In Vitro Evaluation of Real-Time Viscoelastic and Coagulation Properties of Various Classes of Topical Hemostatic Agents Using a Novel Contactless Nondestructive Technology

Tuning chitosan properties to enhance blood coagulation

The search for new hemostatic materials remains a priority for researchers, as the problem of uncontrolled hemorrhage during surgical interventions or traumatic injuries represents a significant challenge. The objective of the study was to identify novel polysaccharide structures with enhanced hemostatic properties based on chitosan. The number of chitosan derivatives with two substituents was synthesized and characterized by 1H NMR, FTIR. One of these was a structural analogue of L-DOPA - N-(3,4-dihydroxybenzyl), while the other comprised fragments of different nature, including hydrophobic N-(4-(tetradecyloxy)benzyl), negatively charged groups N-(4-carboxybenzyl) and aminocaproic acid residue. The hemostatic potential of the novel compounds was evaluated in vitro/in vivo on human blood and in mouse model of tail bleeding. Solutions of chitosan derivatives showed the ability to aggregate with blood about 3-5 times higher than chitosan in a neutral saline medium (0.9 % NaCl) and slightly acidic conditions both when (Ca2+) was added and in the case of citrated blood. Chitosan derivatives demonstrated low toxicity (3T3, HepG2 and Huh7) and did not induce plasma coagulation or platelet aggregation at low concentrations. The novel compounds can be used to modify the surface of biomaterials in order to improve their hemostatic properties.

External Bleeding and Advanced Biomacromolecules for Hemostasis

Hemorrhage is a significant medical problem that has been an active area of research over the past few decades. The human body has a complex response to bleeding that leads to blood clot formation and hemostasis. Many biomaterials based on various biomacromolecules have been developed to either accelerate or improve the body's natural response to bleeding. This review examines the mechanisms of hemostasis, types of bleeding, and the in vitro or in vivo models and techniques used to study bleeding and hemostatic materials. It provides a detailed overview of the diverse hemostatic materials, including those that are highly absorbent, wet adhesives, and those that accelerate the biochemical cascade of blood clotting. These materials are currently marketed, under preclinical testing, or being researched. In exploring the latest advancements in hemostatic technologies, this paper highlights the potential of these materials to significantly improve bleeding control in clinical and emergency situations.

Novel Honeycomb Nanoclay Frameworks With Hemostatic and Antibacterial Properties

Our laboratory recently developed a new class of high surface area, honeycomb Nanoclay Microsphere Framework absorbents (NMFs) that prompt rapid hemostasis. In the present work, we propose a novel approach to develop antibacterial Topical Hemostatic Agents (THAs) by anchoring silver nanoparticles (AgNPs) onto NMFs. This combination was obtained by a chemical co-reduction approach, followed by freeze-processing, and was shown to ensure stability and on-site delivery of AgNPs, without altering the hemostatic properties of NMFs. Silver-loaded NMFs showed no change in their unique architecture and led to a 55% increase in clot strength, compared to standard control plasma or commercially available THA, and a significant decrease in mean fibrin fiber diameter. Silver nanoparticles were successfully released when solubilized and prevented the growth of both Pseudomonas aeruginosa and Staphylococcus aureus at concentrations of 22 and 30 ppm of silver released, respectively. Overall, cell mortality was between 9.1 ± 5.1% and 6.3 ± 3.2%, depending on AgNP concentration, confirming a low cytotoxicity. Silver-loaded nanoclay microsphere frameworks appear to constitute promising candidates as topical hemostatic agents for secondary management of hemostasis when infection control is needed.

Polydopamine-Coated Silk Fiber with Controllable Length for Enhanced Hemostatic Application

The development of highly effective hemostatic materials with high biocompatibility and outstanding performance is vital to the field of biomaterials. In this study, we develop a hemostatic fiber material that exhibits high biocompatibility and excellent performance. By incorporating polydopamine (PDA) into the alkaline treatment of silk fibroin (SF), we achieve PDA-coated SF fibers with lengths that can be controlled by the alkaline concentration. The PDA coating significantly enhances the hemostatic ability of the silk fibers and exhibits superior performance in both in vitro and ex vivo experiments. By performing animal studies involving a mouse liver puncture model and a femoral vein incision model, we demonstrate the remarkable hemostatic capability of the PDA-coated SF fibers, as evidenced by the lower blood loss compared to that of a commercial hemostat powder. These findings highlight the potential of applying a PDA-assisted alkaline treatment to SF fibers to efficiently create hemostatic fibers with controllable lengths, which would be promising candidates for clinical hemostatic applications.

Hemostatic Powder vs Standard Endoscopic Treatment for Gastrointestinal Tumor Bleeding: A Multicenter Randomized Trial

BACKGROUND & AIMS

Current guidelines vary as to their recommendations addressing the role of hemostatic powders when managing patients with malignant gastrointestinal (GI) bleeding because these are based on very-low- to low-quality evidence, in large part due to a paucity of randomized trial data.

METHODS

This was a patient- and outcome assessor-blinded, multicenter, randomized controlled trial. Patients presenting with active bleeding from an upper or lower GI lesion suspected to be malignant at index endoscopy between June 2019 and January 2022 were randomly allocated to receive either TC-325 alone or standard endoscopic treatment (SET). The primary outcome was 30-day rebleeding, and secondary objectives included immediate hemostasis and other clinically relevant endpoints.

RESULTS

Overall, 106 patients made up the study population (55 TC-325 and 51 SET, after 1 exclusion in the TC-325 group and 5 in the SET group). Baseline characteristics and endoscopic findings did not differ between the groups. Thirty-day rebleeding was significantly lower in the TC-325 (2.1% TC-325 vs 21.3% SET; odds ratio, 0.09; 95% confidence interval [CI], 0.01-0.80; P = .003). Immediate hemostasis rates were 100% in the TC-325 group vs 68.6% in the SET group (odds ratio, 1.45; 95% CI, 0.93-2.29; P < .001). Other secondary outcomes did not differ between the 2 groups. Independent predictors of 6-month survival included the Charlson comorbidity index (hazard ratio, 1.17; 95% CI, 1.05-1.32; P = .007) and receiving an additional nonendoscopic hemostatic or oncologic treatment during 30 days after the index endoscopy (hazard ratio, 0.16; 95% CI, 0.06-0.43; P < .001) after adjustment for functional status, Glasgow-Blatchford score, and an upper GI source of bleeding.

CONCLUSION

The TC-325 hemostatic powder results in greater immediate hemostasis rates followed by lower 30-day rebleeding rates when compared to contemporary SET. (ClinicalTrials.gov, Number: NCT03855904).

Effect of Fibrillization pH on Gelation Viscoelasticity and Properties of Biofabricated Dense Collagen Matrices via Gel Aspiration-Ejection

Reconstituted hydrogels based on the self-assembly of acid-solubilized collagen molecules have been extensively used as in vitro models and precursors in biofabrication processes. This study investigated the effect of fibrillization pH-ranging from 4 to 11-on real-time rheological property changes during the gelation of collagen hydrogels and its interplay with the properties of subsequently biofabricated dense collagen matrices generated via automated gel aspiration-ejection (GAE). A contactless, nondestructive technique was used to characterize the temporal progression in shear storage modulus (G', or stiffness) during collagen gelation. There was a relative increase in G' of the hydrogels from 36 to 900 Pa with an increase in gelation pH. Automated GAE, which simultaneously imparts collagen fibrillar compaction and alignment, was then applied to these precursor collagen hydrogels to biofabricate native extracellular matrix-like densified gels. In line with viscoelastic properties, only hydrogels fibrillized in the 6.5 < pH ≤ 10 range could be densified via GAE. There was an increase in both fibrillar density and alignment in the GAE-derived matrices with an increase in gelation pH. These factors, combined with a higher G' in the alkaline precursor hydrogels, led to a significant increase in the micro-compressive modulus of GAE-densified gels of pH 9 and 10. Furthermore, NIH/3T3 fibroblast-seeded GAE-derived matrices densified from gels fibrillized in the pH range of 7 to 10 exhibited low cell mortality with >80% viability. It is anticipated that the results of this study can be potentially applicable to other hydrogel systems, as well as biofabrication techniques involving needles or nozzles, such as injection and bioprinting.