Degradation-controlled tissue extracellular sponge for rapid hemostasis and wound repair after kidney injury

Patients diagnosed with T1a cancer undergo partial nephrectomy to remove the tumors. In the process of removing the tumors, loss of kidney volume is inevitable, and current surgical methods focus solely on hemostasis and wound closure. Here, we developed an implantable form of decellularized extracellular matrix sponge to target both hemostasis and wound healing at the lesion site. A porous form of kidney decellularized matrix was achieved by fabricating a chemically cross-linked cryogel followed by lyophilization. The prepared kidney decellularized extracellular matrix sponge (kdES) was then characterized for features relevant to a hemostasis as well as a biocompatible and degradable biomaterial. Finally, histological evaluations were made after implantation in rat kidney incision model. Both gelatin sponge and kdES displayed excellent hemocompatibility and biocompatibility. However, after a 4-week observation period, kdES exhibited more favorable wound healing results at the lesion site. This suggests a promising potential for kdES as a supportive material in facilitating wound closure during partial nephrectomy surgery. KdES not only achieved rapid hemostasis for managing renal hemorrhage that is comparable to commercial hemostatic sponges, but also demonstrated superior wound healing outcomes.

Quaternized chitosan/oxidized bacterial cellulose cryogels with shape recovery for noncompressible hemorrhage and wound healing

Management of noncompressible torso hemorrhage is an urgent clinical requirement, desiring biomaterials with rapid hemostasis, anti-infection and excellent resilient properties. In this research, we have prepared a highly resilient cryogel with both hemostatic and antibacterial effects by chemical crosslinking and electrostatic interaction. The network structure crosslinked by quaternized chitosan and genipin was interspersed with oxidized bacterial cellulose after lyophilization. The as-prepared cryogel can quickly return to the original volume when soaking in water or blood. The appropriately sized pores in the cryogel help to absorb blood cells and further activate coagulation, while the quaternary ammonium salt groups on quaternized chitosan inhibit bacterial infections. Both cell and animal experiments showed that the cryogel was hypotoxic and could promote the regeneration of wound tissue. This research provides a new pathway for the preparation of double crosslinking cryogels and offers effective and safe biomaterials for the emergent bleeding management of incompressible wounds.

Porosity controlled soya protein isolate-polyethylene oxide multifunctional dual membranes as smart wound dressings

Multifunctional membranes S7P0.7, S7P3.0, and dual membranes composed of soya protein isolate (SPI) and polyethylene oxide (PEO) were produced for wound dressing applications. The internal structure of the membranes was confirmed by scanning electron microscopy (SEM) to be homogeneous and coarser with a porous-like network. S7P3.0 showed the tensile strength of 0.78 ± 0.04 MPa. In the absence of antibiotics, the dual membrane (combination of S7P0.7 and S7P3.0) exhibited potential antibacterial activity against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria. Hemolysis quantitative data presented in the image demonstrates that all samples exhibited hemolysis levels below 5 %. Dual membrane showed 77.93 ± 9.5 % blood uptake which reflects its absorption capacity. The combination of S7P0.7 and S7P3.0 influenced the dual membrane's antibacterial, biocompatibility, and good hemolytic potentials. The dual membranes' promising histology features after implantation suggest they could be used as wound dressings.

Silk composite interfacial layer eliminates rebleeding with chitosan-based hemostats

Chitosan foams are among the approved hemostats for pre-hospital hemorrhagic control but suffer from drawbacks related to mucoadhesiveness and rebleeding. Herein, we have developed a designer bilayered hemostatic foam consisting of a bioactive layer composed of silica particles (≈300 nm) and silk fibroin to serve as the tissue interfacing component on a chitosan foam. The foam composition was optimized based on the in vitro clotting behavior and cytocompatibility of individual components. In vivo analysis in a rat model demonstrated that the developed hemostat could achieve rapid clotting (31 ± 4 s), similar to a chitosan-based hemostat, but the former had significantly lower blood loss. Notably, removal of the bilayered hemostat prevented rebleeding, unlike the chitosan foam, which was associated with markedly higher incidences of rebleeding (50 %) and left behind material residue. Thus, the designer bilayered foam presented here is a potent inducer of blood clotting whilst affording easy removal with minimal rebleeding.

Natural Scaffolds Used for Liver Regeneration: A Narrative Update

Annually chronic liver diseases cause two million death worldwide. Although liver transplantation (LT) is still considered the best therapeutic option, the limited number of donated livers and lifelong side effects of LT has led researchers to seek alternative therapies. Tissue engineering (TE) as a promising method is considered for liver repair and regeneration. TE uses natural or synthetic scaffolds, functional somatic cells, multipotent stem cells, and growth factors to develop new organs. Biological scaffolds are notable in TE because of their capacity to mimic extracellular matrices, biodegradability, and biocompatibility. Moreover, natural scaffolds are classified based on their source and function in three separate groups. Hemostat-based scaffolds as the first group were reviewed for their application in coagulation in liver injury or surgery. Furthermore, recent studies showed improvement in the function of biological hydrogels in liver regeneration and vascularity. In addition, different applications of natural scaffolds were discussed and compared with synthetic scaffolds. Finally, we focused on the efforts to improve the performance of decellularized extracellular matrixes for liver implantation.

Mussel-inspired adhesive antioxidant antibacterial hemostatic composite hydrogel wound dressing via photo-polymerization for infected skin wound healing

With the increasing prevalence of drug-resistant bacterial infections and the slow healing of chronically infected wounds, the development of new antibacterial and accelerated wound healing dressings has become a serious challenge. In order to solve this problem, we developed photo-crosslinked multifunctional antibacterial adhesive anti-oxidant hemostatic hydrogel dressings based on polyethylene glycol monomethyl ether modified glycidyl methacrylate functionalized chitosan (CSG-PEG), methacrylamide dopamine (DMA) and zinc ion for disinfection of drug-resistant bacteria and promoting wound healing. The mechanical properties, rheological properties and morphology of hydrogels were characterized, and the biocompatibility of these hydrogels was studied through cell compatibility and blood compatibility tests. These hydrogels were tested for the in vitro blood-clotting ability of whole blood and showed good hemostatic ability in the mouse liver hemorrhage model and the mouse-tail amputation model. In addition, it has been confirmed that the multifunctional hydrogels have good inherent antibacterial properties against Methicillin-resistant Staphylococcus aureus (MRSA). In the full-thickness skin defect model infected with MRSA, the wound closure ratio, thickness of granulation tissue, number of collagen deposition, regeneration of blood vessels and hair follicles were measured. The inflammation-related cytokines (CD68) and angiogenesis-related cytokines (CD31) expressed during skin regeneration were studied. All results indicate that these multifunctional antibacterial adhesive hemostatic hydrogels have better healing effects than commercially available Tegaderm™ Film, revealing that they have become promising alternative in the healing of infected wounds.

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Antibacterial antioxidant adhesion hydrogel was obtained by photopolymerization.

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These hydrogels exhibited good hemostatic property and cell compatibility.

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The hydrogels showed good antibacterial property against MRSA.

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The hydrogels significantly enhanced wound healing of infected skin wound.

Comparison of the efficacy of five standard topical hemostats: a study in porcine liver and spleen models of surgical bleeding

Background

Several topical hemostats are available to help control surgical bleeding. Cutanplast is a highly absorbent and porous gelatin product that is available in Fast sponge and powder forms. This study investigated the hemostatic efficacy of Cutanplast Standard and Fast gelatin sponge and powder and Emosist oxidized regenerated cellulose (ORC) gauze in porcine liver and spleen surgical bleeding models.

Methods

Cutanplast Standard and Fast gelatin sponge and Emosist ORC gauze were tested in liver abrasion/incision, liver puncture and spleen incision/puncture injuries, and Cutanplast Standard and Fast gelatin powder products were tested in liver abrasion/incision injuries. There were 13 liver injury (five abrasion, five incision and three puncture) and six spleen injury (three puncture and three incision sites) sites per animal.

Results

Rapid hemostasis (≤ 2–5 min) was achieved in the liver abrasion and incision models with all Cutanplast gelatin sponge and powder products and Emosist ORC gauze, except in the liver incision model, time to hemostasis was > 5 min with Cutanplast Standard gelatin powder and Emosist ORC gauze. Rapid hemostasis occurred with Cutanplast Fast gelatin sponge and Emosist ORC gauze in the liver puncture and spleen puncture and incision models. In the spleen incision model, Cutanplast Standard gelatin sponge had a time to hemostasis approaching 10 min.

Conclusion

Cutanplast gelatin sponge and powder products and Emosist ORC gauze may be suitable for surgical applications involving parenchymal organ bleeding, but certain products may perform better than others, including Cutanplast gelatin powder in diffuse mild bleeding (such as liver abrasion), and Cutanplast Fast gelatin sponge and Emosist ORC gauze for splenic bleeding.

Mechanomedicine

It has been a long time since the term mechanobiology became widely accepted, and broad research approaches, ranging from basic biology to medical research, have been conducted from the perspective of mechanobiology. Our group created the term “mechanomedicine” focusing on the field encompassing studies of the pathology and treatment of various diseases based on the knowledge obtained from mechanobiological studies and have promoted studies in this field. In the respiratory and cardiovascular systems, not only humoral factors but also physical factors such as contraction and expansion phenomena, and feedback from such phenomena to tissues and cells are important stimuli for maintaining homeostasis. Loss of homeostasis is considered to lead to pathological conditions. This review aims to provide an overview of mechanomedicine by introducing several mechanosensitive channels including one particular type of mechanosensor that we discovered in the cardiovascular system and by describing stretchable three-dimensional cell culture scaffolds using self-assembled peptides, a highly motile sperm sorter using a sperm sorting technique based on microfluidic mechanics, and a device to promote the development of fertilized ova.

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.

A novel injectable tissue adhesive based on oxidized dextran and chitosan

A surgical adhesive that can be used in different surgical situations with or without sutures is a surgeons' dream and yet none has been able to fulfill many such demanding requirements. It was therefore a major challenge to develop an adhesive biomaterial that stops bleeding and bond tissues well, which at the same time is non-toxic, biocompatible and yet biodegradable, economically viable and appealing to the surgeon in terms of the simplicity of application in complex surgical situations. With this aim, we developed an in situ setting adhesive based on biopolymers such as chitosan and dextran. Dextran was oxidized using periodate to generate aldehyde functions on the biopolymer and then reacted with chitosan hydrochloride. Gelation occurred instantaneously upon mixing these components and the resulting gel showed good tissue adhesive properties with negligible cytotoxicity and minimal swelling in phosphate buffered saline (PBS). Rheology analysis confirmed the gelation process by demonstrating storage modulus having value higher than loss modulus. Adhesive strength was in the range 200-400gf/cm² which is about 4-5 times more than that of fibrin glue at comparable setting times. The adhesive showed burst strength in the range of 400-410mm of Hg which should make the same suitable as a sealant for controlling bleeding in many surgical situations even at high blood pressure. Efficacy of the adhesive as a hemostat was demonstrated in a rabbit liver injury model. Histological features after two weeks were comparable to that of commercially available BioGlue®. The adhesive also demonstrated its efficacy as a drug delivery vehicle. The present adhesive could function without the many toxicity and biocompatibility issues associated with such products.

STATEMENT OF SIGNIFICANCE

Though there are many tissue adhesives available in market, none are free of shortcomings. The newly developed surgical adhesive is a 2-component adhesive system based on time-tested, naturally occurring polysaccharides such as chitosan and dextran which are both biocompatible and biodegradable. Simple polymer modification has been carried out on both polysaccharides so that when aqueous solutions of both are mixed, the solutions gel in less than 10s and forms an adhesive that seals a variety of incisions. The strength of the adhesive is over 5-times the strength of commercially available Fibrin glue and is more tissue compliant than BioGlue®. This adhesive biomaterial showed excellent tissue bonding, was hemostatic, biocompatible and biodegradable. The significance of this work lies on the features of the developed tissue adhesive that it stops bleeding, bond the tissues well, can act as a drug delivery vehicle and would appeal to the surgeon in terms of the simplicity of application in complex surgical situations. There is no need for special delivery systems for application of this adhesive. The two-component adhesive can be applied one over the other using syringes. There is also no need for light curing with UV or visible light and the gelation between the two components spontaneously takes place on application leading to excellent tissue bonding.

Porous chitosan microspheres for application as quick in vitro and in vivo hemostat

Controlling massive hemorrhage is of great importance to lower transfusional medical cost, and to reduce death and mobility rate in battlefield and civilian accidents. We reported the fabrication of porous chitosan microspheres (CSMS) with tunable surface pore size by microemulsion combined with thermally induced phase separation technique, and its application as a quick hemostat. Their hemostatic property was characterized by blood clotting kinetics, adherence interaction between red blood cells/platelets and CSMS, in vitro and in vivo hemostasis by rat tail amputation and liver laceration models, and histological analysis. Their density, surface area, porosity, water absorption ratio were 0.04-0.06g/cm³, 28.2-31.5m²/g, 98%, and 15.5-23.2g/g, respectively. The surface pore was controlled to be smaller than 2.0μm. The porous CSMS showed increasing hemostatic efficacy with decreasing surface pore size. Compared to the conventional compact chitosan particles (CCSP), the porous CSMS had much improved in vitro and in vivo hemostatic potential with respect to formation of blood clot, hemostatic time, and blood loss. For instance, the hemostatic time and blood loss of CSMS in the rat liver laceration model were down to respectively 70s and 0.026g from 175s and 0.28g of CCSP. Histological examination showed that application of porous CSMS to liver laceration caused no destruction of underlying hepatocytes, inflammatory reaction, and thermal injury to liver tissue. The porous CSMS is a biodegradable, quick and safe hemostat, which can be used in various wounds including complex and non-compressive ones.

Rapid purification of high purity thrombin and preparation of a novel hemostat for clinical purposes

Thrombin was prepared from crude prothrombin enriched plasma by activation using Russell's viper venom. Prothrombin was prepared by barium sulphate adsorption and elution of prothrombin enriched fraction using high concentrations of sodium citrate. This fraction was directly activated with venom and thrombin was purified by SP Sepharose ion-exchange chromatography and subsequently over Phenyl-sepharose column. This product exhibits a purity of >98% with an activity of at least 6000U/mg or higher. The Thrombin was further used in the preparation of a novel bio-absorbable hemostat using Calcium Alginate fiber sheet which acts as an absorbable hemostat. The present hemostat is highly porous, easy to use and has faster clotting time due to higher solubility of calcium fibers and thereby releasing thrombin.