Tetrahydropalmatine promotes random skin flap survival in rats via the PI3K/AKT signaling pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Flap necrosis is the most common complication after flap transplantation, but its prevention remains challenging. Tetrahydropalmatine (THP) is the main bioactive component of the traditional Chinese medicine Corydalis yanhusuo, with effects that include the activation of blood circulation, the promotion of qi, and pain relief. Although THP is widely used to treat various pain conditions, its impact on flap survival is unknown. AIM OF THE STUDY: To explore the effect and mechanism of THP on skin flap survival. MATERIALS AND METHODS: In this study, we established a modified McFarlane flap model, and the flap survival rate was calculated after 7 days of THP treatment. Angiogenesis and blood perfusion were evaluated using lead oxide/gelatin angiography and laser Doppler, respectively. Flap tissue obtained from zone II was evaluated histopathologically, by hematoxylin and eosin staining, and in assays for malondialdehyde content and superoxide dismutase activity. Immunofluorescence was performed to detect interleukin (IL)-6, tumor necrosis factor (TNF)-α, hypoxia-inducible factor (HIF)-1α, Bcl-2, Bax, caspase-3, caspase-9, SQSTM1/P62, Beclin-1, and LC3 expression, and Western blot to assess PI3K/AKT signaling pathway activation and Vascular endothelial growth factor (VEGF) expression. The role played by the autophagy pathway in flap necrosis was examined using rapamycin, a specific inhibitor of mTOR. RESULTS: Experimentally, THP improved the survival rate of skin flaps, promoted angiogenesis, and improved blood perfusion. THP administration reduced the inflammatory response, oxidative stress, and apoptosis in addition to inhibiting autophagy via the PI3K/AKT/mTOR pathway. Rapamycin partially reversed these effects. CONCLUSION: THP promotes skin flap survival via the PI3K/AKT signaling pathway.

Chronic Cinacalcet improves skin flap survival in rats: the suggested role of the nitric oxide pathway.

Cinacalcet is a calcimimetic medicine that has been used to treat secondary hyperparathyroidism and parathyroid cancer. Various studies have proposed the positive role of calcium and its receptor in skin wound healing. Furthermore, Cinacalcet interacts with other skin repair-related mechanisms, including inflammation and nitric oxide pathways. The present study evaluated the effect of Cinacalcet on the random-pattern skin flap survival. Eighty-four Wistar male rats were used. Multiple doses of Cinacalcet (30, 3, 1, 0.3, and 0.05 mg/kg) were used in 3 different routes of administration before the surgery. Histopathological evaluations, quantitative assessment of IL-6, TNF-α, and nitric oxide (NO), and the expression of calcium-sensing receptor (CaSR) and E-cadherin were evaluated in the skin tissue. To assess the role of NO, a NO synthase inhibitor, N-nitro-L-arginine methyl ester hydrochloride (L-NAME), was used, and histopathological effects were investigated. Cinacalcet pretreatment at the IP chronic 1 mg/kg dose significantly increased the skin flap survival rate and enhanced the NO tissue level compared to the control. However, the administration of L-NAME abolished its protective effects. IP Chronic 1 mg/kg of Cinacalcet could also decline the levels of IL-6 and TNF-α and also increase the expression of CaSR and E-cadherin in the flap tissue compared with the control group. Chronic Cinacalcet at 1 mg/kg could improve skin flap survival, probably mediated by the CaSR, NO, and inflammation-related pathways.

Therapeutic potential of naringin in improving the survival rate of skin flap: A review.

Naringin is the main component of Drynaria. Modern pharmacological studies have shown that naringin has a wide range of pharmacological activities, including antioxidant, anti-inflammatory, anti-apoptotic, anti-ulcer, and anti-osteoporosis effects. Its therapeutic effects have been observed in various clinical models, such as atherosclerosis, cardiovascular diseases, diabetes, neurodegenerative diseases, and rheumatic diseases. This review investigates the pharmacological effects of naringin and the associated mechanisms in improving flap survival. This review will also provide a reference for future rational application of naringin, especially in research to improve flap survival.

All-trans retinoic acid improves the viability of ischemic skin flaps in diabetic rat models.

AIMS: Endothelial progenitor cells (EPCs) play a critical role in neovascularization, which enhances proliferation under all-trans retinoic acid (ATRA) treatment. However, the effects of ATRA on the skin flap survival in diabetic flap ischemia remains unknown. METHODS: Ischemic random skin flaps were made in 40 diabetic Sprague-Dawley rats with 20 normal rats used as control in this study. At 7 days postoperatively, the surviving area of each skin flap was measured. Immunofluorescence staining was used to analyze capillary density and EPCs recruited to the flaps. The expression of ANG2 and VEGF was determined by Western blotting. Circulating EPC number was determined by flow cytometry. In vitro tube formation experiment was used to analyze the function of EPCs. RESULTS: The flap survival rate and capillary density of ATRA-treated flap were significantly increased. Fluorescence-activated cell sorting (FACS) analysis demonstrated a marked increase in systemic CD34+/Flk-1+ EPCs in ATRA-treated rat. The expression of ANG2 and VEGF was increased in diabetic flap tissues under ATRA administration. Furthermore, ATRA administration restored the impaired function of diabetic EPCs in tube formation. CONCLUSION: ATRA could notably exert preventive effects against skin flap necrosis and promote neovascularization in diabetic rats, which may partially through elevating the expression of ANG2 and VEGF, and augmenting EPC mobilization.

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.

Fibroblast Growth Factor-1 vs. Fibroblast Growth Factor-2 in Ischemic Skin Flap Survival in a Rat Animal Model.

BACKGROUND: One of the main challenges in skin flap surgery is tissue ischemia and following necrosis. The present study compares the effects of fibroblast growth factors 1 and 2 on increasing cutaneous vasculature, improving ischemia, and preventing distal necrosis in ischemic skin flaps in rat model. METHODS: Thirty rats were allocated into 3 groups (n=10) and 2×8 cm dorsal random-pattern skin flaps were raised after four daily subdermal injections of normal saline (control group), fibroblast growth factor 1 (FGF-1 group; 2.5 µg/day), or fibroblast growth factor 2 (FGF-2 group; 2.5 µg/day) at designated flap areas. Skin flap viability and number of blood vessels were evaluated on day 10 after elevation by planimetric analysis and histological examination. RESULTS: It was shown that administrations of FGF-1 and FGF-2 significantly decreased the percentage of flap necrosis and improved the percentage of ischemic survivable area, compared to the control samples. Meanwhile, the differences between these factors in terms of preventing skin flap necrosis and improving ischemia were also significant. The number of visible blood vessel sections was also higher in FGF-1 and FGF-2 groups than in the control group. CONCLUSION: These findings suggest that, while FGF-2 is still much more potent than FGF-1, treatment with either of these drugs could be very effective in increasing the survival of surgical flaps at risk (length to width ratio>3) in situations that other therapeutic options could not be considered.

Combination of vascular endothelial growth factor-loaded microspheres and hyperbaric oxygen on random skin flap survival in rats.

The present study aimed to investigate the role of hyperbaric oxygen (HBO) and treatment with vascular endothelial growth factor (VEGF)-loaded microspheres, and HBO plus VEGF on the survival of random skin flaps in rats. The modified McFarlane flap model was established in 40 rats and evaluated within four groups: VEGF (n=10), HBO (n=10), HBO plus VEGF (n=10) and controls (n=10). Seven days following treatment, the necrotic area of the flap was measured. The specimens were stained with hematoxylin and eosin for histological analysis. Immunohistochemical staining was used to analyze the positive expression levels of VEGF. The percentages of necrosis of the skin flaps in all groups were: 49.66±2.64% in controls, 26.85±1.77% in VEGF, 28.27±2.21% in HBO and 10.44±2.48% in the combination group. Histological analysis demonstrated angiogenesis with mean vessel density per mm2 in the groups were: 16.68±2.69 in controls, 22.96±3.29 in VEGF, 24.74±3.19 in HBO and 34.81±3.93 in the combination group. The expression of VEGF of the controls, VEGF, HBO and the combination group were 28.33±4.98, 52.54±4.55, 49.32±4.62 and 78.97±4.90 integral absorbance, respectively. For all measurements, the combination group showed greater improvement in random skin flap survival than others (P<0.05). No significant difference was detected between the VEGF and HBO group. The control group exhibited lower survival rates compared with the other groups (P<0.05). Combination of VEGF and HBO improved random skin flap survival compared with the effect of VEGF or HBO alone, suggesting these two agents exhibited a synergistic effect.

Prevention of skin flap necrosis by use of adipose-derived stromal cells with light-emitting diode phototherapy.

BACKGROUND AIMS: The aim of this study was to investigate the effects of low-level light therapy (LLLT) on transplanted human adipose-derived mesenchymal stromal cells (ASCs) in the skin flap of mice. METHODS: LLLT, ASC transplantation and ASC transplantation with LLLT (ASC + LLLT) were applied to the skin flap. Immunostaining and Western blot analysis were performed to evaluate cell survival and differentiation and secretion of vascular endothelial growth factor and basic fibroblast growth factor by the ASCs. Vascular regeneration was assessed by means of immunostaining in addition to hematoxylin and eosin staining. In the ASC + LLLT group, the survival of ASCs was increased as the result of the decreased apoptosis of ASCs. RESULTS: The secretion of growth factors was higher in this group as compared with ASCs alone. ASCs contributed to tissue regeneration through vascular cell differentiation and secretion of angiogenic growth factors. The ASC + LLLT group displayed improved treatment efficacy including neovascularization and tissue regeneration compared with ASCs alone. Transplanting ASCs to ischemic skin flaps improved therapeutic efficacy for ischemia treatment as the result of enhanced cell survival and paracrine effects. CONCLUSIONS: These data suggest that LLLT is an effective biostimulator of ASCs in vascular regeneration, which enhances the survival of ASCs and stimulates the secretion of growth factors in skin flaps.

Locally injected autologous platelet-rich plasma enhanced tissue perfusion and improved survival of long subdermal plexus skin flaps in dogs.

OBJECTIVES: Distal flap necrosis remains a major complication in subdermal plexus (random) skin flaps. Platelet-rich plasma (PRP) has been shown to improve the survival of ischemic random skin flaps in rats. The objective of this study was to evaluate the effect of locally injected autologous PRP on the survival of long (5:1 length-to-width ratio) subdermal plexus skin flaps in dogs. METHODS: A 2x10 cm subdermal plexus skin flap was created bilaterally on the abdominal wall of six Beagle dogs. One randomly selected side received 2.5 ml of fresh auto-logous PRP injected evenly between sutures underneath the flap, whereas the other side was left untreated (control). Skin flap survival was evaluated macroscopically, histologically and by laser-Doppler flowmetry measurements of tissue perfusion. RESULTS: Flap percentage survival on day 10 (96.3% versus 74.5%; p = 0.046) and tissue perfusion (p <0.036) were significantly higher in PRP-treated flaps compared with controls. Histologically, there was less oedema in PRP-treated flaps compared to controls (p = 0.01), whereas collagen production and angiogenesis did not differ significantly between the two groups. CLINICAL SIGNIFICANCE: The use of locally injected autologous PRP increases tissue perfusion and improves the survival of long subdermal plexus skin flaps in dogs.

Phosphodiesterase inhibitors in vascular ischemia: A case report and review of their use in ischemic conditions.

The treatment of digital ischemia remains difficult. Sildenafil (Viagra, Pfizer UK), a selective phosphodiesterase inhibitor, increases blood flow and is currently marketed for the treatment of erectile dysfunction. A case of a 57-year-old man with progressive episodic ischemia and pain of the fingertips resulting in finger tip ulceration is presented. After failure of medical and surgical management, a trial of oral sildenafil resulted in marked symptomatic improvement of his bilateral digital ischemia. Review of the literature shows that, particularly in patients with an underlying disease such as sclero-derma with a vasospastic component, a marked improvement in digital blood flow may be observed with sildenafil use. Overall, based on a number of case reports and preliminary animal studies in the literature, sildenafil appears to have a growing significance in the treatment of hand ischemia. Similarly, there is evidence that phosphodiesterase 5 inhibitors may be used as an adjunct to improving skin flap survival.

Effects of nebivolol on skin flap survival: A randomized experimental study in rats.

BACKGROUND: Skin flaps are among the basic treatment options in the reconstruction of soft tissue defects. To improve skin flap survival, a variety of methods, including pharmacologic agents, have been investigated. The effectiveness of anticoagulants, antioxidants, anti-inflammatory drugs, and vasodilatory drugs in improving flap survival has been studied. Nebivolol is a new-generation selective ß1-adrenoreceptor blocking agent that has vasodilatory, antithrombotic, antioxidative, and anti- inflammatory effects. OBJECTIVE: The aim of this experimental study was to investigate the effects of nebivolol (50 mg/kg/d) on random pattern skin flap survival in rats. METHODS: Male Wistar rats weighing 290 to 310 g were randomly divided into 2 groups-the nebivolol group and the control group. Random patterned, caudally-based, ~3 × 10-cm skin flaps were elevated on the back of each rat. In the nebivolol group, nebivolol 50 mg/kg/d (1 mL, of a racemic solution of nebivolol) was administered orally 2 days before surgery to reach steady-state drug blood concentrations and was continued for 6 days. In the control group, 1 mL/d of sterile saline solution was orally administered 2 days before surgery and was continued for 6 days. To observe the effects of nebivolol, cutaneous blood flow was examined using a laser Doppler flow-meter before and after surgery on days 1, 3, 5, and 7, and flap tissue, malondialdehyde (MDA) and glutathione (GSH) concentrations, and superoxide dismutase (SOD) activity were measured 7 days postsurgery. Flap viability was evaluated 7 days after surgery by measuring necrotic flap area and total flap area. RESULTS: All 20 rats (nebivolol group, n = 10; control group, n = 10) survived throughout the study period. Mean (SD) MDA concentration was significantly lower in the nebivolol group than in the control group (69.25 [5.82] vs 77.67 [6.87] nmol/g tissue; P = 0.009). GSH concentration was significantly higher in the nebivolol group than in the control group (2.14 [0.15] vs 1.88 [0.22] nmol/mg tissue; P = 0.004). SOD activity was significantly greater in the nebivolol group than in the control group (49.28 [5.49] vs 42.09 [4.95] U/g tissue; P = 0.007). The percentage of the flap that was necrotic was significantly lower in the nebivolol group than in the control group (40.27 [4.08] vs 48.87 [6.35]; P = 0.007). CONCLUSIONS: This small, experimental, in vivo animal study found that nebivolol was associated with reduced necrotic random pattern skin flap area. Further studies are needed to clarify these findings.

The effects of montelukast on random pattern skin flap survival: An experimental study in rats.

BACKGROUND: A variety of methods to improve skin flap survival, including the use of pharmacologic agents, have been intensively investigated. Decreasing neutrophil-mediated inflammation and tissue injury has been reported to be effective in improving flap survival. Montelukast is a selective reversible cysteinyl leukotriene receptor-1 antagonist that has been found to have protective effects against renal ischemia reperfusion injury and burn-induced oxidative injury of the skin in rats. However, its effects on skin flap survival have not been previously reported. OBJECTIVE: The aim of this study was to investigate the effects of montelukast on neutrophil-mediated random pattern skin flap survival. METHODS: Male Sprague-Dawley rats weighing 230 to 250 g were randomly divided into 2 groups-the montelukast-treated group and the control group. Caudally based rectangular random pattern skin flaps 3 × 9 cm were elevated on the backs of the rats. The flaps were sutured into their original places. In the montelukast group, 1 mL of solution containing 10 mg/kg montelukast was administered intraperitoneally (IP) 30 minutes before surgery and then daily for 6 days. In the control group, 1 mL of saline was administered IP 30 minutes before surgery and then daily for 6 days. To observe the effects of montelukast, myeloperoxidase (MPO) activity, an index of tissue neutrophil infiltration, was measured from extracted skin tissue 12 hours after flap elevation. Flap viability was evaluated 7 days after surgery by measuring necrotic flap area and total flap area. RESULTS: Sixteen rats (mean [SD] weight, 240.6 [6.6] g) were equally divided between the 2 groups. All rats survived throughout the study period. Mean (SD) MPO activity in flap tissue was significantly lower in the montelukast group than in the control group (14.57 [2.33] vs 21.28 [4.86] U/g protein; P = 0.005). The percentage of necrotic flap area was significantly lower in the montelukast group than in the control group (17.17 [7.95] vs 37.51 [10.72]; P = 0.001). CONCLUSION: This small, experimental, in vivo animal study found that montelukast was associated with both lower MPO activity and a lower percentage of necrotic random pattern skin flap area. Future studies are needed to clarify these findings.