Survival Of Ischemic Skin Flaps Research Articles

Relaxation matters: comparison of in-vitro vasodilatory role of botulinum toxin-A and papaverine in human radial artery grafts

BackgroundRadial artery (RA) is widely used in coronary artery bypass (CABG) surgery and the prevention of spasm is crucial for graft patency. Botulinum toxin A (BTX-A) and B are commonly used for aesthetic reasons and neuromuscular disorders. They are proven to raise blood flow and increase survival of ischemic skin flaps. In this study we evaluated and compared the vasodilator effects of BTX-A and papaverine on human RA grafts.MethodsAfter resting 60 min in isolated organ baths, human RA grafts were examined. Contraction responses for different doses of serotonin (5-HT) and endothelin-1 (ET-1) were evaluated as a percent of maximum contraction response elicited by 80 mM potassium chloride (KCl). The inhibitory effects of BTX-A and papaverine on contraction responses taken at the 0th hour were compared with the 1st and 2nd hour responses. Inhibitory effects of BTX-A and papaverine against the contractile agent were evaluated by comparing the results of the first and last (0th and 2nd hour) application.ResultsIn low concentrations, when we compared the effects of BTX-A (10− 8 M) and papaverine (10− 6 M) on 5-HT, papaverine was found to be more effective at both the 0th and 2nd hour (p < 0.05). Both BTX-A and papaverine inhibited the maximum contractile effect of ET-1 to the same extent at the 0th hour; but, the inhibitory effect of BTX-A was significantly stronger at the 2nd hour (p < 0.05).In high concentrations, when we compared the effects of BTX-A (10− 6 M) and papaverine (10− 4 M) on 5-HT, papaverine showed stronger inhibition (p < 0.05), whereas both agents had similar action of inhibition on ET-1 mediated maximum contraction responses.ConclusionBTX-A inhibits both ET-1 and 5-HT induced contractions and its effectiveness does not decrease over time as observed with papaverine. This study is the first in the literature using human RA for prevention of vasospasm by BTX-A.

Botulinum toxin type A induces protective autophagy in human dermal microvascular endothelial cells exposed to an in vitro model of ischemia/reperfusion injury.

Botulinum toxin type A (BTXA) has been reported to increase the survival of ischemic skin flaps; however, the exact mechanism underlying this effect remains unclear and needs to be further established. The present study aimed to elucidate whether autophagy caused by BTXA functions as a protection mechanism and to identify the mechanisms of its regulation by BTXA in human dermal microvascular endothelial cells (HDMECs) subjected to hypoxia/reoxygenation (H/R)-induced injury. HDMECs were harvested from the upper eyelid tissues of female blepharoplasty patients. HDMECs were exposed to BTXA treatment for 12 h and then subjected to hypoxia for 8 h, followed by reoxygenation for 24 h. Chloroquine diphosphate salt (CQ) was used as an autophagy inhibitor. H/R led to extreme injury to the HDMECs as indicated by the rise in the apoptosis rate, which was significantly attenuated by BTXA pretreatment. The outcomes demonstrated that H/R caused autophagy, as evidenced by a higher type II/type I ratio of light chain 3 (LC3), increased expression of Beclin-1 and increased autophagosome formation. BTXA enhanced autophagy and attenuated apoptosis in a dose-dependent manner, whereas CQ attenuated the BTXA antiapoptotic effects and inhibited the formation of autophagolysosomes, which caused clustering of the LC3-II in cells. In conclusion, autophagy promoted by BTXA serves as a potential protective effect on ischemia/reperfusion injury.

LB1612 Botulinum toxin B suppresses the pressure ulcer formation in cutaneous ischemia-reperfusion injury mouse model: Possible regulation of oxidative and endoplasmic reticulum stress

There is increasing evidence that cutaneous ischemia-reperfusion (I/R) injury is associated with the development of pressure ulcers (PUs). Botulinum toxin (BTX) suppress the release of neurotransmitters such as acetylcholine in the neuromuscular junction. Several studies have demonstrated that BTX enhanced the blood flow and survival of ischemic skin flaps in animal cutaneous flap models. The objective of this study is to assess the effects of BTX-B on the formation of PUs in the cutaneous I/R injury. In the cutaneous I/R injury mouse model, I/R injury-induced vascular damage, hypoxic area, and the number of oxidative stress-associated DNA-damaged cells and apoptotic cells were suppressed by BTX-B injection. BTX-B significantly inhibited cutaneous I/R injury-induced oxidative stress in OKD48 mice by bioluminescence. BTX-B reduced the I/R-induced mRNA levels of oxidative stress-associated factors, including HO-1, Nox2, and Nrf2. In an in vitro assay, BTX-B significantly inhibited the oxidant-induced ROS and apoptotic endothelial cells and fibroblasts. In addition, BTX-B significantly inhibited cutaneous I/R injury-induced endoplasmic reticulum (ER) stress in ERAI mice by bioluminescence. Cutaneous I/R injury-induced ER stress-response factors and GRP78/BiP- and CHOP-positive cells in the I/R area were significantly decreased by BTX-B injection. These results suggest that BTX-B injection might have protective effects against PU formation after cutaneous I/R injury by reducing vascular damage, inhibiting hypoxia-induced oxidative cellular damage, decreasing oxidative and ER stress, and preventing apoptosis.

Effects of Morroniside on the Viability of Random Skin Flaps in Rats

ABSTRACTObjective: The purpose of our experiment was to determine whether morroniside can improve the survival of ischemic skin flaps in rats. Methodology: A total of 40 male Sprague-Dawley rats were randomly divided into two groups (control group and treatment group). Modified McFarlane flaps were performed (causally based, 9 cm × 3 cm). The percentage of survival of each flap was calculated. Flap blood flows were measured by Laser-Doppler flowmeter. Flap vasculature was assessed by angiography after Lead oxide-gelatin injection. Vascular endothelial growth factor (VEGF) was evaluated by immunochemistry. Superoxide Dismutase (SOD) level and malondiadehyde (MDA) content were determined using assay kits. Results: At the seventh postoperative day, the morroniside-treated rats showed a higher percentage of flap survival than the control rats. Flap perfusion and the level of vascular endothelial growth factor were significantly elevated in the morroniside-treated group. In the treatment group, the distal section of the flap was nearly saturated with contrast agent, while in the control group, the contrast agent perfused only half of the flap. In the treatment group, morroniside administration significantly increased SOD level and reduced MDA content. Conclusion: Morroniside can enhance ischemic flap survival.

Enhanced survival of ischemic skin flap by combined treatment with bone marrow-derived stem cells and low-level light irradiation.

The aim of this study is to examine the enhanced survival effect of ischemic skin flap by combined treatment with bone marrow-derived stem cells (BMSCs) and low-level light irradiation (LLLI). The neovasculogenic effect of BMSCs induced by LLLI was detected using a wound healing and tube formation assay. ICR mice were divided into four groups: control group, LLLI group, BMSCs group, and combine-treated group. The percentage of skin flap necrosis area was calculated on the seventh post-operative day. Specimens were harvested for histologic analyses. LLLI promoted BMSC migration and tube formation. The flap survival rate of combined treated group was significantly higher than that of the control group. Histologic results demonstrated a significant increase in neovascularization in the combined treatment group. This study demonstrates that combination treatment of BMSCs and LLLI could enhance the survival of ischemic skin flap in a mouse model.

Evaluation of the Effect of Bosentan-Mediated Endothelin Receptor Blockade on Flap Survival in Rats: An Experimental Study.

Local skin flaps are important tools for performing plastic surgery. Skin flaps are used for closure of defects after tumor excision or in tissue losses after trauma. However, problems associated with these flaps are commonly encountered, particularly in areas of marginal necrosis. Bosentan is a vasodilator that exerts its effect through endothelin receptor blockade, and has been shown to prevent ischemic tissue damage. However, no reports have addressed the effect of bosentan on skin flaps. The aim of the study was to investigate the effects of bosentan, which may be applied clinically to promote survival of ischemic skin flaps. A modified McFarlane flap was elevated in the dorsum of 20 Albino Wistar rats with a width-to-length ratio of 3 to 10 cm, respectively, with the caudal base. Perioperatively, 0.9% of physiologic NaCl and injectable distilled water of identical volume were injected into rats in Group 1 (n = 10), and 5 mg/kg bosentan was injected intraperitoneally into rats in Group 2 (n = 10). All of the rats were followed up for 7 days postoperatively. The surviving parts of the flaps were measured at the end of day 7. Acute and chronic inflammation, amount of granulation tissue, fibroblast maturation, amount of collagen, and amounts of reepithelialization and neovascularization present in the ischemic zones of the distal parts of the flaps were evaluated histopathologically, and results were compared statistically. The mean flap survivals were 61.1% in Group 1 and 91.1% in Group 2; the percentage of the surviving flap area in Group 2 was higher than that in Group 1 (p < 0.005). In both groups, there was significantly less acute inflammation in the ischemic zones in Group 2 than in Group 1 (p < 0.005). No significant difference was found in the amounts of chronic inflammation and granulation tissue between the two groups (p > 0.005). Fibroblast maturation, amount of collagen, and amounts of reepithelialization and neovascularization investigated in Group 2 were statistically significantly higher than those in Group 1 (p < 0.005). We believe that bosentan may be used prophylactically to increase survival in risky skin flaps because it decreases ischemic necrosis distal to skin flaps, thus exerting favorable effects on flap survival.

Effect of Amniotic Membrane Homogenate on Ischemic Skin Flap Survival in Rat Model

Effect of Amniotic Membrane Homogenate on Ischemic Skin Flap Survival in Rat Model

Effect of Amniotic Membrane Homogenate Homogenate on Ischemic Skin Flap Survival in Rat Model

Effect of Amniotic Membrane Homogenate Homogenate on Ischemic Skin Flap Survival in Rat Model

The effect of autologous endothelial progenitor cell transplantation combined with extracorporeal shock-wave therapy on ischemic skin flaps in rats

BackgroundEndothelial progenitor cells (EPCs) have been used to revascularize ischemic tissues, but only limited effect can be achieved. Extracorporeal shock-wave therapy (ESWT) is a promising angiogenic strategy. We hypothesized that EPC transplantation combined with ESWT would greatly benefit the survival of ischemic skin flaps. MethodsSixty-four male Sprague-Dawley rats were divided into 4 groups (n = 16 in each group): group 1 (serving as sham control), group 2 (treated with subcutaneous EPC implantation, 1.0 × 106 cells), group 3 (treated with ESWT, 300 impulses at 0.10 mJ/mm2) and group 4 (treated with EPCs implantation combined with ESWT). Ischemic skin flaps were made on the backs of rats and treated accordingly. Blood flow of skin flaps was measured periodically after operation, and flap survival rates were compared. Tissue samples were harvested at 2 weeks postoperatively from each group. ResultsThe survival rate of skin flaps in group 4 was 87.5 ± 10.23%, which was statistically significantly higher than other groups. Histologic examination showed that the capillary density was higher in the dual-treatment group than in the two single-treatment groups. Compared with groups 2 and 3, blood perfusion increased significantly in group 4. A drastic increase of vWF+ cells was observed in the ischemic skin flaps on immunofluorescence staining in group 4. The expressions of chemotactic factors and angiogenic factors were higher in group 4. ConclusionsCombined treatment with EPCs and ESWT is superior to either EPCs or ESWT alone in improving the survival of ischemic skin flaps in rats.

Effect of pcDNA3.1(+)-mediated vascular endothelial growth factor gene on the survival of skin flap

Objective To investigate the effectiveness of PcDNA3.1 ( + )-mediated gene therapy of vascular endothelial growth factor (VEGF) delivered into the subcutaneous space to treat experimental skin flaps in rats.Methods Thirty Sprague-Dawley rats were randomly divided into three groups ( n =10each).In pcDNA3.1 ( + )-VEGF group,rats were given subcutaneous injections of pcDNA3.1 ( + )-VEGF 30 μg/100 μL; In VEGF group,rats were given subcutaneous injections of VEGF 100 ng/100 μL;In NS group,rats were given subcutaneous injections of normal saline.Pedicled flap (7 cm× 3 cm) of full thickness was made on rats back in each group 48 h after subcutaneous injections.The survival rate was measured and immunohistochemical examinations were done 10 days after operation.Results The survival rate of the flap in pcDNA3.1-VEGF group was increased significantly as compared with the other two groups (P＜0.01).Immunohistochemical staining showed that VEGF was highly expressed in the pcD-NA3.1 ( + )-VEGF group.Conclusion Subcutaneous injections of pcDNA3.1 ( + )-VEGF efficiently improve the survival of ischemic skin flap. Key words: Vascular endothelial growth factor; Skin flap; Gene therapy

Local Transplant of Human Umbilical Cord Matrix Stem Cells Improves Skin Flap Survival in a Mouse Model

A skin flap is a piece of skin that has its own blood supply, which is useful to repair large skin defects and deep wounds in plastic surgery. However, partial skin flap necrosis usually occurred. Bone marrow mesenchymal stem cells (BM MSCs) are effective in improving the ischemic flap survival, but their clinical application is restricted by their limited source. Human umbilical cord matrix stem (HUCMS) cells are easily isolated in a large number, compared to BM MSCs. In this study, we evaluated the therapeutic potential of HUCMS to improve the survival of ischemic skin flap. HUCMS cells were characterized with surface markers, and were labeled with 5-acetylene base-2 'deoxidizing uracil nucleoside (EdU) in vitro. Twenty male immunodeficient BALB/c mice with an epigastric flap were randomly divided into two groups. HUCMS cells or Dulbecco's Modified Eagle Medium (DMEM) were injected into the subcutaneous flap tissues. On the 7th postoperative day, flap survival, capillary density, levels of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), and EdU-positive cells in the skin flap were examined. Results showed that flap survival rate was higher in the HUCMS cell group (P < 0.05). Capillary density, VEGF level, and bFGF level were higher in the HUCMS cell group (P < 0.05). EdU-labeled HUCMS cells were mainly distributed in the subcutaneous flap tissues. These findings suggest that HUCMS cells can improve the survival of ischemic skin flap by promoting vascularization, which may be attributed to the increased expression of VEGF and bFGF.

Chronic Lithium Impairs Skin Tolerance to Ischemia in Random-Pattern Skin Flap of Rats

Despite its apparent anti-apoptotic effect, lithium impairs endothelium-dependent vasorelaxation in various tissues. In this study, we assessed the effect of lithium treatment on ischemic skin flap survival and its interaction with nitric oxide pathway. Seventy-six male Sprague-Dawley rats were randomly assigned into 13 groups. For skin flap surgery, dorsal skin flap measuring 8 × 2 cm was elevated on the midline. After local injections (if needed), the cranial pedicle was cut and flap was sutured back. Flap survival was assessed after 7 d. Animals in the chronic lithium group received lithium chloride in tap water for 4 wk preoperatively and 7 d postoperatively. Acute lithium groups received 3 nmol, 10 nmol and 3 μmol/flap lithium locally. In another experiment, interaction with nitric oxide synthase inhibitor L-NAME as well as nitric oxide precursor L-arginine was studied, and the effect of ischemic preconditioning on skin flap survival in lithium treated rats was investigated. Chronic lithium group had mean flap survival value of 32.6% ± 5.2% (mean ± SD), which was significantly lower than normal subjects (52.7% ± 6.1%, P < 0.001), while acute local lithium treatment had no effect. In chronic lithium group, systemic L-NAME (10 mg/kg, 30 min before flap elevation) failed to significantly decrease the survival, while sub-effective systemic L-arginine (100 mg/kg) and ischemic preconditioning significantly increased flap survival (P < 0.001 and P < 0.01, respectively). We conclude that long-term lithium treatment impairs the skin tolerance to ischemia in rats, which seems to be nitric oxide mediated. This effect is prevented by ischemic preconditioning or L-arginine treatment. The results suggest that skin-involving interventions should be applied more cautiously in patients who are on lithium treatment.

Activated Protein C Improves Ischemic Flap Survival and Modulates Proangiogenic and Antiinflammatory Gene Expression

Flap necrosis remains a major complication in reconstructive surgery. The authors evaluated whether systemic activated protein C, a natural serum anticoagulant with anti-inflammatory, proangiogenic, and cytoprotective properties, can improve ischemic skin flap survival. Cranially based dorsal cutaneous flaps were elevated on 44 rats. Animals received intravenous injections of activated protein C (25 microg/kg) or saline. Rats were divided into three groups depending on the timing of the first injection: postoperative (45 minutes postoperatively, n = 12), late preoperative (45 minutes preoperatively, n = 5), and early preoperative (3 hours preoperatively, n = 5). In all groups, second and third injections were performed at 3 and 24 hours postoperatively. Flap survival was measured on day 7. Histological and real-time polymerase chain reaction specimens were collected on days 2 and 7 and at 3 and 24 hours, respectively. Postoperative activated protein C improved flap survival (68.9 +/- 4.3 percent) compared with control treatment (39.3 +/- 1.5 percent; p < 0.001). Late preoperative treatment produced diffuse flap hemorrhage. Early preoperative activated protein C injection produced near-complete flap survival (96.1 +/- 1.1 percent for activated protein C versus 50.1 +/- 3.3 percent for control; p < 0.001). Significantly fewer inflammatory cells, improved muscle viability, and increased blood vessel density were observed in activated protein C-treated versus control rats. Activated protein C treatment significantly reduced mRNA levels of intercellular adhesion molecule-1 and tumor necrosis factor-alpha, while increasing levels of Egr-1, vascular endothelial growth factor receptor 2, and Bcl-2. Systemic activated protein C modulates genes involved in angiogenesis, inflammation and apoptosis and improves ischemic flap survival.

The Effect of Fibrin on the Survival of Ischemic Skin Flaps in Rats

Skin flap necrosis is one of the hazards encountered in plastic and reconstructive surgery. Angiogenic agents may be useful for treating it by increasing blood flow. The angiogenic effect of fibrin in vitro has been demonstrated, but little is known about its in vivo effect. Te authors tested the hypothesis that local application of fibrin can improve the survival of ischemic skin flaps. A cranially based dorsal skin flap (3 x 7 cm) was made in each rat. Fibrin (8 mg suspended in 400 microl of phosphate-buffered saline) was applied to the subcutaneous side of elevated skin flaps in the experimental group (n = 15), and phosphate-buffered saline alone was delivered in the control group (n = 15). Tissue blood flow of the skin flaps was measured four times (before the operation and on days 1, 3, and 7) at 1, 3, and 5 cm distal to the baseline of the skin flap. The survival rate of the skin flaps was measured on day 7 and histologic assessments were performed. The blood flow change rate at 5 cm in the experimental group was significantly higher than that in the control group on day 7 (60.9 +/- 5.7 percent versus 13.7 +/- 4.8 percent, p < 0.001). The survival rate of skin flaps was also significantly improved in the experimental group (77.0 +/- 2.0 percent) in comparison with the control group (54.7 +/- 2.2 percent, p < 0.01). Histologic analysis showed many more blood vessels in the experimental group in comparison with the control group. The local application of fibrin could improve the blood flow and survival of ischemic skin flaps.

Oral administration of nicorandil enhances the survival of ischemic skin flaps in rats

Nicorandil has an anti-apoptotic effect on ischemic myocardium through the activation of ATP-sensitive potassium (K ATP) channel. We tested the hypothesis that oral administration of nicorandil had a protective effect on ischemic skin flaps. A cranially based skin flap measuring 3 × 7 cm in full thickness was made on the back of rats. The rats were divided into a control group and 8 nicorandil groups (group 1–8) according to different doses and timings of administration. On day 7 at 5 cm, groups 1 to 6 (10 or 30 mg/kg twice per day for 3 days starting at 24 h before, 0.5 h before or 0.5 h after the operation) showed significantly higher blood perfusion change rate (73.3 ± 2.9%–79.1 ± 4.1% vs. 25.9 ± 8.6%, P < 0.01), and significantly higher survival rate (68.8 ± 4.8–75.2 ± 8.2% vs. 47.0 ± 2.8%, P < 0.05) than the control group. Many more surviving blood vessels were also observed in these groups. In contrast, no significant effects were found either in group 7 (30 mg/kg twice per day for 3 days starting 24 h after the operation) or group 8 (30 mg/kg once at 0.5 h after the operation). We did not find an angiogenic effect of nicorandil in vitro. Therefore, our results confirmed that the oral administration of nicorandil could protect tissues from necrosis in ischemic skin flaps. In addition, its protective effect depends on the time of first administration and the duration.

Efficacy of Combination Gene Therapy with Multiple Growth Factor cDNAs to Enhance Skin Flap Survival in a Rat Model

The objective of this study was to investigate the efficacy of combination gene therapy with multiple angiogenic growth factor cDNAs to enhance survival of ischemic skin flaps in a rat model. Sixty Sprague-Dawley rats were divided into six groups. Varying combinations of VEGF165, PDGF-B, and bFGF-plasmids were injected to prefabricate the flaps. Random skin flaps were raised on the dorsal aspect of rats following prefabrication with growth factor cDNAs. Flap viability was determined by measurement of percentage area of survival. The efficacy of gene therapy was evaluated by flap survival and neovascularization of representative histologic sections stained immunohistologically. The VEGF165 plus bFGF cDNAs enhanced the viability of the flap and neovascularization most effectively; the flap survival area was 64.3 +/- 8.7% after transfer of these two growth factor genes. Addition of PDGF-B cDNA is deleterious to the effects of combined VEGF165 and bFGF, leading to a significant decrease in flap viability (44.9 +/- 2.7%). Viability of the flaps with combined VEGF165 and bFGF cDNA transfer was significantly greater than that of the flaps with VEGF165 transfer alone (57.6 +/- 5.2%) or sham plasmid control (52.3 +/- 5.0%). Combined transfer of VEGF165 and bFGF cDNA is the most effective combination of multiple growth factor genes to improve flap viability in this model. Simultaneous transfer of three growth factor genes (VEGF165, PDGF-B, and bFGF) is deleterious to flap survival, at least for the ratio of lipofectin:transgene employed.

Gene transfer of bFGF to recipient bed improves survival of ischemic skin flap

The recipient bed is a promising target of angiogenic therapy to treat ischemic skin flaps. We delivered basic fibroblast growth factor (bFGF) gene to the recipient bed by a plasmid-based method with electroporation, and assessed the effects on flap viability in a rat dorsal skin flap model. A 25 x 90 mm(2) axial skin flap was elevated on the back of male Sprague-Dawley rats. Two days before flap elevation, an expression plasmid vector containing the bFGF gene with the signal sequence was injected into the dorsal muscles beneath the skin flap, and then electroporation was delivered (FGF-E(+) group). As control, rats were injected with a plasmid vector containing LacZ gene (LacZ-E(+) group), instead of bFGF gene. Other groups of animals received plasmid vector containing bFGF (FGF-E(-) group) or LacZ (LacZ-E(-) group) gene without electroporation. Seven days later, the area of necrosis and neovascularisation of the skin flap were evaluated. The bFGF gene was successfully transferred to the dorsal muscles, and bFGF was expressed in muscle tissue. The area of flap necrosis (%) in the FGF-E(+) group (21.7+/-5.3%) was significantly smaller than that in the LacZ-E(+) (28.3+/-4.1%), FGF-E(-) (29.7+/-3.3%), and LacZ-E(-) (28.1+/-2.5%) groups. Postmortem angiograms and histological analyses showed that vascularisation in the distal part of the skin flap was significantly increased in the FGF-E(+) group compared with the other groups. These findings suggested that gene delivery of bFGF to the recipient bed muscles enhanced vascularity and viability of an ischemic skin flap, and that plasmid-based gene delivery with electroporation was a suitable delivery method.

Promotion of the survival of ischemic skin flap by transplanted endothelial progenitor cells transfected with VEGF165 gene: an experimental study with mice

To investigate the feasibility of transplanted endothelial progenitor cells transfected with VEGF165 gene to ischemic flap with increased neovascularization and augmented the survival areas. EPCs were isolated from human cord blood and cultured in vitro. Plasmid PcDNA3.1(-)/VEGF165 containing VEGF gene was transfected into the EPCs. EPCs transfected with blank plasmid, and EPCs without transfection were used as controls. ELISA was used to detect the expression of VEGF protein in the culture fluids. The EPCs were dyed with CM-DiI 7 days later. Ischemic skin flaps were made on the backs of 27 nude mice. The mice were randomly divided into 3 equal groups with their skin flaps being transplanted with EPCs transfected with 3.1(-)/VEGF165 plasmid, EPCs not transfected with 3.1(-)/VEGF165 plasmid, and injected with M199 medium at the basal part. Four days after the peduncles of the skin flaps were cut. Seven days after the cutting-off of the peduncles the survival rate of skin flap was observed and the blood perfusion was observed with laser Doppler flowmetry, 10 days after the density of capillary arteries were observed with microcirculation microscope. Three specimens of skin flap were taken 7 and 11 days after the skin flaps were made to undergo histological examination to detect the density of capillary arteries by CD34 immunohistochemistry and to observe the proliferation of EPCs with fluorescence microscopy. Peripheral blood samples were collected 1, 4, 7, 14, and 28 days after the skin flaps were made to undergo ELISA to detect the levels of VEGF protein The VEGF levels in the culture supernatants of the groups A, B, and C were 352 ng/L +/- 35 ng/L, 45 ng/L +/- 5 ng/L, and 0 ng/L respectively with significant difference between any 2 groups (all P < 0.05). The skin flap survival rates of the three groups were 97.2%, 60.3%, and 34.2% respectively with significant difference between any 2 groups (all P < 0.05) and the survival quality of the group A was the best. The capillary density of the group A was greater than those of the groups B and C. The VEGF levels at any time point of the group A were all significantly higher than those of the group B and C (all P < 0.05) and there was not a significant difference between the groups B and C. The capillary density levels at different time points decreased progressively in the order of groups A, B, and C with significant difference between any 2 groups (all P < 0.05). No EPC was shown by fluorescence microscopy in the skin flaps of the group C. The EPC density in skin flap 7 and 11 days after the flaps were made were 136 +/- 10 and 75 +/- 6/mm(2) and 305 +/- 26 and 199 +/- 18/mm(2) respectively with significant differences between the groups A and B. (both P < 0.05). The EPCs from human cord blood, especially those transfected with VEGF165 gene increases the neovascularization in ischemic skin flaps and augments their survival rate.

Efficacy of postoperative steroids on ischemic skin flap survival in rats

Necrosis of skin flaps remains a significant clinical problem. This study examined whether steroids improve skin flap survival in rats. Random skin flaps were raised in 30 male Sprague-Dawley rats. Intramuscular methylprednisolone (n=15) or saline solution (n=15) were administered 1, 24, and 48 h after flap elevation. Surviving flap areas were measured after 7 days. The mean surviving flap area in the methylprednisolone group was greater than that in controls (916 vs. 675 mm). These results suggest that postoperative methylprednisolone improves skin flap viability in the ischemic rat flap model.

Role of vitamin E in ischemic skin flap survival in rats.

Role of vitamin E in ischemic skin flap survival in rats.