Topical Vascular Endothelial Growth Factor Research Articles

Adjuvant therapy and interdisciplinary follow-up care of conjunctival melanoma

Despite microscopically controlled tumor excision, malignant melanomas of the conjunctiva have a propensity for local recurrence, lymphatic spread and distant metastases. This review outlines the options of adjuvant therapy as well as the structure of interdisciplinary follow-up care for patients with conjunctival melanoma. The study provides a PubMed literature review and own clinical results. In conjunctival melanoma complete tumor excision using a minimal touch technique should always be combined with adjuvant therapy, such as cryotherapy, radiotherapy, topical chemotherapy and/or immunotherapy. For locally circumscribed lesions of the bulbar conjunctiva adjuvant brachytherapy can be supplemented and for non-bulbar, extensive, diffuse or multilocular tumor growth, complementary adjuvant topical mitomycin C therapy or proton radiotherapy can be used. Novel adjuvant approaches include topical interferon alpha-2b immunotherapy, topical vascular endothelial growth factor (VEGF) inhibitors or in cases of BRAF mutations personalized therapy using selective BRAF inhibitors or in combination with mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK), MAPK/ERK (MEK) inhibitors. All patients should be integrated into an interdisciplinary follow-up care program including quarter yearly checkups in the first 5 years and psycho-oncological healthcare. Following microscopically controlled tumor excision, adjuvant treatment using cryotherapy, radiotherapy, topical chemotherapy and/or immunotherapy as well as interdisciplinary follow-up care are mandatory for the modern management of patients with conjunctival melanoma.

Structural Study of Prepuce in Hypospadias—Does Topical Treatment With Testosterone Produce Alterations in Prepuce Vascularization?

Androgen stimulation before hypospadias surgery has resulted in increased penile size, fewer complications and improved cosmesis, and suggests increased neovascularization. To our knowledge the real effect on neovascularization remains to be proved. We studied the histological effects of testosterone on neovascularization. A total of 26 boys with hypospadias were randomly allocated to 2 groups before surgical correction. Group 1 did not receive any treatment and group 2 received 1% testosterone propionate ointment twice daily for 30 days before surgery. During the surgical procedure a fragment of prepuce was excised and prepared for histological evaluation. The number and volume density of blood vessels were determined by labeling for von Willebrand's factor. Blood vessel quantification as volume density was done using a video microscopy system with a superimposed cycloid arch test system. The groups were similar in age and hypospadias classification. Testosterone treated prepuces (group 2) had an increased absolute number of blood vessels (mean ± SD 8.5 ± 1.3 vs 4.8 ± 1.8 vessels per field) and increased blood vessel volume density (mean 50.5% ± 7.8% vs 24.8% ± 8.6% vessels per point) (each p <0.001) compared to those in untreated patients (group 1). The use of 1% testosterone propionate ointment before hypospadias surgery produces neovascularization in absolute numbers and in volume density.

Evaluating Revascularization and Flap Survival Using Vascular Endothelial Growth Factor in an Irradiated Rat Model

To evaluate the role of vascular endothelial growth factor (VEGF) plasmid DNA (pDNA) in improving flap revascularization in a previously developed rat model. Our hypothesis was that the uptake and expression of VEGF pDNA in the wound bed would improve revascularization and flap viability. Twenty-eight male Sprague-Dawley rats received a total dose of 40 Gy electron beam radiation to the ventral abdominal wall. After a recovery period, they underwent a ventral fasciocutaneous flap procedure with a 2-hour ischemia period. Group 1 (n = 14) received topical VEGF pDNA, in vivo cationic polymer, and fibrin sealant. Group 2 (n = 14) received topical cationic polymer and fibrin sealant only. Seven of the rats from each group underwent pedicle ligation at 8 or 14 days. The primary outcome measure was percentage of flap revascularization 5 days after pedicle ligation. Rats receiving VEGF pDNA had a significantly higher rate of flap revascularization (90.8% vs 79.8%) after pedicle ligation at 14 days (P = .045). At 8 days, rats receiving VEGF pDNA (group 1) had an increased rate of flap revascularization (58.2% vs 42.8%) that approached significance (P = .11). This study demonstrates the potential of VEGF pDNA to improve revascularization and flap viability in previously irradiated tissue.

Antiangiogene Therapie bei Pterygiumrezidiven

A pterygium is defined as a fibrovascular and hyperplastic proliferative degeneration tissue of the limbus. Although the pathogenesis is not yet clearly understood there are indications that vascular endothelial growth factor (VEGF) may play a significant role in the development. Despite various surgical approaches recurrence remains the major postoperative problem. Bevacizumab is a human monoclonal antibody against VEGF. Its antiangiogenic effect is used in ophthalmology as an off-label treatment for retinal disease. We report about the use of Bevacizumab eye drops to prevent repeated recurrence of pterygia. In our clinic 5 eyes (4 patients) were treated with topical Bevacizumab eye drops (25 mg/ml) 2-8 times per day for 5-24 weeks as an adjunct after excision of recurrent pterygia and conjunctival autograft. Patients were examined preoperatively and over a follow-up period ranging from 3-14 months (median 12 months). Visual acuity improved in 3 out of 5 eyes and in 1 eye no pterygium recurrence was noted. Two eyes showed conjunctival hyperemia (stage 1 recurrence) and one eye showed fibrosis of the limbus (stage 2 recurrence). In one eye an early recurrence with corneal vascularisation and superficial punctate keratopathy was observed (stage 3 recurrence). No serious permanent complications were observed. Considering the previously multiple recurrences in our patients we think that these first clinical mid-term follow-up experiences support the use of topical VEGF inhibitors in recurrent pterygia.

Endotracheal Stent Granulation Stenosis Resolution after Colchicine Therapy in a Dog

Endotracheal Stent Granulation Stenosis Resolution after Colchicine Therapy in a Dog

Topical vascular endothelial growth factor reverses delayed wound healing secondary to angiogenesis inhibitor administration

The prevention of new blood vessel growth is an increasingly attractive strategy to limit tumor growth. However, it remains unclear whether anti-angiogenesis approaches will impair wound healing, a process thought to be angiogenesis dependent. Results of previous studies differ as to whether angiogenesis inhibitors delay wound healing. We evaluated whether endostatin at tumor-inhibiting doses delayed excisional wound closure. C57/BL6J mice were treated with endostatin or phosphate-buffered solution 3 days prior to the creation of two full-thickness wounds on the dorsum. Endostatin was administered daily until wound closure was complete. A third group received endostatin, but also had daily topical vascular endothelial growth factor applied locally to the wound. Wound area was measured daily and the wounds were analyzed for granulation tissue formation, epithelial gap, and wound vascularity. Endostatin-treated mice showed a significant delay in wound healing. Granulation tissue formation and wound vascularity were significantly decreased, but reepithelialization was not effected. Topical vascular endothelial growth factor application to wounds in endostatin-treated mice resulted in increased granulation tissue formation, increased wound vascularity, and wound closure approaching that of control mice. This study shows that the angiogenesis inhibitor endostatin delays wound healing and that topical vascular endothelial growth factor is effective in counteracting this effect.

Topical Vascular Endothelial Growth Factor Accelerates Diabetic Wound Healing through Increased Angiogenesis and by Mobilizing and Recruiting Bone Marrow-Derived Cells

Diminished production of vascular endothelial growth factor (VEGF) and decreased angiogenesis are thought to contribute to impaired tissue repair in diabetic patients. We examined whether recombinant human VEGF(165) protein would reverse the impaired wound healing phenotype in genetically diabetic mice. Paired full-thickness skin wounds on the dorsum of db/db mice received 20 microg of VEGF every other day for five doses to one wound and vehicle (phosphate-buffered saline) to the other. We demonstrate significantly accelerated repair in VEGF-treated wounds with an average time to resurfacing of 12 days versus 25 days in untreated mice. VEGF-treated wounds were characterized by an early leaky, malformed vasculature followed by abundant granulation tissue deposition. The VEGF-treated wounds demonstrated increased epithelialization, increased matrix deposition, and enhanced cellular proliferation, as assessed by uptake of 5-bromodeoxyuridine. Analysis of gene expression by real-time reverse transcriptase-polymerase chain reaction demonstrates a significant up-regulation of platelet-derived growth factor-B and fibroblast growth factor-2 in VEGF-treated wounds, which corresponds with the increased granulation tissue in these wounds. These experiments also demonstrated an increase in the rate of repair of the contralateral phosphate-buffered saline-treated wound when compared to wounds in diabetic mice never exposed to VEGF (18 days versus 25 days), suggesting that topical VEGF had a systemic effect. We observed increased numbers of circulating VEGFR2(+)/CD11b(-) cells in the VEGF-treated mice by fluorescence-activated cell sorting analysis, which likely represent an endothelial precursor population. In diabetic mice with bone marrow replaced by that of tie2/lacZ mice we demonstrate that the local recruitment of bone marrow-derived endothelial lineage lacZ+ cells was augmented by topical VEGF. We conclude that topical VEGF is able to improve wound healing by locally up-regulating growth factors important for tissue repair and by systemically mobilizing bone marrow-derived cells, including a population that contributes to blood vessel formation, and recruiting these cells to the local wound environment where they are able to accelerate repair. Thus, VEGF therapy may be useful in the treatment of diabetic complications characterized by impaired neovascularization.

Topical VEGF enhances healing of thoracic aortic anastomosis for coarctation in a rabbit model.

Recurrent stenosis after extended end-to-end anastomosis for aortic coarctation is the primary indication for further interventions in children. Tension because of the extended resection and local arterial wall hypoxia are possible pathogenetic mechanisms. We hypothesized that (1) tension interferes with healing and (2) that vascular endothelial growth factor (VEGF), a hypoxia sensitive angiogenic inducer, may enhance healing of the vascular anastomosis. In a model of coarctation repair, rabbits underwent thoracic aortic end-to-end anastomosis after transection (no-tension; n=15), resection of an aortic ring (tension; n=14) or resection and topical VEGF treatment (0.75 microg VEGF165; tension+VEGF; n=14). Gross and histologic characteristics of the aortic wall were assessed at 1 week, 1 and 2 months. In the tension only group at 1 month, the severity of vascular remodeling was increased with fibrosis and calcification compared with controls. At 2 months, this group also revealed more luminal stenosis (29% versus 19%; P<0.001). Exogenous VEGF resulted in significantly less fibrosis, calcification and chondroid metaplasia at 1 month (P<0.05) and luminal area was only reduced 3% at 2 months (P<0.001 versus tension group). In a rabbit model of coarctation repair, the addition of tension on the vascular anastomosis resulted in poor healing and luminal stenosis. Topical VEGF maintained luminal integrity by decreasing fibrosis and calcification. These findings suggest that topical VEGF may be a promising new strategy to enhance healing and improve the outcome of vascular anastomoses for coarctation of the aorta.

Healing of a free tracheal autograft is enhanced by topical vascular endothelial growth factor in an experimental rabbit model

Objective: In 1996, we introduced the free tracheal autograft technique for repair of congenital tracheal stenosis from complete tracheal rings in infants and children. Sources of possible concern with this procedure include the potential for autograft ischemia, patch dehiscence, and recurrent stenosis. Vascular endothelial growth factor is a potent angiogenic inducer (particularly in the setting of ischemia, hypoxia, or both) and is postulated to promote tissue healing. The purpose of this study was to test the hypothesis that pretreatment of tracheal autografts with topical vascular endothelial growth factor would enhance tracheal healing. Methods: In a rabbit model of tracheal reconstruction (n = 32), an elliptically shaped portion of the anterior tracheal wall was excised. The excised portion of trachea was one third of the tracheal circumference and 2 cm in length (6 tracheal rings). This portion of trachea (the autograft) was soaked in either vascular endothelial growth factor (5 μg/mL, n = 16) or normal saline solution (n = 16) for 15 minutes before being reimplanted in the resultant tracheal opening. Animals were killed and autografts were examined at 2 weeks, 1 month, and 2 months postoperatively for gross and microscopic characteristics. Results: By 2 weeks, and progressing through 1 and 2 months, autografts treated with vascular endothelial growth factor, as compared with control autografts, had reduced luminal stenosis, submucosal fibrosis, and inflammatory infiltrate ( P < .05). The autografts tended to become malaligned in control animals, whereas the tracheal architecture was preserved in rabbits treated with vascular endothelial growth factor. Microvascular vessel density was significantly greater in all vascular endothelial growth factor groups ( P < .05) at all time intervals. Conclusions: Topical treatment of free tracheal autografts with vascular endothelial growth factor in a rabbit tracheal reconstruction model enhanced healing, as evidenced by accelerated autograft revascularization, reduced submucosal fibrosis and inflammation, and preservation of the normal tracheal architecture. Topical vascular endothelial growth factor may improve future results of tracheal reconstruction.

Reduction of ischemic damage by application of vascular endothelial growth factor in rat brain after transient ischemia.

Vascular endothelial growth factor (VEGF) is a secreted polypeptide and plays a pivotal role in angiogenesis in vivo. However, it also increases vascular permeability, and might exacerbate ischemic brain edema. The effect of this factor on the brain after transient ischemia was investigated in terms of infarct volume and edema formation, as well as cellular injury. After 90 minutes of transient middle cerebral artery occlusion, VEGF (1.0 ng/microL, 9 microL) was topically applied on the surface of the reperfused rat brain. A significant reduction of infarct volume was found in animals with VEGF application (P < 0.001) at 24 hours of reperfusion as compared with cases with vehicle treatment. Brain edema was significantly reduced in VEGF-treated animals (P = 0.01), and furthermore, extravasation of Evans blue was also decreased in those animals (P < 0.01). Terminal deoxynucleotidyl transferase-mediated dUTP-biotin in situ nick end labeling and immunohistochemical analysis for 70-kDa heat shock protein showed an amelioration of the stainings at 24 and 48 hours after reperfusion with VEGF treatment, which indicated reduction of neuronal damage. These results indicate that treatment with topical VEGF application significantly reduces ischemic brain damage, such as infarct volume, edema formation, and extravasation of Evans blue, and that the reductions were associated with that of neuronal injury.

Reduction of vein graft intimal hyperplasia and preservation of endothelium-dependent relaxation by topical vascular endothelial growth factor

Purpose: Recent evidence suggests that vascular endothelial growth factor (VEGF), in addition to stimulating angiogenesis, also serves a repair/maintenance or survival function, modulating various aspects of endothelial cell function. This study was designed to examine the effect of VEGF pretreatment in a model of vein graft intimal hyperplasia. Methods: Reversed jugular vein–to–common carotid artery interposition grafts were constructed in New Zealand White rabbits. Vein conduits were immersed in solution containing 500 mg rhVEGF165 or saline solution for 20 minutes before implantation. Twenty-eight days later the vein grafts and contralateral control jugular veins were harvested for either histologic or isometric tension studies. Results: VEGF-treated vein grafts showed a 23% reduction in intimal area (0.76 ± 0.07 mm 2 vs 0.98 ± 0.06 mm 2; p = 0.028) and a 30% reduction in intimal thickness (62 ± 6 μm vs 89 ± 5 μm; p = 0.001) when compared with control grafts. After precontraction with norepinephrine, the maximal relaxation to acetylcholine (endothelium-dependent, receptor-mediated agonist) for control vein grafts was 0%, whereas for VEGF-treated vein grafts it was 25% ± 9% ( p < 0.05 vs control grafts). The maximal relaxation to the calcium ionophore A23187 (endothelium-dependent, receptor-independent agonist) was also greater in VEGF-treated grafts than in control grafts (172.3% ± 19.4% vs 122.5% ± 13.7%; p < 0.05). There was no difference in the response to sodium nitroprusside (endothelium-independent agonist) between the two groups. Conclusions: A single topical application of VEGF before implantation reduces intimal hyperplasia and improves endothelial function in a rabbit vein graft model. Further evaluation of this simple strategy to improve vein graft patency appears warranted. (J Vasc Surg 1998;27:167-73.)

28.3 Reduction of vein graft intimal hyperplasia and preservation of endothelium-dependent relaxation by topical vascular endothelial growth factor

28.3 Reduction of vein graft intimal hyperplasia and preservation of endothelium-dependent relaxation by topical vascular endothelial growth factor