Functional effect of hemostatic pad based on a collagen with chitosan by addition of batroxobin

의과대학/석사Uncontrolled excessive bleeding in daily life, whether due to sudden accident, surgical operations, or combat may cause infectious complications that may lead to death by shock. Therefore, topical hemostats and sealants are required to assist effective treatment, arrest bleeding, and stabilize the casualty before definitive care. This study use collagen and chitosan, which are both natural materials and are one of the most widely used hemostats these days. The materials are role in platelet activation, adhesion and aggregation. The use of chitosan helps the blood coagulation as it combines with red blood cells. However, these materials have been reported to lack sufficient hemostatic effect in a timely manner. Hence, in this research, a novel pad made a faster and more effective sponge type hemostats by using the recombinant batroxobin, a venomous component from the snake Bothrops atrox moojeni, which transforms the fibrinogen to fibrin in the process of hemostasis; it expected that recombinant batroxobin would support natural substances to achieve a synergetic effect of hemostasis performances. First, collagen and chitosan were dissolved with batroxobin in acetic acid for fabrication of a novel hemostatic pad and then characteristic analysis using Scanning Electron Microscope. Fabricated sponge groups were collagen-only, chitosan-only, collagen with chitosan, collagen or chitosan containing recombinant batroxobin 1, 2 and 3 BU/well for in vitro studies, collagen or chitosan containing recombinant batroxobin 3 and 5 BU/well for in vivo studies and collagen with chitosan containing recombinant batroxobin 1, 2, 3 and 5 BU/well. Fibrinogen assay and platelet activation assays represented respective hemostats mechanism, even combination of the materials. Whole blood clotting assay and animal experiments investigated blood coagulation activities in the injury sites. In addition, H&E and PTAH staining methods for histological analysis. Through the experimentations result, a novel hemostatic pad confirmed that the substances maintained to their hemostatic properties in the pad, also coagulation studies proved pad effectively reduced blood loss and shortened bleeding time by addition of batroxobin. In conclusion, the novel hemostatic pad is reasonable that an enormous potential for excessive bleeding injury and improve effects of natural substance hemostatic pad when it is cooperated with recombinant batroxobin.ope

Stem cell passage affects directional migration of stem cells in electrotaxis

Stem cells can differentiate into various body tissues and organs and thus are considered as promising tools for cell therapy and tissue engineering. Early passage stem cells have high differentiation ability compared to late passage stem cells. Thus, it is important to use early passage stem cells in cell therapy. Here, we investigated whether cell migration could be used to compare young and senescent cells. We used 'electrotaxis' where cells under electric treatment move towards the anode or cathode. Without an electric stimulus, stem cells moved randomly. However, under a direct electric current, the cells moved with directionality. Under stimulation with a direct electric current, early passage stem cells moved towards the anode; when the cells became senescent with increasing passages, the percentage of cells migrating to the anode decreased. These results suggest that the behavior of stem cells under the influence of a direct electric current is also related to their passage number. Therefore, electrotaxis migration analysis can be used to distinguish between young cell and senescent cells.ope

Locally delivered ethyl-2,5-dihydroxybenzoate using 3D printed bone implant for promotion of bone regeneration in a osteoporotic animal model

Osteoporosis is a disease characterized by low bone mass, most commonly caused by an increase in bone resorption that is not matched by sufficient bone formation. The most common complications of postmenopausal osteoporosis are bone-related defects and fractures. Fracture healing is a multifactorial bone regeneration process, influenced by both biological and mechanical factors related to age, osteoporosis and stability of the osteosynthesis. During the treatment of bone defects in osteoporotic conditions, imbalanced bone remodeling is the leading cause for implant failure. To overcome these problems, ethyl-2,5-dihydroxybenzoate (E-2,5-DHB), a drug that promotes bone formation and inhibits bone resorption, was used. E-2,5-DHB-incorporating titanium (Ti) implants using poly(lactic-co-glycolic acid) (PLGA) coating for local delivery of E-2,5-DHB were developed and the effects on bone healing of femoral defects were evaluated in an osteoporotic model. The release of E-2,5-DHB resulted in decreased bone resorption and increased bone formation around the implant. Thus, it was confirmed that, in the osteoporotic model, bone healing was increased and implant fixation was enhanced. These results suggested that E-2,5-DHB-coated Ti implants have great potential as an ultimate local drug delivery system for bone tissue scaffolds.ope

Homogeneity evaluation of mesenchymal stem cells based on electrotaxis analysis

Stem cell therapy that can restore function to damaged tissue, avoid host rejection and reduce inflammation throughout body without use of immunosuppressive drugs. The established methods were used to identify and to isolate specific stem cell markers by FACS or by immunomagnetic cell separation. The procedures for distinguishing population of stem cells took a time and needed many preparations. Here we suggest an electrotaxis analysis as a new method to evaluate the homogeneity of mesenchymal stem cells which can observe the stem cell population in culture condition and wide use to various types of stem cells. Human mesenchymal stem cell, adipose derived stem cell, tonsil derived stem cell and osteogenic differentiated cells migrated toward anode but the migration speed of differentiated cells was significantly decreased versus that of stem cells. In mixture of stem cells and differentiated cells condition, we identified that the ratio of stem cell versus differentiated cell was matched with the homogeneity evaluation data of stem cells based on electrotaxis analysis. As a result, our evaluation tool has the possibility of the wide use to stem cell homogeneity evaluation and might be used as the stem cell quality control during stem cell culture without any additional antibodies.ope

Titanium surface modification by using microwave-induced argon plasma in various conditions to enhance osteoblast biocompatibility

BACKGROUND: Titanium is a well proven implantable material especially for osseointegratable implants by its biocompatibility and anti-corrosive surface properties. Surface characteristics of the implant play an important role for the evolution of bone tissue of the recipient site. Among the various surface modification methods, plasma treatment is one of the promising methods for enhance biocompatibility. We made microwave-induced argon plasma at atmospheric pressure to improve in titanium surface biocompatibility. RESULTS: Various states of emission spectra from excited species-argon, nitrogen atoms and oxygen atoms were observed. The electron energy band structures are the unique characteristics of atoms and functional groups. Microwave-induced argon plasma treatment changed the titanium surface to be very hydrophilic especially on the 5 s short treatment and 30 s, 90 s long treatment samples that detected by contact angle measurement. MC3T3-E1 attachment and proliferation assay significantly increased in 5 s at short treatment, 30 s, and 90 s at long treatment after 5 days incubation. CONCLUSIONS: Result indicated that microwave-induce argon plasma treatment would be an effective method to modify titanium surface for enhancing cell-material interactions.ope

염증 약화를통해 상처 치유를 촉진하기 위한 아시아티코사이드와 입실론 폴리라이신이 방출되는 인공 대체제

prohibition박

Zwitterionic sulfobetaine polymer-immobilized surface by simple tyrosinase-mediated grafting for enhanced antifouling property

Introducing antifouling property to biomaterial surfaces has been considered an effective method for preventing the failure of implanted devices. In order to achieve this, the immobilization of zwitterions on biomaterial surfaces has been proven to be an excellent way of improving anti-adhesive potency. In this study, poly(sulfobetaine-co-tyramine), a tyramine-conjugated sulfobetaine polymer, was synthesized and simply grafted onto the surface of polyurethane via a tyrosinase-mediated reaction. Surface characterization by water contact angle measurements, X-ray photoelectron spectroscopy and atomic force microscopy demonstrated that the zwitterionic polymer was successfully introduced onto the surface of polyurethane and remained stable for 7days. In vitro studies revealed that poly(sulfobetaine-co-tyramine)-coated surfaces dramatically reduced the adhesion of fibrinogen, platelets, fibroblasts, and S. aureus by over 90% in comparison with bare surfaces. These results proved that polyurethane surfaces grafted with poly(sulfobetaine-co-tyramine) via a tyrosinase-catalyzed reaction could be promising candidates for an implantable medical device with excellent bioinert abilities. STATEMENT OF SIGNIFICANCE: Antifouling surface modification is one of the key strategy to prevent the thrombus formation or infection which occurs on the surface of biomaterial after transplantation. Although there are many methods to modify the surface have been reported, necessity of simple modification technique still exists to apply for practical applications. The purpose of this study is to modify the biomaterial's surface by simply immobilizing antifouling zwitterion polymer via enzyme tyrosinase-mediated reaction which could modify versatile substrates in mild aqueous condition within fast time period. After modification, pSBTA grafted surface becomes resistant to various biological factors including proteins, cells, and bacterias. This approach appears to be a promising method to impart antifouling property on biomaterial surfaces.restrictio

Heparin-functionalized polymer graft surface eluting MK2 inhibitory peptide to improve hemocompatibility and anti-neointimal activity

The leading cause of synthetic graft failure includes thrombotic occlusion and intimal hyperplasia at the site of vascular anastomosis. Herein, we report a co-immobilization strategy of heparin and potent anti-neointimal drug (Mitogen Activated Protein Kinase II inhibitory peptide; MK2i) by using a tyrosinase-catalyzed oxidative reaction for preventing thrombotic occlusion and neointimal formation of synthetic vascular grafts. The binding of heparin-tyramine polymer (HT) onto the polycarprolactone (PCL) surface enhanced blood compatibility with significantly reduced protein absorption (64.7% decrease) and platelet adhesion (85.6% decrease) compared to bare PCL surface. When loading MK2i, 1) the HT depot surface gained high MK2i-loading efficiency through charge-charge interaction, and 2) this depot platform enabled long-term, controlled release over 4weeks (92-272μg/mL of MK2i). The released MK2i showed significant inhibitory effects on VSMC migration through down-regulated phosphorylation of target proteins (HSP27 and CREB) associated with intimal hyperplasia. In addition, it was found that the released MK2i infiltrated into the tissue with a cumulative manner in ex vivo human saphenous vein (HSV) model. This present study demonstrates that enzymatically HT-coated surface modification is an effective strategy to induce long-term MK2i release as well as hemocompatibility, thereby improving anti-neointimal activity of synthetic vascular grafts.restrictio

Golgi polarization effects on infiltration of mesenchymal stem cells into electrospun scaffolds by fluid shear stress: Analysis by confocal microscopy and Fourier transform infrared spectroscopy

The polarization of the Golgi apparatus is an important phenomenon in the directional migration of many types of cells, including fluid shear stress enhanced infiltration of cells into scaffolds. Fourier transform infrared (FT-IR) spectroscopy would be a potential tool to study cell infiltration into scaffolds because this technique has simple, reproducible, non-destructive characteristics. Here, we investigated the effect of Golgi polarization on the directional migration and infiltration of human mesenchymal stem cells (hMSCs) into poly(lactic-co-glycolic acid) (PLGA) scaffolds by fluid shear stress. The cell infiltration into scaffolds by fluid shear stress was observed by immunofluorescence and FT-IR. 2 μM of Brefeldin A (BFA) inhibited the reorganization of Golgi polarization in hMSCs. The blocking of Golgi reorganization by BFA caused the suppression of directional migration and infiltration into PLGA scaffolds induced by 8 dyne/cm2 of fluid shear stress condition. In this study, we investigated how Golgi polarization plays an important role in the directional migration and infiltration of hMSCs into scaffolds by responding to the fluid shear stress. The possibility of FT-IR to be a potential tool for analysis of cell infiltration into scaffolds was identified since the immunofluorescence data matched FT-IR data.restrictio

Functional improvement of hemostatic dressing by addition of recombinant batroxobin

Although a number of natural materials have been used as hemostatic agents, many substances do not act quickly enough. Here, we created a novel dressings using collagen and chitosan with recombinant batroxobin (r-Bat) to promote faster and more effective hemostasis. We hypothesized that r-Bat would promote synergetic blood coagulation because it contains a blood coagulation active site different than those of collagen and chitosan. Our results suggest that each substances can maintain hemostatic properties while in the mixed dressings and that our novel hemostatic dressings promotes potent control of bleeding, as demonstrated by a whole blood assay and rat hemorrhage model. In a rat femoral artery model, the scaffold with a high r-Bat concentration more rapidly controlled excessive bleeding. This novel dressings has enormous possible for rapidly controlling bleeding and it improves upon the effect of collagen and chitosan used alone. Our novel r-Bat dressings is a possible candidate for improving preoperative care and displays promising properties as an absorbable agent in hemostasis. STATEMENT OF SIGNIFICANCE: Despite the excellent hemostatic properties of collagen and chitosan pads, they reported to brittle behavior and lack sufficient hemostatic effect within relevant time. Therefore, we created a novel pad using collagen and chitosan with recombinant batroxobin (r-Bat). r-Bat acts as a thrombin-like enzyme in the coagulation cascade. Specifically, r-Bat, in contrast to thrombin, only splits fibrinopeptide A off and does not influence other hemostatic factors or cells, which makes it clinically useful as a stable hemostatic agent. Also the materials in the pad have synergetic effect because they have different hemostatic mechanisms in the coagulation cascade. This report propose the novel hemostatic pad isreasonable that a great potential for excessive bleeding injury and improve effects of natural substance hemostatic pad.restrictio