The long term immunological response of swine after two exposures to a salmon thrombin and fibrinogen hemostatic bandage

Hemostatic materials in wound care

Blood plays an essential role in the human body. Hemorrhage is a critical cause of both military and civilian casualties. The human body has its own hemostatic mechanism that involves complex processes and has limited capacity. However, in emergency situations such as battlefields and hospitals, when the hemostatic mechanism of the human body itself cannot stop bleeding effectively, hemostatic materials are needed for saving lives. In this review, the hemostatic mechanisms and performance of the most commonly used hemostatic materials, (including fibrin, collagen, zeolite, gelatin, alginate, chitosan, cellulose and cyanoacrylate) and the commercial wound dressings based on these materials, will be discussed. These materials may have limitations, such as poor tissue adhesion, risk of infection and exothermic reactions, that may lessen their hemostatic efficacy and cause secondary injuries. High-performance hemostatic materials, therefore, have been designed and developed to improve hemostatic efficiency in clinical use. In this review, hemostatic materials with advanced performances, such as antibacterial capacity, superhydrophobicity/superhydrophilicity, superelasticity, high porosity and/or biomimicry, will be introduced. Future prospects of hemostatic materials will also be discussed in this review.

Hemostatic nanotechnologies for external and internal hemorrhage management

An uncontrolled hemorrhage can easily lead to death during surgery and military operations. Despite the significant advances in hemostatic research, there is still an urgent and increasing need for safer and more effective hemostatic materials. Recently, nanotechnologies have been receiving increasing interest owing to their unique advantages and have been propelling the developement of hemostatic materials. This review summarizes the fundamentals of hemostasis and emphasizes the recent developments regarding hemorrhage-related hemostatic nanotechnologies. In terms of external accessible hemorrhage management, natural and synthetic polymers and inorganic components that have been used in traditional hemostats provide novel nanoscale solutions. Regarding internal noncompressible hemorrhage management, current research endeavors are dedicated to the development of substitutes for blood components, and nanoformulated hemostatic drugs. This review also briefly discusses the main and persistent problems of hemostatic nanomaterials, including safety concerns and clinical translation challenges. This review is hoped to provide critical insight into hemostatic nanomaterial development.

Biomaterials and Advanced Technologies for Hemostatic Management of Bleeding

Bleeding complications arising from trauma, surgery, and as congenital, disease-associated, or drug-induced blood disorders can cause significant morbidities and mortalities in civilian and military populations. Therefore, stoppage of bleeding (hemostasis) is of paramount clinical significance in prophylactic, surgical, and emergency scenarios. For externally accessible injuries, a variety of natural and synthetic biomaterials have undergone robust research, leading to hemostatic technologies including glues, bandages, tamponades, tourniquets, dressings, and procoagulant powders. In contrast, treatment of internal noncompressible hemorrhage still heavily depends on transfusion of whole blood or blood's hemostatic components (platelets, fibrinogen, and coagulation factors). Transfusion of platelets poses significant challenges of limited availability, high cost, contamination risks, short shelf-life, low portability, performance variability, and immunological side effects, while use of fibrinogen or coagulation factors provides only partial mechanisms for hemostasis. With such considerations, significant interdisciplinary research endeavors have been focused on developing materials and technologies that can be manufactured conveniently, sterilized to minimize contamination and enhance shelf-life, and administered intravenously to mimic, leverage, and amplify physiological hemostatic mechanisms. Here, a comprehensive review regarding the various topical, intracavitary, and intravenous hemostatic technologies in terms of materials, mechanisms, and state-of-art is provided, and challenges and opportunities to help advancement of the field are discussed.

Hemostasis and Safety of a Novel Fibrin Dressing Versus Standard Gauze in Bleeding Cancellous Bone in a Caprine Spine Surgery Model

BACKGROUND

Decorticated bone is a significant source of blood loss in scoliosis surgery. Current hemostatic methods include packed gauze (GS), physical barriers such as bone wax, and xenograft collagen-based materials. We assessed the safety and efficacy of a novel fibrin dressing (dextran-thrombin-fibrinogen [DTF]) compared to GS. This dressing comprises lyophilized thrombin and fibrinogen embedded in an elastic electrospun nanofiber dextran matrix.

PURPOSE

The study tests the hypothesis that DTF is more efficacious than GS in control of bleeding from cancellous bone.

STUDY DESIGN

A preclinical Good Laboratory Practices (GLP) study.

METHODS

We enrolled 10 goats that were followed for 28 ± 1 days. Each animal was randomly assigned to the test or control group. Both test and control animals had 4 cancellous bone injuries. Test animal injuries were treated with DTF, whereas standard GS was used to control bleeding in the control animals. Bleeding at the bone injury site was characterized as either none, oozing, flowing, or pulsatile and was assessed at 4 and 8 minutes after dressing application. Goats were survived 28 ± 1 days and then necropsied.

RESULTS

Application of the fibrin dressing to bleeding cancellous bone, both posterior spinal lamina, and iliac crest graft sites, resulted in control of bleeding within 4 minutes at all injury sites. Eighty percent of control injury sites continued to bleed after 8 minutes and required application of bone wax to control bleeding. There were no differences in prothrombin time, partial thromboplastin time, or fibrinogen levels between test and control animals at 1 or 28 days. We observed no adverse histologic reactions at 28 days.

CONCLUSION

The fibrin dressing is an efficacious and safe method of controlling blood loss from cancellous bone in a spine surgery model.

Study on preparation of fibrinogen-loaded poly (L-lactic) acid nano-fabrics and its haemostatic performance in swine traumatic haemorrhage models

Haemorrhage is the major cause of death in civilian trauma and the leading cause of preventable death in military trauma. It is very important to develop a haemostatic material with definite haemostatic effects. In this study, a nano-fabric membrane containing fibrinogen (Fbg) (2.5%, w/v) was successfully prepared by electrospinning as a haemostatic dressing. The average fibre diameter was 400 nm by scanning electron microscope (SEM), and it was indicated that fibrinogen and fibrin possessed excellent compatibility with poly (L-lactic)-acid (PLLA) from X-ray diffraction (XRD). Swine traumatic haemorrhage models including spleen haemorrhage, liver haemorrhage and femoral arteriovenous fistula haemorrhage were developed to detect haemostatic effects of this dressing. The results showed that the Fbg-loaded PLLA nano-fibre can significantly decrease the bleeding time, blood loss and mortality rate, which suggested that Fbg-loaded PLLA nano-fibre was efficacious on the models of traumatic uncontrolled haemorrhage, and further study of this dressing would be warranted to determine its potential in first aid and field trauma care.

Salmon fibrin treatment of spinal cord injury promotes functional recovery and density of serotonergic innervation

The neural degeneration caused by spinal cord injury leaves a cavity at the injury site that greatly inhibits repair. One approach to promoting repair is to fill the cavity with a scaffold to limit further damage and encourage regrowth. Injectable materials are advantageous scaffolds because they can be placed as a liquid in the lesion site then form a solid in vivo that precisely matches the contours of the lesion. Fibrin is one type of injectable scaffold, but risk of infection from blood borne pathogens has limited its use. We investigated the potential utility of salmon fibrin as an injectable scaffold to treat spinal cord injury since it lacks mammalian infectious agents and encourages greater neuronal extension in vitro than mammalian fibrin or Matrigel®, another injectable material. Female rats received a T9 dorsal hemisection injury and were treated with either salmon or human fibrin at the time of injury while a third group served as untreated controls. Locomotor function was assessed using the BBB scale, bladder function was analyzed by measuring residual urine, and sensory responses were tested by mechanical stimulation (von Frey hairs). Histological analyses quantified the glial scar, lesion volume, and serotonergic fiber density. Rats that received salmon fibrin exhibited significantly improved recovery of both locomotor and bladder function and a greater density of serotonergic innervation caudal to the lesion site without exacerbation of pain. Rats treated with salmon fibrin also exhibited less autophagia than those treated with human fibrin, potentially pointing to amelioration of sensory dysfunction. Glial scar formation and lesion size did not differ significantly among groups. The pattern and timing of salmon fibrin's effects suggest that it acts on neuronal populations but not by stimulating long tract regeneration. Salmon fibrin clearly has properties distinct from those of mammalian fibrin and is a beneficial injectable scaffold for treatment of spinal cord injury.

The potential for salmon fibrin and thrombin to mitigate pain subsequent to cervical nerve root injury

Nerve root compression is a common cause of radiculopathy and induces persistent pain. Mammalian fibrin is used clinically as a coagulant but presents a variety of risks. Fish fibrin is a potential biomaterial for neural injury treatment because it promotes neurite outgrowth, is non-toxic, and clots readily at lower temperatures. This study administered salmon fibrin and thrombin following nerve root compression and measured behavioral sensitivity and glial activation in a rat pain model. Fibrin and thrombin each significantly reduced mechanical allodynia compared to injury alone (p < 0.02). Painful compression with fibrin exhibited allodynia that was not different from sham for any day using stimulation by a 2 g filament; allodynia was only significantly different (p < 0.043) from sham using the 4 g filament on days 1 and 3. By day 5, responses for fibrin treatment decreased to sham levels. Allodynia following compression with thrombin treatment were unchanged from sham at any time point. Macrophage infiltration at the nerve root and spinal microglial activation were only mildly modified by salmon treatments. Spinal astrocytic expression decreased significantly with fibrin (p < 0.0001) but was unchanged from injury responses for thrombin treatment. Results suggest that salmon fibrin and thrombin may be suitable biomaterials to mitigate pain.