What else should hemostatic materials do beyond hemostasis: A review

Massive blood loss due to injury is the leading cause of prehospital deaths in disasters and emergencies. Hemostatic materials are used to realize rapid hemostasis and protect patients from death. Researchers have designed and developed a variety of hemostatic materials. However, in addition to their hemostatic effect, hemostatic materials must be endowed with additional functions to meet the practical application requirements in different scenarios. Here, strategies for modifications of hemostatic materials for use in different application scenarios are listed: effective positioning at the site of deep and narrow wounds to stop bleeding, resistance to high blood pressure and wound movement to maintain wound formation, rapid and easy removal from the wound without affecting further treatment after hemostasis is completed, and continued function when retained in the wound as a dressing (such as antibacterial, antiadhesion, tissue repair, etc.). The problems encountered in the practical use of hemostatic materials and the strategies and progress of researchers will be further discussed in this review. We hope to provide valuable references for the design of more comprehensive and practical hemostatic materials.

The characterization and analysis of the compound hemostatic cotton based on Ca2+/poly (vinyl alcohol)/soluble starch-fish skin collagen

Accidental bleeding is an unavoidable problem in daily life. To avoid the risk of excessive blood loss, it is urgent to design a functional material that can quickly stop bleeding. In this study, an efficient wound dressing for hemostasis was investigated. Based on the characteristics that Ca2+ and fish skin collagen (FSC) could activate the coagulation mechanism, hemostatic cotton was prepared by solvent replacement method using CaCl2, FSC, soluble starch (SS), and polyvinyl alcohol (PVA) as raw materials. The cytotoxicity test showed the Ca2+PVA/FSC-SS hemostatic cottons had good biocompatibility. The activated partial thromboplastin time (APTT) of Ca2+PVA/FSC-SS(4) was 35.34 s, which was 22.07 s faster than that of PVA/FSC-SS, indicating Ca2+PVA/FSC-SS mediated the endogenous coagulation system. In vitro coagulation test, Ca2+PVA/FSC-SS(4) could stop bleeding rapidly within 39.60 ± 5.16 s, and the ability of wound healing was higher than commercial product (Celox). This study developed a rapid procoagulant and hemostatic material, which had a promising application in a variety of environments.

Cellulose based composite sponges with oriented porous structure and superabsorptive capacity for quick hemostasis

Excessive bleeding is the leading cause of death in accidents and operations. Ca2+ crosslinked carboxyl nanocellulose (CN)/montmorillonite (MMT) composite (CaCNMMT) sponges were prepared by uniform mixing and directional freeze-drying methods which was inspired by the coordination mechanism of blood clot formation and coagulation cascade activation in natural hemostasis process. Carboxyl nanocellulose (CaCN) sponge has instantaneous water absorption capacity, and CaCNMMT sponges could further activate clotting factors. Therefore, CaCNMMT sponges achieved quick hemostasis by efficient concentrating blood, inducing hemocyte aggregation and stimulating coagulation cascade activation based on the synergistic effects of CN and MMT. Blood clotting index of CaCNMMT (15.90 ± 0.52 %) was significantly lower than CaCN (59.3 ± 1.43 %), and APTT time (22 ± 2 s) was almost equivalent to MMT (20 ± 2 s). CaCNMMT sponge showed good quick hemostatic effect on massive hemorrhage in both tail-breaking and liver injury model which provided a new strategy for the application of MMT in hemostatic and trauma treatment fields.

Enhancement of hemostatic properties of Cyclotella cryptica frustule through genetic manipulation

BACKGROUND

The silicified cell wall of diatoms, also known as frustule, shows huge potential as an outstanding bio-nanomaterial for hemostatic applications due to its high hemostatic efficiency, good biocompatibility, and ready availability. As the architectural features of the frustule determine its hemostatic performance, it is of great interest to develop an effective method to modify the frustule morphology into desired patterns to further improve hemostatic efficiency.

RESULTS

In this study, the gene encoding Silicalemma Associated Protein 2 (a silicalemma-spanning protein) of Cyclotella cryptica (CcSAP2) was identified as a key gene in frustule morphogenesis. Thus, it was overexpressed and knocked down, respectively. The frustule of the overexpress lines showed no obvious alteration in morphology compared to the wild type (WT), while the size, specific surface area (BET), pore volume, and pore diameter of the knockdown strains changed greatly. Particularly, the knockdown frustules achieved a more pronounced coagulation effect and in vivo hemostatic performance than the WT strains. Such observations suggested that silicalemma proteins are ideal genetic encoding targets for manipulating frustule morphology associated hemostatic properties. Furthermore, the Mantel test was adopted to identify the key morphologies associated with C. cryptica bleeding control. Finally, based on our results and recent advances, the mechanism of frustule morphogenesis was discussed.

CONCLUSION

This study explores a new strategy for enhancing the hemostatic efficiency of the frustule based on genetic morphology modification and may provide insights into a better understanding of the frustule morphogenesis mechanism.

An injectable hemostatic PEG-based hydrogel with on-demand dissolution features for emergency care

Uncontrolled bleeding from internal noncompressible wounds is a major cause of prehospital death in military personnel and civilian populations. An ideal hemostatic sealant for emergency care should quickly control blood loss and be removed without debridement for the follow-up treatment in the operating room, yet the lack of suitable materials to meet both requirements is the bottleneck. Herein, we suggest an injectable and dissolvable hydrogel sealant for hemorrhage management of noncompressible wounds. To this end, a 4-arm poly(ethylene glycol) (PEG) crosslinker modified with thioester linkages and terminated with aldehyde groups is designed and synthesized, and to modulate the gel properties and make it suitable as a hemostatic sealant, a mixed amino component composed of poly(ethylene imine) and adipic dihydrazide is employed to react with the PEG crosslinker to form the adhesive and elastic sealant for the first time. The aldehyde groups provide the adhesion to the tissues, and the amino component affords the procoagulant ability. More importantly, the thioester moieties allow the on-demand dissolution of sealant via a thiol-thioester exchange reaction upon exposure to an exogenous thiolate solution. In the rat femoral artery puncture and liver injury models, the administration of the hydrogel sealant dramatically reduces blood loss, and its subsequent removal does not induce rebleeding. Consequently, this hydrogel sealant with the unique feature of on-demand dissolution can not only efficiently control bleeding in emergent scenarios, but also allow non-traumatic re-exposure of wounds during subsequent surgical care. STATEMENT OF SIGNIFICANCE: Sealants, adhesives or hemostatic dressings currently used in emergency situations not only require manual pressure to control bleeding, but also face removal by cutting and mechanical debridement to enable eventual surgical treatment. In this study, we design and develop an injectable and adhesive hydrogel sealant with good procoagulant capacity and on-demand dissolution feature. The application of the hydrogel sealant substantially reduces bleeding from internal noncompressible wounds without the need for direct pressure, and demonstrates for the first time that its controlled removal without debridement does not cause rebleeding. Considering that there are currently no commercial wound sealant systems with the feature of on-demand dissolution, the hydrogel sealant developed by us is expected to address an unmet clinical need.

Evaluation of self-prepared absorbable hemostatic cellulose fibrils

To evaluate the effectiveness and safety of self-prepared absorbable hemostatic fibrils.A kind of absorbable hemostatic fibrils were prepared by self-developed patent technique. The physical form and molecular structure of the fibrils and a marketed product Surgicel were characterized by general observation and infrared spectroscopy; the carboxyl content, pH value and relative molecular mass of fibrils were determined by potentiometric titration method, pH meter and copper ethylenediamine method, respectively. The behavior of the fibrils and Surgicel in contact with blood was observed by inverted microscope, the cytotoxicity was evaluated by agarose diffusion cell assay . The external iliac artery hemorrhage model and the back muscle infiltration model in rats were established. The hemostatic effectiveness of the fibrils was investigated by hemostasis time and blood weight, and the degradation and biosafety of fibrils were investigated by observation photography, immune organ weighing, hematology and coagulation index measuring, and histopathological examination. The fibrils and Surgicel had similar molecular structures. Compared with the raw material regenerated cellulose, the typical carboxyl stretching vibration absorption peak of -COOH appeared near in both fibrils and Surgicel. The carboxyl content of the two materials was about 20%, and the pH value was about 3. The relative molecular mass of the fibers after oxidation was 4466±79, which was close to that of Surgicel(>0.05). After contacting with blood, the volume of fibrils and Surgicel expanded, and absorbed blood of dozens of times as their own weight. The results of agar diffusion test showed that the fibrils had no cytotoxicity. The results of animal experiments showed that the hemostasis completed within and there was no significant difference in blood weight and speed of hemostasis between two products (both >0.05). The fibrils could be degraded 1 week after being implanted to the bleeding sites of the muscle. There were no pathological effects on the appearance, body weight, food intake, immunological tissue thymus, spleen, lymph nodes, hematology and coagulation indexes of the rats, and no obvious abnormality found in the histopathological examination. The prepared absorbable hemostatic fibrils have excellent biological safety and effectiveness.

Highly Absorbent Silk Fibroin Protein Xerogel

Highly absorbent polymers have a wide range of applications in biomaterials, agriculture, physiological products of daily uses, and others. Silk fibroin, as a natural biomaterial with excellent biocompatibility and tunable mechanical properties, shows good prospects in the field of biomedicine applications. However, the dried fibroin hydrogel has very low absorbency. In this work, silk fibroin protein is used as the carrier, riboflavin as the photosensitizer, and accordingly, the hydrogel is prepared by free radical cross-linking under ultraviolet light. The fibroin in the hydrogel contains mainly the random coil structure. The covalent bond cross-linking hinders the crystallization of the silk fibroin, thereby an amorphous silk fibroin hydrogel is obtained. After drying, this xerogel can absorb water 90 times more than its own mass and assimilates a good amount of water within a minute. In vitro and in vivo rabbit ear hemostasis experiments show that this fabricated xerogel has good hemostatic properties. Therefore, this xerogel exhibits good promise for rapid hemostasis of wounds and absorbing other body exudates.

[Clinical Evaluation of Absorbable Regenerated Oxidized Cellulose in Lung Cancer Surgery]

背景与目的

胸腔镜下安全有效的止血是开展胸外科快速康复的重要条件，术中放置止血材料是肺癌腔镜手术中常用的方法，其中可吸收再生氧化纤维素是常用的止血材料。本研究旨在观察可吸收再生氧化纤维素在肺癌手术中的止血效果。

方法

回顾性分析2018年7月1日-2018年12月1日于浙江大学医学院附属第一医院胸外科行胸腔镜肺癌根治手术且术中使用可吸收再生氧化纤维素止血的42例患者的临床病理资料，选取围手术期指标作为结局事件进行统计分析。

结果

平均手术时间为（120.5±57.3）min，术中平均出血量为（26.8±21.6）mL，术后平均引流量为（513.6±359.5）mL，术后胸管平均留置时间为（2.6±1.2）d。

结论

胸腔镜肺癌根治术术中使用可吸收再生氧化纤维素具有良好的止血效果，适用于淋巴结清扫后创面填塞止血。