Impact of different antithrombotics on the microcirculation and viability of perforator-based ischaemic skin flaps in a small animal model

In-situ Sprayed platelet-derived small extracellular vesicles for the skin flap survival by reducing PANoptosis

Necrosis at the distal end of random skin flaps remains a significant challenge, limiting the clinical application of these flaps in plastic and reconstructive surgery. Inhibiting ischemia/reperfusion (I/R) injury and promoting the formation of neovascular networks are critical preventive strategies. Platelet-derived small extracellular vesicles (PL-sEV) are nanocarriers of growth factors that provide an alternative to clinically used platelet-rich plasma and platelet lysates, offering higher growth factor concentrations and lower immunogenicity. In this study, PANoptosis, a distinct form of inflammatory cell death, was fully characterized in a random skin flap model. Subcutaneous injection of PL-sEV improved ischemic skin flap survival by enhancing blood perfusion and reducing PANoptosis levels. In vitro, PL-sEV inhibited oxygen-glucose deprivation/reoxygenation-induced dysfunction in human umbilical vein endothelial cells. Furthermore, PL-sEV was incorporated into a thermosensitive triblock hydrogel, creating a sprayable delivery system (PLEL@PL-sEV). Mechanistic analysis through RNA sequencing indicated that the protective effects of PL-sEV against PANoptosis likely resulted from its anti-inflammatory properties, particularly via suppression of the NF-κB signaling pathway. This novel hydrogel system demonstrated controlled release of PL-sEV and proved effective in improving skin flap transplantation outcomes.

Hypoxia-Inducible Factor-1α Potentiates Multiterritory Perforator Flap Survival by Augmenting Vascular Endothelial Growth Factor Expression in the Choke II Zone

BACKGROUND

Hypoxia-inducible factor-1α (HIF-1α), regulated by prolyl hydroxylase, plays a central role in tissue adaptation to ischemia. This study investigates the impact of HIF-1α on angiogenesis in the Choke II zone of multiterritory perforator flaps.

METHODS

Ninety male Wistar rats were allocated into 3 groups, with 30 rats in each group: the dimethyloxalylglycine (DMOG) group, the 3-(5-hydroxymethyl-2-furyl)-1-benzylindazole (YC-1) group, and the normal saline (NS) group. All rats underwent multiterritory perforator flap surgeries on their dorsal side. Subsequently, they received intraperitoneal injections of DMOG (40 mg/kg), YC-1 (10 mg/kg), and normal saline on postoperative days 1, 2, and 3, respectively. After treatment, angiogenesis in the Choke II zone of the flap on day 7 was observed through transillumination tests and lead oxide/gelatin x-ray angiography. Histological features were determined using hematoxylin and eosin staining, and the expression of HIF-1α and vascular endothelial growth factor (VEGF) in the Choke II region of the flap was assessed via immunohistochemistry and western blotting.

RESULTS

Compared to the YC-1 and NS groups, the DMOG group exhibited significant angiogenesis, resulting in a denser vascular network in the Choke II zone of the flap. The DMOG group showed significantly higher microvessel density in the Choke II zone than the YC-1 and NS groups (7.10 ± 0.99 vs 24.30 ± 3.65; 14.30 ± 2.40 vs 24.30 ± 3.65, both P<0.05). Additionally, the DMOG group demonstrated higher expression of VEGF and HIF-1α in the flaps than the other groups (P < 0.05).

CONCLUSIONS

In summary, HIF-1α enhances the expression of VEGF, promoting angiogenesis in the Choke II zone of the multiterritory perforator flap, thus increasing the survival area.

Clinical study on anterolateral femoral interregional flap with turbocharge technique in the repair of large limb wounds

OBJECTIVES

To compare the clinical outcomes of anterolateral femoral interregional flap with turbocharge technique and traditional anterolateral femoral flap in repair of large limb wounds.

METHODS

Clinical data of 38 patients with large limb surface wound (11 cm×39 cm-16 cm×65 cm) admitted to the Sir Run Run Shaw Hospital, Zhejiang University School of Medicine from May 2018 to May 2022 were retrospectively analyzed. Eighteen patients were treated by anterolateral thigh perforator flap combined with superficial circumflex iliac artery flap (ALTP-SCIAP) with turbocharge technique (interregional flap group); while 20 patients were treated with unilateral or bilateral anterolateral femoral flaps, combined with skin grafting if necessary (traditional anterolateral femoral flap group). The survival of skin flap, repair of donor area, complications and patient satisfaction were compared between the two groups.

RESULTS

In interregional flap group, 18 flaps were harvested and transplanted, the flap width, length and the viable area were (9.9±2.0) cm, (44.2±3.5) cm and (343.2±79.9) cm2, respectively. In traditional anterolateral femoral flap group, 29 flaps were harvested and transplanted, the flap width, length and the viable area were (11.0±2.8) cm, (21.7±3.2) cm and (186.4±49.2) cm2, respectively. There were significant differences in the flap length and the viable area between the two groups (t=22.365 and 8.345, both P<0.05). In the interregional flap group, the donor site of flap was closed by direct suture in 11 flaps, by skin retractor assisted suture in 6 flaps, and by skin grafting in one flap. In traditional anterolateral femoral flap group, the donor site of flap was closed by direct suture in 12 flaps, by skin retractor assisted suture in 11 flaps, and by skin grafting in 6 flaps. The skin graft rates of the two groups were 5.6% (1/18) and 20.7% (6/29), respectively (χ2=2.007, P>0.05). The interregional flap group had lower postoperative complications rate (5.6% vs. 35.0%, χ2=4.942, P<0.05) and higher patient satisfaction rate (94.4% vs. 70.0%, χ2=4.448, P<0.05) than traditional anterolateral femoral flap group.

CONCLUSIONS

Compared with the traditional anterolateral femoral flap, the anterolateral femoral interregional flap with turbocharge technique has a larger flap area, most of the donor areas of the flap can be sutured directly without skin grafting and with less complications and a higher patient satisfaction rate.

Hirudin enhances perforator flap survival: Clinical application report and mechanistic exploration

BACKGROUND AND PURPOSE

Hirudin, a potent anticoagulant, is used in traditional Chinese medicine (TCM) to treat thrombotic conditions and prevent postoperative thrombosis. Coagulation-related vascular complications are a common cause of perforator flaps failure. This study explores hirudin's potential to enhance flap growth by mitigating coagulation-related issues.

MATERIALS AND METHODS

Patients were divided into GroupⅠ(hirudin group) and GroupⅡ(control). Laboratory tests covered red blood cell count (RBC), hematocrit (HCT), platelet count (PLT), monocyte count (MONO), prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (FIB), and D-Dimer. Clinical parameters, including capillary refill time (CRT), flap swelling, and survival status, were evaluated. Animal experiments used Sprague-Dawley (SD) rats to establish random skin flaps. The experimental side received hirudin injection, while the control side received saline. Flaps were photographed to calculate survival rate, and CD31 immunohistochemical (IHC) analysis was performed to calculate microvessel density (MVD).

RESULTS

The study, with 29 patients, found significant CRT differences between groups on postoperative days 2 and 6 (p = 0.027; p = 0.019), favoring GroupⅠ. Swelling severity varied significantly over time; GroupⅡhad more pronounced swelling. GroupⅠshowed superior flap growth with fewer complications, statistically significant (p = 0.033). Specific lab indicators (MONO, PT, and FIB) were significant at certain times. In animal experiments, the experimental side consistently had higher flap survival and slightly increased CD31 expression at various times, with higher MVD on days 2 and 6.

CONCLUSIONS

Hirudin enhances flap survival through diverse mechanisms, supporting its role as a complementary approach in perforator flap surgeries.

Clinical effectiveness of postoperative prostaglandin E1 administration in reducing flap necrosis following microsurgical reconstruction

BACKGROUND

Extensive experimental evidence has suggested the potential efficacy of prostaglandin E1 (PGE1) in enhancing flap survival, leading to its widespread empirical use following free flap operation. However, the translation of these experimental findings into clinical benefits remains uncertain. This study aimed to assess the clinical effectiveness of postoperative PGE1 administration on the outcomes of microsurgical reconstruction.

METHODS

A retrospective review was conducted for patients who underwent free flap-based reconstruction between September 2020 and November 2022, dividing into two cohorts. For all consecutive cases conducted during the formal half, PGE1 was administered for postoperative 7 days (PGE1 cohort), and for those during the latter, PGE1 was not given (non-PGE1 cohort). The profiles of perfusion-related complications (PRC) were compared between the two cohorts. Further analyses after propensity-score matching were performed.

RESULTS

In total, 274 cases were analyzed, consisting of 142 in PGE1 and 132 in non-PGE1 cohort. Baseline characteristics were similar between the two cohorts, except for higher rates of comorbidities and chronic wound-related defects in the PGE1 cohort. Overall PRC developed in 37 cases (13.5%), including 6 (2.1%) total loss and 38 (10.2%) partial necrosis. Compared to the control, the PGE1 cohort exhibited significantly lower rates of overall PRC and partial flap necrosis. This difference remained significant on multivariable analyses. The rate of total flap loss did not differ between the cohorts. Consistent associations were observed in the propensity-score matching analysis.

CONCLUSION

Postoperative administration of PGE1 appears to be associated with reduced risks for the development of partial flap necrosis.

Necrosis reduction efficacy of subdermal biomaterial mediated oxygen delivery in ischemic skin flaps

Inadequate tissue blood supply as may be found in a wound or a poorly vascularised graft, can result in tissue ischemia and necrosis. As revascularization is a slow process relative to the proliferation of bacteria and the onset of tissue necrosis, extensive tissue damage and loss can occur before healing is underway. Necrosis can develop rapidly, and treatment options are limited such that loss of tissue following necrosis onset is considered unavoidable and irreversible. Oxygen delivery from biomaterials exploiting aqueous decomposition of peroxy-compounds has shown some potential in overcoming the supply limitations by creating oxygen concentration gradients higher than can be attained physiologically or by air saturated solutions. We sought to test whether subdermal oxygen delivery from a material composite that was buffered and contained a catalyst, to reduce hydrogen peroxide release, could ameliorate necrosis in a 9 × 2 cm flap in a rat model that reliably underwent 40 % necrosis if untreated. Blood flow in this flap reduced from near normal to essentially zero, along its 9 cm length and subdermal perforator vessel anastomosis was physically prevented by placement of a polymer sheet. In the middle, low blood flow region of the flap, treatment significantly reduced necrosis based on measurements from photographs and histological micrographs. No change was observed in blood vessel density but significant differences in HIF1-α, inducible nitric oxide synthase and liver arginase were observed with oxygen delivery.

Pharmacological mechanism and clinical study of Qiming granules in treating diabetic retinopathy based on network pharmacology and literature review

ETHNOPHARMACOLOGY RELEVANCE

Diabetic retinopathy (DR) is a general complication of diabetes, which has become a serious threat to human health worldwide. However, the best treatment is still under development. Qiming (QM) granules are mainly composed of Astragalus membranaceus, Pueraria lobata, Rehmannia Glutinosa, Lycium barbarum, Cassiae Semen, Fructus Leonuri, Pollen Typhae, and Leech, which are beneficial to qi, nourish liver and kidney, and clear collaterals and eyes. The treatment of DR is a comprehensive application based on the above traditional Chinese medicine. In recent years, satisfactory results have been achieved for DR.

AIM OF THE STUDY

Through the traditional application analysis, network pharmacology analysis and clinical research summary of QM granules, to review the effectiveness and advantages of QM granules in the treatment of DR comprehensively.

MATERIALS AND METHODS

Analysis of main active components of QM granules by network pharmacology and prediction of mechanism of action of QM granules on DR. Further, PubMed, Web of Science, and China National Knowledge Infrastructure were used to search literature, using the keywords of "Qiming granules", "diabetic retinopathy", "clinical research" and their combinations, mainly from 1999 to 2022.

RESULTS

Traditional pharmacological analysis, Network pharmacological analysis, animal experiments, and clinical studies have confirmed that QM granules plays a role in the treatment of DR through multiple components, multiple targets, and multiple channels.

CONCLUSIONS

This systematic review for the first time provides meaningful information for the further study of the pharmacodynamic material basis and pharmacological mechanism of QM granules, and also provides a basis for further study of quality markers and quality control of QM granules.

Cannabidiol Improves Random-Pattern Skin Flap Survival in Rats: Involvement of Cannabinoid Type-2 Receptors

BACKGROUND

 One of the major complications associated with random-pattern skin flaps is distal necrosis. Cannabidiol (CBD) has recently gained much attention as a therapeutic anti-inflammatory agent. We aimed to evaluate the efficacy of CBD on the random-pattern skin flap survival (SFS) in rats and to explore the possible involvement of cannabinoid type-2 (CB2) receptors.

METHODS

 In this controlled experimental study, we randomly divided male Wistar rats into seven study groups (six rats each). We performed a random-pattern skin flap model in each rat following pretreatment with vehicle (control) or multiple doses of CBD (0.3, 1, 5, or 10 mg/kg). In a separate group, we injected SR144528 (2 mg/kg), a high affinity and selective CB2 inverse agonist, before the most effective dose of CBD (1 mg/kg). A sham nontreated and nonoperated group was also included. Seven days after surgeries, the percentage of necrotic area (PNA) was calculated. Histopathological microscopy, CB2 expression level, and interleukin (IL)-1β and tumor necrosis factor (TNF)-α concentrations were also investigated in the flap tissue samples.

RESULTS

 A PNA of 72.7 ± 7.5 (95% confidence interval [CI]: 64.8-80.6) was captured in the control group. Following treatment with CBD 0.3, 1, 5, and 10 mg/kg, a dose-dependent effect was observed with PNAs of 51.0 ± 10.0 (95% CI: 40.5-61.5; p <0.05), 15.4 ± 5.8 (95% CI: 9.3-21.5; p <0.001), 37.1 ± 10.2 (95% CI: 26.3-47.8; p <0.001), and 46.4 ± 14.0 (95% CI: 31.7-61.1; p <0.001), respectively. Histopathologically, tissues enhanced significantly. Besides, CB2 expression surged remarkably, IL-1β and TNF-α concentrations decreased considerably after treatment with CBD of 1 mg/kg compared with the control (p <0.05 and <0.001, respectively). Administering SR144528 reversed the favorable effects of CBD of 1 mg/kg, both macroscopically and microscopically.

CONCLUSION

 Pretreatment with CBD of 1 mg/kg improved SFS considerably in rats and exerted desirable anti-inflammatory effects which were possibly mediated by CB2 receptors.

Experimental study of the effects of nitroglycerin, botulinum toxin A, and clopidogrel on bipedicled superficial inferior epigastric artery flap survival

Beneficial effects could be achieved by various agents such as nitroglycerin, botulinum toxin A (BoTA), and clopidogrel to improve skin flap ischaemia and venous congestion injuries. Eighty rats were subjected to either arterial ischaemia or venous congestion and applied to a bipedicled U-shaped superficial inferior epigastric artery (SIEA) flap with the administration of nitroglycerin, BoTA, or clopidogrel treatments. After 7 days, all rats were sacrificed for flap evaluation. Necrotic area percentage was significantly minimized in flaps treated with clopidogrel (24.49%) versus the ischemic flaps (34.78%); while nitroglycerin (19.22%) versus flaps with venous congestion (43.26%). With ischemia, light and electron microscopic assessments revealed that nitroglycerin produced degeneration of keratinocytes and disorganization of collagen fibers. At the same time, with clopidogrel administration, there was an improvement in the integrity of these structures. With venous congestion, nitroglycerin and BoTA treatments mitigated the epidermal and dermal injury; and clopidogrel caused coagulative necrosis. There was a significant increase in tissue gene expression and serum levels of vascular endothelial growth factor (VEGF) in ischemic flaps with BoTA and clopidogrel, nitroglycerin, and BoTA clopidogrel in flaps with venous congestion. With the 3 treatment agents, gene expression levels of tumor necrosis factor-α (TNF-α) were up-regulated in the flaps with ischemia and venous congestion. With all treatment modalities, its serum levels were significantly increased in flaps with venous congestion and significantly decreased in ischemic flaps. Our analyses suggest that the best treatment option for ischemic flaps is clopidogrel, while for flaps with venous congestion are nitroglycerin and BoTA.

Full versus Baby Dose Aspirin for Antithrombotic Prophylaxis in Free Tissue Transfer: Does Size Matter?

The postoperative prophylactic use of aspirin is a common practice among plastic surgeons after free tissue transfer. The use of baby aspirin (81 mg) has become more popular due to previously published literature in other fields. We hypothesized that a full dose daily aspirin is nonsuperior to a baby dose daily aspirin in preventing arterial thrombosis in free tissue transfer.

METHODS

All patients undergoing free tissue transfer of the extremities from 2008 to 2020 were retrospectively reviewed. They were divided into two groups based on the postoperative dose of aspirin administered (full versus baby dose). The decision to administer full or baby dose was based on the surgeon's preference. Primary outcome was revision of the arterial anastomosis. Secondary outcomes included flap complications.

RESULTS

A total of 183 patients were identified. Out of those, 78 patients received full dose aspirin postoperatively, whereas 105 received a baby dose of aspirin. Patients who received baby aspirin did not have a higher incidence of returning to the operating room for revision of their arterial anastomosis [7.6% versus 7.7%; adjusted odds ratio, 0.93 (95% confidence interval, 0.28-3.11); adjusted P, 0.906]. No differences were found between the two groups in complete and partial flap loss, wound dehiscence, or infection. None of the patients experienced any aspirin-related gastrointestinal complications.

CONCLUSIONS

In patients undergoing free tissue transfer, thrombosis of the arterial anastomosis is rare. Administration of a full dose of aspirin postoperatively was not superior to a baby dose of aspirin in preventing arterial-related complications.

Quantification of Dermal Microcirculatory Changes after Topical Administration of Capsaicin: A Randomized Placebo-Controlled Study in 46 Subjects

BACKGROUND

Dermal blood flow is crucial for wound healing and survival of flaps in dermatologic surgery. To improve flap viability in cases of compromised perfusion topical agents can easily be applied. The aim of this placebo-controlled study was to characterize changes of DBF in healthy subjects by quantitatively assessing perfusion dynamics after application of capsaicin to establish a reference for measurements at injured sites.

METHODS

In 46 healthy subjects perfusion dynamics after local application with capsaicin and placebo was noninvasively assessed, determining cutaneous oxygen saturation, relative hemoglobin count and blood flow using an Oxygen-to-See device.

RESULTS

A significant raise in superficial (162% p = 0.000) and deep (144%, p = 0.000) skin oxygenation after 30 min was provoked. A highly significant raise in measurements of flow and velocity was present in superficial (523%, p = 0.000) and deep (242%, p = 0.000) sites.

CONCLUSION

With the introduced model applied to observe changes in parameters of dermal blood flow in healthy subjects the authors can reliably monitor effects of topically administered capsaicin. This baseline can be used as reference for further studies in the settings of endangered flap survival or critically perfused wounds as has been proven in animal studies.

Cold Atmospheric Plasma, Platelet-Rich Plasma, and Nitric Oxide Synthesis Inhibitor: Effects Investigation on an Experimental Model on Rats

The evolution of reconstructive methods for defects of the human body cannot yet replace the use of flap surgery. Research is still preoccupied with the ideal techniques for offering the best chances of survival of the flaps. In our study, we investigated the effects of cold atmospheric plasma (CAP), N-nitro-L-arginine methyl ester (L-NAME), and platelet-rich plasma (PRP) injectable solutions on flap survival using an in vivo model. Twenty-four Wistar rats (four groups) had the McFarlane flap raised and CAP, L-NAME, and PRP substances tested through a single dose subcutaneous injection. The control group had only a saline solution injected. To the best of our knowledge, this is the first study that evaluated a CAP activated solution through injection on flaps. The flap survival rate was determined by clinical examination (photography documented), hematology, thermography, and anatomopathological tests. The image digital analysis performed on the flaps showed that the necrosis area (control—49.64%) was significantly lower for the groups with the three investigated solutions: CAP (14.47%), L-NAME (18.2%), and PRP (23.85%). Thermography exploration revealed less ischemia than the control group on the CAP, L-NAME, and PRP groups as well. Anatomopathological data noted the best degree of angiogenesis on the CAP group, with similar findings on the L-NAME and PRP treated flaps. The blood work did not indicate infection or a strong inflammatory process in any of the subjects. Overall, the study shows that the CAP activated solution has a similar (better) impact on the necrosis rate (compared with other solutions with known effects) when injected on the modified dorsal rat skin flap, and on top of that it can be obtained fast, in unlimited quantities, non-invasively, and through a standardized process.

Should Antiplatelet Therapy Be Withheld Perioperatively? The First Study Examining Outcomes in Patients Receiving Dual Antiplatelet Therapy in the Lower Extremity Free Flap Population

BACKGROUND

Antiplatelet agents are typically withheld perioperatively because of bleeding concerns. Dual antiplatelet therapy, such as aspirin and clopidogrel, has significant morbidity and mortality benefits in patients with ischemic heart disease or peripheral vascular disease. This study aims to evaluate the impact of perioperative dual antiplatelet therapy in the lower extremity free tissue transfer population.

METHODS

Lower extremity free tissue transfers performed by the senior author (K.K.E.) from 2011 to 2019 were retrospectively reviewed. Demographics, comorbidities, perioperative dual antiplatelet therapy, and free tissue transfer characteristics were recorded. Outcomes of interest included flap success, hematoma formation, blood transfusion requirements, and cardiac event occurrence.

RESULTS

One hundred ninety-five free tissue transfers were included. Median age at the time of free tissue transfer was 56.5 years. Median Charlson Comorbidity Index was 3. Thirty-four patients were on clopidogrel, which was either withheld (n = 20) or continued (n = 14) on the day of free tissue transfer. Incidence of blood transfusion was significantly higher in both the withheld and continued versus nonclopidogrel groups. Flap success was statistically equivalent between groups (withheld, 90.0 percent; continued, 92.9 percent; nonclopidogrel, 95.0 percent; p = 0.346). Cardiac events occurred most often in the continued group (21.4 percent) compared to the withheld (5.0 percent) and nonclopidogrel (0.6 percent) groups. On multivariate analysis, holding clopidogrel remained significant for increased odds of postoperative transfusion. The clopidogrel group was no longer significant for intraoperative transfusion.

CONCLUSIONS

Despite increases in volume of blood products transfused, free tissue transfer can be performed safely with perioperative dual antiplatelet therapy. Withholding dual antiplatelet therapy on the day of free tissue transfer was not associated with decreased intraoperative transfusion; thus, dual antiplatelet therapy can safely be continued throughout the operative course to minimize cardiovascular risk.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Distal Arterialized Venous Supercharging Improves Perfusion and Survival in an Extended Dorsal Three-Perforasome Perforator Flap Rat Model

BACKGROUND

Perforator flaps are commonly applied for a variety of skin defects. Many strategies (e.g., hyperbaric oxygen and preconditioning) have been investigated to improve flap survival, but a postoperative 2.03 to 18.2 percent flap necrosis frequency remains a major complication. The authors hypothesized that a distal arterialized venous supercharged (DAVS) flap procedure might improve perfusion and survival in an extended three-perforasome perforator flap rat model and rescue flap ischemia intraoperatively.

METHODS

One hundred twenty male Sprague-Dawley rats (200 to 300 g) were divided into the thoracodorsal artery (TDA) flap group and the DAVS flap group (n = 60 per group). An approximately 11 × 2.5-cm2 flap based on the TDA perforasome was designed in the TDA flap. A DAVS flap was designed based on the TDA flap and supercharged by anastomosing the rat caudal artery with the deep circumflex iliac vein. At postoperative times 1, 3, 6, and 12 hours and 1, 3, 5, and 7 days, perfusion and angiography were compared. On day 7, flap viability and angiogenesis were assessed using histology and Western blotting.

RESULTS

The DAVS flap showed a higher survival rate compared with the TDA flap (100 percent versus 81.93 ± 5.38 percent; p < 0.001). All blood flow ratios of deep circumflex iliac artery to TDA perforasome and of choke zone II to choke zone I were higher in the DAVS flap (all p < 0.05). Angiography qualitatively revealed that choke vessels in choke zone II dilated earlier and extensively in the DAVS flap group. CD34+ vessels (68.66 ± 12.53/mm2 versus 36.82 ± 8.99/mm2; p < 0.001) and vascular endothelial growth factor protein level (0.22 ± 0.03 versus 0.11 ± 0.03; p < 0.001) were significantly increased in the DAVS flap group.

CONCLUSIONS

The DAVS procedure improves three-perforasome perforator flap survival and can be used for rescuing flap ischemia intraoperatively. Further study is needed before possible clinical adoption for reconstructive operations.

Hirudotherapy for neonatal limb ischemia during ECMO support: A word of caution

INTRODUCTION

Disordered coagulation, clot formation and distal limb ischemia are complications of extracorporeal membrane oxygenation (ECMO) with significant morbidity and mortality. Medicinal leech therapy (hirudotherapy) has been attempted in plastic and orthopedic surgeries to improve venous congestion and salvage ischemic flaps. To our knowledge this has not been reported in pediatric cardiac surgery or during ECMO support. We present a complex neonate whose ECMO course was complicated by distal limb ischemia for whom leech therapy was attempted.

PATIENT AND INTERVENTION

A 2-week-old 2.7 kg infant required ECMO support secondary to perioperative multiorgan system dysfunction following repair of critical coarctation and ventricular septal defect. Despite systemic anticoagulation, his clinical course was complicated by arterial thrombus, vasopressor-induced vascular spasm and bilateral distal limb ischemia. Medicinal leech therapy was tried after initially failing conventional measures.

RESULT

Following the third leech application, this patient developed significant hemorrhage from the web space adjacent to the left great toe. An estimated 450 ml of blood loss occurred and more than 300 ml of blood product transfusions were required. He ultimately progressed to irreversible systemic end organ dysfunction and comfort care was provided.

CONCLUSION

The use of medicinal leech therapy in pediatric cardiac surgery may be considered to minimize the consequences of advanced limb ischemia and venous congestion. However, this should be used with caution while patients are systemically anticoagulated during ECMO support. A directed review is presented here to assist in determining optimal application and potential course of therapy.

Positive Effect of Andrographolide Induced Autophagy on Random-Pattern Skin Flaps Survival

Random-pattern skin flap replantation is generally used in the reconstruction of surgical tissues and covering a series of skin flap defects. However, ischemia often occurs at the flap distal parts, which lead to flap necrosis. Previous studies have shown that andrographolide (Andro) protects against ischemic cardiovascular diseases, but little is known about the effect of Andro on flap viability. Thus, our study aimed to building a model of random-pattern skin flap to understand the mechanism of Andro-induced effects on flap survival. In this study, fifty-four mice were randomly categorized into the control, Andro group, and the Andro+3-methyladenine group. The skin flap samples were obtained on postoperative day 7. Subsequently, the tissue samples were underwent a series of evaluations such as changes in the appearance of flap tissue, the intensity of blood flow, and neovascularization density of skin flap. In our study, the results revealed that Andro enhanced the viability of random skin flaps by enhancing angiogenesis, inhibiting apoptosis, and reducing oxidative stress. Furthermore, our results have also demonstrated that the administration of Andro caused an elevation in the autophagy, and these remarkable impact of Andro were reversed by 3-methyladenine (3-MA), the most common autophagy inhibitor. Together, our data proves novel evidence that Andro is a potent modulator of autophagy capable of significantly increasing random-pattern skin flap survival.

Endothelial inflammatory and thrombogenic expression changes in microvascular anastomoses - An immunohistochemical analysis

The aim of this study was to investigate intraluminal vessel diameters and endothelial expression levels of pro-inflammatory and -thrombotic mediators in patent and non-patent microvascular anastomoses. Endothelial expression of CD31, VCAM-1, E- and P-Selectin, eNOS, iNOS and PAI-1 was evaluated by immunohistochemistry and compared to non-anastomosed arteries as controls. Intraluminal diameters were determined via H.E.-staining. In 20 human anastomoses (8 patent, 12 non-patent) neither the analysis of endoluminal de-endothelialization (p = 0.966) nor luminal narrowing (p = 0.750) revealed any significant differences between patent and non-patent microanastomoses. Expressions of pro-inflammatory mediators were significantly higher in patent anastomoses compared to controls but did not show any difference compared to non-patent anastomoses (p > 0.050). iNOS was higher in non-patent compared to patent anastomoses (p = 0.030) and controls (p = 0.001), whereas eNOS did not reveal any differences between these groups (p = 0.611 and p = 0.130). In non-patent anastomoses PAI-1 was expressed higher compared to patent anastomoses and controls (p = 0.021 and p < 0.001). Irrespective of their patency, anastomoses are characterized by endothelial dysfunction with a pro-inflammatory and pro-thrombotic milieu. Avoiding endothelial trauma during suturing is essential in order not to aggravate existing endothelial dysfunction in microanastomoses. Additionally, the influence of medication-related changes on anastomoses should be investigated as this is still an indistinctive topic.

Butylphthalide Inhibits Autophagy and Promotes Multiterritory Perforator Flap Survival

Multiterritory perforator flap is an important plastic surgery technique, yet its efficacy can be limited by partial necrosis at the choke Ⅱ zone. Butylphthalide (NBP) has been used for many diseases but has not been studied in the multiterritory perforator flap. With the effect of NBP, we observed increasing in capillary density, inhibition of autophagy and oxidative stress, and a reduction in apoptosis of cells, all consistent with increased flap survival. However, the protective effect of NBP on multiterritory perforator flap was lost following administration of the autophagy agonist rapamycin (Rap). Through the above results, we assumed that NBP promotes flap survival by inhibiting autophagy. Thus, this study has found a new pharmacological effect of NBP on the multiterritory perforator by inhibiting autophagy to prevent distal postoperative necrosis and exert effects on angiogenesis, oxidative stress, and apoptosis within the flap.

Detrimental Effect of Sitagliptin Induced Autophagy on Multiterritory Perforator Flap Survival

Multiterritory perforator flap survival is commonly applied in surgical tissue reconstructions and covering of large skin defects. However, multiple risk factors such as ischemia, reperfusion injury, and apoptosis after reconstructive surgeries cause necrosis in distal parts with outcomes ranging from poor aesthetic appearance to reconstructive failure. A few studies have reported that sitagliptin (Sit) promotes angiogenesis and inhibits apoptosis. However, little is known about Sit-induced autophagy especially on the flap model. Therefore, our study investigated the effect of Sit and its induced autophagy on the perforator flap survival. Ninety male Sprague-Dawley rats were randomly separated into control, Sit, and Sit+3-methyladenine group. Results revealed that Sit significantly promoted flap survival by enhancing angiogenesis, reducing oxidative stress, and attenuating apoptosis. In addition, flap survival was further improved after co-administration with 3-methyladenine to inhibit autophagy. Overall, our results established that Sit has positive effects in promoting survival of multiterritory perforator flap. Sit-induced autophagy was detrimental for flap survival and its inhibition may further improve flap survival.

Effect of dipyridamole on random pattern skin flap viability in rats

Ischemic necrosis has been most dreaded complication of flap reconstruction. Therefore, researchers have tried to improvise modalities to prevent or treat it since the onset of flap surgery. So far these researches have failed to identify a pharmacological therapy equally effective as surgical delay in augmenting skin flap viability. In the path of search for this substance, dipyridamole attracted our attention as an antiaggregant agent. Put together with pathophysiological mechanisms underlying ischemic flap necrosis, we concluded dipyridamole might have beneficial effect on survival of skin flaps. In this research random pattern dorsal rat skin flap model of McFarlane is used. Subjects are separated in a randomized fashion between two groups. Experiment group is given dipyridamole with a dose of 20 mg/kg twice daily. Control group is given same amount of saline. At seventh day viability of skin flaps is assessed and compared between groups. Also on 7th day, pathologic specimens are obtained and evaluated histopathologically in terms of neutrophil and lymphocyte infiltration, edema and fibrosis. Necrosis percentage in experiment group is found to be significantly lower than that of control group (p < 0.01*). Neutrophil infiltration and edema found to be significantly lower in dipyridamole group (p < 0.05*). No significant difference is observed in lymphocyte infiltration and fibrosis. Dipyridamole is shown in this research to be effective in augmenting viability of random pattern skin flaps in rats. Nevertheless, more extensive researches are needed to fully determine its precise mechanism, side effects and appropriate doses.

Rip 1-dependent endothelial necroptosis participates in ischemia-reperfusion injury of mouse flap

BACKGROUND

Ischemia reperfusion injury plays an important role in free flap necrosis. However, the detailed mechanism is not clear, and effective methods for improving the survival rate of skin flap are still lacking.

OBJECTIVE

To investigate the regulation and functional link between necroptosis and ischemia-reperfusion injury of mouse flap.

METHODS

We established a mouse ischemia-reperfusion injury flap model and a cell Oxygen Glucose Deprivation (OGD) model intervened with Necrostatin-1. The mouse flap tissues were harvested in vivo for histological immunofluorescence analysis and western blotting analyses. The HUVECs cells with various treatments in vitro were assessed by using Transwell assay, tube formation assay, cell counting kit-8 analysis and flow cytometry. A Rip3-knockout cell line and a TNFR1-knockout cell line were generated from HUVEC cells using the CRISPR-Cas9 technology and were subsequently used to explore the related mechanisms.

RESULTS

The expression of p-Rip3 is positive in both mouse and cell culture models. When necroptosis is completely or partially inhibited in vivo, damaged tissues are repaired with better efficiency. The cells treated with Necrostatin-1 in vitro exhibit faster migration, proliferation and better tube formation. Deficiency of TNFR1 can block the necroptosis pathway by blocking the phosphorylation of Rip3 in HUVEC OGD/ROG model. Meanwhile, the levels of APJ, HIF-1α, and VEGF are reduced when necroptosis is inhibited by Necrostatin-1.

CONCLUSION

TNFR1 mediates Rip1/Rip3 in ischemia-reperfusion injury. Inhibition of necroptosis attenuates the ischemia-reperfusion injury of flap and may enhance hypoxic tolerance of HUVECs and vascular homeostasis through regulation of the HIF-1α signaling pathways.

Anti-atherosclerotic effects between a combined treatment with simvastatin plus hirudin and single simvastatin therapy in patients with early type 2 diabetes mellitus

Background

This study aimed to investigate the efficacy and safety of simvastatin plus hirudin in preventing atherosclerosis in the patients with early type 2 diabetes mellitus (T2DM).

Methods

This was a 24-week, randomized, open-label and controlled study in which 150 outpatients initially diagnosed with T2DM were randomly assigned into either simvastatin (40 mg daily at night) plus hirudin (3 g thrice daily) group [combined group (CG) n=75] or simvastatin (40 mg once daily) group [monotherapy group (MG) n=75]. The therapeutic efficacy was evaluated by the score of carotid artery atherosclerosis, plaque size, peak systolic velocity (PSV) and end-diastolic velocity (EDV) on carotid ultrasonography at three and six months after treatment. Logistic regression analysis was used to investigate the correlation between treatment and carotid atherosclerosis.

Results

One hundred and thirty-one patients completed this study, and there were no significant differences in the dropout rate in the CG (14.67%) and the MG (10.67%). Significant difference was found in the incidence of adverse events in the CG compared with the MG (37.50% vs. 17.91%, P<0.05) due to the higher risk of hemorrhage (12.50% vs. 1.49%, P<0.05), which did not affect the treatment compliance. The efficacy of combined treatment was better than monotherapy in the enhancement of carotid artery atherosclerosis scores (P<0.01), the plaque thickness (P<0.05) and the change of PSV (P<0.05) and EDV (P<0.05) since three months after treatment, which maintained to the end of observation. In addition, hirudin treatment was able to independently predict the carotid artery atherosclerosis scores (β=2.37, P<0.05), the plaque thickening (β=3.51, P<0.01) and the change of PSV (β=1.69, P<0.05) and EDV (β=1.79, P<0.05).

Conclusions

Combined use of simvastatin and hirudin is well tolerated and possesses better anti-atherosclerotic effects than simvastatin alone in patients with early T2DM.

Effects of bradykinin on the survival of multiterritory perforator flaps in rats

Background

Bradykinin, a vasoactive peptide, has many biological functions. For example, it accelerates angiogenesis. Thus, we studied the effects of bradykinin on the survival of perforator flaps.

Methods

Averagely, 50 male Sprague–Dawley rats were divided into control and bradykinin groups and underwent procedures to the multiterritory perforator flap. Areas of flap survival were tested 7 days later. Flap perfusion was evaluated by laser Doppler imaging. We assessed the extent of autophagy by determining LC3-II/I, Beclin 1, and p62. Flap angiogenesis was assessed by immunohistochemistry and H&E staining. We measured the level of vascular endothelial growth factor (VEGF) protein using western blot. We assessed oxidative stress by measuring the activity of superoxide dismutase (SOD) and malondialdehyde (MDA) levels. The apoptotic index was also evaluated by western blot, and we determined nitric oxide (NO) production using an NO assay kit.

Results

The bradykinin group exhibited significantly larger areas of flap survival, higher blood supply, and more neovascularization. The bradykinin group also had higher SOD activity, higher VEGF expression and NO content, and reduced MDA compared to the control group. Rats treated with bradykinin also had lower levels of apoptosis and autophagy relative to the control group.

Conclusion

Our results suggest that bradykinin promotes the survival of multiterritory perforator flaps by increasing angiogenesis, promoting the release of NO, suppressing apoptosis, reducing oxidative stress, and inhibiting autophagy.

[Progress of monitoring methods and preventions of disorder of blood supplying of expanded flaps]

Objective

To summarize the monitoring methods and preventions of the disorder of blood supplying of expanded flaps, so as to provide some references for improving the survival of expanded flaps.

Methods

The domestic and abroad related literature about the disorder of blood supplying of expanded flaps was reviewed and analyzed.

Results

Handheld Doppler, digital subtraction angiography, computer tomographic angiography, magnetic resonance angiography, and fluorescein angiography can be used as reliable preoperative imaging methods in designing expanded flaps with rich blood supply. Several techniques can be used for monitoring the blood supply of expanded flaps during the early postoperative period including traditional monitoring via physical examination, monitoring via dynamic infrared thermography, near-infrared spectroscopy tissue oximeter, external and implantable Doppler, and more recently developed diffuse correlation spectroscopy. Surgical delay, bloodletting, leech therapy, hyperbaric oxygen, and so on can decrease the risk of necrosis in expanded flaps.

Conclusion

The survival of expanded flap is influenced by many factors. Preoperative design by using handheld Doppler and new imaging technology and postoperative early detection of blood supply can provide references of timely intervention, so that ischemic necrosis of the flaps can be reduced, and the success rate of surgery can be improved.

Detrimental effect of Hypoxia-inducible factor-1α-induced autophagy on multiterritory perforator flap survival in rats

Hypoxia-inducible factor-1α (HIF-1α) plays a key role in angiogenesis, improves flap survival, and activates autophagy. The effect of HIF-1α-induced autophagy is still debatable. Thus, we investigated the effect of HIF-1α-induced autophagy on multiterritory perforator flap survival. In this study, 99 male Sprague-Dawley rats received multiterritory perforator flap procedure and were divided into three groups with 33 each. The dimethyloxalylglycine (DMOG) plus 3-methyladenine (3-MA) group received intraperitoneal injection of DMOG (40 mg/kg) and 3-MA (10 mg/kg). The DMOG group and control group received comparative DMOG and saline respectively. On postoperative day (POD) 7, HIF-1α’s activities of flap survival and perfusion improvement were confirmed in DMOG group, however, its positive effects were further enhanced by co-administration of autophagy inhibitor, 3-MA. On POD 1, vascular endothelial growth factor, mean microvascular density and blood perfusion were not affected by HIF-1α up-regulation or autophagy inactivation. However, HIF-1α-induced autophagy augments apoptosis and oxidative stress. The increased level of apoptosis and oxidative stress was reversed by 3-MA and resulted in further flap survival improvement. In conclusion, HIF-1α-induced autophagy has a detrimental effect on multiterritory perforator flap survival and the flap survival was determined by the combined effects of ischemia and reperfusion injury.