Relación del tratamiento y coste con la ganancia de agudeza visual en la degeneración macular asociada a la edad / Relationship between treatment and cost with visual acuity improvement in age-related macular degeneration

Fundamento. Relacionar la ganancia de agudeza visual (AV) con el coste asistencial y de tratamiento con terapia anti-factor de cre-cimiento endotelial vascular (antiVEGF) en pacientes diagnostica-dos de degeneración macular asociada a la edad exudativa (DMAE exudativa).Pacientes y métodos. Estudio observacional, longitudinal, retros-pectivo, de pacientes ≥50 años diagnosticados de DMAE exudativa, con AV logMAR entre 0,6 y 0,06, en seguimiento y tratamiento en nuestro hospital de tercer nivel entre el 01/01/2014 y el 31/12/2018.Resultados. Se incluyeron 778 pacientes, 62,2% mujeres y media de edad 79,83±7,94 años, con 957 ojos con DMAE exudativa. La AV final global (0,65±0,45) aumentó un 3,2% respecto de la inicial. El 60,3% de los ojos recibieron antiVEGF con ranibizumab, el 10,2% con aflibercept y el 29,5% con ambos (mixto). El grupo mixto in-crementó significativamente la AV respecto de la inicial, sin dife-rencias entre grupos. Aunque el seguimiento/tratamiento fue más largo para el grupo mixto, este recibió menos inyecciones antiVE-GF y tomografías de coherencia óptica (OCT). El gasto total por año y ojo tratado fue de 1.972,7 €±824,5; los costes fueron mayores para visita, OCT y tratamiento en el grupo de aflibercept, y menores para angiografías con fluoresceína, tratamiento antiVEGF y costes totales en el grupo mixto. La ganancia decimal de AV tuvo un coste de 872 €±1.077,7 sin diferencias significativas entre grupos.Conclusiones. Los tratamientos antiVEGF con ranibizumab, afli-bercept y ambos mantuvieron la AV en pacientes con DMAE exu-dativa. En general, los costes asistenciales y de tratamiento fueron menores en el grupo que recibió ambos fármacos (AU)

Background. We examined the relationship between visual acuity changes (VA) and the cost of care and treatment with anti-vascular endothelial growth factors (antiVEGF) in patients diagnosed with age-related exudative macular degeneration(exudative AMD).Methods. Observational, longitudinal, retrospective study of pa-tients ≥50 years of age diagnosed with exudative AMD, with a log-MAR VA between 0.6 and 0.06. and 0.06. Follow-up and treatment were done in our tertiary hospital between January 1, 2014 and December 31, 2018.Results. The study included 778 patients; 62.2% female and mean age 79.83±7.94 years; 957 eyes had exudative AMD. Mean of final VA (0.65±0.45) increasing 3.2% compared to initial values. Ranibi-zumab was administered to 60.3% of the eyes, aflibercept to 10.2% and ranibizumab + aflibercept (mixed group) to 29.5%. Significant increase in VA was seen in the group with the mixed treatment, with no inter-group differences. Although follow-up/treatment was longer for the mixed group, they received fewer anti-VEGF injections and optical coherence tomography (OCT). The total expenditure per year and treated eye was €1,972.7±824.5; costs were higher for visit, OCT, and treatment in the aflibercept group, and lower for fluorescein angiography, antiVEGF treatment, and total costs in the mixed group. Decimal VA gain had a cost of €872±1,077.7 with no significant inter-group differences.Conclusion. AntiVEGF treatments (ranibizumab, aflibercept, or both) maintained VA in patients with exudative AMD. Overall, care and treatment costs were lower in the group that received both drugs (AU)

Effectiveness of microperimetry in evaluating anti-vascular endothelial growth factor therapy for diabetic macular edema patients with relatively good vision: A retrospective observational study.

ABSTRACT: No studies have evaluated the retinal sensitivity (RS) for diabetic macular edema (DME) patients with good vision. Therefore, this study aimed to determine the effectiveness of microperimetry in evaluating the effectiveness of anti-vascular endothelial growth factor (anti-VEGF) treatment for DME patients with relatively good vision.Twenty-seven eyes of 27 patients (mean age, 61.3 ±â€Š11.2 years) with DME and decimal best-corrected visual acuity (BCVA) ≥0.6 were studied. All patients received 3 consecutive monthly injections of intravitreal anti-VEGF agents. The BCVA, central subfield macular thickness (CMT), and RS were evaluated by microperimetry (MAIA) within the 10 degree of the foveal center. To determine significant differences between the values, we used paired t tests.Patients were evaluated at baseline and 4 weeks after the third injection. The BCVA improved significantly from 0.18 ±â€Š0.06 logarithm of the minimum angle of resolution (logMAR) units to 0.13 ±â€Š0.13 logMAR units (P = .002; paired t test). The CMT decreased significantly from 464.3 ±â€Š91.8 µm to 393.4 ±â€Š129.0 µm (P = .005), and the RS also improved significantly from 21.8 ±â€Š3.1 dB to 24.1 ±â€Š2.8 dB at 4 weeks after treatment (P = .006). Among the patients with a decimal BCVA of 0.7 or better at baseline, there was no significant improvement in the BCVA (P = .28). However, the CMT decreased significantly from 479.5 ±â€Š79.1 µm to 394.0 ±â€Š99.8 µm at 4 weeks after treatment (P = .007). The RS also improved significantly from 22.0 ±â€Š2.4 dB to 24.0 ±â€Š3.1 dB at 4 weeks after treatment (P = .004).Measuring RS by microperimetry is a good option for evaluating the effectiveness of anti-VEGF treatment for DME patients with a relatively good BCVA.

Local delivery of hydrogel encapsulated vascular endothelial growth factor for the prevention of medication-related osteonecrosis of the jaw.

The anti-angiogenic effects of bisphosphonates have been hypothesized as one of the major etiologic factors in the development of medication-related osteonecrosis of the jaw (MRONJ), a severe debilitating condition with limited treatment options. This study evaluated the potential of a gelatine-hyaluronic acid hydrogel loaded with the angiogenic growth factor, vascular endothelial growth factor (VEGF), as a local delivery system to aid in maintaining vascularization in a bisphosphonate-treated (Zoledronic Acid) rodent maxillary extraction defect. Healing was assessed four weeks after implantation of the VEGF-hydrogel into extraction sockets. Gross examination and histological assessment showed that total osteonecrosis and inflammatory infiltrate was significantly reduced in the presence of VEGF. Also, total vascularity and specifically neovascularization, was significantly improved in animals that received VEGF hydrogel. Gene expression of vascular, inflammatory and bone specific markers within the defect area were also significantly altered in the presence of VEGF. Furthermore, plasma cytokine levels were assessed to determine the systemic effect of locally delivered VEGF and showed similar outcomes. In conclusion, the use of locally delivered VEGF within healing extraction sockets assists bone healing and prevents MRONJ via a pro-angiogenic and immunomodulatory mechanism.

Difference in the efficacy of intravitreal dexamethasone implant before and after silicone oil removal: A case report.

RATIONALE: An intravitreal dexamethasone (IV-DEX) implant is safe and effective for the treatment of macular edemas; however, the efficacy of IV-DEX implants in silicone oil (SO)-filled eyes remains controversial. There is no previous study comparing an IV-DEX implant in the same eye with and without intravitreal SO. PATIENT CONCERNS: A 72-year-old man with proliferative diabetic retinopathy, macular edema, and rhegmatogenous retinal detachment, treated with pars plana vitrectomy with SO tamponade had refractory macular edema. DIAGNOSIS: Refractory macular edema. INTERVENTION: Subtenon triamcinolone injection, intravitreal anti-vascular endothelial growth factor injection, and IV-DEX implantation were performed; this was followed by intravitreal SO removal combined with IV-DEX implantation. OUTCOMES: The macular edema did not decrease significantly with posterior subtenon triamcinolone injection, intravitreal anti-vascular endothelial growth factor injection, and IV-DEX implantation; however, the edema was relieved after SO removal and a new IV-DEX implantation. LESSONS: IV-DEX implant may be less efficacious in the treatment of macular edema in an SO-filled eye than that in a normal vitreous cavity.

Post-loading of proangiogenic growth factors in PLGA microspheres.

Active self-encapsulation (ASE) is a recently developed post-loading method based on absorption of (positively charged) proteins in microporous PLGA microspheres loaded with negatively charged polysaccharides (trapping agents). The aim of this study was to investigate ASE for simultaneous loading and controlled release of multiple growth factors. For this purpose, vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF) and insulin-like growth factor (IGF) were loaded in microspheres containing high molecular weight dextran sulfate (HDS) as trapping agent; loading was performed in a concentrated growth factor solution of low ionic strength and of pH 5 under conditions at which the proteins are positively charged. Subsequent pore closure was induced by incubation of the growth factor-loaded microspheres at 42.5 °C, i.e. above the Tg of (hydrated) PLGA (~30 °C). A 1:1:1 combination of VEGF, FGF and IGF was loaded with high loading (4.3%) and loading efficiency (91%). The in vitro release kinetics and bioactivity of loaded growth factors were studied for 4 weeks using ELISA and an endothelial cell proliferation assay, respectively. While IGF was released quickly, VEGF and FGF were continuously released for 4 weeks in their bioactive form, whereby a growth factor combination had a synergistic angiogenic effect. Therefore, ASE is a suitable method for co-loading growth factors which can provide sustained release profiles of bioactive growth factors, which is attractive for vascularization of biomaterial implants.

Vascular endothelial growth factor-loaded poly-lactic-co-glycolic acid nanoparticles with controlled release protect the dopaminergic neurons in Parkinson's rats.

Vascular endothelial growth factor (VEGF) had neuroprotective effects on dopaminergic (DA) neurons. In order to overcome the gastrointestinal digestion and bioaccessibility, VEGF was encapsulated with poly-lactic-co-glycolic acid nanospheres (NS) in order to prevent the VEGF degradation until its release. The caudal administration of VEGF and NS encapsulated VEGF at different doses (1.0, 10.0, and 100.0 ng/ml) on the rats with Parkinson's disease lesion was evaluated. Intravenous injected VEGF at the dose of 1 ng/ml displayed the strongest neuroprotective effect than other groups as well as the stereotaxic group. The NS encapsulated with VEGF can pass through blood-brain barrier and protect the DA neurons. There was no significant difference between intravenous injection method and stereotaxic method, while the first method is simpler and convenient. Injection of NS encapsulated with VEGF may become a valuable neurorescuing therapeutic approach for Parkinson's disease.

Severe ocular pain after anti-VEGF intravitreal injection / Dolor ocular severo tras inyección intravítrea con anti-VEGF

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Anti-Nogo-A antibodies prevent vascular leakage and act as pro-angiogenic factors following stroke.

Angiogenesis is a key restorative process following stroke but has also been linked to increased vascular permeability and blood brain barrier (BBB) disruption. Previous pre-clinical approaches primarily focused on the administration of vascular endothelial growth factor (VEGF) to promote vascular repair after stroke. Although shown to improve angiogenesis and functional recovery from stroke, VEGF increased the risk of blood brain barrier disruption and bleedings to such an extent that its clinical use is contraindicated. As an alternative strategy, antibodies against the neurite growth inhibitory factor Nogo-A have recently been shown to enhance vascular regeneration in the ischemic central nervous system (CNS); however, their effect on vascular permeability is unknown. Here, we demonstrate that antibody-mediated Nogo-A neutralization following stroke has strong pro-angiogenic effects but does not increase vascular permeability as opposed to VEGF. Moreover, VEGF-induced vascular permeability was partially prevented when VEGF was co-administered with anti-Nogo-A antibodies. This study may provide a novel therapeutic strategy for vascular repair and maturation in the ischemic brain.

The Preparation of the Recipient Site in Fat Grafting: A Comprehensive Review of the Preclinical Evidence.

BACKGROUND: Several methods to prepare the recipient site in fat grafting have been proposed in recent decades. However, to date, these procedures have never been reviewed exhaustively. The purpose of the present study is to provide a comprehensive overview of the different techniques to prepare the recipient site for fat grafting as they were investigated in preclinical studies, with resulting outcomes and underlying mechanisms of action. METHODS: The PubMed/MEDLINE database was queried to search for preclinical investigations on the preparation of the recipient site in fat grafting using the following algorithm: ((recipient site) AND (fat grafting) OR (lipofilling) OR (lipograft)). A priori criteria were applied to review the resulting articles. RESULTS: Thirteen animal studies met inclusion criteria. Overall, five techniques were identified: external volume expansion, implantation of alloplastic material (silicone sheets), administration of cell-proliferation factors (i.e., vascular endothelial growth factor, adipose tissue-derived stromal vascular fraction, and interleukin-8), ischemia, and microneedling. A positive effect on cellular activity (cell proliferation and angiogenesis) was demonstrated by all studies and achieved with all techniques. Seven of the eight authors who examined this aspect reported enhancement of fat graft survival. CONCLUSIONS: Improvement of fat grafting surgical outcomes is documented preclinically using different recipient-site preparation techniques, particularly through enhancement of vascularization and soft-tissue expansion. This understanding will lead to further clinical research, especially for those cases where improvement of the recipient site is recommended, such as contracted scars or preirradiated tissues.

The Rabbit Corneal Pocket Assay.

The rabbit corneal micropocket angiogenesis assay uses the avascular cornea as a substrate canvas to study angiogenesis in vivo. Through the use of standardized slow-release pellets, a predictable angiogenic response is generated over the course of 1-2 weeks and then quantified. Uniform slow-release pellets are prepared by mixing purified angiogenic growth factors such as basic fibroblast growth factor or vascular endothelial growth factor and a synthetic polymer to allow slow release. A micropocket is surgically created in the rabbit cornea under anesthesia and a pellet implanted. On the days later, the angiogenic response is measured and qualified using a slit lamp, as well as the concomitant vascular phenotype or inflammatory features. The results of the assay are used to assess the ability of potential therapeutic molecules to modulate angiogenesis in vivo, both when released locally or given by ocular formulations or through systemic treatment. In this chapter, the experimental details of the rabbit cornea assay and technical implementations to the original protocol are described.

Non-physician delivered intravitreal injection service is feasible and safe - a systematic review.

INTRODUCTION: Non-physicians such as nurses are trained to give injections into the vitreous body of the eye to meet the increasing demand for intravitreal therapy with vascular endothelial growth factor inhibitors against common eye diseases, e.g. age-related macular degeneration and diabetic retinopathy. We systematically reviewed the existing literature to provide an overview of the experiences in this transformational process. METHODS: We searched for literature on 22 September 2015 using PubMed, Embase, the Cochrane Library, CINAHL and the Web of Science. Eligible studies had to address any outcome based on non-physician delivered intravitreal therapy regardless of the study design. Being non-physician was defined as the injecting personnel not being a physician, but no further restrictions were made. RESULTS: Five studies were included with a total of 31,303 injections having been performed by 16 nurses. The studies found that having nurses perform the intravitreal injections produced to a short-term capacity improvement and liberated physicians for other clinical work. Training was provided through courses and direct supervision. The rates of endophthalmitis were 0-0.40‰, which is comparable to reported rates when the intravitreal therapy is given by physicians. CONCLUSION: Non-physician delivered intravitreal therapy seems feasible and safe.

A novel bispecific immunotoxin delivered by human bone marrow-derived mesenchymal stem cells to target blood vessels and vasculogenic mimicry of malignant gliomas.

BACKGROUND: In previous years, immunotoxins have been shown to be a greatly promising therapeutic tool for brain malignancies, such as gliomas. Human mesenchymal stem cells (hMSCs) exhibit tropism to tumor tissue. However, the effect of bispecific immunotoxins in malignant gliomas is still unknown. The aim of this study was to investigate the function of bispecific immunotoxins in human malignant gliomas. MATERIALS AND METHODS: In the present study, the bispecific immunotoxin VEGF165-ephrin A1-PE38KDEL was established using deoxyribonucleic acid shuffling and cloning techniques. The VEGF165-ephrin A1-PE38KDEL was delivered by hMSCs to mouse malignant gliomas. The effects of the bispecific immunotoxins on glioma-derived blood vessels and vasculogenic mimicry to elucidate the molecular mechanisms underlying the antitumorigenic effects of immunotoxins were examined in vivo. RESULTS: In vitro, transfected hMSCs significantly inhibited the cell viability of gliomas cell lines U87 and U251 in a dose-dependent manner compared with untransfected hMSCs (P<0.01). In vivo, the intratumoral injection of engineered hMSCs was effective at inhibiting tumor growth in a malignant glioma tumor model. CONCLUSION: The bispecific immunotoxin secreted from hMSCs acts as a novel strategy for improving treatment options for malignant gliomas in the clinic.

A First Step in De Novo Synthesis of a Living Pulp Tissue Replacement Using Dental Pulp MSCs and Tissue Growth Factors, Encapsulated within a Bioinspired Alginate Hydrogel.

INTRODUCTION: A living, self-supporting pulp tissue replacement in vitro and for transplantation is an attractive yet unmet bioengineering challenge. Our aim is to create 3-dimensional alginate-based microenvironments that replicate the shape of gutta-percha and comprise key elements for the proliferation of progenitor cells and the release of growth factors. METHODS: An RGD-bearing alginate framework was used to encapsulate dental pulp stem cells and human umbilical vein endothelial cells in a ratio of 1:1. The alginate hydrogel also retained and delivered 2 key growth factors, vascular endothelial growth factor-121 and fibroblast growth factor, in a sufficient amount to induce proliferation. A method was then devised to replicate the shape of gutta-percha using RGD alginate within a custom-made mold of thermoresponsive N-isopropylacrylamide. Plugs of alginate containing different permutations of growth factor-based encapsulates were tested and evaluated for viability, proliferation, and release kinetics between 1 and 14 days. RESULTS: According to scanning electron microscopic and confocal microscopic observations, the encapsulated human endothelial cells and dental pulp stem cell distribution were frequent and extensive throughout the length of the construct. There were also high levels of viability in all test environments. Furthermore, cell proliferation was higher in the growth factor-based groups. Growth factor release kinetics also showed significant differences between them. Interestingly, the combination of vascular endothelial growth factor and fibroblast growth factor synergize to significantly up-regulate cell proliferation. CONCLUSIONS: RGD-alginate scaffolds can be fabricated into shapes to fill the pulp space by simple templating. The addition of dual growth factors to cocultures of stem cells within RGD-alginate scaffolds led to the creation of microenvironments that significantly enhance the proliferation of dental pulp stem cell/human umbilical vein endothelial cell combinations.

Combined VEGF and LMP-1 delivery enhances osteoprogenitor cell differentiation and ectopic bone formation.

A novel strategy to enhance bone repair is to combine angiogenic factors and osteogenic factors. We combined vascular endothelial growth factor (VEGF) and LIM mineralization protein-1 (LMP-1) by using an internal ribosome entry site to link the genes within a single plasmid. We then evaluated the effects on osteoblastic differentiation in vitro and ectopic bone formation in vivo with a subcutaneously placed PLAGA scaffold loaded with a cloned mouse osteoprogenitor cell line, D1, transfected with plasmids containing VEGF and LMP-1 genes. The cells expressing both genes elevated mRNA expression of RunX2 and ß-catenin and alkaline phosphatase activity compared to cells from other groups. In vivo, X-ray and micro-CT analysis of the retrieved implants revealed more ectopic bone formation at 2 and 3 weeks but not at 4 weeks compared to other groups. The results indicate that the combination of the therapeutic growth factors potentiates cell differentiation and may promote osteogenesis.

3D systems delivering VEGF to promote angiogenesis for tissue engineering.

In most cases, vascularization is the first requirement to achieve tissue regeneration. The delivery from implants of angiogenic factors, like VEGF, has been widely investigated for establishing a vascular network within the developing tissue. In this report, we investigated if encapsulation of VEGF in nanoparticles could enhance angiogenesis in vivo as compared to free VEGF when incorporated into two different types of 3D matrices: Matrigel™ hydrogels and PLGA scaffolds. Negatively charged nanoparticles encapsulating VEGF were obtained with a high efficiency by complex formation with dextran sulfate and coacervation by chitosan. After 2weeks, encapsulation reduced VEGF release from hydrogels from 30% to 1% and increased VEGF release from scaffolds from 20% to 30% in comparison with free VEGF. VEGF encapsulation consistently improved angiogenesis in vivo with both type of 3D matrices: up to 7.5- to 3.5-times more endothelial and red blood cells were observed, respectively, into hydrogels and scaffolds. Hence, encapsulation in nanoparticles enhanced VEGF efficiency by protection and controlled release from 3D implants. Encapsulation and incorporation of VEGF into 3D implants that, in addition to sustaining cell infiltration and organization, will stimulate blood vessel are a promising approach for tissue regeneration engineering.

Gene therapy and angiogenesis in patients with coronary artery disease.

Not all patients with severe coronary artery disease can be treated satisfactorily with current recommended medications and revascularization techniques. Various vascular growth factors have the potential to induce angiogenesis in ischemic tissue. Clinical trials have only evaluated the effect of VEGF and FGF in patients with coronary artery disease. The initial small and unblinded studies with either recombinant growth factor proteins or genes encoding growth factors were encouraging, demonstrating both clinical improvement and evidence of angiogenesis. However, subsequent larger double-blind placebo-controlled trials could not confirm the initial high efficacy of either the growth factor protein or the gene therapy approaches observed in earlier small trials. The clinical studies so far have all been without any gene-related serious adverse events. Future trials will focus on whether an improvement in clinical results can be obtained with a cocktail of growth factors or by a combination of gene and stem cell therapy in patients with severe coronary artery disease, which cannot be treated effectively with current treatment strategies.

VEGF-induced angiogenesis following localized delivery via injectable, low viscosity poly(trimethylene carbonate).

The purpose of this study was to examine the potential of low molecular weight poly(trimethylene carbonate) for localized vascular endothelial growth factor (VEGF) delivery. Poly(trimethylene carbonate) of various molecular weights was prepared by ring-opening polymerization initiated by 1-octanol. The resultant polymers were liquid at room temperature with low glass transition temperatures and viscosities at 37 degrees C that permitted their injection through an 18 (1/2) G 1.5'' needle. Particles consisting of VEGF co-lyophilized with trehalose were mixed into the polymers and the rate of release of VEGF was assessed in vitro. With a 1% particle loading, VEGF was released from the polymer at a rate of 20 ng/day over a period of 3 weeks. This release behavior was independent of the molecular weight of polymer used. Increasing the VEGF content in the lyophilized particles did not increase the VEGF release rate, an effect attributed to the solubility limit of VEGF in the solution formed upon dissolution of the particles. The VEGF released retained its bioactivity at greater than 95% of that of as-lyophilized VEGF, as assessed using a human aortic endothelial cell proliferation assay. This high bioactivity was supported by in vivo release experiments, wherein VEGF containing polymer implants induced the generation of significantly greater numbers of blood vessels towards the polymer implant than controls. The blood vessels did not remain stable and were reduced in number by three weeks, due to the unsustained and low concentration of VEGF released. This formulation approach, of using a low viscosity polymer delivery vehicle, is potentially useful for localized delivery of acid-sensitive proteins, such as VEGF.

Revascularization of rat fasciocutaneous flap using CROSSEAL with VEGF protein or plasmid DNA expressing VEGF.

BACKGROUND: Fasciocutaneous tissue transfer is a common reconstructive procedure. Revascularization of flap tissue is an important component of tissue healing. Gene therapy offers an avenue through which the period of pedicle vascular dependency can be reduced. MATERIALS AND METHODS: Rat fasciocutaneous flaps were elevated and a two-hour ischemic time induced. Polycation complex (jet PEI) and human fibrin sealant CROSSEAL was applied between flap and underlying abdominal tissues. Group 1 (six rats) was the control; Group 2 (seven rats) had vascular endothelial growth factor (VEGF) protein applied; Group 3 (seven rats) had plasmid DNA expressing VEGF applied. Vascular pedicles were ligated on postoperative day 5, percentage flap survival evaluated on day 7. RESULTS: All flaps survived initial ischemia. Mean +/- SD percentage area of the flap that survived was 28.1 +/- 12.4 (Group 1), 71.6 +/- 16.2 (Group 2), and 77.5 +/- 12.7 (Group 3) (P < 0.001, Group 1-3, 2-3). No differences were observed between Groups 2 and 3. CONCLUSIONS: Locally administered VEGF protein or plasmid DNA expressing VEGF enhanced survival of fasciocutaneous flaps.

Recombinant leptin administration improves early angiogenesis in full-thickness skin flaps: an experimental study.

BACKGROUND: Leptin is a potent direct angiogenic factor that stimulates endothelial cell migration and activation in vitro, and angiogenesis in vivo. In addition, leptin seems to play an important role in angiogenesis as it promotes the formation of new blood vessels. OBJECTIVE: To determine the effect of local application of exogenous leptin on the survival of full thickness skin flaps in an experimental animal model. MATERIALS AND METHODS: Ninety Sprague-Dawley rats were used in this study. A full thickness dorsal flap (10 cm x 2 cm) with the pedicle located at the level of the iliac crest was designed. Animals were divided into ten groups of nine animals each. In the distal two thirds of the flap and by means of subdermal injection at 8 different locations, rats were injected with 100 ng/ml leptin, 250 ng/ml leptin, 500 ng/ml leptin, 1000 ng/ml leptin (groups A, B, C and D), 1 microg/ml VEGF (group E), or 1 ml saline (control group), respectively. For each of the four leptin doses used, another animal group was injected with a combination of leptin/antileptin: 100 ng/ml leptin with 150 ng/ml antileptin, 250 ng/ml leptin with 375 ng/ml antileptin, 500 ng/ml leptin with 750 ng/ml antileptin or 1000 ng/ml leptin with 1500 ng/ml antileptin (groups A1, B1, C1 and D1, respectively), in order to study the inhibition of the leptin factor. Nine rats served as controls and were injected with 1 ml saline solution. Rats were sacrificed 3, 7 and 9 days postoperatively. After sacrifice of the animals, the skin was grossly arranged on its appearance, colour and texture. Full thickness skin flaps were dissected for histological examination. A qualitative analysis of angiogenesis in the flap 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: Immunohistochemical staining revealed that more granulation tissue and improved angiogenesis were observed in group D (1000 ng/ml leptin) flaps compared to those in the VEGF, leptin/antileptin and saline groups. In addition, skin flap survival rate in group D (1000 ng/ml leptin) and group E (1 microg/ml VEGF) were significantly better than those of the other groups. The most impressive formation of new blood vessels was noted in the groups with the higher leptin doses. Surgical wounds in the control, as well as in the leptin/antileptin groups, did not demonstrate any new vessels. CONCLUSION: Exogenous administration of recombinant leptin increases early skin flap angiogenesis in an experimental animal model. Local application of leptin could efficiently improve survival of ischemic skin flaps.

[The effects of vascular endothelial growth factor on survival of reverse flow axial skin flaps].

OBJECTIVE: To research the effects of vascular endothelial growth factor (VEGF) on the survival of reverse flow axial skin flaps. METHODS: A 8 cm x 2 cm full thickness transverse dorsal flap based on right deep circumflex iliac artery was elevated in 20 Sprague-Dawley rats, which length crossing midline was 4.0 cm. The rats were randomized into two groups:experimental group n = 10), subcutaneous VEGF injections into the flap (200 ng, 200 microl) after flap elevation; control group (n = 10), subcutaneous saline injections into the flap (200 microl) after flap elevation. The flap was immediately sutured to its recipient beds then the injection was executed. Seven days after operation, the survival area of flaps and density of vessels were observed and measured, meanwhile its histological representation of the flaps was examined. RESULTS: After 7 days of recovery, the mean survival area of flaps was 15.55+/-0.27 cm2 in experimental group and 13.42+/-0.57 cm2 in control group. The difference was significant between experimental group and control group (P<0.01). The mean vessel density of flaps was 21.00+/-3.16 in control group and 34.40+/-3.75 in experimental group. The difference was significant between experimental group and control group (P < 0.01). Histological analysis demonstrated that a qualitatively greater amount of granulation tissue, regular collagen fiber and a lot of fibrillated cells were observed in experimental group. Erythrocytes were leaked out from vessels, and inflammatory cells were observed around in control group. CONCLUSION: In early survival of flaps, the VEGF can improve the survival of a reverse flow axial skin flap through improving angiogenesis and increasing the perfusion of vessel. It is an effective method of improving the survival of reverse flow axial skin flaps that VEGF is fully injected in subcutaneous flaps by single, when flaps are elevated.