A Novel Volume-Stable Collagen Matrix Induces Changes in the Behavior of Primary Human Oral Fibroblasts,Periodontal Ligament,and Endothelial Cells

The aim of the present study was to investigate the influence of a novel volume-stable collagen matrix (vCM) on early wound healing events including cellular migration and adhesion, protein adsorption and release, and the dynamics of the hemostatic system. For this purpose, we utilized transwell migration and crystal violet adhesion assays, ELISAs for quantification of adsorbed and released from the matrix growth factors, and qRT-PCR for quantification of gene expression in cells grown on the matrix. Our results demonstrated that primary human oral fibroblasts, periodontal ligament, and endothelial cells exhibited increased migration toward vCM compared to control cells that migrated in the absence of the matrix. Cellular adhesive properties on vCM were significantly increased compared to controls. Growth factors TGF-β1, PDGF-BB, FGF-2, and GDF-5 were adsorbed on vCM with great efficiency and continuously delivered in the medium after an initial burst release within hours. We observed statistically significant upregulation of genes encoding the antifibrinolytic thrombomodulin, plasminogen activator inhibitor type 1, thrombospondin 1, and thromboplastin, as well as strong downregulation of genes encoding the profibrinolytic tissue plasminogen activator, urokinase-type plasminogen activator, its receptor, and the matrix metalloproteinase 14 in cells grown on vCM. As a general trend, the stimulatory effect of the vCM on the expression of antifibrinolytic genes was synergistically enhanced by TGF-β1, PDGF-BB, or FGF-2, whereas the strong inhibitory effect of the vCM on the expression of profibrinolytic genes was reversed by PDGF-BB, FGF-2, or GDF-5. Taken together, our data strongly support the effect of the novel vCM on fibrin clot stabilization and coagulation/fibrinolysis equilibrium, thus facilitating progression to the next stages of the soft tissue healing process.     

Uncertainty model of electro-optical thrombus growth estimation for early risk detection

It is proposed a device for the study of the real-time aggregation of white thrombi in whole blood. This device allows extrapolating the 3D-shape of platelets clotting within artificial capillaries, by simultaneously monitoring the electrical impedance between a pair of specifically designed gold electrodes and 2D optical image of pixel luminance of the fluorescent labeled platelets. Up to 30 3D images per minute have been obtained, for a process which requires few minutes before the aggregation of large thrombi structures, a noticeable result with respect to other 3D-shape reconstruction methods. The contribution of this paper mainly consists in the study of an uncertainty model which, in our opinion, is of fundamental importance to provide a valuable metrological estimation of thrombus growth under flow conditions.     

Characterization of GPVI- or GPVI-CD39-Coated Nanoparticles and Their Impact on In Vitro Thrombus Formation

Traditional antithrombotic agents commonly share a therapy-limiting side effect, as they increase the overall systemic bleeding risk. A novel approach for targeted antithrombotic therapy is nanoparticles. In other therapeutic fields, nanoparticles have enabled site-specific delivery with low levels of toxicity and side effects. Here, we paired nanotechnology with an established dimeric glycoprotein VI-Fc (GPVI-Fc) and a GPVI-CD39 fusion protein, thereby combining site-specific delivery and new antithrombotic drugs. Poly(lactic-co-glycolic acid) (PLGA) nanoparticles, NP-BSA, NP-GPVI and NP-GPVI-CD39 were characterized through electron microscopy, atomic force measurements and flow cytometry. Light transmission aggregometry enabled analysis of platelet aggregation. Thrombus formation was observed through flow chamber experiments. NP-GPVI and NP-GPVI-CD39 displayed a characteristic surface coating pattern. Fluorescence properties were identical amongst all samples. NP-GPVI and NP-GPVI-CD39 significantly impaired platelet aggregation. Thrombus formation was significantly impaired by NP-GPVI and was particularly impaired by NP-GPVI-CD39. The receptor-coated nanoparticles NP-GPVI and the bifunctional molecule NP-GPVI-CD39 demonstrated significant inhibition of in vitro thrombus formation. Consequently, the nanoparticle-mediated antithrombotic effect of GPVI-Fc, as well as GPVI-CD39, and an additive impact of CD39 was confirmed. In conclusion, NP-GPVI and NP-GPVI-CD39 may serve as a promising foundation for a novel therapeutic approach regarding targeted antithrombotic therapy.     

Beyond Hemostasis: Platelet Innate Immune Interactions and Thromboinflammation

There is accumulating evidence that platelets play roles beyond their traditional functions in thrombosis and hemostasis, e.g., in inflammatory processes, infection and cancer, and that they interact, stimulate and regulate cells of the innate immune system such as neutrophils, monocytes and macrophages. In this review, we will focus on platelet activation in hemostatic and inflammatory processes, as well as platelet interactions with neutrophils and monocytes/macrophages. We take a closer look at the contributions of major platelet receptors GPIb, α_IIbβ₃, TLT-1, CLEC-2 and Toll-like receptors (TLRs) as well as secretions from platelet granules on platelet–neutrophil aggregate and neutrophil extracellular trap (NET) formation in atherosclerosis, transfusion-related acute lung injury (TRALI) and COVID-19. Further, we will address platelet–monocyte and macrophage interactions during cancer metastasis, infection, sepsis and platelet clearance.     

Development of Synthetic Platelet‐Activating Hydrogel Matrices to Induce Local Hemostasis

Several hemostatic strategies rely on the use of blood components such as fibrinogen and thrombin, which suffer from high cost and short shelf‐life. Here, a cost‐effective synthetic biomaterial is developed for rapid local hemostasis. Instead of using thrombin, thrombin‐receptor‐agonist‐peptide‐6 (TRAP6) is covalently engineered in polyvinyl alcohol (PVA) hydrogels. Soluble PVA‐TRAP6 is first prepared by covalent attachment of cysteine‐containing TRAP6 onto the backbone of PVA‐norbornenes (PVA‐NB) through photoconjugation. Cytotoxicity studies using C2C12 myoblasts indicate that PVA‐NB and PVA‐TRAP6 are nontoxic. Thromboelastography reveals that hemostatic activity of TRAP6 is retained in conjugated form, which is comparable to free TRAP6 solutions with equal concentrations. A 0.1% PVA‐TRAP6 solution can shorten the clotting time (CT) to ca. 45% of the physiological CT. High platelet‐activating efficiency is further confirmed by platelet aggregation assay and flow cytometry (FACS). For potential clinical applications, TRAP6‐presenting hydrogel particulates (PVA‐TRAP6‐P) are developed for local platelet activation and hemostasis. PVA‐TRAP6‐P is prepared by biofunctionalization of photopolymerized PVA‐NB hydrogel particulates (PVA‐NB‐P) with TRAP6. It is demonstrated that PVA‐TRAP6‐P can effectively shorten the CT to ca. 50%. FACS shows that PVA‐TRAP6‐P can activate platelets to a comparable extent as soluble TRAP6 control. Altogether, PVA‐TRAP6‐P represents a promising class of biomaterials for safe hemostasis and wound healing.     

Tetra‐PEG Based Hydrogel Sealants for In Vivo Visceral Hemostasis

Medical sealant devices for in vivo hemostasis are far from satisfactory in the aged society. A major challenge is effective integration of quick hemorrhage control of the increased anticoagulated patients, high safety, and facile accessibility. Here, a well‐defined ammonolysis‐based Tetra‐PEG hydrogel sealant is developed with rapid gelation speed, strong tissue adhesion, and high mechanical strength. Introduction of cyclized succinyl ester groups into a hydrogel matrix endows the sealant with fast degradable and controllably dissolvable properties. The hydrogel possesses outstanding hemostatic capabilities even under the anticoagulated conditions while displaying excellent biocompatibility and feasibility. These results reveal that the optimized hydrogel may be a facile, effective, and safe sealant for hemorrhage control in vivo.     

Heat preservation,antifouling, hemostatic and antibacterial aerogel wound dressings for emergency treatment

Hemostatic dressings with multiple functions are superior to current hemostatic dressings for use in the complex situation of emergency accidents. In particular, the existing dressings lack consideration for the prevention of hypothermic shock after massive hemorrhage. In this study, gelatin (GN) and oxidized pectin (OP) were used for Schiff base cross-linking, and then polyvinyl alcohol (PVA) solution mixed with hemostatic caffeic acid (CA) was introduced to obtain aerogel substrate material (CB) after lyophilization. Polydimethylsiloxane (PDMS) and silver nanowires (Ag NWs) were used to construct a hydrophobic layer, an antibacterial layer and an infrared reflective layer on both sides of CB to prepare a multifunctional aerogel wound dressing with heat preservation, antifouling, hemostasis and antibacterial properties (PDMS-Ag NW-CB). The results showed that the infrared transmittance of PDMS-Ag NW-CB is almost 0, so that thermal energy loss from the body is minimized. The contact angles with water and blood are 129° and 120°, respectively, which have the effect of antifouling. This dressing can absorb blood quickly within 10 min, adhere to and gather platelets, and achieve hemostasis. It has good antibacterial and biocompatibility. Therefore, PDMS-Ag NW-CB has great potential in application to emergency treatment.     

南极磷虾壳聚糖的提取及止血研究

南极磷虾生活在南冰洋的南极洲水域,是壳聚糖的新型来源,其具有无污染的天然优势,巨大的生物质存量有利于提高提取的天然生物材料质量稳定性;同时,极端的自然环境可使其具有特殊的理化性质。该研究以南极磷虾虾壳作为原料,通过化学方法提取壳聚糖,并对提取工艺的不同脱钙、脱蛋白以及脱乙酰条件进行探索和优化。结果显示,提取的南极磷虾壳聚糖粉末呈亮白色,脱乙酰度达90.6%,分子量为 123 kDa,灰分含量为0.095%。在凝血实验评价中,南极磷虾壳聚糖的止血效果明显优于其他商品化来源的壳聚糖,在止血方面具有潜在应用前景。     

Synthesis of superabsorbent hydrogel nanocomposites for use as hemostatic agent

Uncontrolled hemorrhage continues to be the major cause of death in trauma. In this study, the authors prepared hydrogel nanocomposites (HNCs) using three different nanoparticles, SiO₂, natural clinoptilolite (nC), and Ca²⁺-modified clinoptilolite (mC). Fast-swelling superabsorbent hydrogel was used as a matrix of NCs. The hydrogel and HNCs were characterized by FTIR, XRD, FE-SEM, and TGA. The hemocompatibility of HNCs was evaluated by hemolysis test and blood cells function. HNC formed a physical barrier by dehydrating the injury site and concentrating clotting factors. Additionally, highly charged nanoparticles, promoted local hemostasis by activating the intrinsic pathway of the blood coagulation cascade.