Hemostatic efficacy of two topical adjunctive hemostats in a porcine spleen biopsy punch model of moderate bleeding

Topical hemostatic agents have become essential tools to aid in preventing excessive bleeding in surgical or emergency settings and to mitigate the associated risks of serious complications. In the present study, we compared the hemostatic efficacy of SURGIFLO® Hemostatic Matrix Kit with Thrombin (Surgiflo—flowable gelatin matrix plus human thrombin) to HEMOBLAST™ Bellows Hemostatic Agent (Hemoblast—a combination product consisting of collagen, chondroitin sulfate, and human thrombin). Surgiflo and Hemoblast were randomly tested in experimentally induced bleeding lesions on the spleens of four pigs. Primary endpoints included hemostatic efficacy measured by absolute time to hemostasis (TTH) within 5 min. Secondary endpoints included the number of product applications and the percent of product needed from each device to achieve hemostasis. Surgiflo demonstrated significantly higher hemostatic efficacy and lower TTH (p < 0.01) than Hemoblast. Surgiflo-treated lesion sites achieved hemostasis in 77.4% of cases following a single product application vs. 3.3% of Hemoblast-treated sites. On average, Surgiflo-treated sites required 63% less product applications than Hemoblast-treated sites (1.26 ± 0.0.51 vs. 3.37 ± 1.16). Surgiflo provided more effective and faster hemostasis than Hemoblast. Since both products contain thrombin to activate endogenous fibrinogen and accelerate clot formation, the superior hemostatic efficacy of Surgiflo in the porcine spleen punch biopsy model seems to be due to Surgiflo’s property as a malleable barrier able to adjust to defect topography and to provide an environment for platelets to adhere and aggregate. Surgiflo combines a flowable gelatin matrix and a delivery system well-suited for precise application to bleeding sites where other methods of hemostasis may be impractical or ineffective.

Management of Visceral Artery Pseudoaneurysms by Combined Technique of Percutaneous Thrombin Injection and Endovascular Coiling

Purpose To describe our initial experience with percutaneous thrombin injection combined with endovascular coiling of high-flow visceral artery pseudoaneurysms. Materials and Methods Institutional review board approval was obtained. Between January 2019 and February 2020, 21 patients with nonvariceal upper gastrointestinal (GI) bleed underwent multidetector CT angiography. Four patients with acute pancreatitis and large pseudoaneurysms were selected for the combined technique. Human thrombin reconstituted with calcium chloride was injected percutaneously. Partially thrombosed aneurysms were treated up to three times. Simultaneously or within 15 days, coil embolization of the neck or patent part of pseudoaneurysm was performed. Patients were followed up to 1 month postprocedure. Results The size of the pseudoaneurysms ranged from 3 cm to 6 cm. All were accessed percutaneously by 22G Chiba needle under ultrasound guidance and 500 to 1500 units of thrombin was injected in one to three attempts. Subsequently, endovascular coiling of the neck of the pseudoaneurysm or of the feeding artery was performed. Technical success with cessation of flow was achieved in all four patients. One patient developed obstructive jaundice postprocedure and another continued to have GI bleeding despite thrombin injection. Conclusion Percutaneous thrombin injection is an easy to use and effective tool for treating visceral artery pseudoaneurysms and can be combined with endovascular coiling for successful occlusion of large pseudoaneurysms.

The use of state-of-the-art haemostatic materials in gastrointestinal surgery

Haemostatic materials such as: gelatine sponges, oxygenated cellulose meshes, tissue sealants, collagen matrices with human thrombin and fibrinogen are gaining on popularity in gastrointestinal surgery, especially in colorectal surgery. We searched for available scientific publications in the Pubmed and Cochrane database on the use of individual hemostatic materials in the field of gastrointestinal surgery. The analysis focused on the assessment of the safety of the use of individual materials in terms of the rate of bleeding complications and the rate of anastomotic leakage cases. The use of haemostatic materials has for years been a recognized method of reducing the rate of intra- and postoperative complications, both in gastrointestinal surgery and in other surgical specialties. Based on the available studies, it can be concluded that the use of hemostatic materials such as matrices, sponges and adhesives in gastrointestinal surgery, even in patients at high risk of anastomotic leakage and bleeding complications, reduces the incidence of complications. The growing popularity of haemostatics and sealants in surgery means that they are currently used in a wide range of indications, and surgeons are more and more willing to use them even in case of standard surgical procedures, which is reflected in the available studies. Choosing a haemostat should be a conscious decision, taking into account the site and type of bleeding, mechanism of action, ease of use, efficacy, safety, and price, among others.

Functional Characterization of Antithrombin Mutations by Monitoring of Thrombin Inhibition Kinetics

Inactivation of thrombin by the endogenous inhibitor antithrombin (AT) is a central mechanism in the regulation of hemostasis. This makes hereditary AT deficiency, which is caused by SERPINC1 gene mutations, a major thrombophilic risk factor. Aim of this study was to assess to what extent AT mutations impair thrombin inhibition kinetics. The study population included 36 thrombophilic patients with 19 different mutations and mean AT levels of 65% in a thrombin-based functional assay, and 26 healthy controls. To assess thrombin inhibition kinetics, thrombin (3.94 mU/mL final concentration) was added to citrated plasma. Subsequently, endogenous thrombin inhibition was stopped by addition of the reversible thrombin inhibitor argatroban and the amount of argatroban-complexed thrombin quantified using an oligonucleotide-based enzyme capture assay. The plasma half-life of human thrombin was significantly longer in patients with AT mutations than in the controls (119.9 versus 55.9 s). Moreover, it was disproportionately prolonged when compared with preparations of wild type AT in plasma, in whom a comparable thrombin half-life of 120.8 s was reached at a distinctly lower AT level of 20%. These findings may help to better understand the increased thrombotic risk of SERPINC1 mutations with near normal AT plasma levels in functional assays.

Bifunctional Aptamer Drug Carrier Enabling Selective and Efficient Incorporation of an Approved Anticancer Drug Irinotecan to Fibrin Gels

We have previously developed a bifunctional aptamer (bApt) binding to both human thrombin and camptothecin derivative (CPT1), and showed that bApt acts as a drug carrier under the phenomenon named selective oligonucleotide entrapment in fibrin polymers (SOEF), which enables efficient enrichment of CPT1 into fibrin gels, resulting in significant inhibition of tumor cell growth. However, although the derivative CPT1 exhibits anticancer activity, it is not an approved drug. In this study, we evaluated the binding properties of bApt to irinotecan, a camptothecin analog commonly used for anticancer drug therapy, in addition to unmodified camptothecin (CPT). Furthermore, we have revealed that irinotecan binds to bApt like CPT1 and is selectively concentrated on fibrin gels formed around the tumor cells under the SOEF phenomenon to suppress cell proliferation.

Evolution of a highly functional circular DNA aptamer in serum

Circular DNA aptamers are powerful candidates for therapeutic applications given their dramatically enhanced biostability. Herein we report the first effort to evolve circular DNA aptamers that bind a human protein directly in serum, a complex biofluid. Targeting human thrombin, this strategy has led to the discovery of a circular aptamer, named CTBA4T-B1, that exhibits very high binding affinity (with a dissociation constant of 19 pM), excellent anticoagulation activity (with the half maximal inhibitory concentration of 90 pM) and high stability (with a half-life of 8 h) in human serum, highlighting the advantage of performing aptamer selection directly in the environment where the application is intended. CTBA4T-B1 is predicted to adopt a unique structural fold with a central two-tiered guanine quadruplex capped by two long stem–loops. This structural arrangement differs from all known thrombin binding linear DNA aptamers, demonstrating the added advantage of evolving aptamers from circular DNA libraries. The method described here permits the derivation of circular DNA aptamers directly in biological fluids and could potentially be adapted to generate other types of aptamers for therapeutic applications.