Cystoscopic application of PuraStat® in the treatment of radiation-induced haemorrhagic cystitis

The use of radiotherapy has increased in recent years, especially for pelvic neoplasms, and this can result in long-term complications such as recurrent haemorrhagic radiation cystitis (RHC). A 73-year-old male patient presented to a hospital emergency department multiple times with visible haematuria and clots leading to urinary clot retention; he was finally diagnosed with RHC. During the last presentation, the bladder was irrigated continuously with saline using a three-way catheter. During hospitalisation, a cystourethroscopy was performed for bladder evaluation and clot evacuation. Multiple bleeding ulcers were recognised on the bladder wall, biopsies were taken for histopathology, and the ulcers cauterised. Packed red blood cell transfusions were required, and sodium hyaluronate (CystiStat®) bladder instillations were tried. There was no clinical improvement following any of these interventions. In light of the patient's deteriorating condition, cystoscopic application of PuraStat® 3ml was administered, which led to remission of the urinary bleeding in the short term. We continue to monitor the effects in the medium and long term. Based on current data, PuraStat® haemostatic agent therapy may be considered for RHC, when traditional treatments are ineffective or infeasible, potentially eliminating the need for more aggressive therapy such as cystectomy.

Short Peptide Nanofiber Biomaterials Ameliorate Local Hemostatic Capacity of Surgical Materials and Intraoperative Hemostatic Applications in Clinics

Short designer self-assembling peptide (dSAP) biomaterials are a new addition to the hemostat group. It may provide a diverse and robust toolbox for surgeons to integrate wound microenvironment with much safer and stronger hemostatic capacity than conventional materials and hemostatic agents. Especially in noncompressible torso hemorrhage (NCTH), diffuse mucosal surface bleeding, and internal medical bleeding (IMB), with respect to the optimal hemostatic formulation, dSAP biomaterials are the ingenious nanofiber alternatives to make bioactive neural scaffold, nasal packing, large mucosal surface coverage in gastrointestinal surgery (esophagus, gastric lesion, duodenum, and lower digestive tract), epicardiac cell-delivery carrier, transparent matrix barrier, and so on. Herein, in multiple surgical specialties, dSAP-biomaterial-based nano-hemostats achieve safe, effective, and immediate hemostasis, facile wound healing, and potentially reduce the risks in delayed bleeding, rebleeding, post-operative bleeding, or related complications. The biosafety in vivo, bleeding indications, tissue-sealing quality, surgical feasibility, and local usability are addressed comprehensively and sequentially and pursued to develop useful surgical techniques with better hemostatic performance. Here, the state of the art and all-round advancements of nano-hemostatic approaches in surgery are provided. Relevant critical insights will inspire exciting investigations on peptide nanotechnology, next-generation biomaterials, and better promising prospects in clinics.

Development potential of extracellular matrix hydrogels as hemostatic materials

The entry of subcutaneous extracellular matrix proteins into the circulation is a key step in hemostasis initiation after vascular injury. However, in cases of severe trauma, extracellular matrix proteins are unable to cover the wound, making it difficult to effectively initiate hemostasis and resulting in a series of bleeding events. Acellular-treated extracellular matrix (ECM) hydrogels are widely used in regenerative medicine and can effectively promote tissue repair due to their high mimic nature and excellent biocompatibility. ECM hydrogels contain high concentrations of extracellular matrix proteins, including collagen, fibronectin, and laminin, which can simulate subcutaneous extracellular matrix components and participate in the hemostatic process. Therefore, it has unique advantages as a hemostatic material. This paper first reviewed the preparation, composition and structure of extracellular hydrogels, as well as their mechanical properties and safety, and then analyzed the hemostatic mechanism of the hydrogels to provide a reference for the application and research, and development of ECM hydrogels in the field of hemostasis.

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.

Endoscopically delivered Purastat for the treatment of severe haemorrhagic radiation proctopathy: a service evaluation of a new endoscopic treatment for a challenging condition

BACKGROUND

A total of 30 000 people are treated with pelvic radiotherapy annually in the UK. Rectal bleeding is common following pelvic radiotherapy and one of the main causes is radiation proctopathy (RP). Six per cent develop severe bleeding from RP, leading to anaemia requiring iron +/- blood transfusion. There are very few safe, effective, evidence-based treatments. Purastat is a haemostatic agent licensed for gastrointestinal bleeding. It is a self-assembling peptide that forms a molecular mesh in contact with blood, thereby sealing blood vessels. There are numerous studies showing its efficacy and safety in various surgical/endoscopic settings. This service evaluation reports the first experience of the use of Purastat in RP.

METHODS

Consecutive patients attending pelvic radiation disease clinic with severe refractory RP were offered treatment with Purastat. This was defined as rectal bleeding into the pan±anaemia with no response to rectal sucralfate. Purastat was applied endoscopically at four weekly intervals up to three times, with more as required. Bleeding severity, endoscopic grade and haemoglobin were recorded.

RESULTS

Twenty-one patients were treated (18 men, median age 76 years) with a median of three treatments. Ten were on antithrombotics, 1 had thrombocytopenia and 13 had anaemia at baseline. Median episodes of bleeding reduced from 4.5 (0-27) to 2 (0-16) in the 7 days prior to the first and third treatment, respectively. Endoscopic grade was improved. Mean haemoglobin increased from 116.0 to 122.7. There were no complications.

CONCLUSION

Even in this cohort of severe refractory RP, there was an improvement in bleeding and endoscopic grade with Purastat. A randomised controlled trial is planned.

An anti-inflammatory gelatin hemostatic agent with biodegradable polyurethane nanoparticles for vulnerable brain tissue

Hemostasis plays a fundamental and critical role in all surgical procedures. However, the currently used topical hemostatic agents may at times undesirably induce inflammation, infection, and foreign body reaction and hamper the healing process. This may be serious in the central nervous system (CNS), especially for some neurosurgical diseases which have ongoing inflammation causing secondary brain injury. This study was aimed to develop a hemostatic agent with anti-inflammatory property by incorporating carboxyl-functionalized biodegradable polyurethane nanoparticles (PU NPs) and to evaluate its functionality using a rat neurosurgical model. PU NPs are specially-designed anti-inflammatory nanoparticles and absorbed by a commercially available hemostatic gelatin powder (Spongostan™). Then, the gelatin was implanted to the injured rat cortex and released anti-inflammatory PU NPs. The time to hemostasis, the cerebral edema formation, and the brain's immune responses were examined. The outcomes showed that PU NP-contained gelatin attenuated the brain edema, suppressed the gene expression levels of pro-inflammatory M1 biomarkers (e.g., IL-1β level to be about 25%), elevated the gene expression levels of anti-inflammatory M2 biomarkers (e.g., IL-10 level to be about 220%), and reduced the activation of inflammatory cells in the implanted site, compared with the conventional gelatin. Moreover, PU NP-contained gelatin increased the gene expression level of neurotrophic factor BDNF by nearly 3-folds. We concluded that the PU NP-contained hemostatic agents are anti-inflammatory with neuroprotective potential in vivo. This new hemostatic agent will be useful for surgery involving vulnerable tissue or organ (e.g., CNS) and also for diseases such as stroke, traumatic brain injury, and neurodegenerative diseases.

Bioinspired Non-Immunogenic Multifunctional Sealant for Efficient Blood Clotting and Suture-Free Wound Closure

Engineering bioinspired peptide-based molecular medicine is an emerging paradigm for the management of traumatic coagulopathies and inherent bleeding disorder. A hemostat-based strategy in managing uncontrolled bleeding is limited due to the lack of adequate efficacy and clinical noncompliance. In this study, we report an engineered adhesive peptide-based hybrid regenerative medicine, sealant 5, which is designed integrating the structural and functional features of fibrin and mussel foot-pad protein. AFM studies have revealed that sealant 5 (55.8 ± 6.8 nN adhesive force) has higher adhesive force than fibrin (46.4 ± 7.3 nN adhesive force). SEM data confirms that sealant 5 retains its network-like morphology both at 37 and 60 °C, inferring its thermal stability. Both sealant 5 and fibrin exhibit biodegradability in the presence of trypsin, and sealant 5 also showed biocompatibility in the presence of fibroblast cells. Engineered sealant 5 efficiently promotes hemostasis with enhanced adhesiveness and less blood-loss than fibrin. In vivo data suggests that in heparinized conditions, sealant 5 ceases bleeding at 212.3 ± 15.1 s, whereas fibrin halts bleeding at 294.3 ± 21.4 s and blood-loss is ∼4-fold less in sealant 5 than in fibrin. In a heparinized system, sealant 5 facilitates faster blood-clotting than fibrin (∼82 s faster) and RADA-16, a reported peptide-based sealant (∼113 s faster). Additionally, in the case of sealant 5, the process of clotting mimicry-like fibrin is independent of the body's own coagulation system. Sealant 5 efficiently halts bleeding for both external and internal wounds, even for a heparinized system overcoming the bacterial infection. ELISA data and PMBC cell proliferation data support the non-immunogenic feature of sealant 5. Though fibrin and sealant 5 have exhibited comparable efficacy in suture-free wound closure, in vivo H&E staining images have revealed infiltration of very few immune cells as well as the presence of abundant collagen formation in the case of sealant 5-treated wound. Such nature-inspired non-immunogenic sealants offer exciting possibilities for the treatment of uncontrolled bleeding vis-à-vis wound closure.

On the analysis of microrheological responses of self-assembling RADA16-I peptide hydrogel

This work aims to obtain a hydrogel based on self-assembling RADA16-I with proper rheological properties for hemostasis application. Response surface methodology (RSM) was performed to predict the gelation and stiffness of the hydrogel in different concentrations of peptide and NaCl in water and blood serum milieus. Particle tracking microrheology technique was used to evaluate Brownian motion of polystyrene particles in the peptide solutions to obtain their trajectories and measure the viscoelastic properties (G'', G″, and tan δ). Formation of gel was influenced by the concentrations of peptide and salt and their interactions. Optimum response for maximizing elastic modulus was obtained in the presence of blood serum in comparison with water. Negative effect of excess amount of NaCl was predicted by RSM model and confirmed by animal study. Circular dichroism (CD) analysis showed formation of β-sheet secondary structure in water. On the other hand, in the presence of blood serum, tertiary structure was formed. Dimensional characterization of peptide fibers was performed by means of AFM. Peptide self-assembly in blood serum (pH around 7) which contains different ions, led to enhancing bonds between fibers, caused increasing the fiber diameter and length by 20 and 10 times, respectively. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 330-338, 2019.

Engineered isopeptide bond stabilized fibrin inspired nanoscale peptide based sealants for efficient blood clotting

Designing biologically inspired nanoscale molecular assembly with desired functionality is a challenging endeavour. Here we report the designing of fibrin-inspired nanostructured peptide based sealants which facilitate remarkably fast entrapping of blood corpuscles (~28 seconds) in contrast to fibrin (~56 seconds). Our engineered sealants are stabilized by lysine-aspartate ionic interactions and also by N^ε(γ-glutamyl) lysine isopeptide bond mediated covalent interaction. Each sealant is formed by two peptides having complementary charges to promote lysine-aspartate ionic interactions and designed isopeptide bond mediated interactions. Computational analysis reveals the isopeptide bond mediated energetically favourable peptide assemblies in sealants 1–3. Our designed sealants 2 and 3 mimic fibrin-mediated clot formation mechanism in presence of transglutaminase enzyme and blood corpuscles. These fibrin-inspired peptides assemble to form sealants having superior hemostatic activities than fibrin. Designed sealants feature mechanical properties, biocompatibility, biodegradability and high adhesive strength. Such nature-inspired robust sealants might be potentially translated into clinics for facilitating efficient blood clotting to handle traumatic coagulopathy and impaired blood clotting.

Nano-hemostats and a Pilot Study of Their Use in a Large Animal Model of Major Vessel Hemorrhage in Endoscopic Skull Base Surgery

Nano-hemostats are synthetic amino acid chains that self-assemble into a scaffold under certain conditions. These have been shown to be effective in stopping bleeding in small animal models of hemorrhage. Proposed mechanisms for their effect are that they form a mesh analogous to the fibrin plug in native hemostasis and that they may potentiate both platelet activation and the coagulation cascade. These may potentially become valuable adjuncts to endoscopic skull base surgery where there is the potential for both major vessel injury and smaller perforator injury to eloquent areas where bipolar cautery may not be suitable. We present a summary of the clinical studies to date and a small pilot study of nano-hemostat in an endoscopic sheep model of major vessel hemorrhage to determine its efficacy in stopping bleeding in this potentially catastrophic complication.

Clotting Mimicry from Robust Hemostatic Bandages Based on Self-Assembling Peptides

Uncontrolled bleeding from traumatic wounds is a major factor in deaths resulting from military conflict, accidents, disasters and crime. Self-assembling peptide nanofibers have shown superior hemostatic activity, and herein, we elucidate their mechanism by visualizing the formation of nanofiber-based clots that aggregate blood components with a similar morphology to fibrin-based clots. Furthermore, to enhance its direct application to a wound, we developed layer-by-layer assembled thin film coatings onto common materials used for wound dressings-gauze and gelatin sponges. We find these nanofibers elute upon hydration under physiological conditions and generate nanofiber-based clots with blood. After exposure to a range of harsh temperature conditions (-80 to 60 °C) for a week and even 5 months at 60 °C, these hemostatic bandages remain capable of releasing active nanofibers. In addition, the application of these nanofiber-based films from gauze bandages was found to accelerate hemostasis in porcine skin wounds as compared to plain gauze. The thermal robustness, in combination with the self-assembling peptide's potent hemostatic activity, biocompatibility, biodegradability, and low cost of production, makes this a promising approach for a cheap yet effective hemostatic bandage.

A nanostructured synthetic collagen mimic for hemostasis

Collagen is a major component of the extracellular matrix and plays a wide variety of important roles in blood clotting, healing, and tissue remodeling. Natural, animal derived, collagen is used in many clinical applications but concerns exist with respect to its role in inflammation, batch-to-batch variability, and possible disease transfection. Therefore, development of synthetic nanomaterials that can mimic the nanostructure and properties of natural collagen has been a heavily pursued goal in biomaterials. Previously, we reported on the design and multihierarchial self-assembly of a 36 amino acid collagen mimetic peptide (KOD) that forms nanofibrous triple helices that entangle to form a hydrogel. In this report, we utilize this nanofiber forming collagen mimetic peptide as a synthetic biomimetic matrix useful in thrombosis. We demonstrate that nanofibrous KOD synthetic collagen matrices adhere platelets, activate them (indicated by soluble P-selectin secretion), and clot plasma and blood similar to animal derived collagen and control surfaces. In addition to the thrombotic potential, THP-1 monocytes incubated with our KOD collagen mimetic showed minimal proinflammatory cytokine (TNF-α or IL-1β) production. Together, the data presented demonstrates the potential of a novel synthetic collagen mimetic as a hemostat.

Generation of Chimeric "ABS Nanohemostat" Complex and Comparing Its Histomorphological In Vivo Effects to the Traditional Ankaferd Hemostat in Controlled Experimental Partial Nephrectomy Model

Purpose. Using the classical Ankaferd Blood Stopper (ABS) solution to create active hemostasis during partial nephrectomy (PN) may not be so effective due to insufficient contact surface between the ABS hemostatic liquid agent and the bleeding area. In order to broaden the contact surface, we generated a chimeric hemostatic agent, ABS nanohemostat, via combining a self-assembling peptide amphiphile molecule with the traditional Ankaferd hemostat. Materials and Methods. In order to generate ABS nanohemostat, a positively charged Peptide Amphiphile (PA) molecule was synthesized by using solid phase peptide synthesis. For animal experiments, 24 Wistar rats were divided into the following 4 groups: Group 1: control; Group 2: conventional PN with only 0.5 ml Ankaferd hemostat; Group 3: conventional PN with ABS + peptide gel; Group 4: conventional PN with only 0.5 ml peptide solution. Results. Mean warm ischemia times (WITs) were 232.8  ±  56.3, 65.6 ± 11.4, 75.5 ± 17.2, and 58.1 ± 17.6 seconds in Group 1 to Group 4, respectively. Fibrosis was not different among the groups, while inflammation was detected to be significantly different in G3 and G4. Conclusions. ABS nanohemostat has comparable hemostatic efficacy to the traditional Ankaferd hemostat in the partial nephrectomy experimental model. Elucidation of the cellular and tissue effects of this chimeric compound may establish a catalytic spark and open new avenues for novel experimental and clinical studies in the battlefield of hemostasis.

Initial evaluation of a nano-engineered hemostatic agent in a severe vascular and organ hemorrhage swine model

OBJECTIVES

An advanced hemostatic dressing, Rapid Trauma Hemostat (RTH), was developed using nano-engineered inorganic nanofibers with hemostatic surface properties.

METHODS

Yorkshire swine were treated with RTH or Combat Gauze (CBG) to stop bleeding from either an arterial puncture (G-RTH and G-CBG) or a liver lobe laceration (L-RTH and L-CBG). All animals received 500 mL of Hextend at 10 minutes after injury and were monitored for a total time of 180 minutes.

RESULTS

Uncontrolled hemorrhage was similar in all animals in both models and was immediately controlled with the application of either dressing. After blood pressure was restored with fluid resuscitation, the RTH hemostatic treatment was less effective than CBG in the groin (puncture) model (rebleeding incidence, four of seven for G-RTH vs. one of seven for G-CBG; p = 0.034) but showed similar efficacy in the liver injury model (lower pressure bleeding). Interestingly, RTH exhibited a trend for higher efficacy in terms of hemostatic plug formation at the end of the experiment (no bleeding occurred after dressing removal) in the liver injury model.

CONCLUSION

Overall, RTH was not as effective at stopping high-shear rate (arterial) bleeding, but it presented some advantages for intracavitary treatment with potential for long-term evacuation.