Ischemic Preconditioning and Iloprost Reduces Ischemia-Reperfusion Injury in Jejunal Flaps: An 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.

EARLY AND CONCOMITANT ADMINISTRATION OF NOREPINEPHRINE AND ILOMEDIN IMPROVES MICROCIRCULATORY PERFUSION WITHOUT IMPAIRING MACROCIRCULATION IN AN INTESTINAL ISCHEMIA-REPERFUSION INJURY SWINE MODEL: A RANDOMIZED EXPERIMENTAL TRIAL

ABSTRACT

Background: Intestinal ischemia-reperfusion injury is associated with both macrocirculatory and microcirculatory failure. Association of a vasoconstrictor in combination with a vasodilator such as ilomedin may improve macrocirculation parameters, microcirculation perfusion and reduce endothelial dysfunction. The primary objective was to demonstrate a difference in mean arterial pressure (MAP) after intestinal reperfusion with the concomitant administration of norepinephrine and ilomedin during ischemia compared with traditional hemodynamic treatment strategies (fluid resuscitation and vasopressors only). Secondary objectives were to demonstrate an improvement in peripheral and intestinal microcirculatory perfusion and endothelial dysfunction after intestinal reperfusion using this association. Methods: We conducted a randomized preclinical trial in 21 large white pigs, in which a 2-h small bowel ischemia was performed using a segmental mesenteric occlusion model, followed by a 2-h reperfusion. Pigs were randomized into the following three groups: goal-directed fluid therapy, early administration of norepinephrine before reperfusion and early administration of ilomedin and norepinephrine before reperfusion. Macrocirculatory (MAP and Cardiac Index (CI), microcirculatory (Sublingual with SideStream Dark Field system and intestinal hemoglobin oxygen saturation with hyperspectral imaging) measurements and biological analysis (biomarkers of endothelial dysfunction) were performed. Results: There were no significant differences in the MAP ( P = 0.499) and the CI ( P = 0.659) between the three groups. Perfused vessel density in sublingual microcirculation was significantly higher immediately after reperfusion and 2 h after reperfusion in the early administration of ilomedin and norepinephrine group compared with the other two groups ( P < 0.05). Hemoglobin oxygen saturation measured at the intestinal level was significantly higher immediately after reperfusion in the early administration of ilomedin and norepinephrine group compared with the other two groups ( P < 0.01). There were no significant differences in biomarkers of endothelial dysfunction between the three groups. Creatinine, AST and alkaline phosphatases increased significantly 2 h after reperfusion in the early administration of ilomedin and norepinephrine group compared with baseline ( P < 0.05). Conclusions: Early administration of norepinephrine and ilomedin during ischemia improved short-term postreperfusion sublingual and intestinal microcirculation without worsening macrocirculatory parameters in an intestinal ischemia-reperfusion injury model. However, use of this strategy seemed to worsen both liver and kidney function.

Iloprost: Old and New Indications

Iloprost is a synthetic long-acting prostacyclin-analog drug used to treat various vascular diseases. The Federal Drug Administration approved the drug in 2004 for pulmonary arterial hypertension, and it has since been shown to be helpful in other vascular conditions such as scleroderma and Raynaud phenomenon. The Federal Drug Administration has now approved the use of iloprost for severe frostbite. This review summarizes the pharmacologic properties of iloprost, its clinical applications, and potential therapeutic benefits in vascular conditions.

Local carbachol application induces oral microvascular recruitment and improves gastric tissue oxygenation during hemorrhagic shock in dogs

Introduction

Hemorrhagic shock is characterized by derangements of the gastrointestinal microcirculation. Topical therapy with nitroglycerine or iloprost improves gastric tissue oxygenation but not regional perfusion, probably due to precapillary adrenergic innervation. Therefore, this study was designed to investigate the local effect of the parasympathomimetic carbachol alone and in combination with either nitroglycerine or iloprost on gastric and oral microcirculation during hemorrhagic shock.

Methods

In a cross-over design five female foxhounds were repeatedly randomized into six experimental groups. Carbachol, or carbachol in combination with either nitroglycerine or iloprost were applied topically to the oral and gastric mucosa. Saline, nitroglycerine, or iloprost application alone served as control groups. Then, a fixed-volume hemorrhage was induced by arterial blood withdrawal followed by blood retransfusion after 1h of shock. Gastric and oral microcirculation was determined using reflectance spectrophotometry and laser Doppler flowmetry. Oral microcirculation was visualized with videomicroscopy. Statistics: 2-way-ANOVA for repeated measurements and Bonferroni post-hoc analysis (mean ± SEM; p < 0.05).

Results

The induction of hemorrhage led to a decrease of gastric and oral tissue oxygenation, that was ameliorated by local carbachol and nitroglycerine application at the gastric mucosa. The sole use of local iloprost did not improve gastric tissue oxygenation but could be supplemented by local carbachol treatment. Adding carbachol to nitroglycerine did not further increase gastric tissue oxygenation. Gastric microvascular blood flow remained unchanged in all experimental groups. Oral microvascular blood flow, microvascular flow index and total vessel density decreased during shock. Local carbachol supply improved oral vessel density during shock and oral microvascular flow index in the late course of hemorrhage.

Conclusion

The specific effect of shifting the autonomous balance by local carbachol treatment on microcirculatory variables varies between parts of the gastrointestinal tract. Contrary to our expectations, the improvement of gastric tissue oxygenation by local carbachol or nitroglycerine application was not related to increased microvascular perfusion. When carbachol is used in combination with local vasodilators, the additional effect on gastric tissue oxygenation depends on the specific drug combination. Therefore, modulation of tissue oxygen consumption, mitochondrial function or alterations in regional blood flow distribution should be investigated.

Remodelling of the superficial vascular network of skin flaps in rats, following a vasodilatory cream application, before elevation

Flap necrosis on random pattern skin flaps continues to be a challenge. In this study, we evaluated whether topical application of a vasodilator substance (the prostaglandin PGI₂ analogue, Iloprost^®, in cream form) as pre-treatment, would increase blood flow and improve flap viability. Wistar rats randomly allocated into four groups with 7 rats per group and two flaps 4cm × 2cm in the same rat i.e. 56 flaps were developed. Flaps on the wright side received pre-treatment with Cream in different drug concentrations, 2.5μgr/gr, 5 μgr/gr, and 10μgr/gr and 20 μgr/gr containing the active factor Iloprost^®® ZK 36,374(M. W 360.5) prepared with white petrolatum as a base. Flaps on the left side received placebo cream (white petrolatum). After 10 days of flap pre-treatment, evaluation of blood flow by laser Doppler flowmetry (LDF) were recorded, then flap elevation and re suturing back were performed. After 7 days we estimated flap viability on digital imaging and the percentages of flap survival estimated. Means and standard deviations were used to describe blood flow measurements and survival percentages. The significance was set at 0.05 in all cases and the analysis were carried out with the use of the SPSS v23.0. Furthermore, we performed dynamic analyses of circulation using the radioisotope 99mTc which confirmed hyperaemia of the treated areas relative to that observed in control areas. These findings demonstrated that pretreatment of skin flaps with Iloprost^® cream for 10 days prior to elevation increased blood flow in the flap and improved their overall survival rate.

Exosomes Derived from Bone Marrow Mesenchymal Stem Cells Alleviate Ischemia-Reperfusion Injury and Promote Survival of Skin Flaps in Rats

Free tissue flap transplantation is a classic and important method for the clinical repair of tissue defects. However, ischemia-reperfusion (IR) injury can affect the success rate of skin flap transplantation. We used a free abdomen flap rat model to explore the protective effects of exosomes derived from bone marrow mesenchymal stem cells (BMSCs-exosomes) against the IR injury of the skin flap. Exosomes were injected through the tail vein and the flaps were observed and obtained on day 7. We observed that BMSCs-exosomes significantly reduced the necrotic lesions of the skin flap. Furthermore, BMSCs-exosomes relieved oxidative stress and reduced the levels of inflammatory factors. Apoptosis was evaluated via the terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay and Western blot analysis of Bax, Bcl-2. Simultaneously, BMSCs-exosomes promoted the formation of new blood vessels in the IR flap, as confirmed by the increased expression level of VEGFA and the fluorescence co-staining of CD31 and PCNA. Additionally, BMSCs-exosomes considerably increased proliferation and migration of human umbilical vein endothelial cells and promoted angiogenesis in vitro. BMSCs-exosomes could be a promising cell-free therapeutic candidate to reduce IR injury and promote the survival of skin flaps.

miR-211-5p Alleviates the Myocardial Ischemia Injury Induced by Ischemic Reperfusion Treatment via Targeting FBXW7

Cardiovascular diseases, a class of the most common diseases, seriously threaten human health, which is a direct inducement of death in most countries. The restoration of blood supply is an impactful intervention way for cardiovascular disease treatments while the injury induced by oxygen-glucose deprivation and ischemic reperfusion (I/R) may further impact the tissues of the patients. Myocardial reperfusion is a precondition for saving ischemic myocardial tissues in acute myocardial infarction while the injury induced by immediate reperfusion takes a great challenge for cardiovascular disease treatment. Howbeit, the reperfusion of coronary blood could aggravate the injury triggered by ischemia. At present, several studies have focused on the etiopathogenesis and therapeutic strategies of ischemia-reperfusion injury of the myocardium. The report has verified that miR-211-5p was elevated in the pathological specimens, while the influence of miR-211-5p in I/R-mediated injury of myocardial cells remains unclear. This research is aimed at illustrating the role of miR-211-5p in the progression of I/R injury of myocardial cells, and qRT-PCR, western blot, CCK-8, and TUNEL assay were used to investigate the functions of miR-211-5p on I/R-mediated injury of myocardial cells. The result mirrored that miR-211-5p was distinctly reduced in the I/R-induced AC16, and reduced miR-211-5p could evidently improve the viability of I/R-induced AC16. miR-211-5p could directly target FBXW7, and FBXW7 upregulation could reverse the improvement of AC16 in viability and apoptosis level after suffering I/R. Moreover, it was also proved that miR-211-5p can mediate the activation of Wnt/β-catenin via attenuating FBXW7. Consequently, this investigation identified miR-211-5p as a positive role to attenuate the injury of myocardial cells when suffering I/R treatment.

Integrative omics reveals subtle molecular perturbations following ischemic conditioning in a porcine kidney transplant model

BACKGROUND

Remote Ischemic Conditioning (RIC) has been proposed as a therapeutic intervention to circumvent the ischemia/reperfusion injury (IRI) that is inherent to organ transplantation. Using a porcine kidney transplant model, we aimed to decipher the subclinical molecular effects of a RIC regime, compared to non-RIC controls.

METHODS

Kidney pairs (n = 8 + 8) were extracted from brain dead donor pigs and transplanted in juvenile recipient pigs following a period of cold ischemia. One of the two kidney recipients in each pair was subjected to RIC prior to kidney graft reperfusion, while the other served as non-RIC control. We designed an integrative Omics strategy combining transcriptomics, proteomics, and phosphoproteomics to deduce molecular signatures in kidney tissue that could be attributed to RIC.

RESULTS

In kidney grafts taken out 10 h after transplantation we detected minimal molecular perturbations following RIC compared to non-RIC at the transcriptome level, which was mirrored at the proteome level. In particular, we noted that RIC resulted in suppression of tissue inflammatory profiles. Furthermore, an accumulation of muscle extracellular matrix assembly proteins in kidney tissues was detected at the protein level, which may be in response to muscle tissue damage and/or fibrosis. However, the majority of these protein changes did not reach significance (p < 0.05).

CONCLUSIONS

Our data identifies subtle molecular phenotypes in porcine kidneys following RIC, and this knowledge could potentially aid optimization of remote ischemic conditioning protocols in renal transplantation.

Intestinal ischemia‑reperfusion induces the release of IL‑17A to regulate cell inflammation, apoptosis and barrier damage

Intestinal ischemia-reperfusion (I/R) injury promotes the release of IL-17A, and previous studies have indicated that TGF-β activated kinase 1 (TAK1) is an important signaling molecule in the regulatory function of IL-17A. The present study aimed to explore the potential effects of IL-17A release in intestinal I/R injury, and to investigate the underlying regulatory mechanisms. Initially, the expression levels of TAK1 and JNK in a hypoxia/reoxygenation model were determined, and the effects of TAK1-knockdown on JNK phosphorylation and the viability, inflammation, apoptosis and barrier function of Caco-2 cells were assessed using Cell Counting Kit-8, reverse transcription-quantitative PCR, TUNEL and transepithelial electrical resistance assays, respectively. Subsequently, an antibody targeting IL-17A was used, and the effects of the IL-17A antibody on the expression levels of TAK1 as well as cell viability, inflammation, apoptosis and barrier function were determined. The results of the present study demonstrated that TAK1-knockdown markedly reduced JNK phosphorylation and improved the levels of cell viability, inflammation, apoptosis and barrier function via the MAPK signaling pathway. In addition, treatment with the IL-17A antibody inhibited the expression of TAK1, and reversed the aforementioned effects of TAK1 on Caco-2 cells. In conclusion, intestinal I/R induces the release of IL-17A to regulate cell viability, inflammation, apoptosis and barrier damage via the TAK1/MAPK signaling pathway.

Intestinal ischemic reperfusion injury: Recommended rats model and comprehensive review for protective strategies

Intestinal ischemic reperfusion injury (IIRI) is a life-threatening condition with high morbidity and mortality in the clinic. IIRI was induced by intestinal ischemic diseases such as, small bowel transplantation, aortic aneurysm surgery, and strangulated hernias. Although related mechanisms have not been fully elucidated, during the last decade, researches have demonstrated that many factors are crucial in the pathological process, including oxidative stress (OS), epithelial barrier function disorder, and so on. Rats model, as the most applied animal IIRI model, provides specific targets for researches and therapeutic strategies. Moreover, various treatment strategies such as, anti-oxidative stress, anti-apoptosis, and anti-inflammation, have shown promising effects in alleviating IIRI. However, current researches cannot solve the clinical problems of IIRI, and specific treatment strategies are still needed to be exploited. This review focuses on a recommended experimental IIRI rat model and understanding of the involved mechanisms such as, OS, gut bacteria translocation, apoptosis, and necroptosis, aim at providing novel ideas for therapeutic strategies of IIRI.

Thermal Preconditioning for Surgery: A Systematic Review

BACKGROUND

Optimising patients pre-operatively reduces the chance of complications. This may be achieved by preconditioning. Thermal preconditioning refers to the supraphysiological heating of organisms or specific organs prior to an environmental insult. This review explores the current application and efficacy of thermal preconditioning for surgery.

METHODS

A comprehensive search of Medline (via PubMed), Embase and the Cochrane library was performed. Only articles evaluating the use of supraphysiological heating prior to a surgical intervention were included. Qualitative syntheses of data were undertaken due to the heterogeneity of the studies. The quality of each article was appraised using risk of bias tools (Cochrane and SYRCLE).

RESULTS

The primary literature search returned 3175 articles. After screening and reviewing reference lists, 28 papers met the inclusion criteria. The majority of studies were performed in animals, with only three clinical trials. Although there was broad coverage of different surgical techniques, flap transfer was the most commonly performed procedure. Most studies demonstrated a beneficial effect of thermal preconditioning, ranging from increased joint mobility to improved flap or organ transplant survival rates. The quality of evidence was variable, with experimental animal studies limited by a lack of methodological detail.

CONCLUSIONS

Thermal preconditioning for surgery has been primarily investigated using animal models. A beneficial effect has been demonstrated in most cases, across specialties ranging from plastic to general surgery. Future studies should aim to assess the clinical significance through large multicentre randomised controlled trials.