Flap Model Research Articles

Effect of Hyperbaric Oxygen Therapy and Adipocyte Stem Cell on the Viability of Degloving Injury: A Murine Model.

Degloving soft tissue injuries (DSTIs) involve skin and tissue detachment from muscle or fascia. Surgical treatments exist, but they cannot prevent necrosis. Our aim was to investigate the effects of hyperbaric oxygen therapy (HOT) and adipocyte stem cell (ASC) treatment on tissue viability in degloving injuries in a murine model. 32 animals were submitted to a degloving flap surgery in the dorsal region and were allocated in four groups (n=8/group): Control: suture only; HOT: 2-hour daily therapy in 100% oxygen at 2.0 ATA for 7 days; ASC: injected with 1x106 stem cells; ASC+HOT: stem cells injection plus HOT therapy. We performed macroscopic measurements, blood flow, histology, and expression of inflammation genes. After 7days, HOT, ASC, and ASC+HOT groups had significantly more viable tissue compared to Control (97%, 90%, 81% vs. 6%). Viable area ratios were higher in HOT and ASC than Control. Blood flow in the injury's distal region was higher in HOT, ASC, and ASC+HOT compared to Control. Vascular density was higher in HOT and ASC+HOT than Control. Inflammatory cells decreased by 40% in HOT, 50% in ASC+HOT, and 75% in ASC. Gene Cd68 expression was lower in HOT than Control. Il10 expression was lower in HOT but higher in ASC and ASC+HOT than Control. This study suggests that the HOT can benefit the degloving injury flap model in the early phase of wound healing, and the association of ASC with HOT could benefit the wound healing in a later phase. This journal requires that authors assign a level of evidence to each submission to which evidence-based medicine rankings are applicable. This excludes review articles, book reviews, and manuscripts that concern basic science, animal studies, cadaver studies, and experimental studies. 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 .

Caudal vertebra rat free flap in the groin: A preliminary study of a new combined osteocutaneous flap model

IntroductionMurins were used for microsurgical training but in the literature, only a few papers reported about murin combination of flaps and fewer about osteocutaneous ones. We proposed a rat model of a combined osteocutaneous flap in which the pedicle axis is intentionally lengthened. Technical noteFrom June to August 2020, one corpse and eight living Albinos Wistar rats were dissected. The 4th vertebra was harvested with its vessels and transferred to the groin with end-to-side anastomosis to the femoral vessels. Surviving rats were dissected to explore the combined osteocutaneous flap. Only two rats survived until second dissection. Transfixiant arterial and veinous stitches were observed in failed procedures. Caudal pedicles and epigastric pedicles were permeable in surviving animal with bleeding of the vertebra body surface. DiscussionPerspective of simultaneous vertebral free flap and bone graft could build up a potential rat model of comparison with a prelaminar flap.

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.

Quercetin activates autophagy in the distal ischemic area of random skin flaps through Beclin1 to enhance the adaptability to energy deficiency

Random flaps are frequently employed in treating substantial skin abnormalities and in surgical tissue-rebuilding interventions. The random flap technique provides flaps of specific dimensions and contours to fit the surgical incision. However, blood supply deficiency and subsequent ischemia-reperfusion injury can cause severe oxidative stress and apoptosis, eventually leading to distal necrosis, which limits the clinical application of the flap. Quercetin (QUE) is primarily found in the glycoside form in many plant parts, such as stem bark, flowers, leaves, buds, seeds, and fruits. Cellular, animal, and clinical studies have demonstrated the antioxidant, anti-apoptosis, anti-inflammatory, and activation of autophagy properties of QUE. In previous studies, high doses of QUE effectively suppressed the survival of human umbilical vein endothelial cells (HUVECs) stimulated by hydrogen peroxide. However, different concentration gradients of QUE on HUVECs revealed a significant protective effect at a concentration of 10 mM. The protective impact of QUE on HUVECs was evaluated using scratch tests, CCK-8 assays, and EDU assays. Simultaneously, a mouse model of random skin flap was created, and the impact of QUE on skin flap survival was examined by intragastric injection. The QUE group showed a significantly larger survival area of the random flap and higher blood flow intensity compared to the control group. Furthermore, the beneficial effects of QUE were reversed by the autophagy inhibitor 3-MA. Therefore, autophagy plays a significant role in the therapeutic benefits of QUE on flap survival.

GPER deficiency impedes murine myocutaneous revascularization and wound healing

Estrogens regulate numerous physiological and pathological processes, including wide-ranging effects in wound healing. The effects of estrogens are mediated through multiple estrogen receptors (ERs), including the classical nuclear ERs (ERα and ERβ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\upbeta }$$\\end{document}), that typically regulate gene expression, and the 7-transmembrane G protein-coupled estrogen receptor (GPER), that predominantly mediates rapid “non-genomic” signaling. Estrogen modulates the expression of various genes involved in epidermal function and regeneration, inflammation, matrix production, and protease inhibition, all critical to wound healing. Our previous work demonstrated improved myocutaneous wound healing in female mice compared to male mice. In the current study, we employed male and female GPER knockout mice to investigate the role of this estrogen receptor in wound revascularization and tissue viability. Using a murine myocutaneous flap model of graded ischemia, we measured real-time flap perfusion via laser speckle perfusion imaging. We conducted histologic and immunohistochemical analyses to assess skin and muscle viability, microvascular density and vessel morphology. Our results demonstrate that GPER is crucial in wound healing, mediating effects that are both dependent and independent of sex. Lack of GPER expression is associated with increased skin necrosis, reduced flap perfusion and altered vessel morphology. These findings contribute to understanding GPER signaling in wound healing and suggest possible therapeutic opportunities by targeting GPER.

Application of Photoplethysmography Combined with Deep Learning in Postoperative Monitoring of Flaps

Photoelectric volumetric tracing (PPG) exhibits high sensitivity and specificity in flap monitoring. Deep learning (DL) is capable of automatically and robustly extracting features from raw data. In this study, we propose combining PPG with 1D convolutional neural networks (1D-CNN) to preliminarily explore the method's ability to distinguish the degree of embolism and to localize the embolic site in skin flap arteries. Data were collected under normal conditions and various embolic scenarios by creating vascular emboli in a dermatome artery model and a rabbit dermatome model. These datasets were then trained, validated, and tested using 1D-CNN. As the degree of arterial embolization increased, the PPG amplitude upstream of the embolization site progressively increased, while the downstream amplitude progressively decreased, and the gap between the upstream and downstream amplitudes at the embolization site progressively widened. 1D-CNN was evaluated in the skin flap arterial model and rabbit skin flap model, achieving average accuracies of 98.36% and 95.90%, respectively. The combined monitoring approach of DL and PPG can effectively identify the degree of embolism and locate the embolic site within the skin flap artery.

A Co-MOF encapsulated microneedle patch activates hypoxia induction factor-1 to pre-protect transplanted flaps from distal ischemic necrosis

Avoiding ischemic necrosis after flap transplantation remains a significant clinical challenge. Developing an effective pretreatment method to promote flap survival postoperatively is crucial. Cobalt chloride (CoCl2) can increase cell tolerance to ischemia and hypoxia condition by stimulating hypoxia-inducible factor-1 (HIF-1) expression. However, the considerable toxic effects severely limit the clinical application of CoCl2. In this study, cobalt-based metal-organic frameworks (Co-MOF) encapsulated in a microneedle patch (Co-MOF@MN) was developed to facilitate the transdermal sustained release of Co2+ for rapid, minimally invasive rapid pretreatment of flap transplantation. The MN patch was composed of a fully methanol-based two-component cross-linked polymer formula, with a pyramid structure and high mechanical strength, which satisfied the purpose of penetrating the skin stratum corneum of rat back to achieve subcutaneous vascular area administration. Benefiting from the water-triggered disintegration of Co-MOF and the transdermal delivery via the MN patch, preoperative damage and side effects were effectively mitigated. Moreover, in both the oxygen-glucose deprivation/recovery (OGD/R) cell model and the rat dorsal perforator flap model, Co-MOF@MN activated the HIF-1α pathway and its associated downstream proteins, which reduced reperfusion oxidative damage, improved blood supply in choke areas, and increased flap survival rates post-transplantation. This preprotection strategy, combining MOF nanoparticles and the MN patch, meets the clinical demands for trauma minimization and uniform administration in flap transplantation. Statement of significanceCobalt chloride (CoCl2) can stimulate the expression of hypoxia-inducible factor (HIF-1) and improve the tolerance of cells to ischemia and hypoxia conditions. However, the toxicity and narrow therapeutic window of CoCl2 severely limit its clinical application. Herein, we explored the role of Co-MOF as a biocompatible nanocage for sustained release of Co2+, showing the protective effect on vascular endothelial cells in the stress model of oxygen-glucose deprivation. To fit the clinical needs of minimal trauma in flap transplantation, a Co-MOF@MN system was developed to achieve local transdermal delivery at the choke area, significantly improving blood supply opening and flap survival rate. This strategy of two-step delivery of Co2+ realized the enhancement of biological functions while ensuring the biosafety.

Investigating the Mechanical Performance of Bionic Wings Based on the Flapping Kinematics of Beetle Hindwings.

The beetle, of the order Coleoptera, possesses outstanding flight capabilities. After completing flight, they can fold their hindwings under the elytra and swiftly unfold them again when they take off. This sophisticated hindwing structure is a result of biological evolution, showcasing the strong environmental adaptability of this species. The beetle's hindwings can provide biomimetic inspiration for the design of flapping-wing micro air vehicles (FWMAVs). In this study, the Asian ladybird (Harmonia axyridis Pallas) was chosen as the bionic research object. Various kinematic parameters of its flapping flight were analyzed, including the flight characteristics of the hindwings, wing tip motion trajectories, and aerodynamic characteristics. Based on these results, a flapping kinematic model of the Asian ladybird was established. Then, three bionic deployable wing models were designed and their structural mechanical properties were analyzed. The results show that the structure of wing vein bars determined the mechanical properties of the bionic wing. This study can provide a theoretical basis and technical reference for further bionic wing design.

Experimental study of slow-released Angiogenin by silicon micro-needle in improving blood support to multiple-territory perforator flaps in rats.

This research aimed to investigate the effect of slow-released angiogenin by silicon micro-needle on angiogenesis in the Choke zone of dorsal multiple-territory perforator flap in rats, as well as its mechanism. Thirty-six adult Sprague-Dawley (SD) rats were randomly divided into control group, model group, and four experimental groups. In model group, slow-release saline through a silicon micro-needle was placed in choke II zone of the flap 7 days before the operation. For rats in four experimental groups, angiogenin was released via micro-needle in the choke I and choke II zones of the cross-zone flap 7 days before and 3 days before flap surgery, respectively. A 12 cm × 3 cm cross-zone perforator flap model was made on the back of all five groups. The flap survival rate in slow-release angiopoietin group was statistically higher than that in model group (P<0.05). Angiogenin in choke zone of the flap was increased in slow-release angiogenin group (P<0.05). In slow-release angiogenin group, the micro-vessel density was increased and the arteriovenous diameter was decreased, while the arteriovenous diameter was increased in model group (P<0.05). The levels of vascularendothelialgrowthfactorA (VEGF-A) and angiotensin 1 (ANG-1) in choke zone were both elevated in slow-release angiogenin group (P<0.05). The expression of CD31 was significantly elevated in flaps of experimental groups (P<0.05). Micro-needle to slow release Angiogenin can increase the drug concentration in the tissues of the choke zone, promote the vascularization of rat dorsal crossover area perforator flap, reduce the possibility of flap ischemic necrosis, and improve the flap survival rate.

Development of a porcine training model for microvascular fasciocutaneous free flap reconstruction

BackgroundIn reconstructive surgery, improvements are needed in the effective teaching of free flap surgery. There is a need for easily accessible and widely available training without high financial costs or ethical concerns while still providing a realistic experience. Our aim was to develop an appropriate training model for microvascular flaps.MethodsWe identified pig head halves as most appropriate regarding availability, cost, and realism. These accrue largely by the food industry, so no animals need to be sacrificed, making it more ethical from an animal welfare perspective. We evaluated the suitability as flap donor site and analyzed the vascular anatomy of 51 specimens.ResultsAnatomical evaluation revealed a reliable and constant vascular anatomy, allowing the design of a flap model that can effectively illustrate the entire process of microvascular flap surgery. The process was divided into 6 key steps. The flap can be harvested after marking the vascular pedicle 5.3 cm from the lateral corner of the mouth. Skin island design and subsequent tissue dissection follow until a fasciocutaneous flap is raised, similar to a radial flap. Upon completion of flap harvesting, it can be freely transferred for defect reconstruction. Microvascular anastomosis can be performed on recipient vessels in the cervical region, and the difficulty can be individually adjusted.ConclusionsThe developed training model is a reasonable compromise in terms of surgical realism, availability, didactic value, and cost/time effectiveness. We believe it is a powerful and effective tool with high potential for improving surgical education and training.

Application of Stem Cells Shows Antiinflammatory Effect in an Irradiated Random Pattern Flap Model.

In reconstructive surgery, local flaps might develop tissue necrosis or partial flap loss especially after previous irradiation, which may be necessary in many tumor entities. The application of stem cells seems promising to improve flap perfusion and might be a possible solution to optimize flap survival. Twenty rats received harvesting of bilateral random pattern fasciocutaneous flaps. The right flaps received 20 Gy ionizing radiation 4 weeks prior to the surgery, while the left flaps served as the non-irradiated control. After flap harvest, four different stem cell mixtures (5 × 106 ASC, ASC-HUVEC, MSC, MSC-HUVEC) were applied under both right and left flaps using 1 mL fibrin glue as the delivery vehicle. Flap size and its necrotic area were examined clinically. Two weeks after the surgery, HE staining and immunohistochemical staining for CD68 and ERG, as well as PCR analysis (Interleukin 6, HIF-1α and VEGF), were performed. Application of ASCs, ASCs-HUVECs and MSCs resulted in a lower number of CD68-stained cells compared to the no cell group. The expression of Hif1α was higher in the ASC group compared to those in the MSC and previously treated no cell groups. Treatment with MSCs and MSCs-HUVECs prevented shrinking of the flaps in this series. Application of ASCs, MSCs and ASCs-HUVECs was shown to have an antiinflammatory effect. Treatment with MSCs and MSCs-HUVECs can prevent early shrinking of the flaps.

Prediction of pedicled flap survival preoperatively by operating indocyanine green angiography at 1,450 nm wavelength: an animal model study.

Predicting flap viability benefits patients by reducing complications and guides flap design by reducing donor areas. Due to varying anatomy, obtaining individual vascular information preoperatively is fundamental for designing safe flaps. Although indocyanine green angiography (ICGA) is a conventional tool in intraoperative assessment and postoperative monitoring, it is rare in preoperative prediction. ICGA was performed on 20 male BALB/c mice under five wavelengths (900/1,000/1,100, /1,250/1,450 nm) to assess vascular resolution after ICG perfusion. A "mirrored-L" flap model with three angiosomes was established on another 20 male BALB/c mice, randomly divided into two equal groups. In Group A, a midline between angiosomes II and III was used as a border. In Group B, the points of the minimized choke vessel caliber marked according to the ICG signal at 1,450 nm wavelength (ICG1450) were connected. Necrotic area calculations, pathohistological testing, and statistical analysis were performed. The vascular structure was clearly observed at 1,450 nm wavelength, while the 900 to 1,100 nm failed to depict vessel morphology. Necrosis was beyond the borderline in 60% of Group A. Conversely, 100% of Group B had necrosis distal to the borderline. The number of choke vessels between angiosomes II and III was positively correlated with the necrotic area (%). The pathohistological findings supported the gross observation and analysis. ICG1450 can delineate the vessel structure in vivo and predict the viability of pedicled skin flaps using the choke vessel as the border between angiosomes.

β-Caryophyllene promotes the survival of random skin flaps by upregulating the PI3K/AKT signaling pathway

BackgroundFlap transplantation is a widely used plastic repair technique in surgical procedures, aimed at addressing skin defects resulting from diverse wounds and diseases. However, due to the insufficient blood supply after flap surgery, the occurrence of ischemia-reperfusion injury, and an excessive sterile inflammatory response, flaps frequently develop complications (e.g., partial or complete ischemic necrosis). These complications have adverse effects on wound healing and repair. β-Caryophyllene (BCP) is a bicyclic sesquiterpene that is widely present in plants. It mitigates oxidative stress and inflammatory responses, demonstrates neuroprotective and analgesic properties, and serves a protective function in organs or tissues subjected to ischemia-reperfusion injury. However, no study has confirmed whether BCP can be used in the field of flap transplantation to improve the flap survival rate. MethodsTo assess the impact of BCP on random flap survival, we constructed a modified McFarlane random flap model on the rat. After 7 consecutive days of gavage with different doses of BCP, we measured the survival area ratio, angiogenesis, blood perfusion, tissue inflammation level, apoptosis-related protein levels, and the PI3K/AKT signaling pathway expression of the random flap. ResultsBCP treatment increased the survival area of the flap in a dose-dependent manner after random flap transplantation in rats. BCP mainly promoted the formation of tissue blood vessels, improved flap blood perfusion, limited the local inflammatory response, and reduced apoptosis. In addition, we demonstrated that BCP works primarily by promoting the PI3K/AKT signaling expression while enhancing the phosphorylation of AKT. Administration of wortmannin, a selective inhibitor of PI3K, eliminated the effects of BCP. ConclusionBCP can promote the survival of random flaps by upregulating the PI3K/AKT signaling pathway, increasing tissue blood perfusion, and limiting the inflammatory response and apoptosis.

Protective effects of the bioactive peptide from maggots against skin flap ischemia‒reperfusion injury in rats

Ischemia‒reperfusion (I/R) injury is a frequently observed complication after flap surgery, and it affects skin flap survival and patient prognosis. Currently, there are no proven safe and effective treatment options to treat skin flap I/R injury. Herein, the potential efficacies of the bioactive peptide from maggots (BPM), as well as its underlying mechanisms, were explored in a rat model of skin flap I/R injury and LPS- or H2O2-elicited RAW 264.7 cells. We demonstrated that BPM significantly ameliorated the area of flap survival, and histological changes in skin tissue in vivo. Furthermore, BPM could markedly restore or enhance Nrf2 and HO-1 levels, and suppress the expression of pro-inflammatory cytokines, including TLR4, p-IκB, NFκB p65, p-p65, IL-6, and TNF-α in I/R-injured skin flaps. In addition, BPM treatment exhibited excellent biocompatibility with an adequate safety profile, while it exhibited superior ROS-scavenging ability and the upregulation of antioxidant enzymes in vitro. Mechanistically, the above benefits related to BPM involved the activation of Nrf2/HO-1 and suppression of TLR4/NF-κB pathway. Taken together, this study may provide a scientific basis for the potential therapeutic effect of BPM in the prevention of skin flap I/R injury and other related diseases.

Fabrication of a tailor-made conductive polyaniline/ascorbic acid-coated nanofibrous mat as a conductive and antioxidant cell-free cardiac patch

Polyaniline (PANI) was in-situ polymerized on nanofibrous polycaprolactone mats as cell-free antioxidant cardiac patches (CPs), providing electrical conductivity and antioxidant properties. The fabricated CPs took advantage of intrinsic and additive antioxidant properties in the presence of PANI backbone and ascorbic acid as a biocompatible dopant of PANI. The antioxidant nature of CPs may reduce the serious repercussions of oxidative stress, produced during the ischemia-reperfusion (I/R) process following myocardial infarction. The polymerization parameters were considered as aniline (60 mM, 90 mM, and 120 mM), ascorbic acid concentrations ([aniline]:[ascorbic acid] = 3:0, 3:0.5, 3:1, 3:3), and polymerization time (1 h and 3 h). Mainly, the more aniline concentrations and polymerization time, the less sheet resistance was obtained. 1,1 diphenyl-2-picrylhydrazyl (DPPH) assay confirmed the dual antioxidant properties of prepared samples. The advantage of the employed in-situ polymerization was confirmed by the de-doping/re-doping process. Non-desirable groups were excluded based on their electrical conductivity, antioxidant properties, and biocompatibility. The remained groups protected H9c2 cells against oxidative stress and hypoxia conditions. Selected CPs reduced the intracellular reactive oxygen species content and mRNA level of caspase-3 while the Bcl-2 mRNA level was improved. Also, the selected cardiac patch could attenuate the hypertrophic impact of hydrogen peroxide on H9c2 cells. The in vivo results of the skin flap model confirmed the CP potency to attenuate the harmful impact of I/R.

The effect of human recombinant epidermal growth factor on neovascularization and pedicle division time in a rat interpolation flap model.

In practice, waiting 2-3 weeks for interpolation flaps pedicle division result in certain morbidities and discomfort for patient. The division time of flap pedicle depends on neovascularization from the recipient bed and includes wound healing stages. We aimed to investigate the effect of recombinant human epidermal growth factor (rhEGF) on the flap viability during early pedicle division. Thirty-six rats were allocated to two main groups as control and study. A cranial based flap measuring 5 × 5 cm was elevated from the back, including all layers of the skin. While the cranial half of the defect was primarily closed, the flap was inset into the distal half. In the study group, a single dose of 20 μg EGF was injected into the recipient site and wound edges before the flap inset. The control group received no treatment. Each main group was divided into three subgroups based on pedicle division time of 8, 11 and 14 days. After pedicle division, each flap was monitored and photographed for 7 days, and histopathological samples were collected. Viable and necrotic areas were compared, and flaps were examined histopathologically. The necrosis area in the study group on the 11th day was significantly lower than that in the control group. The fibroblastic activity, granulation tissue and neovascularization on the 8th day, the granulation tissue level on the 11th day, and the neovascularization level on the 14th day were significantly higher in the study groups. Following the application of EGF, the necrosis area decreased within the study group. Histopathological assessments revealed a statistically significant increase in parameters related to granulation tissue and fibroblastic activity, notably neovascularization, across all subgroups within the study. It was concluded that the use of EGF positively affected the neovascularization, and flaps could be divided earlier.

In vitro and in vivo investigation of Argiope bruennichi spider silk-based novel biomaterial for medical use.

As a natural and biocompatible material with high strength and flexibility, spider silk is frequently used in biomedical studies. In this study, the availability of Argiope bruennichi spider silk as a surgical suture material was investigated. The effects of spider silk-based and commercial sutures, with and without Aloe vera coating, on wound healing were evaluated by a rat dorsal skin flap model, postoperatively (7th and 14th days). Biochemical, hematological, histological, immunohistochemical, small angle x-ray scattering (SAXS) analyses and mechanical tests were performed. A. bruennichi silk did not show any cytotoxic effect on the L929 cell line according to MTT and LDH assays, in vitro. The silk materials did not cause any allergic reaction, infection, or systemic effect in rats according to hematological and biochemical analyses. A. bruennichi spider silk group showed a similar healing response to commercial sutures. SAXS analysis showed that the 14th-day applications of A. bruennichi spider silk and A. vera coated commercial suture groups have comparable structural results with control group. In conclusion, A. bruennichi spider silk is biocompatible in line with the parameters examined and shows a healing response similar to the commercial sutures commonly used in the skin.

Propionyl-l-carnitine mitigates ischemia-reperfusion injury in rat epigastric island flaps

BackgroundIschemia-reperfusion injury presents a substantial concern in various medical scenarios, notably in reconstructive surgery involving tissue flaps. Despite reports on the protective benefits of Propionyl-l-carnitine against ischemia-reperfusion injury, a thorough assessment of its efficacy in epigastric island flap models is currently lacking. MethodsSixteen male Sprague-Dawley rats underwent epigastric island flap surgery and were divided into two groups: a Propionyl-l-carnitine group that received intraperitoneal Propionyl-l-carnitine prior to ischemia induction and a sham group that received saline treatment. A comprehensive evaluation was performed including macroscopic, biochemical and histological assessments encompassing measurements of flap survival areas, lipid peroxidation (malondialdehyde), glutathione, myeloperoxidase, nitric oxide and peripheral neutrophil counts. ResultsThe Propionyl-l-carnitine group demonstrated significantly increased flap survival areas when compared to the sham group. Administration of Propionyl-l-carnitine led to reduced malondialdehyde levels and elevated glutathione levels indicating a reduction in oxidative stress. Furthermore, the Propionyl-l-carnitine group exhibited lower myeloperoxidase levels, higher nitric oxide levels and reduced peripheral neutrophil counts, suggesting a decrease in the inflammatory response. Histopathological analysis revealed decreased levels of inflammation, necrosis, polymorphonuclear leukocyte infiltration and edema in the Propionyl-l-carnitine group. Additionally, vascularity was enhanced in the Propionyl-l-carnitine group. ConclusionThis study provides compelling evidence that Propionyl-l-carnitine administration effectively mitigates the deleterious effects of ischemia-reperfusion injury in epigastric island flaps. This is substantiated by the improved flap survival, diminished oxidative stress and inflammation, as well as the enhanced vascularity observed. Propionyl-l-carnitine emerges as a promising therapeutic intervention to enhance tissue flap survival in reconstructive surgery, warranting further exploration through larger-scale investigations.

The Effect of Necrostatin -1 and Enoxaparin Molecules on Random Pattern Flap Viability

Distal flap necrosis is seen more often in random pattern flaps and is an important complication that shortens the flap length. There has been much research many drugs and molecules in an effort to prevent this complication. The aim of this study was to investigate the efficacy of necrostatin-1 and enoxaparin molecules in preventing distal flap necrosis and increasing flap viability in a random pattern flap model created in rats. A total of 32 Wistar albino female rats, each weighing 300-350 gr were separated into 4 groups. All the animals underwent an operation to create a 3×9 cm caudal-based Mcfarlane flap. The treatments defined for each group were applied. Full layer tisssue samples 1×1 cm2 were taken from all the flaps and stored until histopathological and immunohistochemical examination, the parameters of inflammation, capillary proliferation, necrosis, fibroblast proliferation and fibrosis were compared histopathologically. In the necrostatin-1 group, the inflammation, necrosis and fibrosis scores were observed to be lower and the capillary proliferation and fibroblast proliferation scores were higher. In the enoxaparin group, the fibroblast proliferation and capillary proliferation scores were higher. The receptor interacting protein kinase-1 immunohistochemical staining results showed statistically significantly less staining in the necrostatin-1 group compared to the other groups. The results of this study suggest that necrostatin molecule has important therapeutic potential in increasing flap viability in the random pattern flap model, considering the percentage of flap necrosis, and the immunohistochemical and histopathological data. The flap necrosis percentage and histochemical parameters of the enoxaparin molecule demonstrate that the effects on flap viability are limited.

Extended autologous tracheal replacement by a novel pedicled thoraco-chondro-costal flap: a cadaveric proof of concept.

Our aim was to report an anatomic model of an autologous flap based on the internal thoracic blood supply: the pedicled thoraco-chondro-costal flap; and establish the feasibility of various types of extended tracheal replacement with this novel flap, according to a newly proposed topographic classification. In a cadaveric model, a cervicotomy combined with median sternotomy was performed. The incision was extended laterally to expose the chest wall. The internal thoracic pedicle was freed from its origin down to the upper limit of the delineated flap to be elevated. The perichondria and adjacent periostea were incised longitudinally to remove cartilages and adjacent rib segments, preserving perichondria and periostea. A full-thickness quadrangular chest wall flap pedicled on internal thoracic vessels was then elevated and shaped into a neo conduit to replace the trachea with the pleura as an inner lining. Various types of extended non-circumferential and full-circumferential tracheal replacements were achieved with this composite flap. No anastomosis tension was noticed despite the absence of release manoeuvres. This model could represent a suitable autologous tracheal substitute, which is long, longitudinally flexible and eventually transversely rigid. No microsurgical vascular anastomoses are required. The technique is reproducible. The perichondria and periostea would regenerate vascularized neo-cartilaginous rings, potentially decreasing the need for long-term stenting. The inner pleural lining could potentially transform into ciliated epithelium as shown in previous preclinical studies.