flt-1 and flk-1 in rat gastrocnemius muscle. These findings may provide an explanation for the lack of mammalian skeletal muscle angiogenesis that is observed after chronic hypoxia.     

VEGF and IL-4 gene variability and its association with the risk of coronary heart disease in north Indian population

Vascular endothelial growth factor (VEGF) is a potent angiogenic growth factor that has been shown to play a significant role in neovascularization during inflammation in atherosclerotic plaques, formation of collateral vessels to an area of ischemic myocardium and neovascularization at the edges of a myocardial infarction during its repair. Interleukin-4 (IL-4) has important role in immune cell chemotaxis, formation of endothelial cell adhesion molecules and has numerous anti-inflammatory effects which prevent the complications of atherosclerosis, the primary cause of coronary heart disease (CHD). In this study, we have analyzed the effect of 1154 A/G polymorphism of VEGF and 70 bp VNTR polymorphism of intron 3 in IL-4 genes in coronary heart disease (CHD) patients (n = 300) and their age matched controls (n = 300). To analyze polymorphic alleles, ARMS-PCR and RFLP techniques were used. Multiple logistic regression analysis was carried out with statistical software. GG genotype was associated with a decreased risk of development of CHD (OR 0.22, 95% CI 0.12–0.38, P < 0.001). However, A allele showed an increased risk whereas G allele decreased the risk of CHD with diabetes mellitus, hypertension, chronic mental stress and positive familial history of myocardial infarction (MI)/CHD. GG genotype was found to have protective effect with alcohol intake (OR 0.34, 95% CI 0.14–0.82, P < 0.01) and central obesity (OR 0.15, 95% CI 0.04–0.56, P < 0.001). GG genotype of VEGF has also shown significant association with IL-4 (P2P2 and P1P2) genotypes.     

Sympathetic blockade prevents the decrease in cardiac VEGF expression and capillary supply in experimental renal failure

Uremic cardiomyopathy of men and rodents is characterized by lower myocardial capillary supply that in rats could be prevented by central and peripheral blockade of the sympathetic nervous system. The underlying pathomechanisms remain largely unknown. We investigated whether alterations of cardiac vascular endothelial growth factor (VEGF) gene and protein expression were involved. In our long-term experiment, we analyzed whether VEGF gene and protein expression was altered in the heart of male Sprague-Dawley rats with either sham operation (sham, n=10) or subtotal nephrectomy (SNX, n=10). In our short-term experiment (17 sham, 24 SNX), the effect of a putative downregulation of sympathetic nervous activity by surgical renal denervation (interruption of renal afferent pathways) on cardiac gene expression of VEGF, flt-1, and flk-1 and on myocardial capillary supply was analyzed. In the long-term study, cardiac capillary supply and vascular endothelial growth factor gene and protein expression were significantly lower in SNX than in sham. In the short-term experiment, cardiac VEGF mRNA expression was significantly lower in untreated SNX (4,258±2,078 units) than in both sham groups (11,709±4,169 and 8,998±4,823 units); this decrease was significantly prevented by renal denervation (8,190±3,889, P<0.05). We conclude that cardiac VEGF gene and protein expression is reduced in experimental renal failure, and this may be considered as one potential reason for impaired myocardial adaptation under the situation of cardiac hypertrophy. The beneficial effect of sympathetic downregulation on cardiac structure and function in renal failure may be at least in part explained by increased cardiac VEGF gene expression.     

The Value of Expression of M2-PK and VEGF in Patients with Advanced Gastric Cancer

Glycolytic pyruvate kinase isoenzyme type M2 (M2-PK) plays a key role in tumor metabolism and energy production. Vascular endothelial growth factor (VEGF) is critical in regulating angiogenesis which is an essential process required for tumor growth and metastasis. These two genes may function in accordance with tumor development. The purpose of this study was to investigate the relationship between the expression of M2-PK and VEGF, and their association with clinicopathological features in patients with advanced gastric cancer. Expression of M2-PK and VEGF were examined in 142 cases of paraffin-embedded tissue blocks from patients with advanced gastric cancer. M2-PK expression was found to strongly correlate with that of VEGF (r = 0.718). In addition, expression of M2-PK and VEGF correlates with tumor size (p = 0.0001, and p = 0.0017, respectively), depth of invasion (p = 0.0024, and p = 0.0261, respectively), and lymph node metastasis (p = 0.036, and p = 0.028, respectively). The high expression levels of M2-PK and VEGF may indicate poor prognosis in patients with advanced gastric cancer.     

Analysis of biological functional networks during sciatic nerve repair and regeneration

Altered placental angiogenesis is implicated in the pathophysiology of preeclampsia. We have earlier reported placental regional differences in oxidative stress markers and neurotrophins. Oxidative stress and neurotrophins are reported to regulate angiogenesis. This study aims to examine protein and mRNA levels of vascular endothelial growth factor (VEGF) and VEGF receptor 1 (VEGFR1) in four regions [central maternal (CM), central fetal (CF), peripheral maternal (PM), and peripheral fetal (PF)] of the placenta in normotensive control (NC) women (n = 51) and women with preeclampsia (PE) (n = 43) [18 delivered at term (T-PE) and 25 delivered preterm (PT-PE)]. In all groups, CF region reported highest VEGF protein levels compared to all other regions. VEGF mRNA level was higher in CF region as compared to CM region in PE group (p < 0.05). VEGF levels were lower in all regions of PE, T-PE, and PT-PE groups (p < 0.05) as compared to their respective regions in NC group. VEGFR1 levels were lower in CF (p < 0.05) and PF (p < 0.01) regions as compared to CM region only in control. However, VEGFR1 levels were higher in CF (p < 0.05) and PF (p < 0.01) regions of PT-PE group as compared to control. VEGFR1 mRNA level was higher in PM region of PE group and T-PE group (p < 0.05 for both) as compared to control. VEGF levels in the PF region were positively associated with birth weight and placental weight. This study describes placental regional changes in angiogenic factors particularly highlighting increased VEGF in CF region possibly in response to hypoxic conditions prevailing in placenta.     

Expression of tumor necrosis factor-alpha and vascular endothelial growth factor in different zones of fetal membranes: a possible relation to onset of labor

This study aimed to explore whether the altered expression of tumor necrosis factor-alpha (TNF-α), vascular endothelial growth factor (VEGF) and apoptotic changes in mid zone (MZ) and rupture zone (RZ) of fetal membranes (FM) are regulatory mechanisms associated with labor at term. Fifteen FM specimens were collected after vaginal deliveries and 13 specimens after elective caesarian section. Histological and immunohistochemical analysis were employed. Area percent of TNF-α and VEGF immunostaining and apoptotic index (AI) were evaluated using image analysis. The statistical data revealed significantly higher area % for TNF-α, VEGF immunoexpression and AI in labor compared to non-labor specimens (p < 0.0001). There was a significantly higher percentage of TNF-α immunoexpressed area in MZ compared with RZ in both groups (p < 0.0001). VEGF expression in RZ of both groups proved nearly double or triple the area % of expression relative to MZ with highly significant difference (p < 0.0001). quantitative analysis revealed near two fold increase in the AI in RZ (13.42 % ± 1.2 in labor; 11.20 % ± 0.96 in non-labor groups) when compared to MZ (7.20 % ± 0.6 in labor; 5.08 % ± 0.76 in non-labor groups) with highly significant zonal difference (p < 0.0001). Correlation analysis revealed significant correlation between apoptotic indices and area % of TNF-α (r = 0.575, p = 0.002 in non-labor; r = 0.652, p < 0.0001 in labor) and VEGF (r = 0.795, p < 0.0001 in non-labor; r = 0.668, p < 0.0001 in labor). In conclusion, Apoptosis may be regulated by TNF-α and VEGF expression in FM at labor. MZ is a step back from RZ and could participate actively in rupture of the FM during labor. TNF-α and VEGF increase with onset of labor and differentially expressed in the RZ and the MZ. These findings call for further study with tissue cultures or animal models.     

Selective type 1 angiotensin II receptor blockade attenuates oxidative stress and regulates angiotensin II receptors in the canine failing heart

Background and objective Angiotensin II type 1 receptor (AT₁R) blockade reduces vascular oxidative stress but whether myocardial oxidative stress represents a mechanism for the beneficial effect of AT₁R blockade in heart failure is unclear. Furthermore, the impact of AT₁R blockade on the expression of angiotensin II receptors in heart failure has not been well documented. Accordingly, we examined the impact of the AT₁R blocker candesartan on hemodynamics, left ventricular (LV) remodeling (echocardiography), oxidative stress, and tissue expression of AT₁Rs and angiotensin II type 2 receptors (AT₂Rs) in a canine model of pacing-induced heart failure. Methods and results Animals were randomized to rapid right ventricular-pacing (250 beats/min for 3 weeks) to severe heart failure and treated with candesartan (10 mg/kg daily, n = 8) or placebo (n = 8) from day 3 onwards, or no pacing (sham, n = 7). Candesartan significantly reduced mean pulmonary arterial and LV diastolic pressure, LV end-diastolic and end-systolic volume and ascites, increased cardiac output, dP/dt, and ejection fraction, while reversing the marked increase in aldehydes, a marker of oxidative stress, observed in the placebo group. Although candesartan did not alter LV AT₁R protein expression compared to placebo or sham, it reversed the decrease in AT₂R protein observed in the placebo group. Conclusion Our results indicate that in the pacing model of heart failure, chronic AT₁R blockade attenuates hemodynamic deterioration and limits LV remodeling and dysfunction, in part by reversing oxidative stress and AT₂R downregulation.     

Cardiac magnetic resonance imaging of rapid VCAM-1 up-regulation in myocardial ischemia–reperfusion injury

Inflammatory response plays an important role in myocardial ischaemia–reperfusion (IR) injury. Up-regulation of vascular cell adhesion molecule-1 (VCAM) contributes to this. We examined the feasibility of using intravenously administered VCAM–MPIO (microparticle iron oxide) to characterize VCAM expression patterns in myocardial IR injury. Myocardial ischemia was simulated by 30 min of transient ligation of the left coronary vessel in rats. Purified, monoclonal, rat-specific, mouse VCAM antibody coupled to MPIO was administered through the tail vein at 3 h post reperfusion and the rats were sacrificed 1 h later. High resolution 3D ex vivo MRI images were acquired at 9.4 Tesla. Extensive foci of signal voids were observed on T2*-weighted gradient-echo sequences, which corresponded to focal deposits of MPIOs observed in histological sections. The spatial density of the signal voids (expressed as a percentage of pixels below a threshold value) was increased in the peri-infarct zone compared with non-infarct zone (32.5 ± 4 % vs. 13.9 ± 5 %; n = 6; p < 0.05) and was substantially greater than the signal loss due to non-specific binding seen in rats administered IgG control MPIO (2.0 ± 1 %; n = 6; p < 0.05). The VCAM-specific MPIO signal was also seen in myocardium and pericardium in segments remote from the IR injury, but not in rats undergoing a sham operation. In conclusion, molecular imaging in a model of myocardial IR injury is possible using high field MRI and VCAM–MPIOs and may provide novel insights beyond those achieved by standard histological and molecular analysis.     

Hydrogen sulfide mitigates cardiac remodeling during myocardial infarction via improvement of angiogenesis

Exogenous hydrogen sulfide (H2S) leads to down-regulation of inflammatory responses and provides myocardial protection during acute ischemia/reperfusion injury; however its role during chronic heart failure (CHF) due to myocardial infarction (MI) is yet to be unveiled. We previously reported that H2S inhibits antiangiogenic factors such, as endostatin and angiostatin, but a little is known about its effect on parstatin (a fragment of proteinase-activated receptor-1, PAR-1). We hypothesize that H2S inhibits parstatin formation and promotes VEGF activation, thus promoting angiogenesis and significantly limiting the extent of MI injury. To verify this hypothesis MI was created in 12 week-old male mice by ligation of left anterior descending artery (LAD). Sham surgery was performed except LAD ligation. After the surgery mice were treated with sodium hydrogen sulfide (30 μmol/l NaHS, a donor for H2S, in drinking water) for 4 weeks. The LV tissue was analyzed for VEGF, flk-1 and flt-1, endostatin, angiostatin and parstatin. The expression of VEGF, flk-1 and flt-1 were significantly increased in treated mice while the level of endostatin, angiostatin and parstatin were decreased compared to in untreated mice. The echocardiography in mice treated with H2S showed the improvement of heart function compared to in untreated mice. The X-ray and Doppler blood flow measurements showed enhancement of cardiac-angiogenesis in mice treated with H2S. This observed cytoprotection was associated with an inhibition of anti-angiogenic proteins and stimulation of angiogenic factors. We established that administration of H2S at the time of MI ameliorated infarct size and preserved LV function during development of MI in mice. These results suggest that H2S is cytoprotective and angioprotective during evolution of MI.     

Molecular cloning of Quek 1 and 2, two quail vascular endothelial growth factor (VEGF) receptor-like molecules

We have previously reported the cloning of two partial cDNAs corresponding to two quail (Coturnix coturnix japonica) receptor tyrosine kinases (RTKs), named Quek 1 and Quek 2, and their expression in endothelial cells of the early avian embryo. We here report the cloning of the full-size cDNAs for both molecules. Sequence comparison shows that Quek 1 and 2 share an overall amino acid (aa) identity of 49%. They both comprise seven extracellular immunoglobulin-like (Ig-like) domains, a single transmembrane domain, and an intracellular kinase domain split into two by a 70 aa insertion. These structural characteristics are shared by the members of the recently discovered VEGF receptor (VEGFR) family. We have compared the sequences of Quek 1 and 2 to the other VEGFRs. At the aa level, Quek 1 is most closely related to KDR/flk-1 (VEGFR 2) (aa identity of 69% and 71%, respectively). Quek 2 shows a similar degree of aa identity to flt-4 (VEGFR 3). Quek 1 and 2 display a lower homology to flt-1 (VEGFR 1) (about 45% aa identity). These data suggest that Quek 1 and 2 are the avian homologues of VEGFRs 2 and 3, respectively.     

Mesenchymal stem cells overexpressing integrin-linked kinase attenuate left ventricular remodeling and improve cardiac function after myocardial infarction

In the present study, we investigated whether mesenchymal stem cells (MSCs) overexpressing integrin-linked kinase (ILK) might regulate ventricular remodeling and cardiac function in a porcine myocardial infarction model. ILK-modified MSCs (ILK-MSCs) (n = 8), MSCs (n = 8) or placebo (n = 8) were injected into peri-infarct myocardium 7 days after ligation of the left anterior descending coronary artery. ILK expression was confirmed by immunofluorescence, real-time PCR, Western blot analysis, and flow cytometry. In vitro assays indicated increased proliferation and reduced apoptosis of MSCs due to overexpression of ILK. Echocardiographic, single-photon emission computed tomography and positron emission tomography analyses demonstrated preserved cardiac function and myocardial perfusion. Reduced fibrosis, increased cardiomyocyte proliferation, and enhanced angiogenesis were observed in the ILK-MSC group. Reduced apoptosis, as demonstrated by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling analysis, was also noted. In conclusion, ILK promotes MSC proliferation and suppresses apoptosis. ILK-MSC transplantation improves ventricular remodeling and cardiac function in pigs after MI. It is associated with increased angiogenesis, reduced apoptosis, and increased cardiomyocyte proliferation. This may represent a new approach to the treatment of post-infarct remodeling and subsequent heart failure.     

Impact of repeated intravenous bone marrow mesenchymal stem cells infusion on myocardial collagen network remodeling in a rat model of doxorubicin-induced dilated cardiomyopathy

Bone marrow mesenchymal stem cells (MSCs) transplantation improved cardiac function and reduced myocardial fibrosis in both ischemic and non-ischemic cardiomyopathies. We evaluated the effects of repeated peripheral vein injection of MSCs on collagen network remodeling and myocardial TGF-β1, AT1, CYP11B2 (aldosterone synthase) gene expressions in a rat model of doxorubicin (DOX)-induced dilated cardiomyopathy (DCM). Thirty-eight out of 53 SD rats survived at 10 weeks post-DOX injection (2.5 mg/kg/week for 6 weeks, i.p.) were divided into DCM blank (without treatment, n = 12), DCM placebo (intravenous tail injection of 0.5 mL serum-free culture medium every other day for ten times, n = 13), and DCM plus MSCs group (intravenous tail injection of 5 × 10⁶ MSCs dissolved in 0.5 mL serum-free culture medium every other day for 10 times, n = 13). Ten untreated rats served as normal controls. At 20 weeks after DOX injection, echocardiography, myocardial collagen content, myocardial expressions of types I and III collagen, TGF-β1, AT1, and CYP11B2 were compared among groups. At 20 weeks post-DOX injection, 8 rats (67 %) survived in DCM blank group, 9 rats (69 %) survived in DCM placebo group while 13 rats (100 %) survived in DCM plus MSCs group. Left ventricular end-diastolic diameter was significantly higher and ejection fraction was significantly lower in DCM blank and DCM placebo groups compared to normal control rats, which were significantly improved in DCM plus MSCs group (all p < 0.05 vs. DCM blank and DCM placebo groups). Moreover, myocardial collagen volume fraction, types I and III collagen, myocardial mRNA expressions of TGF-β1, AT1, CYP11B2, and collagen I/III ratio were all significantly lower in DCM plus MSCs group compared to DCM blank and DCM placebo groups (all p < 0.05). Repeated intravenous MSCs transplantation could improve cardiac function by attenuating myocardial collagen network remodeling possibly through downregulating renin–angiotensin–aldosterone system in DOX-induced DCM rats.     

Age-dependent expression of VEGF isoforms and receptors in the rabbit anterior cruciate ligament

Vascular endothelial growth factor (VEGF) gene gives rise to several distinct isoforms of VEGF. Those isoforms differ in biochemical and biological properties, and it has been reported that their expression patterns are tissue and age specific as well. We investigated the expression levels of VEGF isoforms (VEGF121, VEGF165, VEGF183, VEGF189) and its receptors (VEGFR-1, flt-1 and VEGFR-2, flk-1/KDR) in the anterior cruciate ligament (ACL) of 2- to 3-week-, 2-month-, and 18-month-old New Zealand White rabbits using Sybr green Real-Time RT-PCR. VEGF isoforms and both receptors were expressed in the ACL at all investigated ages. VEGF121 was found to be the most abundant isoform at the ages under investigation, followed by VEGF165, VEGF189 and VEGF183. All isoforms showed decreased expression levels with age, however the larger membrane bound isoforms, VEGF183 and VEGF189, showed the most striking age-associated decrease in expression level. VEGFR-1 expression levels increased with age, while the expression level of VEGFR-2 expression was highest at 2-3 weeks and was significantly lower at 2 and 18 months of age. Distinct age-associated differences in the expression level of VEGF isoforms as well as their receptors suggest differential physiological functions during development, maturation and ageing of the ACL.