Wound Healing/Plastic SurgeryAngiogenic effects of injected VEGF165 and sVEGFR-1 (sFLT-1) in a rat flap model
Introduction
Our previous studies have shown that functional angiogenesis can be induced in flap tissue by means of genetic modification and transplantation of isogenic cells 1, 2. Now the impact of local, direct application of vascular endothelial growth factor (VEGF165) to induce functional angiogenesis in the same flap model was examined without using gene transfer techniques. Several authors have recently reported that local application of VEGF165 may improve survival of ischemically challenged tissue 3, 4, 5, 6. However, none of the studies could prove that the induction of angiogenesis was directly VEGF165-dependent. Evidence for this hypothesis can be given only by selective blocking of applied VEGF165.
The soluble human receptor 1, VEGFR-1 (sFLT-1), represents a member of the VEGF-receptor (VEGFR) family and is able to prevent VEGF signaling through the cell surface receptor by several means 7, 8. Therefore, the aim of this study was to examine the angiogenic effects of VEGF165 and its inhibition by sVEGFR-1 in a rat flap model.
Section snippets
Purification of recombinant VEGF165 by heparin-affinity chromatography
For purification of VEGF165 (National Research Center for Biotechnology, Braunschweig, Germany) protein from insect-cell supernatant acid precipitable proteins were removed by acidification of the supernatant to pH 3.5 and centrifugation at 10.000g for 15 min at 4°C. The supernatant was vacuum filtered through a 0.45-μm nitrocellulose membrane. After adjusting the pH to 6.5, the NaCl concentration of the supernatant was increased to 0.4 M and VEGF165 was applied on to a heparin-Sepharose
Induction of DNA synthesis in human vascular endothelial cells by VEGF165
Concentrations between 2.5 and 5.0 ng/ml were sufficient to maximize stimulation of DNA-synthesis. Results are shown in Fig. 2.
Flap survival rate in groups 1 and 2
Flap survival was slightly higher in group 1C, compared with groups 1A and 1B without reaching statistical significance (P = 0.189 for 1C versus 1A, P = 0.341 for 1C versus 1B). Comparing group 1C with 1D, however, significantly more flap tissue survived in group 1C (P = 0.037 for 1C versus 1D). Flaps in group 2C showed slightly better survival rates, compared with all
Discussion
In this study, we tested the impact of direct application of VEGF165 to induce functional angiogenesis in a McFarlane rat flap model. Local application of single-dose VEGF165 1 week prior to ischemia had some, but no significant, angiogenic effects in group 1C clinically. By adding the 10-fold amount of VEGFR-1 in group 1D, flap survival was significantly reduced compared with group 1C (P = 0.037). A single-dose of VEGF165 (group 2C) or VEGF165 plus the 10-fold amount of VEGFR-1 (group 2D)
Acknowledgements
This study was supported by a grant from German Research Society (D.F.G) (Ma1951/2-1).
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Cited by (28)
Co- localization of Flt1 and tryptase of mast cells in skin wound of rats with type I diabetes: Initial studies
2021, Acta HistochemicaCitation Excerpt :They observed that application of VEGF (165) seven days earlier than the ischemia did not have any noteworthy medical angiogenic impact. In their study, VEGF (165)-encouraged angiogenic impacts could be meaningfully suppressed by the addition of Flt-1 in vivo (Machens et al., 2003). Mast cells have been proposed to influence many other biological processes, including responses to bacteria and virus, angiogenesis, wound healing, fibrosis, diabetes, and cancer.
Hirudin promotes angiogenesis by modulating the cross-talk between p38 MAPK and ERK in rat ischemic skin flap tissue
2015, Tissue and CellCitation Excerpt :These results indicate that hirudin suppress TSP-1 expression via inhibiting thrombin/p38 MAPK pathway in ischemic flap tissue. Experimental studies have indicated that up-regulation of VEGF can induce regional angiogenesis and improve the survival rate of overdimensioned flaps (Machens et al., 2003; Zhang et al., 2000). Administration of VEGF at the distal part of a long random skin flap could stimulate neovascularization (Vourtsis et al., 2012).
The influence of different VEGF administration protocols on the perfusion of epigastric flaps in rats
2013, British Journal of Oral and Maxillofacial SurgeryCitation Excerpt :Any differences caused by injection of VEGF into the wound bed have not yet been investigated. This study has shown that in an ischaemic flap model the initiation of angiogenesis in the process of wound healing is more important than the continuous or exact time point of giving VEGF.2,14–17 As indirect measures, SO2, Hb, blood flow, and change in velocity over time progressed as wounds healed and full perfusion was achieved.18,19
Effects of taurine on reperfusion injury
2011, Journal of Plastic, Reconstructive and Aesthetic SurgeryAn old dream revitalised: preconditioning strategies to protect surgical flaps from critical ischaemia and ischaemia-reperfusion injury
2008, Journal of Plastic, Reconstructive and Aesthetic SurgeryCitation Excerpt :This classical preconditioning study showed that VEGF-pretreatment is associated with an increased neovascularisation and an augmented flap survival when compared to local injection into the pedicle after flap elevation.137 Later on, a variety of other studies could confirm a 12 h to 14 day time window before flap creation to successfully protect ischaemically endangered tissue by preconditioning with locally applied or generated VEGF.138–141 Despite progress, ischaemia in distal flap areas and ischaemia and reperfusion (I/R)-injury in microvascular flaps are still a major challenge in reconstructive flap surgery, responsible for a considerable number of deleterious complications, which jeopardise flap survival and substantially increase morbidity.
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Hans-Günther Machens, Ph.D., and Jila Salehi, M.S. contributed equally to this paper.