Betulinic Acid Enhances the Viability of Random-Pattern Skin Flaps by Activating Autophagy.

Random-pattern skin flap replantation is commonly used to repair skin defects during plastic and reconstructive surgery. However, flap necrosis due to ischemia and ischemia-reperfusion injury limits clinical applications. Betulinic acid, a plant-derived pentacyclic triterpene, may facilitate flap survival. In the present study, the effects of betulinic acid on flap survival and the underlying mechanisms were assessed. Fifty-four mice with a dorsal random flap model were randomly divided into the control, betulinic acid group, and the betulinic acid + 3-methyladenine group. These groups were treated with dimethyl sulfoxide, betulinic acid, and betulinic acid plus 3-methyladenine, respectively. Flap tissues were acquired on postoperative day 7 to assess angiogenesis, apoptosis, oxidative stress, and autophagy. Betulinic acid promoted survival of the skin flap area, reduced tissue edema, and enhanced the number of microvessels. It also enhanced angiogenesis, attenuated apoptosis, alleviated oxidative stress, and activated autophagy. However, its effects on flap viability and angiogenesis, apoptosis, and oxidative stress were reversed by the autophagy inhibitor 3-methyladenine. Our findings reveal that betulinic acid improves survival of random-pattern skin flaps by promoting angiogenesis, dampening apoptosis, and alleviating oxidative stress, which mediates activation of autophagy.

Therapeutic potential of pravastatin for random skin flaps necrosis: involvement of promoting angiogenesis and inhibiting apoptosis and oxidative stress.

Background: Random skin flap is frequently used in plastic and reconstructive surgery, but its distal part often occurs ischemia and necrosis. Pravastatin (Prava) with bioactivities of pro-angiogenesis, anti-apoptosis and anti-oxidative stress, may be beneficial for flap survival. Materials and methods: A modified McFarlane flap model was performed in Sprague-Dawley rats. The animals were divided into the Control and Prava groups and treated as follows: the Prava group was injected intraperitoneally with 2 mg/kg Prava for consecutive 7 days, and the Control group received an equal volume of vehicle daily. On day 7, the necrosis skin flaps were observed, while visualization of blood flow below the tissue surface was performed by Laser Doppler blood flow imaging (LDBFI). Then animals were euthanized, and levels of angiogenesis, apoptosis and oxidative stress were analyzed. Results: Prava decreased necrosis and edema of skin flaps compared with the Control group, with more blood flow in the flap under LDBFI. Prava treatment increased the mean vessels density, elevated the expression levels of angiogenic proteins (matrix metallopeptidase 9, vascular endothelial growth factor, Cadherin5) and antioxidant proteins (superoxide dismutase 1 (SOD1), endothelial nitric oxide synthase, heme oxygenase), and decreased the expression of apoptotic factors (BAX, CYC, Caspase3). In addition, malondialdehyde content was reduced, and glutathione level and SOD activity were increased in the skin flaps after treatment with Prava. Conclusion: Prava promotes survival of random skin flap through induction of angiogenesis, and inhibition of apoptosis and oxidative stress.

Protective effects of resveratrol on random-pattern skin flap survival: an experimental study.

Random-pattern skin flap transplantation is a common procedure in plastic surgery, but its distal area usually incurs ischemia and necrosis. Resveratrol (Rev), a natural polyphenol primarily found in peanuts, grapes, and red wine, which exerts multi-bioactivity. In this study, forty-eight rats with the modified "McFarlane flap" model were divided into Control and Rev groups, which were treated with vehicle Control and Rev, respectively. After 7 days of continuous treatment and observation, ischemic flap tissues were harvested to evaluate angiogenesis, apoptosis, oxidative stress, and autophagy. It was observed a greater survival area of flaps, accompanied with reduced water content and stronger blood supply, in the Rev group than in the Control group. In addition, Rev upregulated the expression of MMP9, VEGF, and Cadherin5, indicating that Rev promotes angiogenesis in ischemic flaps. Moreover, Rev decreased the levels of Bax, CYC, and Caspase3, suggesting that it inhibits apoptosis. Besides, Rev increased the expression of SOD1, eNOS, HO1, the activities of SOD and GSH, and reduced the levels of MDA, which uncovers that it depresses oxidative stress in ischemic flaps. Finally, it increased the expression of Beclin1, LC3II, VPS34, and CTSD, and decreased SQSTM1/p62 levels, which reveals that it activates autophagy in the flaps. These results suggest that Rev promotes random skin flap survival through proangiogenic, antiapoptotic, and antioxidative effects; moreover, autophagy is activated in the process, which might be another underlying mechanism for the flap survival.

Metformin Promotes the Survival of Random-Pattern Skin Flaps by Inducing Autophagy via the AMPK-mTOR-TFEB signaling pathway.

Random-pattern skin flaps are widely used to close defects in reconstructive and plastic surgeries; however, they are vulnerable to necrosis, particularly in the distal portion of the flap. Here, we examined the effects of metformin on flap survival and the mechanisms underlying these effects. Following metformin treatment, the survival area, blood flow, and number of microvessels present in skin flaps were increased on postoperative day 7, whereas tissue edema was reduced. In addition, metformin promoted angiogenesis, inhibited apoptosis, relieved oxidative stress, and increased autophagy in areas of ischemia; these effects were reversed by autophagy inhibitors 3-methyladenine (3MA) or chloroquine (CQ). Either 3MA or CQ reversed the metformin-induced increase in flap viability. Moreover, metformin also activated the AMPK-mTOR-TFEB signaling pathway in ischemic areas. Inhibitions of AMPK via Compound C (CC) or AMPK shRNA adeno-associated virus (AAV) vector resulted in the downregulation of the AMPK-mTOR-TFEB signaling pathway and autophagy level in metformin-treated flaps. Taken together, our findings suggest that metformin improves the survival of random-pattern skin flaps by enhancing angiogenesis and suppressing apoptosis and oxidative stress. These effects result from increased autophagy mediated by activation of the AMPK-mTOR-TFEB signaling pathway.

Valproic acid enhances the viability of random pattern skin flaps: involvement of enhancing angiogenesis and inhibiting oxidative stress and apoptosis.

BACKGROUND: Random skin flaps are commonly applied during plastic surgery, but distal flap necrosis limits their clinical applications. Valproic acid (VPA), a histone deacetylase inhibitor and a traditional antiepileptic agent, may promote flap survival. MATERIALS AND METHODS: Sprague-Dawley rats were randomly divided into VPA-treated and control groups. All rats received VPA or saline by intraperitoneal injections once daily for 7 days after the modified McFarlane flap model was established. On postoperative day 7, flap survival, laser Doppler blood flow, and water content were examined for flap viability, hematoxylin and eosin staining (H&E), immunohistochemistry (IHC), and Western blot analysis, and the status of angiogenesis, apoptosis, and oxidative stress were detected in the ischemic flaps. RESULTS: VPA increased the survival area, blood flow, and number of microvessels in skin flaps on postoperative day 7 and reduced edema. VPA promoted angiogenesis by enhancing vascular endothelial growth factor (VEGF) mRNA transcription and upregulating VEGF and cadherin 5 expression, inhibited apoptosis via reduction of caspase 3 cleavage, and relieved oxidative stress by increasing superoxide dismutase (SOD) and glutathione (GSH) levels and reducing the malondialdehyde (MDA) level. CONCLUSION: VPA promoted random skin flap survival by enhancing angiogenesis and inhibiting oxidative stress and apoptosis.

Salvianolic Acid B Promotes the Survival of Random-Pattern Skin Flaps in Rats by Inducing Autophagy.

Random-pattern skin flap transplantation is frequently applied in plastic and reconstructive surgery. However, the distal part of the flap often suffers necrosis due to ischemia. In this study, the effects of salvianolic acid B (Sal B) on flap survival were evaluated, and the underlying mechanisms were investigated. Sal B improved the survival area, reduced tissue edema, and increased the number of microvessels in skin flaps after 7 days, whereas an autophagy inhibitor (3-methyladenine) reversed the Sal B-induced increase in flap viability. In addition, Sal B stimulated angiogenesis, inhibited apoptosis, reduced oxidative stress, and upregulated autophagy in areas of ischemia. Moreover, the effects of Sal B on angiogenesis, apoptosis, and oxidative stress were reversed by autophagy inhibition. Overall, our findings suggest that Sal B has pro-angiogenesis, anti-apoptosis, and anti-oxidative stress effects by stimulating autophagy, which enhances the survival of random-pattern skin flaps.

Effects of the traditional Chinese medicine baicalein on the viability of random pattern skin flaps in rats.

BACKGROUND: Random skin flaps are routinely placed during plastic and reconstructive surgery, but the distal areas often develop ischemia and necrosis. Baicalein, a major flavonoid extracted from the traditional Chinese herbal medicine huangqin, Scutellaria baicalensis Georgi, may improve flap viability. MATERIALS AND METHODS: Rats were randomly divided into baicalein and control groups and they underwent placement of modified McFarlane flaps after intraperitoneal administration of baicalein or vehicle. Flap survival and water content were measured 7 days later, as were angiogenesis, apoptosis, and oxidative stress in ischemic flaps. RESULTS: Baicalein promoted flap survival, reduced edema, increased mean vessel density, and enhanced vascular endothelial growth factor production at both the translational and transcriptional levels. Baicalein reduced caspase 3 cleavage, increased superoxidase dismutase and glutathione levels, and decreased the malondialdehyde level. CONCLUSION: Baicalein promoted flap viability by stimulating angiogenesis and inhibiting apoptosis and oxidation.

Multifaceted effects of astragaloside IV on promotion of random pattern skin flap survival in rats.

Random pattern skin flap transplantation is frequently applied in plastic and reconstructive surgery, but the distal part of skin flaps often suffers necrosis due to ischemia. Astragaloside IV (AS-IV), a natural saponin purified from Astragalus membranaceus, may have beneficial functions for flap survival. In this study, rats were divided into a control group and an AS-IV treatment group, and underwent surgery using a modified "McFarlane flap" model. After intragastric administration of vehicle control or AS-IV for their respective groups, flap survival area and water content were measured 7 days after surgery. Flap tissue was separated to test protein expressions related to angiogenesis, inflammation, oxidative stress and autophagy via western blot, immunohistochemistry, and immunofluorescence. Results showed that AS-IV improved flap survival area and reduced tissue edema. AS-IV also increased mean vessel densities and upregulated levels of VEGF protein, both of which indicate increased angiogenesis. Furthermore, AS-IV depressed leukocyte infiltration, decreased expressions of inflammatory proteins TNF-α, IL1ß and IL6, increased SOD activity, decreased MDA content, and stimulated autophagy. Overall, our results suggest that AS-IV promotes skin flap survival via inducing angiogenesis, depressing inflammation and dampening oxidative stress; it also activates autophagy, which may be an underlying mechanism for oxidative stress depression.