Effects of Lidocaine on Random Skin Flap Survival in Rats

U-Turn Design Metatarsal Artery Flap: Reliable Solution in Distal Forefoot Defect

BACKGROUND

In distal forefoot defect, finding wound closure is challenging because of the distal site and small blood vessels involved. One possible resolution is the utilization of a metatarsal artery flap in a 'U-turn' design. This method offers several advantages, including its long length and a viable option for distal forefoot defect.

METHODS

Thirty-six patients with forefoot injuries from metatarsophalangeal (MTP) joint to distal interphalangeal (DIP) joint due to trauma were consecutively recruited and completed the study. Outcomes were analyzed descriptively, and risk prediction modeling for edge necrosis was performed.

RESULTS

The mean ± SD follow-up time was 27.3 months ±1.9. The median (IQR) MTP-to-DIP joint wound width and length were 1.8 (1.4, 3.0) and 3.2 cm (2.9, 6.2), respectively. The median (IQR) width, length, and width-to-length ratio flap dimensions were 3.6 (2.8, 6.0), 4.7 cm (4.3, 9.3), and 1.5 (1.2, 1.7), respectively. The mean ± SD operative time was 32.9 min ± 5.7. The median (IQR) intraoperative blood loss was 5.0 mL (4.0, 5.0). The mean ± SD hospital length of stay postoperatively was 4.0 days ±1.0. The mean ± SD Foot and Ankle Outcome Score and Foot Function Index were 64.1 ± 2.5 and 7.8% ± 3.3, respectively. All patients had good or excellent aesthetic satisfaction. Spontaneously resolving edge necrosis occurred in 13.9%. The mean ± SD time-to-start-ambulation was 1.7 weeks ±0.5. At the 2-year follow-up visit, all patients had reduced U-turn flap pivot point redundancy without shoe size impact, needing reoperation, or donor site morbidity. Edge necrosis was significantly associated with length-to-width ratio ( P = 0.014) but not with Foot and Ankle Outcome Score or Foot Function Index.

CONCLUSIONS

Metatarsal artery flap of U-turn design was reliable and was associated with a short recovery time, alternative resolution for forefoot area due to short operation time, minimal blood loss, short hospital length of stay, and excellent availability.

Systematic review of pathologic markers in skin ischemia with and without reperfusion injury in microsurgical reconstruction: Biomarker alterations precede histological structure changes

BACKGROUND

Ischemia and ischemia-reperfusion injury contribute to partial or complete flap necrosis. Traditionally, skin histology has been used to evaluate morphological and structural changes, however histology does not detect early changes. We hypothesize that morphological and structural skin changes in response to ischemia and IRI occur late, and modification of gene and protein expression are the earliest changes in ischemia and IRI.

METHODS

A systematic review was performed in accordance with PRISMA guidelines. Studies reporting skin histology or gene/protein expression changes following ischemia with or without reperfusion injury published between 2002 and 2022 were included. The primary outcomes were descriptive and semi-quantitative histological structural changes, leukocyte infiltration, edema, vessel density; secondary outcomes were quantitative gene and protein expression intensity (PCR and western blot). Model type, experimental intervention, ischemia method and duration, reperfusion duration, biopsy location and time point were collected.

RESULTS

One hundred and one articles were included. Hematoxylin and eosin (H&E) showed inflammatory infiltration in early responses (12-24 h), with structural modifications (3-14 days) and neovascularization (5-14 days) as delayed responses. Immunohistochemistry (IHC) identified angiogenesis (CD31, CD34), apoptosis (TUNEL, caspase-3, Bax/Bcl-2), and protein localization (NF-κB). Gene (PCR) and protein expression (western blot) detected inflammation and apoptosis; endoplasmic reticulum stress/oxidative stress and hypoxia; and neovascularization. The most common markers were TNF-α, IL-6 and IL-1β (inflammation), caspase-3 (apoptosis), VEGF (neovascularization), and HIF-1α (hypoxia).

CONCLUSION

There is no consensus or standard for reporting skin injury during ischemia and IRI. H&E histology is most frequently performed but is primarily descriptive and lacks sensitivity for early skin injury. Immunohistochemistry and gene/protein expression reveal immediate and quantitative cellular responses to skin ischemia and IRI. Future research is needed towards a universally-accepted skin injury scoring system.

Pharmacological and cell-based treatments to increase local skin flap viability in animal models

Local skin flaps are frequently employed for wound closure to address surgical, traumatic, congenital, or oncologic defects. (1) Despite their clinical utility, skin flaps may fail due to inadequate perfusion, ischemia/reperfusion injury (IRI), excessive cell death, and associated inflammatory response. (2) All of these factors contribute to skin flap necrosis in 10-15% of cases and represent a significant surgical challenge. (3, 4) Once flap necrosis occurs, it may require additional surgeries to remove the entire flap or repair the damage and secondary treatments for infection and disfiguration, which can be costly and painful. (5) In addition to employing appropriate surgical techniques and identifying healthy, well-vascularized tissue to mitigate the occurrence of these complications, there is growing interest in exploring cell-based and pharmacologic augmentation options. (6) These agents typically focus on preventing thrombosis and increasing vasodilation and angiogenesis while reducing inflammation and oxidative stress. Agents that modulate cell death pathways such as apoptosis and autophagy have also been investigated. (7) Implementation of drugs and cell lines with potentially beneficial properties have been proposed through various delivery techniques including systemic treatment, direct wound bed or flap injection, and topical application. This review summarizes pharmacologic- and cell-based interventions to augment skin flap viability in animal models, and discusses both translatability challenges facing these therapies and future directions in the field of skin flap augmentation.

Activation of aldehyde dehydrogenase-2 improves ischemic random skin flap survival in rats

Objective

Random skin flaps have many applications in plastic and reconstructive surgeries. However, distal flap necrosis restricts wider clinical utility. Mitophagy, a vital form of autophagy for damaged mitochondria, is excessively activated in flap ischemia/reperfusion (I/R) injury, thus inducing cell death. Aldehyde dehydrogenase-2 (ALDH2), an allosteric tetrameric enzyme, plays an important role in regulating mitophagy. We explored whether ALDH2 activated by N-(1,3-benzodioxol-5-ylmethyl)-2,6-dichlorobenzamide (Alda-1) could reduce the risk of ischemic random skin flap necrosis, and the possible mechanism of action.

Methods

Modified McFarlane flap models were established in 36 male Sprague-Dawley rats assigned randomly to three groups: a low-dose Alda-1 group (10 mg/kg/day), a high-dose Alda-1 group (20 mg/kg/day) and a control group. The percentage surviving skin flap area, neutrophil density and microvessel density (MVD) were evaluated on day 7. Oxidative stress was quantitated by measuring the superoxide dismutase (SOD) and malondialdehyde (MDA) levels. Blood perfusion and skin flap angiogenesis were assessed via laser Doppler flow imaging and lead oxide-gelatin angiography, respectively. The expression levels of inflammatory cytokines (IL-1β, IL-6, and TNF-α), vascular endothelial growth factor (VEGF), ALDH2, PTEN-induced kinase 1 (PINK1), and E3 ubiquitin ligase (Parkin) were immunohistochemically detected. Indicators of mitophagy such as Beclin-1, p62, and microtubule-associated protein light chain 3 (LC3) were evaluated by immunofluorescence.

Results

Alda-1 significantly enhanced the survival area of random skin flaps. The SOD activity increased and the MDA level decreased, suggesting that Alda-1 reduced oxidative stress. ALDH2 was upregulated, and mitophagy-related proteins (PINK1, Parkin, Beclin-1, p62, and LC3) were downregulated, indicating that ALDH2 inhibited mitophagy through the PINK1/Parkin signaling pathway. Treatment with Alda-1 reduced neutrophil infiltration and expressions of inflammatory cytokines. Alda-1 significantly upregulated VEGF expression, increased the MVD, promoted angiogenesis, and enhanced blood perfusion.

Conclusion

ALDH2 activation can effectively enhance random skin flap viability via inhibiting PINK1/Parkin-dependent mitophagy. Moreover, enhancement of ALDH2 activity also exerts anti-inflammatory and angiogenic properties.

Standardization of the Rat Dorsal Random Pattern (McFarlane) Flap Model and Evaluation of the Pharmacological Agents Aiming to Salvage Partial Flap Necrosis: A Systematic Review and a Meta-analysis

INTRODUCTION

Partial flap necrosis is a common complication after surgery. McFarlane flap model has been used for assessment of various agents' effects on random flap survival. The aim of this study was to review the methodology of studies using this flap model and reveal the most successful agents.

MATERIALS AND METHODS

PubMed, Scopus, and Web of Science databases were screened for words "McFarlane flap," "flap survival," and ("flap" and "rat") by using time limits between 1965 and 2019. A total of 71 original articles were reviewed. Dimensions and base (cranial/caudal) of the flap, treatment protocol, follow-up period, and survival rates were extracted. Modified survival rates were calculated. Coefficients of variation of cranial/caudally based control group flaps and most commonly used flap models were calculated to assess interstudy variability.

RESULTS

A total of 165 different treatment regimens were studied. One-hundred twelve regimens (67.9%) were found to increase flap survival. Most common flap dimensions were 9 cm × 3 cm, followed by 10 cm × 3 cm, 8 cm × 2 cm and 6 cm × 2 cm. Studies using caudally based flaps showed less interstudy variability, but survival rates were similar. Pentoxifylline, sildenafil, chlorpromazine, phenoxybenzamine, and phentolamine were reported to be successful in multiple studies.

CONCLUSIONS

There are numerous agents found to be effective for treatment of partial flap necrosis, but further clinical research is needed. To overcome standardization problems, use of commonly used flap dimensions with a caudal base and interpretation of results after 7 days of follow-up seems appropriate.

"Pingpong racket" flap model for evaluating flap survival

BACKGROUND

Random skin flap is widely used to repair tissue defects; however, it is often accompanied by ischemia and necrosis of the distal flap due to inferior axial vascularity. Even though different drugs, biomaterials, and stem cell therapies have been developed to improve the survival of random flap, evaluating the promotion of flap survival remains a big challenge. Based on successful clinical practice, we designed a "Pingpong racket" shape flap in the rat. Without the predetected blood vessels procedure, the "pingpong racket" flap provides a preferable option to evaluate the function of drugs and biomaterials in promoting flap survival.

MATERIALS AND METHODS

"Pingpong racket" dorsal flaps with different pedicle lengths were developed in the rats. The survival area was evaluated by digital photography and computer-assisted analysis. The quantitative survival area was considered a useful indicator for analyzing drugs' applicability in improving skin flap survival.

RESULTS

A new model with a pedicle width of 1 cm and a flap diameter of 3 cm, in which the length of the pedicle could be tuned, was established. No iliolumbar vessels passed through the pedicle. The necrosis ratio ( round ) of the flap was 29.88% in the 2 cm long pedicle, 74.69% in the 3 cm long pedicle, 95.52% in the 4 cm long pedicle, and in the 5 cm long pedicle; necrotic area could be found in both the round part and in the pedicle.

CONCLUSION

The new 3 cm long pedicle flap is suitable for evaluating the drugs for promoting skin flap survival. Rat dorsal "Pingpong racket" flap can be easily handled, thus avoiding blood vessels' detection. The flap could achieve comparable results to clinical and alleviate the negative influence of the flap's longitudinal contraction. Besides, it is intuitive and aesthetically pleasing.

Protective effects of dexmedetomidine on the survival of random flaps

BACKGROUND

Random flaps can be used to repair wounds and improve shape and functional reconstruction, but inflammation and necrosis limit their application. Modified McFarlane flap models were constructed on the backs of rats. We hypothesized that dexmedetomidine (DEX) could improve the survival rate of ischemic random flaps.

METHODS

Sixty rats were randomly divided into three groups: a low-dose DEX group (DEX-L group, 10 μg/kg/D), a high-dose DEX group (DEX-H group, 20 μg/kg/D) and a control group (0.9 % saline equivalent). On day 7 after flap construction, the survival percentage of the flap model was calculated. Hematoxylin and eosin staining (H&E) was used to evaluate the histopathological status of the flaps and microvessel density (MVD). Lead oxide/gelatin angiography was used to detect angiogenesis, and laser Doppler flow imaging (LDF) was used to detect blood perfusion. The levels of superoxide dismutase (SOD) and malondialdehyde (MDA) in the middle areas of the flaps were measured to show the level of oxidative stress. The expressions of Toll-like receptor (TLR4), nuclear factor-kappa B (NF-κB), interleukin (IL)-1β, IL-6, tumor necrosis factor-α (TNF-α) and vascular endothelial growth factor (VEGF) were detected by immunohistochemistry.

RESULTS

DEX significantly increased the average survival percentage of the flaps and reduced ischemia and necrosis of the distal end of the flaps. SOD activity significantly increased, while MDA significantly decreased, indicating that DEX reduces oxidative damage. The expression of inflammatory immunoregulatory proteins (TLR4, NF-κB) was downregulated, and the levels of inflammatory factors (IL-1β, IL-6 and TNF-α) were lower. In addition, DEX upregulated VEGF expression, promoted angiogenesis, and increased blood perfusion.

CONCLUSION

In random flap transplantation, a high dose of DEX is beneficial to flap survival.

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

BACKGROUND

Random pattern skin flaps are applicable for reconstructing any defect in plastic surgery. However, they are difficult to apply because of necrosis. Sumatriptan, a selective 5-hydroxytryptamine 1b/1d agonist, is routinely used to offset acute migraine attacks. Recent studies have suggested that sumatriptan may induce vasodilation at lower concentrations. The authors' aim is to investigate the effect of sumatriptan on skin flap survival and the role of nitric oxide in this phenomenon.

METHODS

Seventy-two male Sprague-Dawley rats were divided into eight groups. Increasing doses of sumatriptan (0.1, 0.3, and 1 mg/kg) were given intraperitoneally to three different groups after dorsal random pattern skin flaps were performed. To assess the exact role of 5-hydroxytryptamine 1b/1d receptors, GR-127935 was administered solely and with sumatriptan. N-ω-nitro-L-arginine methyl ester (L-NAME, a nonselective nitric oxide synthase inhibitor) was used to evaluate any possible involvement of nitric oxide in this study. All rats were examined 7 days later.

RESULTS

The authors' results demonstrated that flap survival was increased by lower doses of sumatriptan compared to a control group for both 0.3 mg/kg (p = 0.03, mean difference = 32, SE = 8) and 0.1 mg/kg (p = 0.02, mean difference = 26, SE = 8). This protective effect was eliminated by coadministration of GR-127935 or N-ω-nitro-L-arginine methyl ester with sumatriptan. Histopathologic studies revealed a significant increase in capillary count and collagen deposition and a decreased amount of edema, inflammation, and degeneration.

CONCLUSIONS

Sumatriptan in lower concentration increases skin flap survival by means of activation of 5-hydroxytryptamine 1b/1d receptors. This effect is mediated through the nitric oxide synthase pathway.

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

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

An injectable thermosensitive hydrogel for sustained release of apelin-13 to enhance flap survival in rat random skin flap

With the advantage of handy process, random pattern skin flaps are generally applied in limb reconstruction and wound repair. Apelin-13 is a discovered endogenous peptide, that has been shown to have potent multiple biological functions. Recently, thermosensitive gel-forming systems have gained increasing attention as wound dressings due to their advantages. In the present study, an apelin-13-loaded chitosan (CH)/β-sodium glycerophosphate (β-GP) hydrogel was developed for promoting random skin flap survival. Random skin flaps were created in 60 rats after which the animals were categorized to a control hydrogel group and an apelin-13 hydrogel group. The water content of the flap as well as the survival area were then measured 7 days post-surgery. Hematoxylin and eosin staining was used to evaluate the flap angiogenesis. Cell differentiation 34 (CD34) and vascular endothelial growth factor (VEGF) levels were detected by immunohistochemistry and Western blotting. Tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were assessed by enzyme linked immunosorbent assays (ELISAs). Oxidative stress was estimated via the activity of tissue malondialdehyde (MDA) and superoxide dismutase (SOD). Our results showed that CH/β-GP/apelin-13 hydrogel could not only reduce the tissue edema, but also improve the survival area of flap. CH/β-GP/apelin-13 hydrogel also upregulated levels of VEGF protein and increased mean vessel densities. Furthermore, CH/β-GP/apelin-13 hydrogel was shown to significantly inhibit the expression of TNF-α and IL-6, along with increasing the activity of SOD and suppressing the MDA content. Taken together, these results indicate that this CH/β-GP/apelin-13 hydrogel may be a potential therapeutic way for random pattern skin flap.

Effect of fractional ablative carbon dioxide laser with lidocaine spray on skin flap survival in rats

Background

Lidocaine spray is a local anesthetic that improves random-pattern skin flap survival. The fractional ablative carbon dioxide laser (FxCL) produces vertical microchannels that delivers topically applied drugs to the skin. In this study, we hypothesized that FxCL therapy would enhance the lidocaine effect to improve random-pattern skin flap survival in rats.

Methods

McFarlane random-pattern skin flaps were elevated in 48 rats, which were divided into four groups according to treatment: FxCL+lidocaine, FxCL, lidocaine, and nontreatment (control). On postoperative day 7, necrotic flap areas, the number of capillary vessels, and neutrophil count were evaluated. Anti-rat vascular endothelial growth factor (VEGF) and CD31 antibody activity were also evaluated by immunohistochemical staining.

Results

Flap survival rate was 53.41%± 5.43%, 58.16%± 4.80%, 57.08%± 5.91%, and 69.08%±3.20% in the control, lidocaine, FxCL, and FxCL+lidocaine groups, respectively. Mean neutrophil count in the intermediate zone excluding the necrotic tissue was 41.70± 8.40, 35.43± 6.41, 37.23±7.15, and 27.20± 4.24 cells/field in the control, lidocaine, FxCL, and FxCL+lidocaine groups, respectively. Anti-rat VEGF and CD31 antibody activity were the highest in the FxCL+lidocaine group.

Conclusion

FxCL with lidocaine had a positive effect on random-pattern skin flap survival in rats. Thus, FxCL with lidocaine spray should be considered as a new treatment option to improve flap viability.

Effects of Asiaticoside Treatment on the Survival of Random Skin Flaps in Rats

Background: Asiaticoside (AS) is extracted from the traditional herbal medicine Centella asiatica, and has angiogenic, antioxidant, anti-inflammatory, and wound-healing effects. We investigated the effects of AS on skin flap survival. Methods: Dorsal McFarlane flaps were harvested from 36 rats and divided into two groups: an experimental group treated with 40 mg/kg AS administered orally once daily, and a control group administered normal saline in an identical manner. On day 2, superoxide dismutase (SOD) and malondialdehyde (MDA) levels, and production of the cytokines tumor necrosis factor-α and interleukin (IL)-6 were evaluated. On day 7, tissue slices were stained with hematoxylin and eosin. The expression of vascular endothelial growth factor (VEGF), IL-6, and IL-1β were immunohistochemically evaluated. Microcirculatory flow was measured using laser Doppler flowmetry. Flap angiography, using the lead oxide-gelatin injection technique, was performed with the aid of a soft X-ray machine. Results: The AS group exhibited greater mean flap survival area, improved microcirculatory flow, and higher expression levels of SOD and VEGF compared with the control group. However, MDA levels and the inflammatory response were significantly reduced. Conclusions: AS exhibits promise as a therapeutic option due to its effects on the viability and function of random skin flaps in rats.

Effects of curculigoside A on random skin flap survival in rats

Necrosis in distal areas of random skin flaps remains a challenging issue. Curculigoside A (CA), one of the main bioactive phenolic compounds, has been reported to induce angiogenesis in vitro by increasing proliferation, tube formation, and migration. In addition, CA was shown to increase vascular endothelial growth factor (VEGF) expression. In this study, we investigated the potential use of CA as a novel candidate to enhance the viability of the ischemic skin flap. A modified McFarlane flap was used as a surgical model in Sprague-Dawley rats. Three groups of rats were treated as follows: the control group received 0.9% saline orally, while rats in the two treatment groups were administered 10 mg/kg or 20 mg/kg CA orally for 7 days, respectively. On day7, the mice were killed, and tissue samples were collected for hematoxylin and eosin staining and immunohistochemical examination, while laser Doppler imaging and oxide-gelatin angiography were performed to assess angiogenesis. Kits for the analysis of superoxide dismutase (SOD) and malondialdehyde (MDA) were used to verify the oxidative stress level. Treating animals with CA significantly increased the surviving portion of the flaps. VEGF and SOD expression and microvessel development were markedly increased, and the MDA level was reduced, in the CA treatment groups. Histological studies demonstrated that CA promoted angiogenesis and attenuated inflammatory cell numbers. These findings indicated that CA increases random skin flap survival.

Inhibition of autophagy after perforator flap surgery increases flap survival and angiogenesis

BACKGROUND

The survival ratio of multiterritory perforator flap is variable. Therefore, surviving mechanisms are increasingly explored to identify novel therapeutics. The condition of the choke zone is essential for perforator flap survival. In this study, we investigated autophagy in the choke zone after flap surgery.

MATERIALS AND METHODS

The flap model involved a perforator flap with three territories that was located on the right dorsal side of a rat. A total of 36 rats were divided into six groups, including the control, 0 d postoperative (PO), 1, 3, 5, and 7 d PO groups. In addition, 72 rats were divided into three groups, including a control group, a 3-methyladenine (3-MA) group, and a rapamycin group. Skin tissue of rats was used for measuring autophagy proteins, vascular endothelial growth factor (VEGF) expression, and histological examination. On day 7 after surgery, the survival ratio of each flap was determined.

RESULTS

The expression of autophagy and VEGF in the second choke zone (choke II) was increased after flap surgery. Among the three groups, the survival ratio of flaps in the 3-MA group was the highest. Furthermore, the angiogenesis level in the 3-MA group in choke II was the highest among the three groups.

CONCLUSIONS

Autophagy was initiated by surgery in choke II, and VEGF expression in choke II was increased after flap surgery. Inhibiting autophagy after perforator flap surgery is beneficial for flap survival and for promoting angiogenesis in choke II.

Effect of oxytocin on the survival of random skin flaps

Random flap transplantation is widely used to repair and rebuild skin soft tissue. However, such flaps exhibit poor survival. Plastic surgeons seek to improve flap survival. We explored whether oxytocin improved skin flap survival. Overlength random skin flaps (9 × 3 cm) were established on backs of 80 healthy male SD rats randomly divided into two groups. One group was injected daily with oxytocin (1 mg/kg; test group) and the other with normal saline (control group). On postoperative day 2, malondialdehyde (MDA) and superoxide dismutase (SOD) levels were measured. On postoperative day 7, the flap survival area was measured using transparent graph paper. Microvessel numbers were evaluated histologically by hematoxylin and eosin staining. VEGF expression was assessed immunohistochemically. Angiogenesis was evaluated via lead oxide–gelatin angiography and blood flow via laser Doppler flowmetry. In the test group compared with the control group, the flap survival rate and SOD activity were increased markedly, the MDA level was decreased, and according to hematoxylin and eosin staining, inflammation was significantly attenuated. In addition, the test group exhibited higher levels of VEGF and skin flap angiogenesis. Oxytocin improved flap survival rate by increasing microcirculation and angiogenesis and attenuating ischemia–reperfusion injury.

Naringin improves random skin flap survival in rats

Background

Random-pattern flap transfer is commonly used to treat soft-tissue defects. However, flap necrosis remains a serious problem. Naringin accelerates angiogenesis by activating the expression of vascular endothelial growth factor (VEGF). In the present study, we investigated whether naringin improves the survival of random skin flaps.

Results

Compared with controls, the naringin-treated groups exhibited significantly larger mean areas of flap survival, significantly increased SOD activity and VEGF expression, and significantly reduced MDA level. Hematoxylin and eosin (HE) staining revealed that naringin promoted angiogenesis and inhibited inflammation.

Materials and Methods

“McFarlane flap” models were established in 90 male Sprague-Dawley (SD) rats divided into three groups: a 40 mg/kg control group (0.5 % sodium carboxymethylcellulose), a 40 mg/kg naringin-treated group, and an 80 mg/kg naringin-treated group. The extent of necrosis was measured 7 days later, and tissue samples were subjected to histological analysis. Angiogenesis was evaluated via lead oxide–gelatin angiography, immunohistochemistry, and laser Doppler imaging. Inflammation was evaluated by measurement of serum TNF-α (tumor necrosis factor-α) and IL-6 (interleukin-6) levels. Oxidative stress was assessed by measuring superoxide dismutase (SOD) activity and the malondialdehyde (MDA) level.

Conclusion

Naringin improved random skin flap survival.

The Effect of Botulinum Toxin A on Ischemia-Reperfusion Injury in a Rat Model

Introduction

While studies using various materials to overcome ischemia-reperfusion (IR) injury are becoming increasingly common, studies on the effects of botulinum toxin A (BoTA) on IR injury in musculocutaneous flaps are still limited. The purpose of this study was to examine our hypotheses that BoTA provide protection of musculocutaneous flap from ischemia-reperfusion injury.

Method

Five days after pretreatment injection (BoTA versus normal saline), a right superior musculocutaneous flap (6 × 1.5 cm in size) was made. Ischemia was created by a tourniquet strictly wrapping the pedicle containing skin and muscle for 8 h. After ischemia, the tourniquet was cut, and the musculocutaneous flap was reperfused.

Results

The overall survival percentage of flap after 8 h of pedicle clamping followed by reperfusion was 87.32 ± 3.67% in the control group versus 95.64 ± 3.25% in the BoTA group (p < 0.001). The BoTA group had higher expression of CD34, HIF-1α, VEGF, and NF-kB comparing to control group in qRT-PCR analysis.

Conclusions

In this study, we found that local BoTA preconditioning yielded significant protection against IR injury in a rat musculocutaneous flap model.

Effects of diammonium glycyrrhizinate on random skin flap survival in rats: An experimental study

Partial necrosis of skin flaps continues to restrict the survival of local skin flaps following plastic and reconstructive surgeries. The aim of the present study was to investigate the effects of diammonium glycyrrhizinate (DG), a salt of glycyrrhetinic acid that has been widely used in the therapy of chronic hepatitis and human immunodeficiency virus infection, on random skin flap survival in rats. McFarlane flaps were established in 60 male Sprague-Dawley rats randomly divided into three groups. Group I served as the control group and was injected with saline (10 mg/kg) once per day. Group II and group III were the experimental groups, and were injected with 10 mg/kg DG once and twice per day, respectively. On day 7, the survival area of the flap was measured. Tissue samples were stained with hematoxylin and eosin and immunohistochemically evaluated. Tissue edema, neutrophil density, superoxide dismutase (SOD) activity and malondialdehyde (MDA) levels were evaluated. The mean survival areas of the flaps of group II were significantly larger when compared with those of group I (P<0.05), and the rats of group III exhibited significantly higher survival areas than group II (P<0.05). Histologic and immunohistochemical evaluation showed that microvessel development and the expression level of vascular endothelial growth factor were higher in the two experimental groups than in the control group. Furthermore, SOD activity was significantly increased (P<0.05), while the neutrophil density and MDA level were significantly reduced (P<0.05) in group II when compared with group I. Significant differences between group II and group III with regard to SOD activity and MDA level were also observed (P<0.05). Thus, DG may have a dose-dependent effect on promoting the survival of random skin flaps.

No Effect of Remote Ischemic Conditioning Strategies on Recovery from Renal Ischemia-Reperfusion Injury and Protective Molecular Mediators

Ischemia-reperfusion injury (IRI) is the major cause of acute kidney injury. Remote ischemic conditioning (rIC) performed as brief intermittent sub-lethal ischemia and reperfusion episodes in a distant organ may protect the kidney against IRI. Here we investigated the renal effects of rIC applied either prior to (remote ischemic preconditioning; rIPC) or during (remote ischemic perconditioning; rIPerC) sustained ischemic kidney injury in rats. The effects were evaluated as differences in creatinine clearance (CrCl) rate, tissue tubular damage marker expression, and potential kidney recovery mediators. One week after undergoing right-sided nephrectomy, rats were randomly divided into four groups: sham (n = 7), ischemia and reperfusion (IR; n = 10), IR+rIPC (n = 10), and IR+rIPerC (n = 10). The rIC was performed as four repeated episodes of 5-minute clamping of the infrarenal aorta followed by 5-minute release either before or during 37 minutes of left renal artery clamping representing the IRI. Urine and blood were sampled prior to ischemia as well as 3 and 7 days after reperfusion. The kidney was harvested for mRNA and protein isolation. Seven days after IRI, the CrCl change from baseline values was similar in the IR (δ: 0.74 mL/min/kg [-0.45 to 1.94]), IR+rIPC (δ: 0.21 mL/min/kg [-0.75 to 1.17], p > 0.9999), and IR+rIPerC (δ: 0.41 mL/min/kg [-0.43 to 1.25], p > 0.9999) groups. Kidney function recovery was associated with a significant up-regulation of phosphorylated protein kinase B (pAkt), extracellular regulated kinase 1/2 (pERK1/2), and heat shock proteins (HSPs) pHSP27, HSP32, and HSP70, but rIC was not associated with any significant differences in tubular damage, inflammatory, or fibrosis marker expression. In our study, rIC did not protect the kidney against IRI. However, on days 3-7 after IRI, all groups recovered renal function. This was associated with pAkt and pERK1/2 up-regulation and increased HSP expression at day 7.

Nano-microcapsule basic fibroblast growth factor combined with hypoxia-inducible factor-1 improves random skin flap survival in rats

The present study aimed to investigate the effect of nano-microcapsule-basic fibroblast growth factor (bFGF) combined with hypoxia-inducible factor-1 (HIF-1) on the random skin flap survival of rats. Male Sprague-Dawley rats were used to establish the McFarlane flap model and subsequently, all model rats were randomly divided into four groups: Control, bFGF, HIF-1 and bFGF combined with HIF-1. The model rats were treated with 2.5 µg/day bFGF and 1.0 µg/day HIF-1 for 5 days by intraperitoneal injection. On day 5 following treatment, the boundaries between necrotic and surviving regions were significantly inhibited by bFGF combined with HIF-1. bFGF combined with HIF-1 inhibited oxidative stresses and inflammatory factors in random skin flap survival of rats. bFGF combined with HIF-1 also activated the protein expression levels of cyclooxygenase (COX)-2 and vascular endothelial growth factor (VEGF) in the random skin flap survival of rats. In conclusion, nano-microcapsule bFGF combined with HIF-1 prevented random skin flap survival in rats through antioxidative, anti-inflammatory and activation of the protein expression levels of COX-2 and VEGF.