Increases Skin Flap Survival Research Articles

Oxidative stress-induced endothelial cells-derived exosomes accelerate skin flap survival through Lnc NEAT1-mediated promotion of endothelial progenitor cell function

BackgroundFlap transplantation is commonly used in reconstructive surgery. A prerequisite for skin flap survival is sufficient blood supply. However, such approaches remain unclear. This study aimed to explore the underlying mechanisms of exosomes derived from human umbilical vascular endothelial cells (HUVECs) exposed to oxidative stress on endothelial progenitor cells (EPCs) and their subsequent influence on the survival of skin flaps.MethodsHUVECs were treated with various concentrations of H2O2 to establish an oxidative stress model. To investigate the effects of H2O2-HUVEC-Exos and HUVEC-Exos, Cell Counting Kit-8, tube formation, invasion assays, and quantitative real-time polymerase chain reaction (qRT-PCR) were performed in EPCs. Microarray analysis was used to reveal the differentially expressed long non-coding RNAs (lncRNAs) in the H2O2-HUVEC-Exos and HUVEC-Exos. In addition, gene silencing and western blotting were employed to determine the mechanism behind lncRNA nuclear enrichment enriched transcript 1 (Lnc NEAT1) in EPCs. Further, a rat skin flap model was used to determine the role of the exosomes in skin flap survival in vivo.ResultsHUVECs were stimulated with 100 μmol/L H2O2 for 12 h to establish an oxidative stress model. H2O2-HUVEC-Exos promoted the proliferation, tube formation, and invasion of EPCs and remarkably increased skin flap survival compared to the HUVEC-Exos and control groups. Sequencing of exosome RNAs revealed that the Lnc NEAT1 level was dramatically increased in the H2O2-HUVEC-Exos, leading to activation of the Wnt/β-catenin signaling pathway. Comparatively, knockdown of Lnc NEAT1 in HUVEC-Exos and H2O2-HUVEC-Exos significantly inhibits the angiogenic capacity of EPCs, reduced the survival area of skin flap and downregulated the expression levels of Wnt/β-catenin signaling pathway proteins, whereas Wnt agonist partly reversed the negative effect of NEAT1 downregulation on EPCs through the Wnt/β-catenin signaling pathway.ConclusionsExosomes derived from HUVECs stimulated by oxidative stress significantly promoted the pro-angiogenic ability of EPCs through the Wnt/β-catenin signaling pathway mediated by Lnc NEAT1 and hence enhanced random flap survival in vivo. Therefore, the application of H2O2-HUVEC-Exos may serve as an alternative therapy for improving random skin flap survival.

Standardized Skin Flap Warming Effectively Improves Flap Survival without Obstructing Temperature Monitoring after DIEP.

Objective:This study aimed to determine whether skin flap warming after an operation interferes with temperature monitoring. The postoperative nursing workflow of subabdominal deep inferior epigastric artery perforator (DIEP) flap breast reconstruction was optimized.Methods:A retrospective analysis involving 69 patients who received one-stage breast reconstruction at the Huashan Hospital from July 2017 to December 2019 was performed. The postoperative physical care of patients, including flap temperature monitoring and flap warming, was reviewed.Results:All patients had successful operations. After surgery, all flaps were warmed following the standard protocol. Abnormal temperature and compromised circulation of flaps were observed in three of the patients. These patients received re-exploration surgery and all three flaps survived. A postoperative follow-up shows a high level of patient satisfaction in most cases.Conclusions:The appropriate warming of transplanted flaps did not interfere with temperature monitoring. This helped determine whether there was compromised circulation, leading to increased skin flap survival and improved patient satisfaction.

Effects of microneedle length and duration of preconditioning on random pattern skin flaps in rats

To date, the surgical delay of skin flaps is the most common and reliable method that increases skin flap survival. In this study, we aimed to increase skin flap viability using preconditioning by microneedling. Seventy-two Sprague Dawley rats were randomly divided into control, surgical flap delay (SFD), and four microneedling groups (7 or 14 days of preconditioning with 0.5 mm or 1 mm needles). Modified McFarlane flaps were raised on the back of rats. In Group I, a caudal pedicled skin flap was raised and the flap survival rate was assessed on postoperative day 14. In the SFD group, a bipedicled flap was created and after 14 days of surgical delay, all skin flaps were raised. In the microneedling groups, 0.5 mm or 1 mm needles were used for 7 or 14 days. The flap survival rates of all microneedling and SFD groups were significantly higher than the control group. The plasma levels of vascular endothelial growth factor (VEGF) did not significantly differ between groups, but the VEGF level of skin samples in the SFD group was higher than the control group. The vessel counts of all microneedling and SFD groups were statistically higher than the control group in all skin samples taken before raising the flaps, but skin samples taken 14 days after raising the skin flap did not show any difference between groups. We showed that preconditioning by microneedling can be used to improve the viability of critical ischemic skin flaps at a level similar to surgical delay.

Sumatriptan Increases Skin Flap Survival through Activation of 5-Hydroxytryptamine 1b/1d Receptors in Rats: The Mediating Role of the Nitric Oxide Pathway.

Random pattern skin flaps are applicable for reconstructing any defect in plastic surgery. However, they are difficult to apply because of necrosis. Sumatriptan, a selective 5-hydroxytryptamine 1b/1d agonist, is routinely used to offset acute migraine attacks. Recent studies have suggested that sumatriptan may induce vasodilation at lower concentrations. The authors' aim is to investigate the effect of sumatriptan on skin flap survival and the role of nitric oxide in this phenomenon. Seventy-two male Sprague-Dawley rats were divided into eight groups. Increasing doses of sumatriptan (0.1, 0.3, and 1 mg/kg) were given intraperitoneally to three different groups after dorsal random pattern skin flaps were performed. To assess the exact role of 5-hydroxytryptamine 1b/1d receptors, GR-127935 was administered solely and with sumatriptan. N-ω-nitro-L-arginine methyl ester (L-NAME, a nonselective nitric oxide synthase inhibitor) was used to evaluate any possible involvement of nitric oxide in this study. All rats were examined 7 days later. The authors' results demonstrated that flap survival was increased by lower doses of sumatriptan compared to a control group for both 0.3 mg/kg (p = 0.03, mean difference = 32, SE = 8) and 0.1 mg/kg (p = 0.02, mean difference = 26, SE = 8). This protective effect was eliminated by coadministration of GR-127935 or N-ω-nitro-L-arginine methyl ester with sumatriptan. Histopathologic studies revealed a significant increase in capillary count and collagen deposition and a decreased amount of edema, inflammation, and degeneration. Sumatriptan in lower concentration increases skin flap survival by means of activation of 5-hydroxytryptamine 1b/1d receptors. This effect is mediated through the nitric oxide synthase pathway.

Functional genetic variant in the GABRA6 gene interacts with environmental stress to increase the risk of multiple suicide risk-related phenotypes

To date, the surgical delay of skin flaps is the most common and reliable method that increases skin flap survival. In this study, we aimed to increase skin flap viability using preconditioning by microneedling. Seventy-two Sprague Dawley rats were randomly divided into control, surgical flap delay (SFD), and four microneedling groups (7 or 14 days of preconditioning with 0.5 mm or 1 mm needles). Modified McFarlane flaps were raised on the back of rats. In Group I, a caudal pedicled skin flap was raised and the flap survival rate was assessed on postoperative day 14. In the SFD group, a bipedicled flap was created and after 14 days of surgical delay, all skin flaps were raised. In the microneedling groups, 0.5 mm or 1 mm needles were used for 7 or 14 days. The flap survival rates of all microneedling and SFD groups were significantly higher than the control group. The plasma levels of vascular endothelial growth factor (VEGF) did not significantly differ between groups, but the VEGF level of skin samples in the SFD group was higher than the control group. The vessel counts of all microneedling and SFD groups were statistically higher than the control group in all skin samples taken before raising the flaps, but skin samples taken 14 days after raising the skin flap did not show any difference between groups. We showed that preconditioning by microneedling can be used to improve the viability of critical ischemic skin flaps at a level similar to surgical delay.

Use of Systemic Rosmarinus Officinalis to Enhance the Survival of Random-Pattern Skin Flaps.

Skin flaps are commonly used in soft-tissue reconstruction; however, necrosis can be a frequent complication. Several systemic and local agents have been used in attempts to improve skin flap survival, but none that can prevent flap necrosis have been identified. This study aims to determine whether the use of systemic Rosmarinus officinalis (R. officinalis) extract can prevent flap necrosis and improve skin flap recovery. Animal experimentation. Thirty-five Wistar albino rats were divided in five groups. A rectangular random-pattern flaps measuring 8×2 cm was elevated from the back of each rat. Group I was the control group. In Group II, 0.2 ml of R. officinalis oil was given orally 2h before surgery. R. officinalis oil was then applied orally twice a day for a week. In Group III, R. officinalis oil was given orally twice a day for one week before surgery. At the end of the week, 0.2 mL of R. officinalis oil was given orally 2 h before surgery. In Group IV, 0.2 mL of R. officinalis oil was injected subcutaneously 2 h before surgery. After the surgery, 0.2 mL R. officinalis oil was injected subcutaneously twice a day for one week. In Group V, 0.2 mL R. officinalis oil was injected subcutaneously twice a day for one week prior to surgery. At the end of the week, one last 0.2 mL R. officinalis oil injection was administered subcutaneously 2 h before surgery. After the surgery, 0.2 mL R. officinalis oil was injected subcutaneously twice a day for one week. The mean percentage of viable surface area was significantly greater (p<0.05) in Groups II, III, IV, and V as compared to Group I. Mean vessel diameter was significantly greater (p<0.05) in Groups II, III, IV, and V as compared to Group I. We have determined that, in addition to its anti-inflammatory and anti-oxidant effects, R. officinalis has vasodilatory effects that contribute to increased skin flap survival.

Metformin improves skin flap survival through nitric oxide system

BackgroundMetformin has shown cardioprotective effects in experimental models of ischemia reperfusion, which is partially mediated through nitric oxide (NO) synthesis. We investigated the effects of metformin pretreatment in a rat model of random-pattern skin flap, and the probable role of NO system. Materials and methodsIn the first experiment, the rats received increasing doses of metformin (150, 200, and 300 mg/kg), 4 h before the procedure. Dorsal skin flaps with caudal pedicles were elevated at the midline and flap survival was measured 7 d after surgery. Pathologic review of the skin flap specimen was performed in a subset of animals. In the second experiment, for evaluation of the role of NO, an NO synthase inhibitor N-nitro-L-arginine methyl ester hydrochloride (L-NAME) was administered with and without the effective dose of metformin. In the next experiment, subtherapeutic dose of NO precursor, L-Arginine, was administered with and without subeffective dose of metformin. ResultsMetformin pretreatment at doses of 200 and 300 mg/kg significantly increased skin flap survival rate. However, administration of L-NAME abolished the protective effects of metformin. On the other hand, subtherapeutic dose of L-arginine augmented the effects of low-dose metformin and significantly increased skin flap survival. Skin flaps from those rats that received 300 mg/kg metformin pretreatment and those treated with subtherapeutic doses of L-arginine and metformin showed increased vasodilation compared with control group. ConclusionsMetformin pretreatment can improve skin flap survival through an NO dependent pathway.

Overexpressed HIF-2α in Endothelial Cells Promotes Vascularization and Improves Random Pattern Skin Flap Survival

Background:The local skin flap procedure is very useful for reconstruction. However, flap necrosis caused by circulatory failure can occur at its distal portion. Hypoxia-inducible factors (HIFs) in endothelial cells (ECs) help to maintain ECs and promote vascularization, and HIF-2α is abundantly expressed in ECs. However, the mechanisms of action of HIF-2α in ECs are not yet fully understood. The aim of this study was to evaluate the in vivo effects of overexpression of HIF-2α in ECs on skin flap survival.Methods:A random pattern skin flap (1.0 × 3.0 cm) was elevated on the dorsum of transgenic mice (Tg mice) with EC-specific HIF-2α conditional overexpression and wild-type littermate control mice (n = 6). Flap survival was evaluated on postoperative day 7. Tissue samples from the skin flaps were harvested and analyzed using Western blotting, quantitative reverse transcriptase-polymerase chain reaction, and immunohistochemistry.Results:The HIF-2α mRNA and protein levels were significantly increased in the Tg mice when compared with control mice. Tg mice had significantly increased skin flap survival areas (72.0% ± 2.7%) when compared with wild-type mice (45.7% ± 1.1%). Moreover, histological examination revealed an increase in the subcutaneous blood vessel counts in the Tg mice.Conclusions:Specific overexpression of HIF-2α in ECs promoted vascularization and enhanced skin flap survival in vivo in a mouse model.

Topical application of 17β‐estradiol (E2) improves skin flap survival through activation of endothelial nitric oxide synthase in rats

This study investigates the influence of 17β-estradiol (E2) on nitric oxide (NO) production in endothelial cell cultures and the effect of topical E2 on the survival of skin flap transplants in a rat model. Human umbilical vein endothelial cells were treated with three different E2 concentrations and nitrite (NO2) concentrations, as well as endothelial nitric oxide synthase (eNOS) protein expressions were analyzed. In vivo, random-pattern skin flaps were raised in female Wistar rats 14 days following ovariectomy and treated with placebo ointment (group 1), E2 as gel (group 2), and E2 via plaster (group 3). Flap perfusion, survival, and NO2 levels were measured on postoperative day 7. In vitro, E2 treatment increased NO2 concentration in cell supernatant and eNOS expression in cell lysates (p < 0.05). In vivo, E2 treated (gel and plaster groups) demonstrated significantly increased skin flap survival compared to the placebo group (p < 0.05). E2 plaster-treated animals exhibited higher NO2 blood levels than placebo (p < 0.05) paralleling the in vitro observations. E2 increases NO production in endothelial cells via eNOS activation. Topical E2 application can significantly increase survival of ischemically challenged skin flaps in a rat model and may augment wound healing in other ischemic situations via activation of NO production.

The Effects of Tadalafil on Axial-Pattern Skin Flap Survival in Rats

BACKGROUND Pharmacologic augmentation to mimic the delay phenomenon that increases skin flap survival has been studied extensively. Tadalafil is a phosphodiesterase V inhibitor that is used for treatment of erectile dysfunction by enhancing vascular smooth muscle relaxation. OBJECTIVE The aim of this study was to investigate the effects of local injection of tadalafil in enhancing axial-pattern skin flap survival in rats. MATERIALS AND METHODS Twenty Sprague-Dawley rats were used and a McFarlane-type caudally based axial-pattern skin flap was designed on the dorsum of the rat (2 × 9 cm). Rats were divided into two groups: the treatment group and the control group. Tadalafil 10 mg/kg/day was injected to the distal flap area of the treatment group for 3 days, and normal saline was injected for the control group. On Postoperative Day 7, necrotic flap area was measured and compared, and angiograms of the skin flaps were obtained in the two groups. RESULTS In the treatment group, the mean necrotic area was 21.9±6.4%, and in the control group, 37.7±5.9%. There was a statistically significant increase of skin flap survival in the treatment group (p=.001). Angiography also showed vasodilation of the choke vessels between adjacent angiosomes to form true anastomosis in the treatment group. CONCLUSION The results demonstrate that the use of local injection of tadalafil to failing skin flaps increases the survival of axial-pattern flaps in rats.

The Effects of Tadalafil on Axial-Pattern Skin Flap Survival in Rats

Pharmacologic augmentation to mimic the delay phenomenon that increases skin flap survival has been studied extensively. Tadalafil is a phosphodiesterase V inhibitor that is used for treatment of erectile dysfunction by enhancing vascular smooth muscle relaxation. The aim of this study was to investigate the effects of local injection of tadalafil in enhancing axial-pattern skin flap survival in rats. Twenty Sprague-Dawley rats were used and a McFarlane-type caudally based axial-pattern skin flap was designed on the dorsum of the rat (2 x 9 cm). Rats were divided into two groups: the treatment group and the control group. Tadalafil 10 mg/kg/day was injected to the distal flap area of the treatment group for 3 days, and normal saline was injected for the control group. On Postoperative Day 7, necrotic flap area was measured and compared, and angiograms of the skin flaps were obtained in the two groups. In the treatment group, the mean necrotic area was 21.9+/-6.4%, and in the control group, 37.7+/-5.9%. There was a statistically significant increase of skin flap survival in the treatment group (p=.001). Angiography also showed vasodilation of the choke vessels between adjacent angiosomes to form true anastomosis in the treatment group. The results demonstrate that the use of local injection of tadalafil to failing skin flaps increases the survival of axial-pattern flaps in rats.

Heparin protects against skin flap necrosis: relationship to neutrophil recruitment and anti-coagulant activity

Heparin has been shown to improve survival of surgical skin flaps. However, it is not known whether the protective effect of heparin is related to its anticoagulative or anti-inflammatory effects. Surgical flaps were raised in the dorsal skin of Sprague-Dawley rats. Neutrophil recruitment was determined by measuring the tissue content of myeloperoxidase (MPO) and clotting time was estimated by assessment of activated partial thromboplastin time (APTT) in plasma. Administration of heparin (150 U/kg) significantly increased skin flap survival from 44% in vehicle-treated controls to 91%. This heparin treatment increased APTT by 4.5 fold. However, administration of 150 U/kg of heparin had no effect on skin flap neutrophil recruitment. In contrast, we found that the polysaccharide fucoidan reduced MPO and also improved skin flap survival. In conclusion, we demonstrate that protective effect of clinically relevant doses of heparin correlates with its ability to prolong clotting time and not to inhibition of neutrophil accumulation in the healing of skin flaps.

Acute Difluoromethylornithine Treatment Increases Skin Flap Survival in Rats

Difluoromethylornithine (DFMO) pretreatment for 7 days improved survival of rat abdominal skin flaps in previous studies. The purpose of this study was to determine if acute administration of DFMO enhances survival. Each rat had a 7 x 7-cm abdominal skin flap raised on a single epigastric neurovascular pedicle. Within 1 minute of pedicle ligation, the rats were given 0, 1, or 4 gm/kg of body weight of DFMO intraperitoneally. Putrescine was administered to additional rats alone or with DFMO. After 48 hours, the percentage of flap survival was estimated using fluorescein injection and planimetry to quantify the perfused and unperfused areas. Flap survival increased from 71 +/- 3% in controls to 83 +/- 2% and 92 +/- 3% in rats treated with 1 and 4 gm/kg of DFMO, respectively (p less than 0.005). Putrescine reversed the protective effect of DFMO, suggesting a specific polyamine-related mechanism. This study indicates that there may be both short- and long-term polyamine pools through which DFMO acts. In summary, DFMO may prove to be important in preventing cell death following acute ischemia.

Increased Skin Flap Survival and Arterial Dilation by Calcitonin Gene-Related Peptide: A Study in the Pig

Calcitonin gene-related peptide (CGRP), a recently discovered neuropeptide, is a potent vasodilator and increases blood flow in many vascular beds. The effect of CGRP treatment was investigated in critical pig pedicle and island flaps. Prior to pharmacological treatment the peroperative circulation border was estimated with fluorescein. Intradermal or intraarterial flap treatment with CGRP was given. Control flaps were untreated or injected with saline. Increased or decreased survival was calculated as the difference between the peroperative fluorescein penetration border and the survival border one week after surgery. CGRP treatment significantly increased the survival of both random pedicle and island flaps. CGRP doses as low as 3 ml x 10(-14) M (equal to 0.03 fmoles) increased the survival of random pedicle flaps. In 4 untreated pigs the deep circumflex iliac arteries were excised and artery ring preparations were studied in vitro. A dose-dependent relaxation of artery rings was noted between 10(-9) M and 10(-7) M CGRP.

Deferoxamine increases skin flap survival: additional evidence of free radical involvement in ischaemic flap surgery

This study presents further evidence of free radical involvement in skin flap necrosis in a dorsal rat flap model. Rats receiving deferoxamine, a free radical scavenger and iron chelator had significantly less necrosis (p<0.001) than saline treated rats. In a separate experiment, tissue determinations for malonyldialdehyde (MDA) were consistent with the survival results in showing a significant decrease in MDA in all biopsy sites (p<0.05 or less), indicative of reduced lipoperoxidation in the deferoxamine treated rats.