The role of collagen in thrombosis and hemostasis

Post-operative epidural haematoma as complication of overconsumption of dried fruit in lumbar spinal surgery: a case report and review of the literature

PURPOSE

Mebos, a traditional South Africa confection consisting of dried, pulped, and sugared apricots, is rich in fibre and vitamins, but also contains salicylic acid, flavonoids, and citric acid. We report a case of postoperative surgical site bleeding in a healthy patient who consumed approximately 2 kg of mebos per day prior to his elective spinal surgery.

METHODS

The clinical course of a previously healthy 54-year-old male patient with cauda equina syndrome secondary to lumbar spinal stenosis who underwent surgical intervention with subsequent bleeding into the surgical site is discussed. The cause was investigated through biochemical analysis, thromboelastometry (ROTEM®) and mass and absorption spectrometry were applied to assess flavonoid, citric acid, and salicylic acid content.

RESULTS

ROTEM® revealed an abnormal clotting profile with an increased clot forming time, suggesting intrinsic coagulopathy. Mass and absorption spectrometry revealed a high total flavonoid content as well as citric acid concentration in the mebos. Salicylic acid was at detection limits of the instrument.

CONCLUSION

Results highlighted the effect of flavonoids and citric acid and therefore explain the abnormal clotting profile in this patient. Inhibition of coagulation prior to elective surgery is a known contraindication and may pose great risks in spinal surgery. In the present report, we demonstrated an association between inhibition of coagulation and an excess of the flavonoids content and citric acid concentration in mebos consumed in the days prior to elective spinal surgery.

Topical hemostatic agents in spinal surgery

Spinal surgery can be associated with significant intraoperative blood loss which may lead to various complications. As the number of patients undergoing spinal surgery increases over time, accurate and effective hemostasis becomes critically important. Despite various surgical hemostatic techniques, conventional interventions such as compression, suture, ligation, and heat-generating cautery, are not suitable for osseous and epidural venous plexus bleeding during spinal procedures. Therefore, a variety of hemostatic agents have been developed to promote hemostasis. As they differ in terms of mechanism, form, application and potential adverse reactions, it is important to understand the natural features of existing agents. Here we comprehensively review currently available topical hemostatic agents from different sources and summarize their mechanisms of action, applications, and current or potential utilization in spinal surgery. We found hemostatic agents from different sources exert hemostatic actions through different mechanisms. In addition, topical hemostatic agents play various roles in spinal surgery including as hemostatic agent, dura mater repair, drug-carrier, skin closure, and fibrosis prevention. Compressive neurological complications are the most common complications of these hemostatic agents. Therefore, optimal use in spinal environments should match their features, indications, and efficacy with clinical conditions.

Protective Topical Dual-Sided Nanofibrous Hemostatic Dressing Using Mussel and Silk Proteins with Multifunctionality of Hemostasis and Anti-Bacterial Infiltration

Topical hemostatic agents are preferred for application to sensitive bleeding sites because of their immediate locoregional effects with less tissue damage. However, the majority of commercial hemostatic agents fail to provide stable tissue adhesion to bleeding wounds or act as physical barriers against contaminants. Hence, it has become necessary to investigate biologically favorable materials that can be applied and left within the body post-surgery. In this study, a dual-sided nanofibrous dressing for topical hemostasis is electrospun using a combination of two protein materials: bioengineered mussel adhesive protein (MAP) and silk fibroin (SF). The wound-adhesive inner layer is fabricated using dihydroxyphenylalanine (DOPA)-containing MAP, which promotes blood clotting by aggregation of hemocytes and activation of platelets. The anti-adhesive outer layer is composed of alcohol-treated hydrophobic SF, which has excellent spinnability and mechanical strength for fabrication. Because both proteins are fully biodegradable in vivo and biocompatible, the dressing would be suitable to be left in the body. Through in vivo evaluation using a rat liver damage model, significantly reduced clotting time and blood loss are confirmed, successfully demonstrating that the proposed dual-sided nanofibrous dressing has the right properties and characteristics as a topical hemostatic agent having dual functionality of hemostasis and physical protection.

A synergistic strategy based on active hydroxymethyl amine compounds and fucoidan for bioprosthetic heart valves with enhancing anti-coagulation and anti-calcification properties

With an aging population, the patients with valvular heart disease (VHD) are growing worldwide, and valve replacement is a primary choice for these patients with severe valvular disease. Among them, bioprosthetic heart valves (BHVs), especially BHVs trough transcatheter aortic valve replacement, are widely accepted by patients on account of their good hemodynamics and biocompatibility. Commercial BHVs in clinic are prepared by glutaraldehyde cross-linked pericardial tissue with the risk of calcification and thrombotic complications. In the present study, a strategy combines improved hemocompatibility and anti-calcification properties for BHVs has been developed based on a novel non-glutaraldehyde BHV crosslinker hexakis(hydroxymethyl)melamine (HMM) and the anticoagulant fucoidan. Besides the similar mechanical properties and enhanced component stability compared to glutaraldehyde crosslinked PP (G-PP), the fucoidan modified HMM-crosslinked PPs (HMM-Fu-PPs) also exhibit significantly enhanced anticoagulation performance with a 72 % decrease in thrombus weight compared with G-PP in ex-vivo shunt assay, along with the superior biocompatibility, satisfactory anti-calcification properties confirmed by subcutaneous implantation. Owing to good comprehensive performance of these HMM-Fu-PPs, this simple and feasible strategy may offer a great potential for BHV fabrication in the future, and open a new avenue to explore more N-hydroxymethyl compound based crosslinker with excellent performance in the field of biomaterials.

Soft and Hard Tissue Integration around Percutaneous Bone-Anchored Titanium Prostheses: Toward Achieving Holistic Biointegration

A holistic biointegration of percutaneous bone-anchored metallic prostheses with both hard and soft tissues dictates their longevity in the human body. While titanium (Ti) has nearly solved osseointegration, soft tissue integration of percutaneous metallic prostheses is a perennial problem. Unlike the firm soft tissue sealing in biological percutaneous structures (fingernails and teeth), foreign body response of the skin to titanium (Ti) leads to inflammation, epidermal downgrowth and inferior peri-implant soft tissue sealing. This review discusses various implant surface treatments/texturing and coatings for osseointegration, soft tissue integration, and against bacterial attachment. While surface microroughness by SLA (sandblasting with large grit and acid etched) and porous calcium phosphate (CaP) coatings improve Ti osseointegration, smooth and textured titania nanopores, nanotubes, microgrooves, and biomolecular coatings encourage soft tissue attachment. However, the inferior peri-implant soft tissue sealing compared to natural teeth can lead to peri-implantitis. Toward this end, the application of smart multifunctional bioadhesives with strong adhesion to soft tissues, mechanical resilience, durability, antibacterial, and immunomodulatory properties for soft tissue attachment to metallic prostheses is proposed.

Fundamental considerations for designing endothelialized in vitro models of thrombosis

Endothelialized in vitro models for cardiovascular disease have contributed greatly to our current understanding of the complex molecular mechanisms underlying thrombosis. To further elucidate these mechanisms, it is important to consider which fundamental aspects to incorporate into an in vitro model. In this review, we will focus on the design of in vitro endothelialized models of thrombosis. Expanding our understanding of the relation and interplay between the different pathways involved will rely in part on complex models that incorporate endothelial cells, blood, the extracellular matrix, and flow. Importantly, the use of tissue-specific endothelial cells will help in understanding the heterogeneity in thrombotic responses between different vascular beds. The dynamic and complex responses of endothelial cells to different shear rates underlines the importance of incorporating appropriate shear in in vitro models. Alterations in vascular extracellular matrix composition, availability of bioactive molecules, and gradients in concentration and composition of these molecules can all regulate the function of both endothelial cells and perivascular cells. Factors modulating these elements in in vitro models should therefore be considered carefully depending on the research question at hand. As the complexity of in vitro models increases, so can the variability. A bottom-up approach to designing such models will remain an important tool for researchers studying thrombosis. As new techniques are continuously being developed and new pathways are brought to light, research question-dependent considerations will have to be made regarding what aspects of thrombosis to include in in vitro models.

Application of modified porcine xenograft by collagen coating in the veterinary field: pre-clinical and clinical evaluations

Introduction

This study aimed to identify a collagen-coating method that does not affect the physicochemical properties of bone graft material. Based on this, we developed a collagen-coated porcine xenograft and applied it to dogs to validate its effectiveness.

Methods

Xenografts and collagen were derived from porcine, and the collagen coating was performed through N-ethyl-N'-(3- (dimethylamino)propyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) activation. The physicochemical characteristics of the developed bone graft material were verified through field emission scanning electron microscope (FE-SEM), brunauer emmett teller (BET), attenuated total reflectance-fourier transform infrared (ATR-FTIR), and water absorption test. Subsequently, the biocompatibility and bone healing effects were assessed using a rat calvarial defect model.

Results

The physicochemical test results confirmed that collagen coating increased bone graft materials' surface roughness and fluid absorption but did not affect their porous structure. In vivo evaluations revealed that collagen coating had no adverse impact on the bone healing effect of bone graft materials. After confirming the biocompatibility and effectiveness, we applied the bone graft materials in two orthopedic cases and one dental case. Notably, successful fracture healing was observed in both orthopedic cases. In the dental case, successful bone regeneration was achieved without any loss of alveolar bone.

Discussion

This study demonstrated that porcine bone graft material promotes bone healing in dogs with its hemostatic and cohesive effects resulting from the collagen coating. Bone graft materials with enhanced biocompatibility through collagen coating are expected to be widely used in veterinary clinical practice.

Recent Advances in Topical Hemostatic Materials

Untimely or improper treatment of traumatic bleeding may cause secondary injuries and even death. The traditional hemostatic modes can no longer meet requirements of coping with complicated bleeding emergencies. With scientific and technological advancements, a variety of topical hemostatic materials have been investigated involving inorganic, biological, polysaccharide, and carbon-based hemostatic materials. These materials have their respective merits and defects. In this work, the application and mechanism of the major hemostatic materials, especially some hemostatic nanomaterials with excellent adhesion, good biocompatibility, low toxicity, and high adsorption capacity, are summarized. In the future, it is the prospect to develop multifunctional hemostatic materials with hemostasis and antibacterial and anti-inflammatory properties for promoting wound healing.

Off-target effect of high-dose sildenafil on adenosine 5'- diphosphate and collagen-induced platelet activation through mitogen-activated protein kinase pathway in treated BALB/C mice and in vitro experiments: A preliminary study

ABSTRACT

Sildenafil, a common over-the-counter pill often self-administered at high doses for erectile dysfunction, has been reported to rarely cause prothrombotic events and sudden cardiac death in a few case reports. Therefore, we investigated the in vitro and in vivo effect of sildenafil treatment and dosage on platelet activation and mitogen-activated protein kinase (MAPK) phosphorylation. BALB/C mice were segregated into four groups, each having four mice each (control, low [3.25 mg/kg], medium [6.5 mg/kg], and high [13 mg/kg] sildenafil), and after the treatment, blood was drawn from each mouse and washed platelets prepared. Washed platelets were incubated with CD41 PE-Cy7 and Phospho-p38 MAPK PE antibodies and analyzed using a flow cytometer for platelet activation and adenosine 5'- diphosphate (ADP)/collagen-induced MAPK phosphorylation. Washed platelets obtained from the venous blood of 18 human volunteers, were incubated with PAC-1 FITC and Phospho-p38 MAPK PE antibodies, and platelet activation (ADP and collagen), followed by flow cytometry analysis. There was a significant increase in both platelet activation as well as MAPK phosphorylation in the presence of collagen in the high-dose (13 mg/kg) sildenafil group (P = 0.000774). Further, increased platelet activation was observed in samples that were treated with high-dose sildenafil as compared to the untreated samples (P < 0.00001). These studies show the risk of prothrombotic episodes in patients on high-dose sildenafil (100 mg), in those with even mild endothelial dysfunction due to ADP, and collagen-induced platelet activation through MAPK phosphorylation, which was not seen in the low-and intermediate-dose cohorts.

Effect of Thrombin-Containing Local Hemostatics on Postoperative Spinal Epidural Hematoma in Biportal Endoscopic Spinal Surgery

STUDY DESIGN

Retrospective case-control study.

PURPOSE

This study aimed to investigate the preventive effect of thrombin-containing local hemostatics (TCLH) on postoperative spinal epidural hematoma (POSEH) in biportal endoscopic spinal surgery (BESS). This study compared the incidence of morphometric and symptomatic POSEH with or without TCLH in BESS.

OVERVIEW OF LITERATURE

POSEH is reported not uncommon in BESS when compared with conventional spine surgery (CSS). TCLH achieves hemostasis with a high success rate in CSS. However, few studies have examined the effect of TCLH on BESS.

METHODS

Patients with and without TCLH were assigned to groups A and B, respectively. POSEH between the two groups was compared morphometrically and symptomatically. The risk factors for symptomatic and morphometric POSEH in BESS were identified.

RESULTS

The morphometric POSEH was greater in group B, and the difference was significant (p =0.019). The incidence of symptomatic POSEH was lower in group A with 4.6% (5/109) than in group B with 9.5% (9/95); however, the rate was not significantly different (p =0.136). The morphometric POSEH was classified into two small (hG1 and hG2) and large (hG3 and hG4) and were compared between groups A and B, and the difference was significant (p =0.02). In the multivariable logistic regression, nonuse of TCLH (p =0.004) and preoperative diagnosis of stenosis (p =0.016) were variables found to be significant risk factors of morphometric POSEH.

CONCLUSIONS

Severe compression of the thecal sac by POSEH is more common in patients without TCLH. The risk of hematoma formation was higher when bilateral decompression was needed and the cut bone surface was more exposed.

Bioadhesive Technology Platforms

Bioadhesives have emerged as transformative and versatile tools in healthcare, offering the ability to attach tissues with ease and minimal damage. These materials present numerous opportunities for tissue repair and biomedical device integration, creating a broad landscape of applications that have captivated clinical and scientific interest alike. However, fully unlocking their potential requires multifaceted design strategies involving optimal adhesion, suitable biological interactions, and efficient signal communication. In this Review, we delve into these pivotal aspects of bioadhesive design, highlight the latest advances in their biomedical applications, and identify potential opportunities that lie ahead for bioadhesives as multifunctional technology platforms.

Injectable, Antibacterial, and Hemostatic Tissue Sealant Hydrogels

Hemorrhage and bacterial infections are major hurdles in the management of life-threatening surgical wounds. Most bioadhesives for wound closure lack sufficient hemostatic and antibacterial properties. Furthermore, they suffer from weak sealing efficacy, particularly for stretchable organs, such as the lung and bladder. Accordingly, there is an unmet need for mechanically robust hemostatic sealants with simultaneous antibacterial effects. Here, an injectable, photocrosslinkable, and stretchable hydrogel sealant based on gelatin methacryloyl (GelMA), supplemented with antibacterial zinc ferrite (ZF) nanoparticles and hemostatic silicate nanoplatelets (SNs) for rapid blood coagulation is nanoengineered. The hydrogel reduces the in vitro viability of Staphylococcus aureus by more than 90%. The addition of SNs (2% w/v) and ZF nanoparticles (1.5 mg mL-1 ) to GelMA (20% w/v) improves the burst pressure of perforated ex vivo porcine lungs by more than 40%. Such enhancement translated to ≈250% improvement in the tissue sealing capability compared with a commercial hemostatic sealant, Evicel. Furthermore, the hydrogels reduce bleeding by ≈50% in rat bleeding models. The nanoengineered hydrogel may open new translational opportunities for the effective sealing of complex wounds that require mechanical flexibility, infection management, and hemostasis.

Strategies for Development of Synthetic Heart Valve Tissue Engineering Scaffolds

The current clinical solutions, including mechanical and bioprosthetic valves for valvular heart diseases, are plagued by coagulation, calcification, nondurability, and the inability to grow with patients. The tissue engineering approach attempts to resolve these shortcomings by producing heart valve scaffolds that may deliver patients a life-long solution. Heart valve scaffolds serve as a three-dimensional support structure made of biocompatible materials that provide adequate porosity for cell infiltration, and nutrient and waste transport, sponsor cell adhesion, proliferation, and differentiation, and allow for extracellular matrix production that together contributes to the generation of functional neotissue. The foundation of successful heart valve tissue engineering is replicating native heart valve architecture, mechanics, and cellular attributes through appropriate biomaterials and scaffold designs. This article reviews biomaterials, the fabrication of heart valve scaffolds, and their in-vitro and in-vivo evaluations applied for heart valve tissue engineering.

Platelet Function Testing: Update and Future Directions

Platelets play a key role in maintaining normal hemostasis and are also recognized as partners in the development of arterial thrombosis. Today, platelet function testing is used for very different clinical purposes; first, for investigation of platelet dysfunction in acute bleeding and diagnosis of platelet disorders in patients with long-lasting bleeding tendency, and second, for testing the efficacy of antiplatelet therapy in patients with increased thromboembolic risk. Moreover, it has been discussed whether platelet function testing can be used for prediction of bleeding risk (e.g., prior to major surgery). Ever since light transmission aggregometry was introduced, laboratories around the world have worked on testing platelet function, and during the last decades a wide range of new methods has emerged. Besides the clinical utility of platelet function testing, the present review summarizes the test principles and advantages and disadvantages of the different methods, depending on the purpose for which it is to be used. A critical step in investigation of platelet function is the preanalytical factors that can substantially affect test results. Therefore, this review also provides an overview of preanalytical variables that range from patient-related factors such as smoking, coffee, and exercise prior to blood sampling to selection of anticoagulant, needle gauge, and time from blood sampling to analyses. Finally, this review outlines further perspectives on platelet function testing for clinical practice and for research purposes.

Glycoprotein VI interplay with fibrin(ogen) in thrombosis

Platelets play a central role in the arrest of bleeding. The ability of platelets to engage with extracellular matrix proteins of the subendothelium has long been recognized as a pivotal platelet attribute, underpinning adequate hemostasis. The propensity of platelets to rapidly bind and functionally respond to collagen was one of the earliest documented events in platelet biology. The receptor primarily responsible for mediating platelet/collagen responses was identified as glycoprotein (GP) VI and successfully cloned in 1999. Since that time, this receptor has held the attention of many research groups, and through these efforts, we now have an excellent understanding of the roles of GPVI as a platelet- and megakaryocyte-specific adheso-signaling receptor in platelet biology. GPVI is considered a viable antithrombotic target, as data obtained from groups across the world is consistent with GPVI being less involved in physiological hemostatic processes but participating in arterial thrombosis. This review will highlight the key aspects of GPVI contributions to platelet biology and concentrate on the interaction with recently identified ligands, with a focus on fibrin and fibrinogen, discussing the role of these interactions in the growth and stability of thrombi. We will also discuss important therapeutic developments that target GPVI to modulate platelet function while minimizing bleeding outcomes.

Perilla oil and α-linolenic acid ameliorated thrombosis in rats induced by collagen and epinephrine

Perilla frutescens is an annual herbaceous plant widely cultivated for oil production in China, Japan, and Korea. In this study, we investigated the effect of perilla oil (PO) on thrombosis induced by collagen and epinephrine (CE) in rats. The oral administration of PO significantly increased prothrombin time (PT) and activated partial thromboplastin time (aPTT) in the blood plasma and inhibited the expression of cells adhesion markers (CAMs) such as intercellular CAM-1 (ICAM-1), vascular CAM (VCAM-1), E-selectin and P-selectin in the aorta tissue. Furthermore, pulmonary occlusion induced by CE in rats was suppressed by PO. α-Linolenic acid (ALA) was quantified at 60.14 ± 2.50 g/100 g of PO, and its oral administration at the same concentration with that in PO exerted the similar effect on PT, aPTT, ICAM-1, VCAM-1, E-selectin and P-selectin in CE-induced thrombosis rats. Taken together, PO and ALA significantly ameliorated thrombosis by regulating CAMs.

Antiplatelet, cytotoxic activities and characterization of green-synthesized zinc oxide nanoparticles using aqueous extract of Nephrolepis exaltata

The goal of the current study was to synthesize zinc oxide nanoparticles (ZnO-NPs) using ZnCl₂.2H₂O salt precursor and an aqueous extract of Nephrolepis exaltata (N. exaltata), which act as a capping and reducing agent. N. exaltata plant extract-mediated ZnO-NPs were further characterized by various techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FT-IR), UV-visible (UV-Vis), and energy-dispersive X-ray (EDX) analysis. The nanoscale crystalline phase of ZnO-NPs was analyzed by the XRD patterns. The FT-IR analysis revealed different functional groups of biomolecules involved in the reduction and stabilization of the ZnO-NPs. The light absorption and optical properties of ZnO-NPs were examined by UV-Vis spectroscopy at a wavelength of 380 nm. The spherical shape morphology of ZnO-NPs with mean particle size ranges between 60 and 80 nm was confirmed by SEM images. While the EDX analysis was used to identify the elemental composition of ZnO-NPs. Furthermore, the synthesized ZnO-NPs demonstrate potential antiplatelet activity by inhibiting the platelet aggregation induced by platelet activation factor (PAF) and arachidonic acid (AA). The results showed that synthesized ZnO-NPs were more effective in inhibiting platelet aggregation induced by AA with IC₅₀ (56% and 10 μg/mL) and PAF (63% and 10 μg/mL), respectively. However, the biocompatibility of ZnO-NPs was assessed in human lung cancer cell line (A549) under in vitro conditions. The cytotoxicity of synthesized nanoparticles revealed that cell viability decreased and the IC₅₀ was found to be 46.7% at a concentration of 75 μg/mL. The present work concluded the green synthesis of ZnO-NPs that was achieved by N. exaltata plant extract and showed good antiplatelet and cytotoxic activity, which demonstrates the lack of harmful effects making them more effective for use in pharmaceutical and medical fields to treat thrombotic disorders.

The Role of Extracellular Matrix in Wound Healing

BACKGROUND

Extracellular matrix communicates with surrounding cells to maintain skin homeostasis and modulate multiple cellular processes including wound healing.

OBJECTIVE

To elucidate the dynamic composition and potential roles of extracellular matrix in normal skin, wound healing process, and abnormal skin scarring.

MATERIALS AND METHODS

Literature review was performed to identify relevant publications pertaining to the extracellular matrix deposition in normal skin and wound healing process, as well as in abnormal scars.

RESULTS

A summary of the matrix components in normal skin is presented. Their primary roles in hemostasis, inflammation, proliferation, and remodeling phases of wound healing are briefly discussed. Identification of novel extracellular matrix in keloids is also provided.

CONCLUSION

Abnormal scarring remains a challenging condition with unmet satisfactory treatments. Illumination of extracellular matrix composition and functions in wound healing process will allow for the development of targeted therapies in the future.

Capturing effects of blood flow on the transplanted decellularized nephron with intravital microscopy

Organ decellularization creates cell-free, collagen-based extracellular matrices that can be used as scaffolds for tissue engineering applications. This technique has recently gained much attention, yet adequate scaffold repopulation and implantation remain a challenge. Specifically, there still needs to be a greater understanding of scaffold responses post-transplantation and ways we can improve scaffold durability to withstand the in vivo environment. Recent studies have outlined vascular events that limit organ decellularization/recellularization scaffold viability for long-term transplantation. However, these insights have relied on in vitro/in vivo approaches that need enhanced spatial and temporal resolutions to investigate such issues at the microvascular level. This study uses intravital microscopy to gain instant feedback on their structure, function, and deformation dynamics. Thus, the objective of this study was to capture the effects of in vivo blood flow on the decellularized glomerulus, peritubular capillaries, and tubules after autologous and allogeneic orthotopic transplantation into rats. Large molecular weight dextran molecules labeled the vasculature. They revealed substantial degrees of translocation from glomerular and peritubular capillary tracks to the decellularized tubular epithelium and lumen as early as 12 h after transplantation, providing real-time evidence of the increases in microvascular permeability. Macromolecular extravasation persisted for a week, during which the decellularized microarchitecture was significantly and comparably compromised and thrombosed in both autologous and allogeneic approaches. These results indicate that in vivo multiphoton microscopy is a powerful approach for studying scaffold viability and identifying ways to promote scaffold longevity and vasculogenesis in bioartificial organs.

Pharmacological Inhibition of Glycoprotein VI- and Integrin α2β1-Induced Thrombus Formation Modulated by the Collagen Type

BACKGROUND

 In secondary cardiovascular disease prevention, treatments blocking platelet-derived secondary mediators pose a risk of bleeding. Pharmacological interference of the interaction of platelets with exposed vascular collagens is an attractive alternative, with clinical trials ongoing. Antagonists of the collagen receptors, glycoprotein VI (GPVI), and integrin α2β1, include recombinant GPVI-Fc dimer construct Revacept, 9O12 mAb based on the GPVI-blocking reagent Glenzocimab, Syk tyrosine-kinase inhibitor PRT-060318, and anti-α2β1 mAb 6F1. No direct comparison has been made of the antithrombic potential of these drugs.

METHODS

 Using a multiparameter whole-blood microfluidic assay, we compared the effects of Revacept, 9O12-Fab, PRT-060318, or 6F1 mAb intervention with vascular collagens and collagen-related substrates with varying dependencies on GPVI and α2β1. To inform on Revacept binding to collagen, we used fluorescent-labelled anti-GPVI nanobody-28.

RESULTS AND CONCLUSION

 In this first comparison of four inhibitors of platelet-collagen interactions with antithrombotic potential, we find that at arterial shear rate: (1) the thrombus-inhibiting effect of Revacept was restricted to highly GPVI-activating surfaces; (2) 9O12-Fab consistently but partly inhibited thrombus size on all surfaces; (3) effects of GPVI-directed interventions were surpassed by Syk inhibition; and (4) α2β1-directed intervention with 6F1 mAb was strongest for collagens where Revacept and 9O12-Fab were limitedly effective. Our data hence reveal a distinct pharmacological profile for GPVI-binding competition (Revacept), GPVI receptor blockage (9O12-Fab), GPVI signaling (PRT-060318), and α2β1 blockage (6F1 mAb) in flow-dependent thrombus formation, depending on the platelet-activating potential of the collagen substrate. This work thus points to additive antithrombotic action mechanisms of the investigated drugs.

Minimal Collagen-Binding Epitope of Glycoprotein VI in Human and Mouse Platelets

Glycoprotein VI (GPVI) is a platelet-specific receptor for collagen and fibrin, regulating important platelet functions such as platelet adhesion and thrombus growth. Although the blockade of GPVI function is widely recognized as a potent anti-thrombotic approach, there are limited studies focused on site-specific targeting of GPVI. Using computational modeling and bioinformatics, we analyzed collagen- and CRP-binding surfaces of GPVI monomers and dimers, and compared the interacting surfaces with other mammalian GPVI isoforms. We could predict a minimal collagen-binding epitope of GPVI dimer and designed an EA-20 antibody that recognizes a linear epitope of this surface. Using platelets and whole blood samples donated from wild-type and humanized GPVI transgenic mice and also humans, our experimental results show that the EA-20 antibody inhibits platelet adhesion and aggregation in response to collagen and CRP, but not to fibrin. The EA-20 antibody also prevents thrombus formation in whole blood, on the collagen-coated surface, in arterial flow conditions. We also show that EA-20 does not influence GPVI clustering or receptor shedding. Therefore, we propose that blockade of this minimal collagen-binding epitope of GPVI with the EA-20 antibody could represent a new anti-thrombotic approach by inhibiting specific interactions between GPVI and the collagen matrix.

A functionalized biological heart valve by double bond crosslinking with enhanced biocompatibility and antithrombogenicity

With the advancement of minimally invasive interventional therapy, biological heart valves (BHVs) have been extensively used in clinics. However, BHVs are generally prone to degeneration within 10-15 years after implantation due to defects including cytotoxicity, immune response, calcification and thrombosis, which are closely related to glutaraldehyde-crosslinking. In this work, we prepared a functionalized BHV through the in situ polymerization of methacrylated porcine pericardium and 2-hydroxyethyl methacrylate to avoid and overcome the defects of glutaraldehyde-crosslinked BHVs. The functionalized BHV was proven to be stable against enzymatic degradation and compatible towards HUVECs. After implantation in rats subcutaneously, a significantly mitigated immune response and reduced calcification were observed in the functionalized BHV. With the grafting of hydrophilic 2-hydroxyethyl methacrylate polymers, the antithrombogenicity of BHV was markedly enhanced by resisting the unfavorable adhesion of blood components. Moreover, the hydrodynamics of the functionalized BHV totally conformed to ISO 5840-3 under a wide range of simulated physiological conditions. These results indicate that the functionalized BHV with enhanced biocompatibility, anticalcification property and antithrombogenicity exhibited a low risk of degeneration and should be explored for further application.

Collagen as a Biomaterial for Skin and Corneal Wound Healing

The cornea and the skin are two organs that form the outer barrier of the human body. When either is injured (e.g., from surgery, physical trauma, or chemical burns), wound healing is initiated to restore integrity. Many cells are activated during wound healing. In particular, fibroblasts that are stimulated often transition into repair fibroblasts or myofibroblasts that synthesize extracellular matrix (ECM) components into the wound area. Control of wound ECM deposition is critical, as a disorganized ECM can block restoration of function. One of the most abundant structural proteins in the mammalian ECM is collagen. Collagen type I is the main component in connective tissues. It can be readily obtained and purified, and short analogs have also been developed for tissue engineering applications, including modulating the wound healing response. This review discusses the effect of several current collagen implants on the stimulation of corneal and skin wound healing. These range from collagen sponges and hydrogels to films and membranes.

Perfuse and Reuse: A Low-Cost Three-Dimensional-Printed Perfusion Bioreactor for Tissue Engineering

This article describes fabrication of a customizable bioreactor, which comprises a perfusion system and coverslip-based tissue culture chamber that allow centimeter-scale vascularized or otherwise canalized tissue constructs to be maintained in weeks long static and/or perfusion culture at an exceptionally low cost, with intermittent live imaging and media sampling capabilities. The perfusion system includes a reusable polydimethylsiloxane (PDMS) lid generated from a three-dimensional (3D)-printed poly-lactic acid (PLA) mold and several lengths of perfusion tubing. The coverslip tissue culture chamber includes PDMS components built with 3D-printed PLA molds, as well as 3D-printed PLA frames and glass coverslips that house perfusable hydrogel constructs. As proof of concept, we fabricated a vascularized hydrogel construct, which was subjected to static and perfusion tissue culture, as well as flow studies using fluorescent beads and widefield fluorescent microscopy. This system can be readily reproduced, promoting the advancement of tissue engineering and regenerative medicine research.

The combination of danhong injection plus tissue plasminogen activator ameliorates mouse tail thrombosis-induced by κ-carrageenan

BACKGROUND

After thrombosis, t-PA thrombolysis is the first choice, but the use of t-PA can easily lead to hemorrhagic injury and neurotoxicity. The combination of Danhong injection (DHI) and tissue plasminogen activator (t-PA) therapy may be a new strategy to find high-efficiency anti-thrombosis and low bleeding risk. However, nothing is about the effect of DHI plus t-PA on platelet activation.

PURPOSE

The present research was to explore the optimal dose of DHI and t-PA in vivo and mechanisms involved with the treatment of combining DHI and t-PA for thrombotic disease and determined whether DHI plus t-PA affects thrombotic processes related to platelet activation.

METHODS

Mice were induced by administering κ-carrageenan intraperitoneally, the ratio of different doses of DHI and t-PA in vivo, and the optimal dose effects on platelet aggregation, platelet adhesion, thrombosis formation, and platelet activation were determined. The effects of the αIIbβ3 signaling pathway were analyzed in mice.

RESULTS

In vitro, DHI (62% v/v), t-PA (1 mg/ml), and DHI + t-PA (62% v/v + 1 mg/ml) decreased rat platelet aggregation and adhesion, with a stronger effect from the combination as compared to t-PA monotherapy. In vivo, injections of κ-carrageenan were used to induce BALB/c mice. The optimal dose of DHI, t-PA, and DHI + t-PA is 12 ml/kg, 10 mg/kg, and 12 ml/kg + 7.5 mg/kg. The administration of DHI (12 ml/kg), t-PA (10 mg/kg), and DHI + t-PA (12 ml/kg + 7.5 mg/kg) decreased thrombi in mouse tissue vessels. Furthermore, the reduction of thrombosis formation by DHI, t-PA, and DHI + t-PA was related to lower collagen deposition, and lowered expressions of collagen I, matrix metalloproteinase 2 (MMP-2), and metalloproteinase 9 (MMP-9) in mouse tails, with increased efficacy in combination as compared to t-PA alone. The anti-thrombosis actions of DHI, t-PA, and their combination regulated the expression of CD41, purinergic receptor (P2Y₁₂), guanine nucleotide-binding protein G (q) subunit alpha (GNAQ), phosphatidylinositol phospholipase c beta (PLCβ), Ras-related protein 1 (Rap1), RIAM, talin1, fibrinogen alpha chain (FG), kindlin-3, and RAS guany1-releasing protein 1 (RasGRP1).

CONCLUSIONS

Based on expression, the mechanism responsible for thrombosis may be attributed to platelet activation via the αIIbβ3 signaling pathway. Combination therapy with DHI and t-PA exerted potent thrombolytic effects. Thus, our data can be used as a foundation for further clinical studies examining the efficacy of traditional Chinese medicines for the treatment of thrombosis.

The clinical efficacy of collagen dressing on chronic wounds: A meta-analysis of 11 randomized controlled trials

Objective

This study aims to evaluate the clinical efficacy of collagen dressing for patients with chronic wounds.

Materials and methods

Relevant randomized controlled trials were searched from the databases such as PubMed, EMBASE, and the Cochrane library as of January 2022. For dichotomous outcomes and continuous outcomes, risk ratio and mean difference were calculated, respectively. Subgroup analysis was performed according to the type of chronic ulcer and follow-up. In addition, trial sequential analysis (TSA) was performed to further verify the results. Jadad score was used to assess the quality of trials. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) was utilized to assess the level of evidence for outcomes.

Results

In 11 studies, a total of 961 patients of whom 485 were in the collagen group. Compared with standard of care (SOC) alone, the group that added an extra collagen dressing achieved a higher wound healing rate (Risk Ratio = 1.53; 95% CI, 1.33–1.77). The collagen group also showed a higher healing velocity than the SOC group (Mean Difference, 2.69; 95% CI, 0.87–4.51). In addition, the adverse events related to dressing between the two groups were similar (Risk Ratio = 0.67; 95% CI, 0.44–1.01).

Conclusion

Collagen dressing increases the wound healing rate and may be an effective and safe treatment for chronic wound management. However, more extensive research shall be conducted to substantiate these results.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=245728, identifier: CRD42021245728.

Label-free second harmonic generation imaging of cerebral vascular wall in local ischemia mouse model in vivo

Second harmonic generation (SHG) imaging is label-free and non-invasive, and it has been extensively applied in multiple biological and medical studies, but not in the brain in vivo. In this study, we modified classical two photon excited fluorescence (TPEF) system to perform in vivo simultaneous TPEF and SHG imaging in the local ischemia mouse model. In cerebral vascular walls, we found strong SHG signal, which co-localized with collagen. In the continuous 2 days' in vivo imaging, this SHG signal remained stable in the local ischemic blood vessel in the initial 4 hours, then its signal abruptly increased and got spatially thickened 5 hours after thrombosis, and this tendency continued in the following 48 hours. This study provides direct and precise timeline of rapid collagen change in cerebral vascular walls in vivo, and reveals the subtle but significant temporal-spatial dynamics of this structural signal during local ischemia. Thus, this cerebral in vivo SHG imaging provides a powerful tool to identify the early and subtle pathological change of collagen around clinical key therapeutic time window.

Medical Adhesives and Their Role in Laparoscopic Surgery—A Review of Literature

Laparoscopic surgery is undergoing rapid development. Replacing the traditional method of joining cut tissues with sutures or staples could greatly simplify and speed up laparoscopic procedures. This alternative could undoubtedly be adhesives. For decades, scientists have been working on a material to bond tissues together to create the best possible conditions for tissue regeneration. The results of research on tissue adhesives achieved over the past years show comparable treatment effects to traditional methods. Tissue adhesives are a good alternative to surgical sutures in wound closure. This article is a review of the most important groups of tissue adhesives including their properties and possible applications. Recent reports on the development of biological adhesives are also discussed.

Theaflavin: a natural candidate to restrain thrombosis

Many clinical studies have demonstrated the beneficial effects of black tea on cardiovascular diseases. However, the antiplatelet and antithrombotic activities of theaflavin (TF-1) remain unknown. In this study, we aimed to investigate the beneficial effects of TF-1 on platelet activation and thrombosis formation both in vitro and in vivo. Firstly, the in vitro antiplatelet activity of TF-1 was analyzed using platelets isolated from human blood via aggregometry, flow cytometry, the ELISA kit, western blot and fluorescence microscopy. Subsequently, the in vivo analysis of the hemostatic state and thrombosis formation was carried out in C57BL/6 mice based on the tail bleeding time and an FeCl₃-induced arterial thrombus model. The results showed that TF-1 could prominently inhibit platelet aggregation in a dose-dependent manner, and attenuate P-selectin expression, fibrinogen binding, spreading and thromboxane A2 (TxA2) formation. Western blot analysis showed that TF-1 potently inhibited spleen tyrosine kinase (Syk) and Akt (ser473/474) phosphorylation. The in vivo data further confirmed the inhibition of platelet activation by TF-1 with a prolonged arterial occlusion time (from 15.0 ± 1.1 minutes to 40.0 ± 5.4 minutes). All the results indicated that TF-1 is a powerful inhibitor of platelet activation and thrombosis formation in C57BL/6 mice, and could be developed as a novel food-based inhibitor of thrombotic disorders.

Atherothrombosis-on-Chip: A Site-Specific Microfluidic Model for Thrombus Formation and Drug Discovery

Atherothrombosis, an atherosclerotic plaque disruption condition with superimposed thrombosis, is the underlying cause of cardiovascular episodes. Herein, a unique design is presented to develop a microfluidic site-specific atherothrombosis-on-chip model, providing a universal platform for studying the crosstalk between blood cells and plaque components. The device consists of two interconnected microchannels, namely main and supporting channels: the former mimics the vessel geometry with different stenosis, and the latter introduces plaque components to the circulation simultaneously. The unique design allows the site-specific introduction of plaque components in stenosed channels ranging from 0% to above 50%, resulting in thrombosis, which has not been achieved previously. The device successfully explains the correlation between vessel geometry and thrombus formation phenomenon as well as the influence of shear rate on platelet aggregation, confirming the reliability and the effectiveness of the design. The device exhibits significant sensitivity to aspirin. In therapeutic doses (50 × 10^-6 and 100 × 10^-6 m), aspirin delays and prevents platelet adhesion, thereby reducing the thrombus area in a dose-dependent manner. Finally, the device is effectively employed in testing the targeted binding of the RGD (arginyl-glycyl-aspartic acid) labeled polymeric nanoparticles on the thrombus, extending the use of the device to examine targeted drug carriers.

Biting Innovations of Mosquito-Based Biomaterials and Medical Devices

Mosquitoes are commonly viewed as pests and deadly predators by humans. Despite this perception, investigations of their survival-based behaviors, select anatomical features, and biological composition have led to the creation of several beneficial technologies for medical applications. In this review, we briefly explore these mosquito-based innovations by discussing how unique characteristics and behaviors of mosquitoes drive the development of select biomaterials and medical devices. Mosquito-inspired microneedles have been fabricated from a variety of materials, including biocompatible metals and polymers, to mimic of the mouthparts that some mosquitoes use to bite a host with minimal injury during blood collection. The salivary components that these mosquitoes use to reduce the clotting of blood extracted during the biting process provide a rich source of anticoagulants that could potentially be integrated into blood-contacting biomaterials or administered in therapeutics to reduce the risk of thrombosis. Mosquito movement, vision, and olfaction are other behaviors that also have the potential for inspiring the development of medically relevant technologies. For instance, viscoelastic proteins that facilitate mosquito movement are being investigated for use in tissue engineering and drug delivery applications. Even the non-wetting nanostructure of a mosquito eye has inspired the creation of a robust superhydrophobic surface coating that shows promise for biomaterial and drug delivery applications. Additionally, biosensors incorporating mosquito olfactory receptors have been built to detect disease-specific volatile organic compounds. Advanced technologies derived from mosquitoes, and insects in general, form a research area that is ripe for exploration and can uncover potential in further dissecting mosquito features for the continued development of novel medical innovations.

Oxidized dextran crosslinked polysaccharide/protein/polydopamine composite cryogels with multiple hemostatic efficacies for noncompressible hemorrhage and wound healing

Noncompressible hemorrhage caused by gunshots and sharp objects leads to higher trauma mortality, and cryogels have great potential in controlling noncompressible hemorrhage applications owing to their shape-memory properties. However, the use of non-toxic crosslinkers to prepare cryogels for noncompressible hemorrhage remains a challenge. In this study, a series of cryogels were prepared using oxidized dextran (ODex) as a biocompatible crosslinker, combined with the good hemostatic properties of chitosan (CS) and human-like collagen (HLC), and polydopamine nanoparticles (PDA-NPs) were also introduced to strengthen the shape recovery speed of the cryogels and further enhance their hemostatic performance. The CS/HLC/ODex/PDA-NPs (CHOP) cryogels presented a highly interconnected macroporous structure, powerful water/blood absorption capacity, robust mechanical performance, and rapid water/blood-triggered shape recovery. In vitro coagulation and coagulation mechanism tests showed that CHOP exhibited strong procoagulant ability, high adhesion to blood cells and fibrinogen, and the capacity to activate platelets and intrinsic pathways. In vivo hemostatic tests indicated that CHOP could effectively shorten the bleeding time and reduce the bleeding volume of liver incision bleeding and liver noncompressible hemorrhage. Meanwhile, CHOP exhibited good biocompatibility and biodegradability, and could promote wound healing. These results suggest that CHOP cryogels will be a promising hemostatic dressing.

Engineered Hemostatic Biomaterials for Sealing Wounds

Hemostatic biomaterials show great promise in wound control for the treatment of uncontrolled bleeding associated with damaged tissues, traumatic wounds, and surgical incisions. A surge of interest has been directed at boosting hemostatic properties of bioactive materials via mechanisms triggering the coagulation cascade. A wide variety of biocompatible and biodegradable materials has been applied to the design of hemostatic platforms for rapid blood coagulation. Recent trends in the design of hemostatic agents emphasize chemical conjugation of charged moieties to biomacromolecules, physical incorporation of blood-coagulating agents in biomaterials systems, and superabsorbing materials in either dry (foams) or wet (hydrogel) states. In addition, tough bioadhesives are emerging for efficient and physical sealing of incisions. In this Review, we highlight the biomacromolecular design approaches adopted to develop hemostatic bioactive materials. We discuss the mechanistic pathways of hemostasis along with the current standard experimental procedures for characterization of the hemostasis efficacy. Finally, we discuss the potential for clinical translation of hemostatic technologies, future trends, and research opportunities for the development of next-generation surgical materials with hemostatic properties for wound management.

Tirofiban potentiates agonist-induced platelet activation and degranulation, despite effectively inhibiting aggregation

We aimed to investigate the effects of integrin αIIbβ3 inhibitor tirofiban on hallmarks of platelet activation, degranulation, and aggregation during its use to analyze activated but non-complexed platelets via flow cytometry. To do so, we used washed platelets from healthy human donors. We combined aggregometry, an assay of platelet functionality, with flow cytometry and ELISA to detect and correlate, respectively, platelet aggregation, activation, and granule release. While tirofiban effectively inhibited agonist-induced platelet aggregation (thrombin receptor-activating peptide 6 (TRAP), convulxin (CVX), U46619 and IV.3), the surface expression of P-selectin and CD63 and granule release of RANTES were significantly increased, indicating that tirofiban enhances degranulation, uncoupled from aggregation. The results show that tirofiban alters the activation phenotype of platelets, something that should be considered when using tirofiban to enable flow cytometric analysis of activated but unaggregated platelet suspensions.

Structural insights into collagen binding by platelet receptor glycoprotein VI

Glycoprotein VI (GPVI) mediates collagen-induced platelet activation after vascular damage and is an important contributor to the onset of thrombosis, heart attack, and stroke. Animal models of thrombosis have identified GPVI as a promising target for antithrombotic therapy. Although for many years the crystal structure of GPVI has been known, the essential details of its interaction with collagen have remained elusive. Here, we present crystal structures of the GPVI ectodomain bound to triple-helical collagen peptides, which reveal a collagen-binding site across the β-sheet of the D1 domain. Mutagenesis and binding studies confirm the observed binding site and identify Trp76, Arg38, and Glu40 as essential residues for binding to fibrillar collagens and collagen-related peptides (CRPs). GPVI binds a site on collagen comprising two collagen chains with the core formed by the sequence motif OGPOGP. Potent GPVI-binding peptides from Toolkit-III all contain OGPOGP; weaker binding peptides frequently contain a partial motif varying at either terminus. Alanine-scanning of peptide III-30 also identified two AGPOGP motifs that contribute to GPVI binding, but steric hindrance between GPVI molecules restricts the maximum binding capacity. We further show that no cooperative interactions could occur between two GPVI monomers binding to a stretch of (GPO)5 and that binding of ≥2 GPVI molecules to a fibril-embedded helix requires non-overlapping OGPOGP motifs. Our structure confirms the previously suggested similarity in collagen binding between GPVI and leukocyte-associated immunoglobulin-like receptor 1 (LAIR-1) but also indicates significant differences that may be exploited for the development of receptor-specific therapeutics.

Hemostatic Performance of ɑ-Chitin/gelatin Composite Sponges with Directional Pore Structure

Biomedical materials with effective hemostatic properties are in great demand in clinical and battlefield application for severe hemorrhage control. In this study, nearly amorphous chitin is obtained by treating α-chitin with superfine grinding, and the solubility of chitin in hexafluoro-2-propanol (HFIP) is significantly increased. Chitin and gelatin mixtures are prepared by adding different amount of gelatin to the 8mg ml^-1 chitin solution. In the presence water (non-solvent), the mixtures are gelled as HFIP is replaced by water, and chitin/gelatin composite sponges with directional pore structure are prepared by directional freeze drying of the hydrogel. The structure, porosity, liquid absorbing capacity, biodegradability, and hemostatic properties of the sponges with different ratios of gelatin are investigated. The results show that the sponge with the mass ratio of chitin/gelatin of 1:1 is potential hemostatic material with high absorbing capacity, hemocompatibility, and the best hemostatic performance. The in vivo study demonstrates that hemostatic time of the composite sponge (73 s) is much shorter than of that of gauze (193 s), chitin sponge (132s) as well as gelatin sponge (116 s) in rat femoral artery injury model. This article is protected by copyright. All rights reserved.

Bioactive hydrogels based on polysaccharides and peptides for soft tissue wound management

Due to their inherent and tunable biomechanical and biochemical performances, bioactive hydrogels based on polysaccharides and peptides have shown attractive potential for wound management. In this review, the recent progress of bioactive hydrogels prepared by polysaccharides and peptides for soft tissue wound management is overviewed. Meanwhile, we focus on the elaboration of the relationship between chemical structures and inherent bioactive functions of polysaccharides and peptides, as well as the strategies that are taken for achieving multiple wound repairing effects including hemostasis, adhesion, wound contraction and closure, anti-bacteria, anti-oxidation, immunomodulation, molecule delivery, etc. Some innovative and important works are well introduced as well. In the end, current study limitations, clinical unmet needs, and future directions are discussed.

Preparation of Chitosan/Clay Composites for Safe and Effective Hemorrhage Control

Uncontrolled hemorrhage from trauma or surgery can lead to death. In this study, chitosan/kaolin (CSK) and chitosan/montmorillonite (CSMMT) composites were prepared from chitosan (CS), kaolin (K), and montmorillonite (MMT) as raw materials to control bleeding. The physiochemical properties and surface morphology of CSK and CSMMT composites were analyzed by Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), zeta potentials, and X-ray fluorescence (XRF). The hemostatic mechanism was measured in vitro by activated partial thromboplastin time (APTT), prothrombin time (PT), in vitro clotting time, erythrocyte aggregation, and thromboelastogram (TEG). The hemostasis ability was further verified by using tail amputation and arteriovenous injury models in rats. The biocompatibility of CSK and CSMMT was evaluated by in vitro hemolysis, cytotoxicity assays, as well as acute toxicity test and skin irritation tests. The results show that CSK and CSMMT are promising composite materials with excellent biocompatibility and hemostatic properties that can effectively control bleeding.

Medical Gas Plasma—A Potent ROS-Generating Technology for Managing Intraoperative Bleeding Complications

Cold medical gas plasmas are under pre-clinical investigation concerning their hemostatic activity and could be applied for intra-operative bleeding control in the future. The technological leap innovation was their generation at body temperature, thereby causing no thermal harm to the tissue and ensuring tissue integrity. This directly contrasts with current techniques such as electrocautery, which induces hemostasis by carbonizing the tissue using a heated electrode. However, the necrotized tissue is prone to fall, raising the risk of post-operative complications such as secondary bleedings or infection. In recent years, various studies have reported on the ability of medical gas plasmas to induce blood coagulation, including several suggestions concerning their mode of action. As non-invasive and gentle hemostatic agents, medical gas plasmas could be particularly eligible for vulnerable tissues, e.g., colorectal surgery and neurosurgery. Further, their usage could be beneficial regarding the prevention of post-operative bleedings due to the absence or sloughing of eschar. However, no clinical trials or individual healing attempts for medical gas plasmas have been reported to pave the way for clinical approvement until now, despite promising results in experimental animal models. In this light, the present mini-review aims to emphasize the potential of medical gas plasmas to serve as a hemostatic agent in clinical procedures. Providing a detailed overview of the current state of knowledge, feasible application fields are discussed, and possible obstacles are addressed.

Molecular Correlates of Venous Thromboembolism (VTE) in Ovarian Cancer

BACKGROUND

The incidence of venous thromboembolism (VTE) in patients with ovarian cancer is higher than most solid tumors, ranging between 10-30%, and a diagnosis of VTE in this patient population is associated with worse oncologic outcomes. The tumor-specific molecular factors that may lead to the development of VTE are not well understood.

OBJECTIVES

The aim of this study was to identify molecular features present in ovarian tumors of patients with VTE compared to those without.

METHODS

We performed a multiplatform omics analysis incorporating RNA and DNA sequencing, quantitative proteomics, as well as immune cell profiling of high-grade serous ovarian carcinoma (HGSC) samples from a cohort of 32 patients with or without VTE.

RESULTS

Pathway analyses revealed upregulation of both inflammatory and coagulation pathways in the VTE group. While DNA whole-exome sequencing failed to identify significant coding alterations between the groups, the results of an integrated proteomic and RNA sequencing analysis indicated that there is a relationship between VTE and the expression of platelet-derived growth factor subunit B (PDGFB) and extracellular proteins in tumor cells, namely collagens, that are correlated with the formation of thrombosis.

CONCLUSIONS

In this comprehensive analysis of HGSC tumor tissues from patients with and without VTE, we identified markers unique to the VTE group that could contribute to development of thrombosis. Our findings provide additional insights into the molecular alterations underlying the development of VTE in ovarian cancer patients and invite further investigation into potential predictive biomarkers of VTE in ovarian cancer.

In Vitro Direct and Indirect Cytotoxicity Comparative Analysis of One Pre-Hydrated versus One Dried Acellular Porcine Dermal Matrix

Aim: The aim of the present study was to compare the direct and indirect cytotoxicity of a porcine dried acellular dermal matrix (PDADM) versus a porcine hydrated acellular dermal matrix (PHADM) in vitro. Both are used for periodontal and peri-implant soft tissue regeneration. Materials and methods: Two standard direct cytotoxicity tests—namely, the Trypan exclusion method (TEM) and the reagent WST-1 test (4-3-[4-iodophenyl]-2-[4-nitrophenyl]-2H-[5-tetrazolio]-1,3-benzol-desulphonated)—were performed using human primary mesenchymal stem cells (HPMSCs) seeded directly onto a PDADM and PHADM after seven days. Two standard indirect cytotoxicity tests—namely, lactate dehydrogenase (LTT) and MTT (3-[4,5-dimethyl-2-thiazolyl]-2,5-diphenyl-2H-tetrazoliumbromide)—were performed using HPMSCs cultivated in eluates from the matrices incubated for 0.16 h (10 min), 1 h, and 24 h in a serum-free cell culture medium. Results: The WST and the TEM tests revealed significantly lower direct cytotoxicity values of HPMSCs on the PHADM compared with the PDADM. The indirect cytotoxicity levels were low for both the PHADM and PDADM, peaking in short-term eluates and decreasing with longer incubation times. However, they were lower for the PHADM with a statistically significant difference (p < 0.005). Conclusions: The results of the current study demonstrated a different biologic behavior between the PHADM and the PDADM, with the hydrated form showing a lower direct and indirect cytotoxicity.

Classification Based on Extraction Socket Buccal Bone Morphology and Related Treatment Decision Tree

Background: Alveolar ridge preservation (ARP) can successfully reduce volumetric ridge changes. However, there is still no consensus on what technique is the most advantageous for each specific clinical scenario. Hence, the aim of the present paper was to provide a treatment decision tree to guide the choice of predictable ARP procedures based on extraction socket buccal bone morphology and integrity. Material and Methods: Three socket types (ST) are proposed and discussed based on buccal bone morphology (intact, dehiscence or fenestration). Results: A decision tree for ARP was developed in order to merge ST classification with suitable treatment modalities. In the decision tree, the issue of when to allow unassisted healing or ARP was discussed. Described methods included bone grafting and collagen plug, and absorbable membrane or non-resorbable membrane, with or without flap elevation. Conclusion: A decision tree for ARP procedures was provided to guide clinicians towards the most conservative and predictable treatment approach based on remaining socket anatomical structures after extraction.

Hematohidrosis, Hemolacria, and “Trichorrhage”: A Systematic Review

<b><i>Introduction:</i></b> Hematohidrosis and hemolacria are 2 conditions surrounded in religiousness, mysticism, and supernatural superstitions. While the mechanism is still unclear, these cases have amazed physicians for centuries. <b><i>Methods:</i></b> We performed a systematic review in PubMed from 2000 to mid-2021 accounting for 75 studies from which we included 60 cases in 53 articles which were described. <b><i>Results:</i></b> The median age of apparition was 24 years with the youngest case being 12 and the oldest 81. Some of the diseases were secondary to other causes such as hemangiomas and other neoplasias or epistaxis episodes. Most of the cases have been reported in India and the USA; most of them correspond to hemolacria alone (51.6%). <b><i>Discussion:</i></b> We have stated the basics of the substances involved in the coagulation process that have been described as genetically altered in some patients such as mucins, metalloproteinases, and fibrinogen, as well as propose a mechanism that can explain the signs of this particular entity and approach to its treatment as well as provide the first trichoscopy image of a patient with hemolacria.

Prevention of bleeding after percutaneous biopsy with a small intestinal submucosa hemostatic plug

Percutaneous biopsies (PBs) are the gold standard diagnostic procedures indicated for renal and hepatic disorders. Nevertheless, they can cause hemorrhages and are contraindicated for coagulopathic patients. In this study we designed, fabricated, and evaluated a small intestinal submucosa (SIS) plug to reduce, and potentially cease, bleeding to decrease death risk after percutaneous hepatic and renal biopsies in healthy and coagulopathic in vivo models. First, the plug's blocking capacity was determined with an increase in its diameter of 24 ± 11% after immersion in human blood, and the capacity to induce clotting on its surface. The plug's in vivo performance was evaluated in a healthy porcine model, which showed minimal inflammatory reaction without side effects confirmed by histological results after 30 days. The plug's response in the coagulopathic model was assessed using heparinized swine for 2 days, which revealed localized microhemorrhages and mild inflammatory response without any lesions to the surrounding tissue. No major adverse events nor macroscopic hemorrhages were detected in the animal models. Furthermore, we assessed the plug's efficacy to reduce and stop bleeding using a transplant-discarded human liver model (n = 14). In this case, the mass of blood lost was 43.8 ± 21.8% lower in plugged transplant-discarded human liver biopsies compared to control biopsies without a plug. The bleeding was stopped within three minutes in 92% of plugged cases, but only in 8% of non-plugged cases. We demonstrated the feasibility of making a hemostatic SIS plug, which does not induce major inflammatory reaction and can effectively reduce and stop bleeding after PBs in non-coagulopathic and coagulopathic in vivo models, and in a transplant-discarded human liver model. STATEMENT OF SIGNIFICANCE: Percutaneous biopsy (PB) is a gold standard diagnostic procedure, but it can provoke life-threatening complications and is contraindicated for patients with coagulopathic disorders. This study demonstrates that small intestinal submucosa (SIS) can be manufactured into a biocompatible thrombogenic plug, insertable through a commercial Tru-Cut needle sheath. This device takes advantage of the collagen-rich composition of SIS to stop and reduce bleeding more effectively than the traditional PB, indicating that it could be routinely employed in a traditional biopsy to increase safety, or as a cost and time-reducing alternative to transjugular biopsy for coagulopathic patients.

Reduced Platelet Adhesion for Blended Electrospun Meshes with Low Amounts of Collagen Type I

A clinically approved, tissue engineered graft is needed as an alternative for small-diameter artery replacement. Collagen type I is commonly investigated for naturally derived grafts. However, collagen promotes thrombosis, currently requiring a graft pre-seeding step. This study investigates unique impacts of blending low collagen amounts with synthetic polymers on scaffold platelet response, which would allow for viable acellular grafts that can endothelialize in vivo. While platelet adhesion and activation are confirmed to be high with 50% collagen samples, low collagen ratios surprisingly exhibit the opposite, anti-thrombogenic effect. Different platelet interactions in these blended materials can be related to collagen structure. Low collagen ratios show homogenous distribution of the components within individual fibers. Importantly, blended collagen scaffolds exhibit significant differences from gelatin scaffolds, including retaining percentage of collagen after incubation. These findings correlate with functional benefits including better endothelial cell spreading on collagen versus gelatin blended materials. This appears to differ from the current paradigm that processing with harsh solvents will irreversibly denature collagen into less desirable gelatin, but an important distinction is the interaction between collagen and synthetic materials during processing. Overall, excellent anti-thrombogenic properties of low collagen blends and benefits after grafting show promise for this vascular graft strategy.

In-vitro and in-vivo hemostat evaluation of decellularized liver extra cellular matrix loaded chitosan/gelatin spongy scaffolds for liver injury

Individually, Chitosan (C) and Gelatin (G) are increasingly being used for the simulation and testing of surgical procedures. In the present study, at combination of chitosan/gelatin (CG) was optimized and later enriched by the loading decellularized liver extracellular matrix powder (dLECM) prepared from porcine liver, we hypothesized CG-dLECM combination would enhance wound healing and reduce postoperative complications after liver surgery. Varying concentration of dLECM (1, 4, and 8 mg/ml) were loaded into CG, and evaluation was done to get the optimized composition. Preliminary analysis on the microstructure, in-vitro degradation, and blood clot kinetics and in-vitro cytocompatibility showed that the CG with 4 mg/ml dLECM (CG-E4) was the most suitable composition for further consideration. The prepared CG-E4 spongy scaffold enhances fast post-operative recovery with a higher blood absorption and fast clotting time (~50 s). In addition, CG-E4 spongy scaffold implanted at rat liver wound showed desired biocompatibility as evidenced by reduced wound size, earlier bioabsorption and accelerated liver regeneration. In the present study, we demonstrated that, CG with dLECM spongy scaffold as a potential hemostatic material in the prevention of excessive hemorrhage during surgeries.

Screening Analysis of Platelet miRNA Profile Revealed miR-142-3p as a Potential Biomarker in Modeling the Risk of Acute Coronary Syndrome

Transcriptome analysis constitutes one of the major methods of elucidation of the genetic basis underlying the pathogenesis of various diseases. The post-transcriptional regulation of gene expression is mainly provided by microRNAs. Their remarkable stability in biological fluids and their high sensitivity to disease alteration indicates their potential role as biomarkers. Given the high mortality and morbidity of cardiovascular diseases, novel predictive biomarkers are sorely needed. Our study focuses for the first time on assessing potential biomarkers of acute coronary syndrome (ACS) based on the microRNA profiles of platelets. The study showed the overexpression of eight platelet microRNAs in ACS (miR-142-3p; miR-107; miR-338-3p, miR-223-3p, miR-21-5p, miR-130b-3p, miR-301a-3p, miR-221-3p) associated with platelet reactivity and functionality. Our results show that the combined model based on miR-142-3p and aspartate transaminase reached 82% sensitivity and 88% specificity in the differentiation of the studied groups. Furthermore, the analyzed miRNAs were shown to cluster into two orthogonal groups, regulated by two different biological factors. Bioinformatic analysis demonstrated that one group of microRNAs may be associated with the physiological processes of platelets, whereas the other group may be linked to platelet-vascular environment interactions. This analysis paves the way towards a better understanding of the role of platelet microRNAs in ACS pathophysiology and better modeling of the risk of ACS.

The Effects of Vitamin C on the Multiple Pathophysiological Stages of COVID-19

Currently available anti-viral drugs may be useful in reducing the viral load but are not providing the necessary physiological effects to reduce the SARS-CoV-2 complications efficiently. Treatments that provide better clinical outcomes are urgently needed. Vitamin C (ascorbic acid, AA) is an essential nutrient with many biological roles that have been proven to play an important part in immune function; it serves as an antioxidant, an anti-viral, and exerts anti-thrombotic effects among many other physiological benefits. Research has proven that AA at pharmacological doses can be beneficial to patients with acute respiratory distress syndrome (ARDS) and other respiratory illnesses, including sepsis. In addition, High-Dose Intravenous Vitamin C (HDIVC) has proven to be effective in patients with different viral diseases, such as influenza, chikungunya, Zika, and dengue. Moreover, HDIVC has been demonstrated to be very safe. Regarding COVID-19, vitamin C can suppress the cytokine storm, reduce thrombotic complications, and diminish alveolar and vascular damage, among other benefits. Due to these reasons, the use of HDIVC should be seriously considered in complicated COVID-19 patients. In this article, we will emphasize vitamin C’s multiple roles in the most prominent pathophysiological processes presented by the COVID-19 disease.

Identification of the Antithrombotic Mechanism of Leonurine in Adrenalin Hydrochloride-Induced Thrombosis in Zebrafish via Regulating Oxidative Stress and Coagulation Cascade

Thrombosis is a general pathological phenomenon during severe disturbances to homeostasis, which plays an essential role in cardiovascular and cerebrovascular diseases. Leonurine (LEO), isolated from Leonurus japonicus Houtt, showes a crucial role in anticoagulation and vasodilatation. However, the properties and therapeutic mechanisms of this effect have not yet been systematically elucidated. Therefore, the antithrombotic effect of LEO was investigated in this study. Hematoxylin-Eosin staining was used to detect the thrombosis of zebrafish tail. Fluorescence probe was used to detect the reactive oxygen species. The biochemical indexes related to oxidative stress (lactate dehydrogenase, malondialdehyde, superoxide dismutase and glutathione) and vasodilator factor (endothelin-1 and nitric oxide) were analyzed by specific commercial assay kits. Besides, we detected the expression of related genes (fga, fgb, fgg, pkcα, pkcβ, vwf, f2) and proteins (PI3K, phospho-PI3K, Akt, phospho-Akt, ERK, phospho-ERK FIB) related to the anticoagulation and fibrinolytic system by quantitative reverse transcription and western blot. Beyond that, metabolomic analyses were carried out to identify the expressions of metabolites associated with the anti-thrombosis mechanism of LEO. Our in vivo experimental results showed that LEO could improve the oxidative stress injury, abnormal platelet aggregation and coagulation dysfunction induced by adrenalin hydrochloride. Moreover, LEO restored the modulation of amino acids and inositol metabolites which are reported to alleviate the thrombus formation. Collectively, LEO attenuates adrenalin hydrochloride-induced thrombosis partly via modulating oxidative stress, coagulation cascade and platelet activation and amino acid and inositol metabolites.