Alginate-calcium microsphere loaded with thrombin: A new composite biomaterial for hemostatic embolization

Recent progress in polysaccharide microsphere-based hemostatic material for intravascular and extravascular hemostasis: A review

Hemorrhage, a common consequence of diseases, surgical procedures, and traffic accidents, poses a significant threat to public health. Effective hemostasis is crucial for patient survival and prognosis, particular in case of internal bleeding. While polysaccharide microsphere-based hemostatic materials have gained clinical acceptance due to their effectiveness, good biocompatibility, and versatility in both intravascular and extravascular hemostasis, they are limited by their single function and insufficient hemostatic properties. Recently, booming developments have been witnessed in microsphere-based biomaterials to achieve a combination therapy for hemostasis. This review first examines the fundamentals of coagulation process, hemostatic mechanisms, and microsphere fabrication techniques. We then discuss the latest investigations in functionalized microsphere-based hemostatic materials for controlling intravascular and extravascular hemorrhage, focusing on design strategies, hemostatic properties, and clinical implementation. Finally, we also propose some limitations and challenges of these hemostatic materials, aiming to provide valuable insights for future research in novel polysaccharide microsphere-based biomaterial.

Animal models of hemorrhage, parameters, and development of hemostatic methods

Hemorrhage is a prevalent side effect of various injuries and can be life-threatening in certain instances. It is categorized into compressible and non-compressible types, each necessitating distinct modeling, laboratory assessments, and hemostatic approaches. This study utilized the keywords Hemorrhage, Bleeding, Animal Modeling, and Hemostat in reputable databases. The findings indicate that femoral artery hemorrhage and hepatic parenchymal hemorrhage are the predominant modeling techniques for compressible and non-compressible bleeding, respectively. Furthermore, it is noted that animal models of compressible hemorrhages are primarily situated in superficial body areas to investigate dressing or additive hemostats, while non-compressible hemorrhage models, typically located in visceral organs, are employed to examine adhesive or surgical instrument-based hemostats.

Preparation and Biochemical Activity of Copper-Coated Cellulose Nonwoven Fabric via Magnetron Sputtering and Alginate-Calcium Ion Complexation

Alginate-based materials have gained significant recognition in the medical industry due to their favorable biochemical properties. As a continuation of our previous studies, we have introduced a new composite consisting of cellulose nonwoven fabric charged with a metallic copper core (CNW-Cu0) covered with a calcium alginate (ALG-Ca2+) layer. The preparation process for these materials involved three main steps: coating the cellulose nonwoven fabric with copper via magnetron sputtering (CNW → CNW-Cu0), subsequent deposition with sodium alginate (CNW-Cu0 → CNW-Cu0/ALG-Na+), followed by cross-linking the alginate chains with calcium ions (CNW-Cu0/ALG-Na+ → CNW-Cu0/ALG-Ca2+). The primary objective of the work was to supply these composites with such biological attributes as antibacterial and hemostatic activity. Namely, equipping the antibacterial materials (copper action on representative Gram-positive and Gram-negative bacteria and fungal strains) with induction of blood plasma clotting processes (activated partial thromboplastin time (aPTT) and prothrombin time (PT)). We determined the effect of CNW-Cu0/ALG-Ca2+ materials on the viability of Peripheral blood mononuclear (PBM) cells. Moreover, we studied the interactions of CNW-Cu0/ALG-Ca2+ materials with DNA using the relaxation plasmid assay. However, results showed CNW-Cu0/ALG-Ca2+'s cytotoxic properties against PBM cells in a time-dependent manner. Furthermore, the CNW-Cu0/ALG-Ca2+ composite exhibited the potential to interact directly with DNA. The results demonstrated that the CNW-Cu0/ALG-Ca2+ composites synthesized show promising potential for wound dressing applications.

Immobilized Drugs on Dual-Mode Imaging Ag2S/BaSO4/PVA Embolic Microspheres for Precise Localization, Rapid Embolization, and Local Antitumor Therapy

Transcatheter arterial embolization (TAE) in interventional therapy and tumor embolism therapy plays a significant role. The choice of embolic materials that have good biocompatibility is an essential component of TAE. For this study, we produced a multifunctional PVA embolization material that can simultaneously encapsulate Ag2S quantum dots (Ag2S QDs) and BaSO4 nanoparticles (BaSO4 NPs), exhibiting excellent second near-infrared window (NIR-II) fluorescence imaging and X-ray imaging, breaking through the limitations of traditional embolic microsphere X-ray imaging. To improve the therapeutic effectiveness against tumors, we doped the doxorubicin (DOX) antitumor drug into microspheres and combined it with a clotting peptide (RADA16-I) on the surface of microspheres. Thus, it not only embolizes rapidly during hemostasis but also continues to release and accelerate tumor necrosis. In addition, Ag2S/BaSO4/PVA microspheres (Ag2S/BaSO4/PVA Ms) exhibited good blood compatibility and biocompatibility, and the results of embolization experiments on renal arteries in rabbits revealed good embolic effects and bimodal imaging stability. Therefore, they could serve as a promising medication delivery embolic system and an efficient biomaterial for arterial embolization. Our research work achieves the applicability of NIR-II and X-ray dual-mode images for clinical embolization in biomedical imaging.

Comprehensive Assessment of Collagen/Sodium Alginate-Based Sponges as Hemostatic Dressings

In our search for a biocompatible composite hemostatic dressing, we focused on the design of a novel biomaterial composed of two natural biological components, collagen and sodium alginate (SA), cross-linked using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) and oxidized sodium alginate (OSA). We conducted a series of tests to evaluate the physicochemical properties, acute systemic toxicity, skin irritation, intradermal reaction, sensitization, cytotoxicity, and in vivo femoral artery hemorrhage model. The results demonstrated the excellent biocompatibility of the collagen/sodium alginate (C/SA)-based dressings before and after crosslinking. Specifically, the femoral artery hemorrhage model revealed a significantly shortened hemostasis time of 132.5 ± 12.82 s for the EDC/NHS cross-linked dressings compared to the gauze in the blank group (hemostasis time of 251.43 ± 10.69 s). These findings indicated that C/SA-based dressings exhibited both good biocompatibility and a significant hemostatic effect, making them suitable for biomedical applications.

Multi-functional dual-layer nanofibrous membrane for prevention of postoperative pancreatic leakage

Postoperative pancreatic leakage due to pancreatitis in patients is a life-threatening surgical complication. The majority of commercial barriers are unable to meet the demands for pancreatic leakage due to poor adhesiveness, toxicity, and inability to degrade. In this study, we fabricated mitomycin-c and thrombin-loaded multifunctional dual-layer nanofibrous membrane with a combination of alginate, PCL, and gelatin to resolve the leakage due to suture line disruption, promote hemostasis, wound healing, and prevent postoperative tissue adhesion. Electrospinning was used to fabricate the dual-layer system. The study results demonstrated that high gelatin and alginate content in the inner layer decreased the fiber diameter and water contact angle, and crosslinking allowed the membrane to be more hydrophilic, making it highly biodegradable, and adhering firmly to the tissue surfaces. The results of in vitro biocompatibility and hemostatic assay revealed that the dual-layer had a higher cell proliferation and showed effective hemostatic properties. Moreover, the in vivo studies and in silico molecular simulation indicated that the dual layer was covered at the wound site, prevented suture disruption and leakage, inhibited hemorrhage, and reduced postoperative tissue adhesion. Finally, the study results proved that dual-layer multifunctional nanofibrous membrane has a promising therapeutic potential in preventing postoperative pancreatic leakage.

Current research status and development prospects of embolic microspheres containing biological macromolecules and others

Transcatheter arterial embolization (TACE) has been used in the treatment of malignant tumors, sudden hemorrhage, uterine fibroids, and other diseases, and with advances in imaging techniques and devices, materials science, and drug release technology, more and more embolic agents that are drug-carrying, self-imaging, or have multiple functions are being developed. Microspheres provide safer and more effective therapeutic results as embolic agents, with their unique spherical appearance and good embolic properties. Embolic microspheres are the key to arterial embolization, blocking blood flow and nutrient supply to the tumor target. This review summarizes some of the currently published embolic microspheres, classifies embolic microspheres according to matrix, and summarizes the characteristics of the microsphere materials, the current status of research, directions, and the value of existing and potential applications. It provides a direction to promote the development of embolic microspheres towards multifunctionalization, and provides a reference to promote the research and application of embolic microspheres in the treatment of tumors.

Preparation, evaluation and application of MRI detectable sunitinib-loaded calcium alginate/poly(acrylic acid) hydrogel microspheres

Transcatheter arterial chemoembolization (TACE) is an effective method for the treatment of unresectable hepatocellular carcinoma. Although many embolic agents have been developed in TACE, there are few ideal embolic agents that combine drug loading, imaging properties and vessel embolization. Here, we developed novel magnetic embolic microspheres that could simultaneously load sunitinib malate (SU), be detected by magnetic resonance imaging (MRI) and block blood vessels. Calcium alginate/poly (acrylic acid) hydrogel microspheres (CA/PAA-MDMs) with superparamagnetic iron oxide nanoparticles (SPIONs) modified by citric acid were prepared by a drip and photopolymerization method. The embolization and imaging properties of CA/PAA-MDMs were evaluated through a series of experiments such as morphology, X-ray diffraction and X-ray photoelectron spectroscopy, magnetic responsiveness analysis, elasticity, cytotoxicity, hemolysis test, in vitro MRI evaluation, rabbit ear embolization and histopathology. In addition, the ability of drug loading and drug release of CA/PAA-MDMs were investigated by using sunitinib (SU) as the model drug. In conclusion, CA/PAA-MDMs showed outstanding drug loading capability, excellent imaging property and embolization effect, which would be expected to be used as a potential biodegradable embolic agent in the clinical interventional therapy.

Alginate based biomaterials for hemostatic applications: Innovations and developments

Development of the efficient hemostatic materials is an essential requirement for the management of hemorrhage caused by the emergency situations to avert most of the casualties. Such injuries require the use of external hemostats to facilitate the immediate blood clotting. A variety of commercially available hemostats are present in the market but most of them are associated with limitations such as exothermic reactions, low biocompatibility, and painful removal. Thus, fabrication of an ideal hemostatic composition for rapid blood clot formation, biocompatibility, and antimicrobial nature presents a real challenge to the bioengineers. Benefiting from their tunable fabrication properties, alginate-based hemostats are gaining importance due to their excellent biocompatibility, with >85 % cell viability, high absorption capacity exceeding 500 %, and cost-effectiveness. Furthermore, studies have estimated that wounds treated with sodium alginate exhibited a blood loss of 0.40 ± 0.05 mL, compared to the control group with 1.15 ± 0.13 mL, indicating its inherent hemostatic activity. This serves as a solid foundation for designing future hemostatic materials. Nevertheless, various combinations have been explored to further enhance the hemostatic potential of sodium alginate. In this review, we have discussed the possible role of alginate based composite hemostats incorporated with different hemostatic agents, such as inorganic materials, polymers, biological agents, herbal agents, and synthetic drugs. This article outlines the challenges which need to be addressed before the clinical trials and give an overview of the future research directions.

Indirect co-culture of osteoblasts and endothelial cells in vitro based on a biomimetic 3D composite hydrogel scaffold to promote the proliferation and differentiation of osteoblasts

The field of orthopedics has long struggled with the challenge of repairing and regenerating bone defects, which involves a complex process of osteogenesis requiring coordinated interactions among different types of cells. The crucial role of endothelial cells and osteoblasts in bone vascularization and osteogenesis underscores the importance of their intimate interaction. However, efforts to bioengineer bone tissue have been impeded by the difficulty in establishing proper angiogenesis and osteogenesis in tissue structures. This study presents a novel approach to bone tissue engineering, involving a three-dimensional composite hydrogel scaffold composed of sodium alginate microspheres encapsulated in type I collagen. Using this scaffold, a three-dimensional indirect co-culture system was established for osteoblasts and endothelial cells to evaluate the osteogenic differentiation potential of osteoblasts. Results demonstrate that the non-contact co-culture system of endothelial cells and osteoblasts constructed by the composite hydrogel scaffold loaded with microspheres holds promise for bone tissue engineering. The innovative concept of an indirect co-culture system presents exciting prospects for conducting intercellular communication studies and offers a valuable in vitro tissue platform to investigate tissue regeneration.

Preparation and application of hemostatic microspheres containing biological macromolecules and others

Bleeding from uncontrollable wounds can be fatal, and the body's clotting mechanisms are unable to control bleeding in a timely and effective manner in emergencies such as battlefields and traffic accidents. For irregular and inaccessible wounds, hemostatic materials are needed to intervene to stop bleeding. Hemostatic microspheres are promising for hemostasis, as their unique structural features can promote coagulation. There is a wide choice of materials for the preparation of microspheres, and the modification of natural macromolecular materials such as chitosan to enhance the hemostatic properties and make up for the deficiencies of synthetic macromolecular materials makes the hemostatic microspheres multifunctional and expands the application fields of hemostatic microspheres. Here, we focus on the hemostatic mechanism of different materials and the preparation methods of microspheres, and introduce the modification methods, related properties and applications (in cancer therapy) for the structural characteristics of hemostatic microspheres. Finally, we discuss the future trends of hemostatic microspheres and research opportunities for developing the next generation of hemostatic microsphere materials.

Preparation of thrombin-loaded calcium alginate microspheres with dual-mode imaging and study on their embolic properties in vivo

Transcatheter arterial embolization (TAE) has played a huge role in the interventional treatment of organ bleeding and accidental bleeding. Choosing bio-embolization materials with good biocompatibility is an important part of TAE. In this work, we prepared a calcium alginate embolic microsphere using high-voltage electrostatic droplet technology. The microsphere simultaneously encapsulated silver sulfide quantum dots (Ag2S QDs) and barium sulfate (BaSO4), and fixed thrombin on its surface. Thrombin can achieve an embolic effect while stopping bleeding. The embolic microsphere has good near-infrared two-zone (NIR-II) imaging and X-ray imaging effects, and the luminous effect of NIR-II is better than that of X-rays. This breaks the limitations of traditional embolic microspheres that only have X-ray imaging. And the microspheres have good biocompatibility and blood compatibility. Preliminary application results show that the microspheres can achieve a good embolization effect in the ear arteries of New Zealand white rabbits, and can be used as an effective material for arterial embolization and hemostasis. This work realizes the clinical embolization application of NIR-II combined with X-ray multimodal imaging technology in biomedical imaging, achieving complementary advantages and excellent results, more suitable for studying biological changes and clinical applications.

Armoring a liposome-integrated tissue factor with sacrificial CaCO3 to form potent self-propelled hemostats

The development of hemostatic materials suitable for diverse emergency scenarios is of paramount significance, and there is growing interest in wound-site delivery of hemostasis-enhancing agents that can leverage the body's inherent mechanisms. Herein we report the design and performance of a biomimetic nanoparticle system enclosing tissue factor (TF), the most potent known blood coagulation trigger, which was reconstituted into liposomes and shielded by the liposome-templated CaCO₃ mineralization. The mineral coatings, which mainly comprised water-soluble amorphous and vateritic phases, synergized with the lipidated TF to improve blood coagulation in vitro. These coatings served as sacrificial masks capable of releasing Ca²⁺ coagulation factors or propelling the TF-liposomes via acid-aided generation of CO₂ bubbles while endowing them with high thermostability under dry conditions. In comparison to commercially available hemostatic particles, CaCO₃ mineralized TF-liposomes yielded significantly shorter hemostasis times and less blood loss in vivo. When mixed with organic acids, the CO₂-generating formulation further improved hemostasis by delivering TF-liposomes deep into actively bleeding wounds with good biocompatibility, as observed in a rat hepatic injury model. Therefore, the designed composite mimicry of coagulatory components exhibited strong hemostatic efficacy, which in combination with the propulsion mechanism would serve as a versatile approach to treating a variety of severe hemorrhages.

All-Aqueous Microfluidics Fabrication of Multifunctional Bioactive Microcapsules Promotes Wound Healing

Wound healing involves multiple stages of body responses, including hemostasis, inflammation, cell proliferation, and tissue remodeling. New material design satisfying all demands throughout different stages of wound healing is cherished but rarely discussed. Here we introduce all-aqueous multiphase microfluidics as a novel strategy to fabricate self-assembled, multifunctional alkylated chitosan/alginate microcapsules (SAAMs) as novel therapeutic materials for rapid blood coagulation and wound healing. SAAMs are structurally distinguished by their ultrathin shells with polycationic surface for rapid activation of clotting cascade and their internal porous dextran-rich cores for fast absorption of blood and exudate. These features endow SAAMs with excellent hemostatic properties for acute hemorrhage. Moreover, the alkylated chitosan within the microcapsules exhibits persistent antimicrobial activities against bactericidal infections due to their amphiphilic and cationic surfaces. Besides, cytokines can be safely loaded into the organic-solvent-free microcapsules and released precisely to promote the proliferation of epidermal cells, supporting the subsequent development of granulation tissue and suppression of inflammation in the last stages of wound healing. With the ability to fabricate size-tailored soft microcapsules and to realize time-sequential functions for tissue repairing, the presented "all-aqueous microfluidics generation of multifunctional bioactive SAAMs" create a versatile and robust paradigm for wound treatment.

John J, Khademhosseini A. Recent advances in biopolymer-based hemostatic materials

Hemorrhage is the leading cause of trauma-related deaths, in hospital and prehospital settings. Hemostasis is a complex mechanism that involves a cascade of clotting factors and proteins that result in the formation of a strong clot. In certain surgical and emergency situations, hemostatic agents are needed to achieve faster blood coagulation to prevent the patient from experiencing a severe hemorrhagic shock. Therefore, it is critical to consider appropriate materials and designs for hemostatic agents. Many materials have been fabricated as hemostatic agents, including synthetic and naturally derived polymers. Compared to synthetic polymers, natural polymers or biopolymers, which include polysaccharides and polypeptides, have greater biocompatibility, biodegradability and processibility. Thus, in this review, we focus on biopolymer-based hemostatic agents of different forms, such as powder, particles, sponges and hydrogels. Finally, we discuss biopolymer-based hemostatic materials currently in clinical trials and offer insight into next-generation hemostats for clinical translation.

Berberine coated biocomposite hemostatic film based alginate as absorbable biomaterial for wound healing

In wound treatment, severe bleeding and infection are always primary challenges. Therefore, it is highly desired to develop novel dressing with both hemostatic and antibacterial capability. Herein, a series of biocomposite hemostatic films (BHFs) based alginate/chitosan/collagen-berberine have been prepared and well characterized for further biofunctional study. We have demonstrated that the hemostatic and antibacterial activities were significantly enhanced by calcium/berberine dual-crosslinking system in the film. Through the synergistic effects, BHF-6B exhibited a shorter in vivo clotting and wound healing time than that of commercial dressing in rat tail amputation and full-thickness skin defect models. Additionally, BHF-6B showed excellent bacteriostatic activity with long-term effects. Moreover, hemolysis and cytotoxicity tests in vitro illustrated the prominent biocompatibility of the composite films. Notably, BHF-6B could be degraded quickly and completely in vivo. Overall, the present work indicated that the functionalized BHF-6B has great potential as an absorbable biomaterial for wound treatment.

Application of Alginate-Based Hydrogels in Hemostasis

Hemorrhage, as a common trauma injury and clinical postoperative complication, may cause serious damage to the body, especially for patients with huge blood loss and coagulation dysfunction. Timely and effective hemostasis and avoidance of bleeding are of great significance for reducing body damage and improving the survival rate and quality of life of patients. Alginate is considered to be an excellent hemostatic polymer-based biomaterial due to its excellent biocompatibility, biodegradability, non-toxicity, non-immunogenicity, easy gelation and easy availability. In recent years, alginate hydrogels have been more and more widely used in the medical field, and a series of hemostatic related products have been developed such as medical dressings, hemostatic needles, transcatheter interventional embolization preparations, microneedles, injectable hydrogels, and hemostatic powders. The development and application prospects are extremely broad. This manuscript reviews the structure, properties and history of alginate, as well as the research progress of alginate hydrogels in clinical applications related to hemostasis. This review also discusses the current limitations and possible future development prospects of alginate hydrogels in hemostatic applications.

Recent Advances on Synthetic and Polysaccharide Adhesives for Biological Hemostatic Applications

Rapid hemostasis and formation of stable blood clots are very important to prevent massive blood loss from the excessive bleeding for living body, but their own clotting process cannot be completed in time for effective hemostasis without the help of hemostatic materials. In general, traditionally suturing and stapling techniques for wound closure are prone to cause the additional damages to the tissues, activated inflammatory responses, short usage periods and inevitable second operations in clinical applications. Especially for the large wounds that require the urgent closure of fluids or gases, these conventional closure methods are far from enough. To address these problems, various tissue adhesives, sealants and hemostatic materials are placed great expectation. In this review, we focused on the development of two main categories of tissue adhesive materials: synthetic polymeric adhesives and naturally derived polysaccharide adhesives. Research of the high performance of hemostatic adhesives with strong adhesion, better biocompatibility, easy usability and cheap price is highly demanded for both scientists and clinicians, and this review is also intended to provide a comprehensive summarization and inspiration for pursuit of more advanced hemostatic adhesives for biological fields.

Alginate-based composite microspheres coated by berberine simultaneously improve hemostatic and antibacterial efficacy

It is important to develop effective, biocompatible, easily stored and affordable hemostats for controlling bleeding and preventing infection in prehospital trauma. In this study, we synthesized a series of alginate-based composite microspheres coated by different amounts of berberine (SCC-1B, SCC-5B and SCC-10B), which were further characterized using scanning electron microscopy (SEM), viscometer, particle analyzer and Fourier transform infrared (FT-IR) spectroscopy. The in vitro and vivo results demonstrated that compared to control group (SCC, Composite polysaccharide microspheres without berberine, and CMPHP, Commercial hemostatic agent), SCC-10B with proper content berberine (7%), not only exhibited inherent excellent antibacterial activity, but also enhanced hemostatic effect by increasing adhesion and aggregation of blood cells, which could be considered as synergistic effects. More importantly, through inserting berberine into the cross-linked network, biodegradability and biocompatibility of SCC-10B were also improved. Taken together, SCC-10B could be a candidate for emergency hemostatic and antibacterial treatment in prehospital trauma.

Polysaccharide-Based Lotus Seedpod Surface-Like Porous Microsphere with Precise and Controllable Micromorphology for Ultrarapid Hemostasis

Rapid water absorption rate has become a bottleneck that limits ultrarapid hemostatic performance of hemostatic microspheres. Herein, we reported a "lotus seedpod surface-like" polysaccharide hemostatic microsphere (PHM) with "macropits on surface" morphology and "micropores in macropits" structure. Unique macropits on surface can promote the water absorption rate because they are advantageous to quickly guide blood into the micropores. Special micropores are internally connected with each other, which endows PHM₄ with high water absorption ratio. During the process of blood entering the micropores from micropits, the pore size decreases gradually. In this way, blood clotting factors could be rapidly concentrated. PHM₄ showed the highest water absorption rate (40.7 mL/s/cm²) and rapid hemostatic property in vivo (hemostatic time shortened from 210 to 45 s). Lotus seedpod surface-like PHMs are believed to have further clinical application as an effective hemostasis.

Biocompatibility of a New Kind of Polyvinyl Alcohol Embolic Microspheres: In Vitro and In Vivo Evaluation

The aim of this study is to investigate the biocompatibility of polyvinyl alcohol (PVA) embolic microspheres by in vivo and in vitro evaluations. Two specifications of PVA microspheres including colorless microspheres (1 g microspheres with 7 mL 0.9% sodium chloride (SC) per vial, size: 500-700 µm) and blue microspheres (2 g microspheres with 7 mL 0.9% SC per vial, size: 500-700 µm) were assessed for biocompatibility. The vitro cytotoxicity was evaluated in L929 cells by MTT assay. Acute systemic toxicity and 28-repeat dose intravenous subchronic toxicity were assessed in 20 ICR mice and 40 SD rates, respectively. Skin sensitization was conducted in 30 adult albino guinea pigs by maximization test, in addition, intracutaneous reaction test was performed in New Zealand white rabbits. Hemolysis ratio of PVA microspheres was evaluated with rabbit blood. Moreover, test for genotoxicity was assessed by bacterial reverse mutation test and mouse lymphoma mutagenesis assay. No cytotoxicity, hemolysis, or acute toxicity of PVA microspheres was found, and slight fluctuations of biochemical indexes were observed in test of 28-day repeat dose intravenous subchronic toxicity, while these changes remained within our historical permitted range. Maximization test and intracutaneous reactivity test disclosed no irritation to skin or tissues. According to bacterial reverse mutation test and mouse lymphoma mutagenesis assay, no genotoxicity of PVA microspheres was observed. PVA microspheres showed excellent biocompatibility both in vivo and in vitro, and they were promising embolic materials for drug-eluting beads transarterial chemoembolization (DEB-TACE) therapy.

Sustainable Dual Release of Antibiotic and Growth Factor from pH-Responsive Uniform Alginate Composite Microparticles to Enhance Wound Healing

Hydrogel-based wound dressings provided a moist microenvironment and local release of bioactive molecules. Single drug loading along with fast release rates and usually in hydrogel sheets limited their performance. Hence, uniform alginate/CaCO₃ composite microparticles (∼430 μm) with tunable compositions for sustainable release of drug and pH-sensitivity were successfully fabricated using microfluidic technology. Due to the presence of CaCO₃ and the strong interactions with alginate molecules, lyophilized composite microparticles reverted to hydrogel state after rehydration. Regardless of microparticle states (hydrogel or lyophilized) and pH values (6.4 or 7.4), in vitro release rates of model drug were inversely related with CaCO₃ concentrations and much lower than that for pure alginate microparticles. The release rate at pH 6.4 (simulating wound microenvironment) was always slower than that at pH 7.4 for the same type of microparticles. Rifamycin and basic fibroblast growth factor (bFGF) were independently encapsulated into AD-5-R and AD-40-F to achieve a fast release of rifamycin and a slower, more sustained release of bFGF, respectively; CD-F-R was a mixture of AD-5-R and AD-40-F at weight ratio 1/1. For AD-5-R and CD-F-R, inhibition zones of S. aureus were observed until day 5, showing a sustained antibacterial property. On the basis of in vitro wound healing model of NIH-3T3 cell micropattern on glass coverslips with a hole array, it was found that AD-40-F and CD-F-R significantly promoted cell proliferation and migration rates. In a full-thickness skin wound model of rats, CD-F-R microparticles significantly accelerated wound healing with higher granulation tissue thickness and better bioactivity to stimulate angiogenesis than the control group. Furthermore, CD-F-R microparticles demonstrated a good biocompatibility and biodegradability in vivo. Taken together, CD-F-R composite microparticles may ideally meet the requirements for different stages during wound healing and demonstrated a good potential to be used as dressing materials.

In situ synthesis of poly (γ- glutamic acid)/alginate/AgNP composite microspheres with antibacterial and hemostatic properties

In the present work, a poly(γ-glutamic acid)/alginate/silver nanoparticle (PGA/Alg/AgNP) composite microsphere with excellent antibacterial and hemostatic properties was prepared by the in situ UV reduction and emulsion internal gelation method, and its potential application for antibacterial hemostatic dressing was explored. Well dispersed AgNPs were in situ synthesized by a UV reduction method with alginate as stabilizer and reductant. The AgNPs showed excellent antibacterial activities against both gram-negative and gram-positive bacteria. Additionally, the AgNPs prepared by the in-situ UV reduction exhibited better biocompatibility and antibacterial effects than those prepared by the conventional chemical reduction method. PGA/Alg/AgNP composite microspheres were then prepared with the AgNPs by an emulsion internal gelation method. Such microspheres were found to be a porous and hollow network with pH-sensitive swelling properties and excellent hemostatic performance, indicating its application potentials as an advanced antibacterial hemostatic material.

Lotus leaf-inspired design of calcium alginate particles with superhigh drug encapsulation efficiency and pH responsive release

Drug delivery systems with high drug encapsulation efficiency and controlled release are of great importance in biomedical fields. Herein, we report an ingenious approach inspired from the lotus leaf possessing the ability of strong repellency to water, which enables the rapid fabrication of drug-loaded calcium alginate (Ca-Alg) particles with high drug encapsulation efficiency and controlled drug delivery. The design is achieved by introducing aqueous droplets containing the mixture of dilute sodium alginate solution, dilute calcium chloride solution, and drug onto the superhydrophobic substrate. Due to water evaporation both the concentration of sodium alginate and calcium chloride within the droplets will gradually increase, and the ionic crosslinking reaction of sodium alginate with Ca²⁺ is further occurred to form the drug-embedded Ca-Alg hydrogel particles. The results indicate that the controllable fabrication of Ca-Alg particles can be easily achieved on the superhydrophobic surface, and the swelling behavior can be tuned by the pH of the buffer solution. Importantly, the drug encapsulation efficiencies are measured to be over 88% and the drug exhibits obvious pH responsive release. Findings from this study are expected to contribute to the rational design of drug delivery systems with high drug encapsulation efficiency and controlled release for pharmaceutic science and tissue engineering.

Rational design of temperature-sensitive blood-vessel-embolic nanogels for improving hypoxic tumor microenvironment after transcatheter arterial embolization

Transcatheter arterial embolization (TAE) plays an important role in clinical tumor therapy by accomplishing vessel-casting embolization of tumor arteries at all levels and suppressing tumor collateral circulation and vascular re-canalization. In this study, we describe smart blood-vessel-embolic nanogels for improving the anti-tumor efficacy of TAE therapy on hepatocellular carcinoma (HCC). Methods: In this study, an in vitro model composed of two microfluidic chips was used for simulating the tumor capillary network and analyzing artery-embolization properties. Also, blood-vessel-casting embolization of renal arteries was evaluated in normal rabbits. Using a VX2 tumor-bearing rabbit model, the therapeutic efficacy of TAE on HCC was investigated for tumor growth, necrosis, and proliferation. Neovascularization and collateral circulation were evaluated by immunofluorescent detection of hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), and CD31 following the TAE therapy of VX2 tumor-bearing rabbits. Results: Sufficient embolization of all eight levels of micro-channels was achieved in a tumor-vessel-mimetic model with two microfluidic chips using PIBI-2240, and was further confirmed in renal arteries of normal rabbit. Effective inhibition of tumor collateral circulation and vascular re-canalization was observed in VX2 tumor-bearing rabbits due to the reduced expression levels of HIF-1α, VEGF, and CD31. Conclusions: The exceptional anti-tumor effect of PIBI-2240 observed in this study suggested that it is an excellent blood-vessel-embolic material for tumor TAE therapy.

Coated electrospun alginate-containing fibers as novel delivery systems for regenerative purposes

Aim

The aim of the present work was to develop biodegradable alginate (ALG)-containing fibrous membranes intended for tissue repair, acting as both drug delivery systems and cell growth guidance.

Methods

Membranes were prepared by electrospinning. Since ALG can be electrospun only when blended with other spinnable polymers, dextran (DEX) and polyethylene oxide (PEO) were investigated as process adjuvants. ALG/DEX mixtures, characterized by different rheological and conductivity properties, were prepared in phosphate buffer or deionized water; surfactants were added to modulate polymer solution surface tension. The Design of Experiments (DoE) approach (full factorial design) was used to investigate the role of polymer solution features (rheological properties, surface tension, and conductivity) on electrospun fiber morphology. A high viscosity at 1,000 s^-1 (1.3-1.9 Pa.s) or a high pseudoplasticity index (≥1.7), combined with a low surface tension (30-32 mN/m) and a low conductivity (800-1,000 μS/cm), was responsible for the production of ALG/DEX homogeneous fibers. Such ranges were successfully employed for the preparation of ALG-containing fibers, using PEO, instead of DEX, as process adjuvant. ALG/DEX and ALG/PEO fibers were subsequently subjected to cross-linking/coating processes to make them slowly biodegradable in aqueous medium. In particular, ALG/PEO fibers were cross-linked and coated with CaCl₂/chitosan solutions in water/ethanol mixtures. Due to DEX high content, ALG/DEX fibers were soaked in a polylactide-co-glycolide (PLGA) solution in ethyl acetate.

Results

Both cross-linking and coating processes made fibers insoluble in physiological medium and produced an increase in their mechanical resistance, assessed by means of a tensile test. PLGA-coated ALG/DEX and chitosan-coated ALG/PEO fibers were biocompatible and able to support fibroblast adhesion.

Conclusion

The DoE approach allowed to draw up guidelines useful for the preparation of homogeneous fibers, starting from mixtures of ALG and non-ionic polymers. Such fibers, upon coating, resulted to be good cell substrates, allowing cell adhesion and growth.

Full realization of internal mammary artery injury after blunt chest trauma

Due to the substantial and continual increase in the number of motorized vehicles globally, clinicians are faced with an enormous population at risk for suffering internal mammary artery injuries after blunt chest trauma. Nevertheless, very little attention has been paid to this issue by relevant health practitioners. In addition, there is a scarcity of extant research data, as well as societal guidelines, regarding internal mammary artery injury. In cases with undetected internal mammary artery injury, however, the outcome may be catastrophic or fatal. Thus, investigating and reviewing the anatomy, etiology, diagnostic approaches, and treatment strategies for patients with internal mammary artery injury are urgently needed.

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.

Porous chitosan microspheres containing zinc ion for enhanced thrombosis and hemostasis

Quick hemostats for non-lethal massive traumatic bleeding in battlefield and civilian accidents are important for reducing mortality and medical costs. Chitosan (CS) has been widely used as a clinic hemostat. To enhance its hemostatic efficiency, Zn²⁺ in the form of zinc alginate (ZnAlg) was introduced to CS to make porous CS@ZnAlg microspheres with ZnAlg component on the surface. Such microspheres were prepared by successive steps of micro-emulsion, polyelectrolyte adhesion, and thermally induced phase separation. Their structure and hemostatic performance were analyzed by SEM, FT-IR, XPS and a series of in vitro hemostatic experiments including thromboelastography analysis. The composite microspheres had an outer and internal interconnected porous structure. Their size, surface area, and water absorption ratio were ca. 70μm, 48m²/g, and 1850%, respectively. Compared to the neat chitosan microspheres, the CS@ZnAlg microspheres showed shorter onset of clot formation, much faster in vitro and in vivo whole blood clotting, bigger clot, less blood loss, and shorter hemostatic time in the rat liver laceration and tail amputation models. The synergetic hemostatic effects from (1) the electrostatic attraction between chitosan component and red blood cells, (2) the activation of coagulation factor XII by Zn²⁺ of zinc alginate component, and (3) physical blocking by microsphere matrix, contributed to the enhanced hemostatic performance of CS@ZnAlg microspheres.

Biocompatibility and Effectiveness Evaluation of a New Hemostatic Embolization Agent: Thrombin Loaded Alginate Calcium Microsphere

Background. Until now, there has been no ideal embolization agent for hemorrhage in interventional treatment. In this study, the thrombin was encapsulated in alginate calcium microsphere using electrostatic droplet technique to produce new embolization agent: thrombin loaded alginate calcium microspheres (TACMs). Objectives. The present work was to evaluate the biocompatibility and hemostatic efficiency of TACMs. Methods. Cell cytotoxicity, hemolysis, and superselective embolization of dog liver arteries were performed to investigate the biocompatibility of TACMs. To clarify the embolic effect of TACMs mixed thrombus in vivo, hepatic artery injury animal model of 6 beagles was established and transcatheter artery embolization for bleeding was performed. Results. Coculture with VECs revealed the noncytotoxicity of TACMs, and the hemolysis experiment was negligible. Moreover, the histological study of TACMs in liver blood vessel showed signs of a slight inflammatory reaction. The results of transcatheter application of TACMs mixed thrombus for bleeding showed that the blood flow was shut down completely after the TACMs mixed thrombus was delivered and the postprocedural survival rate of animal models at 12 weeks was 100%. Conclusions. With their good biocompatibility and superior hemostatic efficiency, TACMs might be a promising new hemostatic agent with a wide range of potential applications.

Chitosan–PVA monodisperse millimeter-sized spheres prepared by electrospraying reduce the thromboembolic risk in hemorrhage control

Chitosan–PVA monodisperse millimeter-sized spheres are efficient in hemorrhage control and also reduce the risk of thromboembolic complication.

Design and development of polysaccharide hemostatic materials and their hemostatic mechanism

The formation of stable blood clots or hemostasis is essential to prevent major blood loss and death from excessive bleeding.

Microspheres of carboxymethyl chitosan, sodium alginate and collagen for a novel hemostatic in vitro study

To develop biocompatible composite microspheres for novel hemostatic use, we designed and prepared a novel biomaterial, composite microspheres consisting of carboxymethyl chitosan, sodium alginate, and collagen (CSCM). The ultra-structure of CSCM was investigated by scanning electron microscopy assay. In hemostatic function experiment, it was found that CSCM could facilitate platelet adherence, platelet aggregation, and platelet activation in vitro. Besides, the maximum swelling of CSCM submerged in PBS for 50 min was over 300% of that exhibited by commercial hemostatic compound microporous polysaccharide haemostatic powder (CMPHP). In addition, CSCM exhibited good biodegradability and non-cytotoxicity. These results demonstrated that CSCM may be useful in platelet plug formation, and this study would provide important information for further research on hemostasis experiment in vivo.