Contribution of platelets, the coagulation and fibrinolytic systems to cutaneous wound healing

Serpins in Hemostasis as Therapeutic Targets for Bleeding or Thrombotic Disorders

Bleeding and thrombotic disorders result from imbalances in coagulation or fibrinolysis, respectively. Inhibitors from the serine protease inhibitor (serpin) family have a key role in regulating these physiological events, and thus stand out as potential therapeutic targets for modulating fibrin clot formation or dismantling. Here, we review the diversity of serpin-targeting strategies in the area of hemostasis, and detail the suggested use of modified serpins and serpin inhibitors (ranging from small-molecule drugs to antibodies) to treat or prevent bleeding or thrombosis.

The role of miRNAs in the inflammatory phase of skin wound healing

<abstract> <p>Wound healing (WH) is a fundamental physiological process to keep the integrity of the skin, therefore impaired and chronic WH is a common and severe medical problem and represent one of the biggest challenges of public health. The resolution of the WH inflammatory phase is characterized by a complex series of events that involves many cellular types, especially neutrophils, macrophages and inflammatory mediators, which are crucial for a correct wound closure. MicroRNAs (miRNAs) play essential roles in wound repair. In fact, miR-142 is linked to inflammation modulating neutrophils' chemotaxis and polarization, while the polarization of M1 toward the M2 phenotype is driven by miR-223 and miR-132 is linked to chemokines and cytokines that activate endothelial cells and attract leukocytes and peripheral cells to the damage site. Thus, understanding the dysregulation of miRNAs in WH will be decisive for the development of new and more effective therapies for the management of chronic wounds.</p> </abstract>

Extensive characterization of the composition and functional activities of five preparations of human platelet lysates for dedicated clinical uses

Human platelet lysates (HPLs), rich in various growth factors and cell growth-promoting molecules, encompass a new range of blood products that are being used for regenerative medicine, cell therapies, and tissue engineering. Well-characterized dedicated preparations, tailor-made to best fit specific therapeutic applications, are needed for optimal clinical efficacy and safety. Here, five types of HPL were prepared from the same platelet concentrates and extensively characterized to determine and compare their proteins, growth factors, cytokines, biochemical profiles, thrombin-generating capacities, thrombin-associated proteolytic activities, phospholipid-associated procoagulant potential, contents of extracellular vesicles expressing phosphatidylserine and tissue factor, and antioxidative properties. Our results revealed that all five HPL preparations contained detectable supraphysiological levels, in the ca. 0.1 ~ 350-ng/ml range, of all growth factors assessed, except insulin-like growth factor-1 detected only in HPL containing plasma. There were significant differences observed among these HPLs in total protein content, fibrinogen, complement components C3 and C4, albumin, and immunoglobulin G, and, most importantly, in their functional coagulant and procoagulant activities and antioxidative capacities. Our data revealed that the biochemical and functional properties of HPL preparations greatly vary depending upon their mode of production, with potential impacts on the safety and efficacy for certain clinical indications. Modes of preparation of HPLs should be carefully designed, and the product properties carefully evaluated based on the intended therapeutic use to ensure optimal clinical outcomes.

Platelets as a prognostic marker for sepsis: A cohort study from the MIMIC-III database

During sepsis, platelets dysfunction contributes to organ dysfunction. Studies on platelets dysfunction in the long-term prognosis of sepsis are lacking. The aim of this study was to assess the role of platelets in the long-term prognosis of sepsis patients.A total of 4576 sepsis patients were extracted from MIMIC III Database. Survival was analyzed by the Kaplan-Meier method. Univariate and multivariate cox analyses were performed to identify prognostic factors. Significant prognostic factors were combined to build a nomogram to predict 1 year overall survival (OS). The discriminative ability and predictive accuracy of the nomogram were evaluated using the receiver operating characteristic curve (ROC) analysis and calibration curves used for sepsis.The more abnormal the platelet level, the worse prognosis of patients. After final regression analysis, age, blood urea nitrogen, platelets, international normalized ratio, partial thromboplastin time, potassium, hemoglobin, white blood cell count, organ failures were found to be independent predictors of 1 year OS of sepsis patient and were entered into a nomogram. The nomogram showed a robust discrimination, with an area under the receiver operating characteristic curve of 0.752. The calibration curves for the probability of the prognosis of sepsis patients showed optimal agreement between the probability as predicted by the nomogram and the actual probability.Platelet was an independent prognostic predictor of 1 year OS for patients with sepsis. Platelet-related nomogram that can predict the 1 year OS of sepsis patients. It revealed optimal discrimination and calibration, indicating that the nomogram may have clinical utility.

Delivery of Therapeutics from Layer-by-Layer Electrospun Nanofiber Matrix for Wound Healing: An Update

Increasing incidences of chronic wounds urge the development of effective therapeutic wound treatment. As the conventional wound dressings are found not to comply with all the requirements of an ideal wound dressing, the development of alternative and effective dressings is demanded. Over the past few years, electrospun nanofiber has been recognized as a better system for wound dressing and hence has been studied extensively. Most of the electrospun nanofiber dressings were fabricated as single-layer structure mats. However, this design is less favorable for the effective healing of wounds mainly due to its burst release effect. To address this problem and to simulate the organized skin layer's structure and function, a multilayer structure of wound dressing had been proposed. This design enables a sustained release of the therapeutic agent(s), and more resembles the natural skin extracellular matrix. Multilayer structure is also referred to layer-by-layer (LbL), which has been established as an innovative method of drug incorporation and delivery, combines a high surface area of electrospun nanofibers with the multilayer structure mat. This review focuses on LbL multilayer electrospun nanofiber as a superior strategy in designing an optimal wound dressing.

Heme Oxygenase-1 Induction by Blood-Feeding Arthropods Controls Skin Inflammation and Promotes Disease Tolerance

Hematophagous vectors lacerate host skin and capillaries to acquire a blood meal, resulting in leakage of red blood cells (RBCs) and inflammation. Here, we show that heme oxygenase-1 (HO-1), a pleiotropic cytoprotective isoenzyme that mitigates heme-mediated tissue damage, is induced after bites of sand flies, mosquitoes, and ticks. Further, we demonstrate that erythrophagocytosis by macrophages, including a skin-residing CD163⁺CD91⁺ professional iron-recycling subpopulation, produces HO-1 after bites. Importantly, we establish that global deletion or transient inhibition of HO-1 in mice increases inflammation and pathology following Leishmania-infected sand fly bites without affecting parasite number, whereas CO, an end product of the HO-1 enzymatic reaction, suppresses skin inflammation. This indicates that HO-1 induction by blood-feeding sand flies promotes tolerance to Leishmania infection. Collectively, our data demonstrate that HO-1 induction through erythrophagocytosis is a universal mechanism that regulates skin inflammation following blood feeding by arthropods, thus promoting early-stage disease tolerance to vector-borne pathogens.

Potential Mechanism of Dermal Wound Treatment With Preparations From the Skin Gel of Arabian Gulf Catfish: A Unique Furan Fatty Acid (F6) and Cholesta-3,5-Diene (S5) Recruit Neutrophils and Fibroblasts to Promote Wound Healing

Preparations from Arabian Gulf catfish (Arius bilineatus, Val) epidermal gel secretion (PCEGS) effectively heal chronic wounds in diabetic patients. However, specific lipid components of PCEGS that are responsible for various aspects of wound healing are unknown. Here, we report for the first time that, i) a unique preparation containing only proteins and lipids (Fraction B, FB), derived from the PCEGS accelerated the healing of experimental dermal wounds in female rats (transdermal punch biopsy) in vivo. Histological analyses showed that topical treatment of these wounds with FB promoted the migration of fibroblasts, facilitated the production of extracellular matrix (collagen, fibronectin), induced capillary formation and recruitment of immune cells, and accelerated overall wound healing by day 4 (tested at 1, 2, 3, 4, and 10 days; n=15 for vehicle; n=15 for FB treatment), ii) the lipids responsible for different stages of wound healing were separated into a protein-free bioactive lipid fraction, Ft, which contained a few common long-chain fatty acids, a unique furan fatty acid (F6) and a cholesterol metabolite, cholesta-3,5-diene (S5). Ft (the partially purified lipid fraction of PCEGS), and F6 and S5 present in Ft, proved to be bioactive for wound healing in human dermal fibroblasts. Ft increased the production and extracellular deposition of collagen and fibronectin, ex vivo, iii) Ft and its subcomponents, pure F6 and S5, also promoted human dermal fibroblast migration into the scratch wound gaps, ex vivo, iv) Ft, F6, and S5 promoted the recruitment of neutrophils (Green fluorescence protein labeled) to the site of injury in the transected tailfins of transgenic zebrafish, in vivo, v) Ft, but not F6 or S5, promoted the regeneration of tissues at the wound site in the transgenic zebrafish tailfin, in vivo. Therefore, we conclude that lipid fraction Ft from PCEGS contains the components necessary to promote complete wound healing, and F6 and S5 are responsible for promoting fibroblast and neutrophil recruitment to the site of wounds.

Non-invasive liver fibrosis scores are strongly associated with liver cancer mortality in general population without liver disease

BACKGROUND & AIMS

In a general population without known liver disease, we tested whether: (a) increased liver fibrosis scores (FIB-4 and APRI) are associated with liver cancer mortality and (b) the probability that a person with a higher score died of liver cancer.

METHODS

In a retrospective occupational cohort who underwent annual/biennial health examinations (between 2002 and 2015), subjects were excluded with known chronic liver disease. Based on their baseline FIB-4 and APRI scores, subjects were categorised in low-/intermediate-/high-risk groups for advanced liver fibrosis. Using Cox proportional hazards regression analyses adjusted hazard ratios (aHR) were estimated for liver cancer mortality, with the low-risk FIB-4/APRI group as the reference. Harrell's C statistics were also calculated.

RESULTS

In 200 479 participants, mean (SD) age was 36.4 (7.7) years. Median follow-up was 4.1 years (IQR 2.10-8.03) with 80 liver cancer deaths. High baseline FIB-4 or APRI scores occurred in 0.25% and 0.09% of subjects respectively. A high FIB-4 or APRI score was associated with a markedly increased risk of liver cancer mortality (aHRs 629.10 [95% CI 228.74-1730.20] and 80.42 [95% CI 34.37-188.18]) respectively. C statistics were FIB-4 = 0.841 (95% CI 0.735-0.946) and APRI = 0.933 (95% CI 0.864-0.999).

CONCLUSIONS

In a general population without known liver disease, high FIB-4 or high APRI (in keeping with a high probability of advanced fibrosis) occurred in 0.25% (FIB-4) and 0.09% (APRI) of subjects. Both scores were associated with a markedly increased risk of liver cancer mortality and FIB-4 and APRI models both strongly predicted liver cancer mortality.

Chitosan Film Containing Mansoa hirsuta Fraction for Wound Healing

Chitosan films entrapped with the Mansoa hirsuta fraction (CMHF) was developed as a new dressing for wound care. The chromatographic profile of the M. hirsuta fraction (MHF) was evaluated by ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry, and the results showed that MHF is rich in acid triterpenes. Physicochemical characterization of the films prepared using the solvent casting method was performed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetry (TGA), differential scanning calorimetry (DCS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and mechanical properties. CMHF exhibited characteristic bands of both chitosan and MHF, revealing a physical mixture of both. CMHF presented an amorphous nature, thermostability, and dispersion of MHF in the chitosan matrix, resulting in a rough structure. Incorporation of M. hirsuta fraction into chitosan matrix favorably enhanced the mechanical performance and films thickness. The in vivo wound treatment with CMHF for seven days showed a characteristic area of advanced healing, re-epithelization, cell proliferation, and collagen formation. Furthermore, wound closure reached 100% contraction after 10 days of treatment with modulation of interleukins. The incorporation of M. hirsuta fraction into chitosan films was advantageous and showed great potential for stimulating wound repair and regeneration.

Hemostasis stimulates lymphangiogenesis through release and activation of VEGFC

Hemostasis associated with tissue injury is followed by wound healing, a complex process by which damaged cellular material is removed and tissue repaired. Angiogenic responses are a central aspect of wound healing, including the growth of new lymphatic vessels by which immune cells, protein, and fluid are transported out of the wound area. The concept that hemostatic responses might be linked to wound healing responses is an old one, but demonstrating such a link in vivo and defining specific molecular mechanisms by which the 2 processes are connected has been difficult. In the present study, we demonstrate that the lymphangiogenic factors vascular endothelial growth factor C (VEGFC) and VEGFD are cleaved by thrombin and plasmin, serine proteases generated during hemostasis and wound healing. Using a new tail-wounding assay to test the relationship between clot formation and lymphangiogenesis in mice, we find that platelets accelerate lymphatic growth after injury in vivo. Genetic studies reveal that platelet enhancement of lymphatic growth after wounding is dependent on the release of VEGFC, but not VEGFD, a finding consistent with high expression of VEGFC in both platelets and avian thrombocytes. Analysis of lymphangiogenesis after full-thickness skin excision, a wound model that is not associated with significant clot formation, also revealed an essential role for VEGFC, but not VEGFD. These studies define a concrete molecular and cellular link between hemostasis and lymphangiogenesis during wound healing and reveal that VEGFC, the dominant lymphangiogenic factor during embryonic development, continues to play a dominant role in lymphatic growth in mature animals.

Redox dysregulation in the pathogenesis of chronic venous ulceration

In chronic venous ulcers (CVUs), which account for up to 75% of leg ulcers, the inflammatory stage of wound healing fails to down-regulate, preventing progression to proliferation, remodeling and eventual epithelialisation. The roles of reactive oxygen species (ROS) in the oxidative burst and pathogen killing are well known, but ROS also have important functions in extra-cellular and intra-cellular signalling. Iron deposition, resulting from venous reflux, primes macrophages towards a persistent inflammatory response, with ongoing stimulation by bacteria potentially playing a role. Generation of excessive ROS by activated inflammatory cells causes tissue destruction and disintegration of the dermis, and then at later stages, a failure to heal. Here, we review the evidence for ROS in CVU formation and in normal and delayed healing. We also discuss how ROS modulation might be used to influence the healing of these complex wounds, which cause long-term morbidity and are associated with a significant financial burden to healthcare systems.

Platelet activation in experimental murine neonatal pulmonary hypertension

Serotonin (5-HT) contributes to the pathogenesis of experimental neonatal pulmonary hypertension (PH) associated with bronchopulmonary dysplasia (BPD). Platelets are the primary source of circulating 5-HT and is released upon platelet activation. Platelet transfusions are associated with neonatal mortality and increased rates of BPD. As BPD is often complicated by PH, we tested the hypothesis that circulating platelets are activated and also increased in the lungs of neonatal mice with bleomycin-induced PH associated with BPD. Newborn wild-type mice received intraperitoneal bleomycin (3 units/kg) three times weekly for 3 weeks. Platelets from mice with experimental PH exhibited increased adhesion to collagen under flow (at 300 s-1 and 1,500 s-1 ) and increased expression of the αIIbβ3 integrin and phosphatidylserine, markers of platelet activation. Platelet-derived factors 5-HT and platelet factor 4 were increased in plasma from mice with experimental PH. Pharmacologic blockade of the 5-HT 2A receptor (5-HT 2A R) prevents bleomycin-induced PH and pulmonary vascular remodeling. Here, platelets from mice with bleomycin-induced PH demonstrate increased 5-HT 2A R expression providing further evidence of both platelet activation and increased 5-HT signaling in this model. In addition, bleomycin treatment increased lung platelet accumulation. In summary, platelets are activated, granule factors are released, and are increased in numbers in the lungs of mice with experimental neonatal PH. These results suggest platelet activation and release of platelet-derived factors may increase vascular tone, promote aberrant angiogenesis, and contribute to the development of neonatal PH.

Antithrombotic Therapy: Prevention and Treatment of Atherosclerosis and Atherothrombosis

Atherosclerosis is a multifactorial vascular disease that develops in the course of a lifetime. Numerous risk factors for atherosclerosis have been identified, mostly inflicting pro-inflammatory effects. Vessel injury, such as occurring during erosion or rupture of atherosclerotic lesions triggers blood coagulation, in attempt to maintain hemostasis (protect against bleeding). However, thrombo-inflammatory mechanisms may drive blood coagulation such that thrombosis develops, the key process underlying myocardial infarction and ischemic stroke (not due to embolization from the heart). In the blood coagulation system, platelets and coagulation proteins are both essential elements. Hyperreactivity of blood coagulation aggravates atherosclerosis in preclinical models. Pharmacologic inhibition of blood coagulation, either with platelet inhibitors, or better documented with anticoagulants, or both, limits the risk of thrombosis and may potentially reverse atherosclerosis burden, although the latter evidence is still based on animal experimentation.Patients at risk of atherothrombotic complications should receive a single antiplatelet agent (acetylsalicylic acid, ASA, or clopidogrel); those who survived an atherothrombotic event will be prescribed temporary dual antiplatelet therapy (ASA plus a P2Y12 inhibitor) in case of myocardial infarction (6-12 months), or stroke (<6 weeks), followed by a single antiplatelet agent indefinitely. High risk for thrombosis patients (such as those with peripheral artery disease) benefit from a combination of an anticoagulant and ASA. The price of gained efficacy is always increased risk of (major) bleeding; while tailoring therapy to individual needs may limit the risks to some extent, new generations of agents that target less critical elements of hemostasis and coagulation mechanisms are needed to maintain efficacy while reducing bleeding risks.