Random Pattern Skin Flaps Research Articles

Low-dose estrogen release from silastic capsule enhanced flap wound healing in an animal model.

Deep and extensive wounds usually cannot be closed directly by suturing or skin grafting. Flap transplantation is typically used to reconstruct large wounds clinically. The flap survival is based on a stable blood perfusion. It is established that estrogen promotes wound healing and angiogenesis, and regulates the inflammatory response, leading to enhanced flap survival after transplantation. However, estrogen concentrations administered in previous studies were significantly higher than physiological levels, potentially causing systemic side effects. Estrogen-sustained-release silastic capsules can maintain blood serum estrogen closer to physiological levels. This study aimed to investigate whether administering estrogen at a lower concentration, closer to physiological levels, could still enhance flap survival. This study was performed in a random skin flap model in ovariectomized (OVX) mice. Sustained-release estrogen silastic capsules were implanted into OVX mice to determine the functional role of estrogen in wound healing after flap transplantation. Flap blood perfusion was analysed using a colour laser Doppler scanner. Immunohistochemical staining of CD31, hypoxia-inducible factor 1 alpha (HIF-1α), alpha-smooth muscle actin (α-SMA), cleaved caspase 3 and apoptotic terminal dUTP nick end-labelling stain was used to investigate flap angiogenesis, tissue hypoxia, wound healing and cell death in the flap tissue, respectively. We observed that administering estrogen at a lower concentration enhanced superficial blood perfusion while reducing the flap's ischemic area and tissue necrosis. HIF-1α expression was significantly decreased in the dermis layer but not in the fascia, whereas cleaved caspase 3 levels decreased in the fascia but remained unchanged in the dermis. Additionally, there was no significant difference in CD31and α-SMA expression between the groups. In summary, the study showed that an estrogen silastic capsule maintained physiological estrogen levels and improved superficial perfusion, thereby reducing dermal hypoxia, and cell death in a mouse random pattern skin flap model. Although no significant promotion of angiogenesis was observed, the study suggests that appropriate estrogen supplements could enhance flap wound recovery.

Erastin promotes random-pattern skin flaps survival by inducing mTORC1-TFEB mediated autophagy

Random-pattern skin flaps are important method for skin reconstruction after defect; however, the distal end of flaps is not easily viable due to inadequate nutrient supply. Erastin is a well-established ferroptosis inducer, but our study found that low-dose of erastin (2 μM) may reduce nutrient deficiency induced cell death in human umbilical vein endothelial cells (HUVECs). RNA-seq analysis suggested that its role was related to autophagy regulation. Follow-up studies have shown that the use of autophagy inhibitors or the knockdown of TFEB in HUVECs can both reduce the anti-apoptotic effect of erastin in HUVECs. Mechanism study demonstrated that erastin can suppress mTORC1 and promote TFEB activity in HUVECs, suggesting that the effect of erastin on the survival of HUVECs under nutrient deprivation conditions is regulated by mTORC1/TFEB. Subsequently, we evaluated the effect of erastin on the survival of random-pattern skin flaps in mice in vivo. On the postoperative day 7, we observed a significant increase in flap survival area, blood perfusion, and microvascular density after erastin treatment; also, erastin treatment showed enhanced autophagy within the ischemic region. In summary, our study demonstrates that low-dose of erastin may suppress cell death in endothelial cells under nutrient deficiency condition, and its effects may relate to the mTORC1-TFEB medicated autophagy regulation, erastin treatment may be a potential therapy for random-pattern skin flaps.

Spermidine Exerts Protective Effects in Random-Pattern Skin Flap Survival in Rats: Possible Involvement of Inflammatory Cytokines, Nitric Oxide, and VEGF.

Distal necrosis and inflammation are two of the most common health consequences of random-pattern skin flaps survival (SFS). Anti-inflammatory effects of spermidine have been identified in various studies. On the other hand, considering the involvement of the nitric oxide molecule in the spermidine mode of action and also its role in skin tissue function, we analyzed the possible effects of spermidine on the SFS and also, potential involvement of nitrergic pathway and inflammatory cytokine in these phenomena. Each rat was pretreated with either a vehicle (control) or various doses of spermidine (0.5, 1, 3, 5, 10 and 30 mg/kg) and then was executed a random-pattern skin flap paradigm. Also, spermidine at the dose of 5 mg/kg was selected and one group rats received spermidine 20 min prior to surgery and one additional dose 1 day after operation. Then, 7 days after operations, interleukin (IL)-6, tumor necrosis factor (TNF)-α, interferon-gamma (IFN-γ), and nitrite levels were inquired in the tissue samples by ELIZA kit. Vascular endothelial growth factor expression was assessed by DAPI staining and fluorescent microscopes. The concentrations of three polyamines, including spermidine, spermine, and cadaverine, were analyzed using HPLC. Pretreatment with spermidine 5 mg/kg improved SFS considerably in microscopic skin H&E staining analysis and decreased the percentage of necrotic area. Moreover, spermidine exerted promising anti-inflammatory effects via the modulation of nitric oxide and reducing inflammatory cytokines. Spermidine could improve skin flaps survival, probably through the nitrergic system and inflammation pathways. This preclinical study provides level III evidence for the potential therapeutic effects of spermidine on SFS in rats, based on the analysis of animal models. Further studies are needed to confirm these findings in clinical settings. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Celastrol enhances the viability of random-pattern skin flaps by regulating autophagy through the AMPK-mTOR-TFEB axis.

In reconstructive and plastic surgery, random-pattern skin flaps (RPSF) are often used to correct defects. However, their clinical usefulness is limited due to their susceptibility to necrosis, especially on the distal side of the RPSF. This study validates the protective effect of celastrol (CEL) on flap viability and explores in terms of underlying mechanisms of action. The viability of different groups of RPSF was evaluated by survival zone analysis, laser doppler blood flow, and histological analysis. The effects of CEL on flap angiogenesis, apoptosis, oxidative stress, and autophagy were evaluated by Western blot, immunohistochemistry, and immunofluorescence assays. Finally, its mechanistic aspects were explored by autophagy inhibitor and Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) inhibitor. On the seventh day after surgery, the survival area size, blood supply, and microvessel count of RPSF were augmented following the administration of CEL. Additionally, CEL stimulated angiogenesis, suppressed apoptosis, and lowered oxidative stress levels immediately after elevated autophagy in ischemic regions; These effects can be reversed using the autophagy inhibitor chloroquine (CQ). Specifically, CQ has been observed to counteract the protective impact of CEL on the RPSF. Moreover, it has also been discovered that CEL triggers the AMPK-mTOR-TFEB axis activation in the area affected by ischemia. In CEL-treated skin flaps, AMPK inhibitors were demonstrated to suppress the AMPK-mTOR-TFEB axis and reduce autophagy levels. This investigation suggests that CEL benefits the survival of RPSF by augmenting angiogenesis and impeding oxidative stress and apoptosis. The results are credited to increased autophagy, made possible by the AMPK-mTOR-TFEB axis activation.

Effects of systemically administered tramadol hydrochloride on random pattern skin flap survival in rats

Aim: Tramadol is a weak centrally acting opioid analgesic with µ-opioid receptor agonist effects. It has been explored for its analgesic efficacy through various in-vitro and in-vivo studies. The skin, as the body’s largest organ and the protector barrier, is vulnerable to injuries and wounds that can cause significant challenges due to pain, economic burdens and psychological implications. Successful healing of wound involves complex processes and it is influenced by factors such as angiogenesis and nitric oxide levels. This study investigates the effects of tramadol on wound healing in experimental ischemic wound models in rats. Material and Methods: Two 6 mm ischemic wound models were created on the backs of 30 male Wistar Albino rats, with wound areas cut along the long edges and a sterile silicone material placed between the panniculus carnosus fascia and paraspinosus muscle. Rats were randomized into Tramadol, Control, and Sham groups. The wounds were imaged using a "SONY ILCE-7" camera on days 0, 3, 6, 10, and 14. Wound areas and healing percentages were calculated from the images and recorded for statistical purposes. After 14 days, the animals were sacrificed under general anesthesia for histopathological examination of tissue samples. CD31 and VEGF antibodies were used to evaluate the density and morphology of vascular structures. Results: Tramadol administration accelerated the healing of wound surface area. Significant differences were found between groups in terms of inflammation, and data recorded in CD34, CD31, and VEGF-stained preparations. Conclusion: The study found that tramadol positively contributes to wound healing in the acute phase of ischemic wounds by affecting various processes.

Naringenin reduces oxidative stress and necroptosis, apoptosis, and pyroptosis in random-pattern skin flaps by enhancing autophagy

BackgroundRandom skin flap grafting is one of the most commonly used techniques in plastic and orthopedic surgery. However, necrosis resulting from ischemia and ischemia-reperfusion injury in the distal part of the flap can severely limit the clinical application of the flap. Studies have revealed that naringenin reduces pyroptosis, apoptosis, and necroptosis, inhibits oxidative stress, and promotes autophagy. In this study, the effects of Naringenin on flap viability and its underlying mechanism were evaluated. MethodsMice with random skin flaps were randomly allocated to control, Naringenin, and Naringenin + 3-methyladenine groups. On postoperative day 7, flap tissues were collected to estimate angiogenesis, necroptosis, apoptosis, pyroptosis, oxidative stress, and autophagy via hematoxylin and eosin staining, immunofluorescence, and immunohistochemistry. ResultsThe results revealed that naringenin promoted the viability of the random flaps as well as angiogenesis, while inhibiting oxidative stress and decreasing pyroptosis, apoptosis, and necroptosis. These effects were reversed by the autophagy inhibitor 3-methyladenine. ConclusionsThe findings indicated that naringenin treatment could promote flap survival by inhibiting pyroptosis, apoptosis, necroptosis, and alleviating oxidative stress, caused by the activation of autophagy.

Effect of adipose tissue-derived stromal vascular fraction on the viability of random-pattern skin flaps: an experimental study

Aims: Random pattern skin flaps are still widely used in plastic surgery. However, necrosis in distal flap sections resulting from ischemia is a serious problem, increasing the cost of treatment and hospitalization. The aim of this study was to test the effects of adipose tissue derived stromal vascular fraction (SVF) on random pattern skin flaps in rats. Methods: In this experimental study conducted on Wistar rats, three groups were formed using the simple random sampling technique. Group 1 consisted of rats with a raised flap and a subcutaneous SVF injection. Group 2 comprised rats that underwent a flap operation with no additional treatment. Group 3 included rats with a raised flap and a subcutaneous saline injection. Tissue necrosis and level of survival area was detected with planimetric method and histopathologic examination was performed for detect of level of vascular density. On the 7th day post-operation, the viability assessment was calculated based on the ratio of the living flap area to the total flap area. Results: The mean viability rate in Group 1 was higher compared to other groups, while there was no significant difference between Group 2 and Group 3 (Group 1 = 79.2 ± 4.9 % vs. Group 2 = 41.0 ± 5.9 % vs. Group 3= 39.2 ± 2.7 %, p < 0.001). The mean vascular densities of the flaps were higher in Group 1 compared to the other groups, while it were similar between Group 2 and Group 3 (Group 1 = 29.8 ± 1.2 vs. Group 2 = 8.4 ± 4.6 vs. Group 3= 9.3 ± 1.8, p < 0.001). Conclusion: The use of fat tissue-derived SVF injections has been found to be advantageous in improving the survival of random pattern flaps, frequently utilized in plastic and reconstructive surgery.

Standardized Pre-clinical Surgical Animal Model Protocol to Investigate the Cellular and Molecular Mechanisms of Ischemic Flap Healing

BackgroundSome of the most complex surgical interventions to treat trauma and cancer include the use of locoregional pedicled and free autologous tissue transfer flaps. While the techniques used for these reconstructive surgery procedures have improved over time, flap complications and even failure remain a significant clinical challenge. Animal models are useful in studying the pathophysiology of ischemic flaps, but when repeatability is a primary focus of a study, conventional in-vivo designs, where one randomized subset of animals serves as a treatment group while a second subset serves as a control, are at a disadvantage instigated by greater subject-to-subject variability. Our goal was to provide a step-by-step methodological protocol for creating an alternative standardized, more economical, and transferable pre-clinical animal research model of excisional full-thickness wound healing following a simulated autologous tissue transfer which includes the primary ischemia, reperfusion, and secondary ischemia events with the latter mimicking flap salvage procedure.ResultsUnlike in the most frequently used classical unilateral McFarlane’s caudally based dorsal random pattern skin flap model, in the herein described bilateral epigastric fasciocutaneous advancement flap (BEFAF) model, one flap heals under normal and a contralateral flap—under perturbed conditions or both flaps heal under conditions that vary by one within-subjects factor. We discuss the advantages and limitations of the proposed experimental approach and, as a part of model validation, provide the examples of its use in laboratory rat (Rattus norvegicus) axial pattern flap healing studies. ConclusionsThis technically challenging but feasible reconstructive surgery model eliminates inter-subject variability, while concomitantly minimizing the number of animals needed to achieve adequate statistical power. BEFAFs may be used to investigate the spatiotemporal cellular and molecular responses to complex tissue injury, interventions simulating clinically relevant flap complications (e.g., vascular thrombosis) as well as prophylactic, therapeutic or surgical treatment (e.g., flap delay) strategies in the presence or absence of confounding risk factors (e.g., substance abuse, irradiation, diabetes) or favorable wound-healing promoting activities (e.g., exercise). Detailed visual instructions in BEFAF protocol may serve as an aid for teaching medical or academic researchers basic vascular microsurgery techniques that focus on precision, tremor management and magnification.Graphical

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.

Combined application of gluteus maximus muscle flaps and random pattern skin flaps in repairing sacrococcygeal sinus tracts: a prospective study and technical note.

Sacrococcygeal sinus ulcers are caused by pressure sores, trauma, or surgery. Several surgical techniques have been developed for its treatment; however, studies are ongoing to develop the ideal method. The present study aims to introduce an innovative application of gluteus maximus muscle flaps (GMMFs) packing combined with local random pattern skin flaps (RPSFs) in repairing sacrococcygeal sinus tracts (SSTs). This was a prospective analysis study conducted on the patients (n = 26) with SSTs underwent an innovative repairing surgery in Qilu Hospital of Shandong University, China between December 2015 and December 2020. The repairing surgery was GMMFs combined with RPSFs. The demographic information and the clinical parameters including operative time, postoperative healing time, and recurrence rate were used to evaluate the efficacy of the operation. Except one case of partial necrosis at the edge of the flap due to severe fibrosis, which was cured after dressing change, all the other cases showed effective healing after the operation. The combined application of GMMFs and RPSFs for the treatment of sacrococcygeal sinus tracts gains the advantages of short operative time, quick postoperative recovery, and low postoperative recurrence rate.

Neuregulin-1, a member of the epidermal growth factor family, mitigates STING-mediated pyroptosis and necroptosis in ischaemic flaps

Abstract Background Ensuring the survival of the distal end of a random flap during hypoperfusion (ischaemia) is difficult in clinical practice. Effective prevention of programmed cell death is a potential strategy for inhibiting ischaemic flap necrosis. The activation of stimulator of interferon genes (STING) pathway promotes inflammation and leads to cell death. The epidermal growth factor family member neuregulin-1 (NRG1) reduces cell death by activating the protein kinase B (AKT) signalling pathway. Moreover, AKT signalling negatively regulates STING activity. We aimed to verify the efficacy of NRG1 injection in protecting against flap necrosis. Additionally, we investigated whether NRG1 effectively enhances ischemic flap survival by inhibiting pyroptosis and necroptosis through STING suppression. Methods A random-pattern skin flap model was generated on the backs of C57BL/6 mice. The skin flap survival area was determined. The blood supply and vascular network of the flap was assessed by laser Doppler blood flow analysis. Cluster of differentiation 34 immunohistochemistry (IHC) and haematoxylin and eosin (H&E) staining of the flap sections revealed microvessels. Transcriptome sequencing analysis revealed the mechanism by which NRG1 promotes the survival of ischaemic flaps. The levels of angiogenesis, oxidative stress, necroptosis, pyroptosis and indicators associated with signalling pathways in flaps were examined by IHC, immunofluorescence and Western blotting. Packaging adeno-associated virus (AAV) was used to activate STING in flaps. Results NRG1 promoted the survival of ischaemic flaps. An increased subcutaneous vascular network and neovascularization were found in ischaemic flaps after the application of NRG1. Transcriptomic gene ontology enrichment analysis and protein level detection indicated that necroptosis, pyroptosis and STING activity were reduced in the NRG1 group. The phosphorylation of AKT and forkhead box O3a (FOXO3a) were increased after NRG1 treatment. The increased expression of STING in flaps induced by AAV reversed the therapeutic effect of NRG1. The ability of NRG1 to phosphorylate AKT-FOXO3a, inhibit STING and promote flap survival was abolished after the application of the AKT inhibitor MK2206. Conclusions NRG1 inhibits pyroptosis and necroptosis by activating the AKT-FOXO3a signalling pathway to suppress STING activation and promote ischaemic flap survival.

Time-related variations in viability of random pattern skin flaps: An experimental study in rats

ABSTRACT Chronobiological variations are in the fabric of life. The first ideas regarding the possible effects of circadian rhythm on surgical outcomes were published in the early 2000s. Some studies support and oppose this idea. The lack of experimental evidence in a controlled setting has led to this study. This study aimed to explore the chronobiological implications of surgical outcomes. The rats were divided into four groups. A random pattern dorsal skin flaps were elevated in all groups at six h intervals. Flap necrosis rates and melatonin, oxidant, and antioxidant factors were studied. Flap survival was better in the 06:00 h group. The flap necrosis was higher in the 18:00 h group. Some of the biochemical parameters displayed circadian variations. As an independent variable, the time of surgical intervention changed the flap survival rates. It should be noted that the study was held in a nocturnal animal model thus the pattern of flap survival can be in reversed fashion in a clinical scenario. This study is the first experimental evidence for “Chronosurgery” in a controlled setting. Further studies in all aspects of surgical disciplines are required.

Melatonin Enhances the Viability of Random-Pattern Skin Flaps by Activating the NRF2 pathway

IntroductionRandom skin flap transplantation has been widely used in reconstructive and plastic surgery. As a well-known antioxidant, melatonin has the functions of eliminating reactive oxygen species (ROS), promoting angiogenesis, and protecting ischemia-reperfusion injury (IRI). We explored the effects of melatonin on random skin flap survival and the potential molecular mechanisms.Material and methodsA total of 72 rats were randomly assigned to the control group, the melatonin (MEL) group, and MEL + ML385 groups. After the construction of random skin flap model, these groups were treated with physiological saline, melatonin, and melatonin + ML385. The general conditions of random skin flaps were observed daily after the procedure. Laser doppler blood flow imaging was used to evaluate the subcutaneous vascular network. On postoperative day 7, the animals were euthanized to obtain flap specimens. Hematoxylin-Eosin staining was used to evaluate the vessel density. Immunohistochemistry, immunofluorescence staining, and western blotting were used to evaluate the expression of proteins involved in angiogenesis, oxidative stress, and inflammation.ResultsCompared to the control group, the MEL group exhibited lower tissue water, more abundant vascular, and higher vascular density, thereby enhancing the survival of random flaps. Additionally, the MEL group showed increased expression of angiogenesis-related proteins, enhanced expression of antioxidant proteins, and decreased expression of inflammatory factors. Furthermore, ML385, reversed the beneficial effect of melatonin on random skin flaps.ConclusionsThese findings of our present study demonstrated that melatonin promotes angiogenesis, inhibits oxidative stress, and inflammation by activating NRF2 signaling pathway, thus the improving the survival of random skin flaps.

Effect of adipose derived stem cells on the survival rate of long random pattern skin flap in rats, and the underlying mechanism of action

Purpose: To investigate the effect of adipose-derived stem cells (ADSCs) on the survival rate of long random pattern skin flaps in rats and the likely underlying mechanism.
 Methods: Twenty (20) SPF-grade SD rats were randomly divided into control group and study group, with 10 rats in each group. Rats in the control group were given phosphate buffered saline (PBS), while rats in the study group received ADSCs. The survival rate of the skin flaps was compared between the 2 groups on day 7 after operation, while the levels of indices related to oxidative stress and inflammatory response were compared on the 7th and 14th days after operation.
 Results: Necrosis in the study group was milder (p < 0.05). On the 7th post-operation day, the survival rate of rat skin flap in the study group was significantly higher than that in the control group (p < 0.05), but the MDA level in the study group was lower than that of the control group (p < 0.05). On the 14th day after the operation, the MDA level was decreased in the two groups (p < 0.05), with a lower MDA level in the study group than in the control group (p < 0.05).
 Conclusion: ADSCs inhibit inflammatory response and reduces the level of oxidative stress after long random pattern skin flap transplantation in rats, thereby enhancing blood supply to the flap transplantation area and improving its survival rate. Thus, ADSCs have a potential clinical application in enhancing blood supply in skin transplantation.

Baicalin promotes random-pattern skin flap survival by inducing autophagy via AMPK-regulated TFEB nuclear transcription.

The random-pattern skin flap is a generally used technique to cover the soft tissue defect, while its application is often constrained by complications after the flap transplant. Necrosis of the flap remains a principal obstacle. The purpose of this study was to investigate the effect of Baicalin on skin flap survival and its mechanism. First of all, we discovered that administering Baicalin stimulated cell migration and boosted the formation of capillary tubes in human umbilical vein endothelial cells. Then, we detected that Baicalin reduced apoptosis-induced oxidative stress by using western blot and oxidative stress test kit. After that, we observed that Baicalin increased autophagy and utilized 3MA to block autophagy augmentation substantially reversing the effects of Baicalin therapy. Furthermore, we uncovered the underlying mechanisms of Baicalin-induced autophagy via AMPK-regulated TFEB nuclear transcription. Finally, our in vivo experiment findings showed that Baicalin reduces oxidative stress, inhibits apoptosis, promotes angiogenesis, and boosts the levels of autophagy. After autophagy was blocked, substantially reversing the effects of Baicalin therapy. Our study indicated that Baicalin-induced autophagy via AMPK regulated TFEB nuclear transcription and then promotes angiogenesis and against oxidative stress and apoptotic promotes skin flap survival. These findings highlight the therapeutic potential for the clinical application of Baicalin in the future.

Nuciferine improves random skin flap survival via TFEB-mediated activation of autophagy-lysosomal pathway.

Due to their simplicity and reliability, random-pattern skin flaps are commonly utilized in surgical reconstruction to repair cutaneous wounds. However, the post-operative necrosis frequently happens because of the ischemia and high-level of oxidative stress of random skin flaps, which can severely affect the healing outcomes. Earlier evidence has shown promising effect of Nuciferine (NF) on preventing hydrogen peroxide (H2O2)-induced fibroblast senescence and ischemic injury, however, whether it can function on promoting ischemic flap survival remains unknown. In this work, using network pharmacology analysis, it was possible to anticipate the prospective targets of NF in the context of ischemia. The results revealed that NF treatment minimized H2O2-induced cellular dysfunction of human umbilical vein endothelial cells (HUVECs), and also improved flap survival through strengthening angiogenesis and alleviating oxidative stress, inflammation and apoptosis in vivo. These outcomes should be attributed to TFEB-mediated enhancement of autophagy-lysosomal degradation via the AMPK-mTOR signaling pathway, whilst the restriction of autophagy stimulation with 3MA effectively diminished the above advantages of NF treatment. The increased nuclear translocation of TFEB not only restored lysosome function, but also promoted autophagosome-lysosome fusion, eventually restoring the inhibited autophagic flux and filling the high energy levels. The outcomes of our research can provide potent proof for the application of NF in the therapy of vascular insufficiency associated disorders, including random flaps.

Procyanidin B2 regulates the Sirt1/Nrf2 signaling pathway to improve random-pattern skin flap survival.

Random-pattern skin flaps have been widely used in the reconstruction of damaged tissues. Ischemia-reperfusion injury occurring in the distal regions of the flap is a common issue, which often leads to flap necrosis and restricts its clinical applications. Procyanidin B2 (PB2), a naturally occurring flavonoid in large quantities in various fruits, has been demonstrated to exhibit several significant pharmacological properties. However, the effect of PB2 on flap viability is not clearly known. Here, using Western blot analysis, immunohistochemistry, and immunofluorescence staining, we observed that PB2 significantly reduced oxidative stress and inflammation and enhanced angiogenesis. Mechanically, we provided evidence for the first time that the beneficial effects of PB2 occur through the activation of the Sirt1/Nrf2 signaling pathway. Moreover, co-administration of PB2 and EX527, a selective inhibitor of Sirt1, resulted in down-regulation of the expression of Sirt1, Nrf2, and downstream antioxidants. In summary, our study showed that PB2 might be a novel therapeutic strategy for improving the survival of random-pattern skin flaps.

The effect of Ranolazine on random pattern skin flap survival in rats

Objective: Flap surgery is widely used in the field of plastic surgery for defect reconstruction. The most important problem of this surgery is ischemic necrosis which may occur in the distal of the flap. For this reason, studies have been conducted to develop many treatment methods to solve this problem. Our study aimed to investigate the effects of different doses of ranolazine, a selective late sodium current blocker, on the viability of skin flaps prepared from the back of the rat. Material and Methods: A total of 32 rats, including 8 rats in each group, were included in the study. A random patterned caudal base 3x9 cm width : length modified McFarlane skin flap was elevated from the backs of all rats and adapted back to its place For 7 days postoperatively, 1 cc of saline was added to the control group (Group A), and 45 mg/kg, 90 mg/kg, and 180 mg/kg of ranolazine were added to the study groups (Group B, C, D), respectively, and administered daily with gastric lavage On the 7th postoperative day, photographs were taken to evaluate the viability of the flaps and scintigraphic evaluations were made. After the rats were sacrificed, the flaps were separated from their bases and evaluated histopathologically. Results: As a result of the evaluations, the viable flap area was calculated as 12.7548 cm2 for Group A, 14.9533 cm2, 16.494 cm2 and 16.7599 cm2 for Groups B, C and D, respectively, and a statistically significant difference was found between the groups (P = 0.00 <0.05 ). The viable flap area percentages were calculated as 57.486% for Group A, 68.908% for Group B, 70.174% for Group C and 74.603% for Group D, and a statistically significant difference was found between the groups (P = 0.00 <0.05). As a result of scintigraphic evaluation, the viable flap area was found to be 61.57% for Group A, 71.04% for Group B, 70.21% for Group C and 73.85% for Group D, and a statistically significant difference was found between the groups (P = 0.03 <0.05). Histopathological evaluation revealed a decrease in the flaps' inflammation, edema and necrosis scores with the increasing drug dose. Conclusion: As a result, although flap viability increased with increasing doses in the group given ranolazine, more detailed studies are needed before it can be used clinically.

Macrophage contribution to the survival of transferred expanded skin flap through angiogenesis.

Despite the application of tissue expansion in the reconstruction of significant tissue defects, complications with expanded random-pattern skin flaps remain a major challenge. Insufficient angiogenesis is one of the keys factors in flap ischemia and dysfunction. Macrophages play a key role in promoting tissue angiogenesis, but their effects on expanded flap angiogenesis and the survival of the transferred skin flap are still unknown. A rat scalp expansion model was established to evaluate the dynamic changes of macrophages in expanded skin. Clodronate liposomes (Clo-lipo) were injected into the expanded scalps to deplete the macrophages, and the expanded scalp flaps with macrophage depletion were orthotopically transferred. The remaining expanded rat scalp flaps were treated with either a macrophage-colony stimulating factor (M-CSF) alone or M-CSF in combination with Clo-lipo and transferred. The number of macrophages, blood perfusion, microvascular densities (MVDs), flap survival, histological changes, and gene expression related to macrophage polarization and angiogenesis were determined with immunofluorescence (IF) staining, full-field laser perfusion imager, hematoxylin and eosin (HE) staining, and quantitative real-time polymerase chain reaction. The number of pan-macrophages significantly increased in the expanded scalp on days 14 and 21 after expander placement. The depletion rate after treatment with Clo-lipo was 29.06%, and the number of macrophages was significantly reduced in the group that underwent Clo-lipo treatment on day 14 before flap transfer (P<0.05). Macrophage depletion resulted in decreased blood perfusion, reduced MVDs, lower expression of factors, and poor survival rate. The recruitment of macrophages with a M-CSF led to higher blood perfusion, increased MVDs, greater expression of angiogenic factors, and better flap survival after flap transfer. Alternatively activated macrophages in the expanded flap could significantly promote angiogenesis, improve blood perfusion, and ultimately increase the flap survival rate. Modulating alternatively activated macrophages may provide a key therapeutic strategy to promote expanded skin flap survival. Our study has provided a basis for clinically improving random-pattern skin flap survival.

Fibroblast Growth Factor 9 Inhibited Apoptosis in Random Flap via the ERK1/2-Nrf2 Pathway to Improve Tissue Survival.

The application of random pattern skin flaps is limited in plastic surgery reconstruction due to necrosis. Fibroblast growth factor 9 (FGF9) was reported to exert a protective effect against myocardial damage and cerebral ischemia injury, but the impact of FGF9 in random flap survival is still unclear. In this study, we used a mouse model of random flaps to verify that FGF9 can directly increase flap survival area and blood flow intensity by promoting angiogenesis. In total, 84 male C57BL/6 mice weighing between 22 and 25 g were randomly divided into three groups (n = 28 each group). After skin flap operation, one group served as a control, a treatment group received FGF9, and a treatment group received FGF9+U0126. All flap samples were incised on postoperative day 7. Our results showed that flap survival was significantly increased in the FGF9 group compared with that in the control group. This protective function was restrained by U0126. The results of histopathology, laser Doppler, and fluorescent staining all showed significant increases in capillary count, collagen deposition, and angiogenesis. FGF9 also significantly increased the expression of antioxidant stress proteins SOD1, eNOS, HO-1, vascular marker proteins CD31, VE cadherin, and pericyte marker protein PDGFRβ. Western blot showed that the phosphorylation degree of ERK1/2 increased after FGF9 treatment, and the expression of Nrf2, a downstream factor, was u-regulated. Western blot and immunofluorescence results of apoptosis-related proteins cleaved caspase-3, BAX, and Bcl2 showed that FGF9 inhibited apoptosis. ERK inhibitor U01926 reduced the beneficial effects of FGF9 on skin flap survival, including promoting angiogenesis, and showing antiapoptosis and antioxidative stress activities. Exogenous FGF9 stimulates angiogenesis of random flap and survival of tissue. the impact of FGF9 is closely linked to the prevention of oxidative stress mediated by ERK1/2-Nrf2. In the function of FGF9 in promoting effective angiogenesis, there may be a close interaction in the FGF9-FGFR-PDGFR-ERK-VE cadherin pathway. In particular, PDGFR and VE cadherin may interact.