Development of a direction-sensitive gamma-ray monitoring system using a gamma camera with a dual-sided collimator: A Monte Carlo study.

Nuclear explosions, sabotage, and dirty bomb materials are considered a security threat. This paper discusses the development of a gamma-ray monitoring system that enables the screening of nuclear materials moving simultaneously on both sides of the system at ports. This direction-sensitive gamma-ray monitoring (DSGM) system consists of a monolithic plastic scintillator surrounded by 28 photomultiplier tubes and dual-sided parallel-hole lead collimators. With Monte Carlo simulation, the monitoring performance of the DSGM system was assessed for static and moving sources. A multilayer perceptron model was employed to estimate the energy-deposited position of the gamma-rays emitted by nuclear materials in the scintillator.

Asiaticoside and polylysine-releasing collagen complex for effectively reducing initial inflammatory response using inflamed induced in vitro model.

Inflammation is a significant clinical problem that can arise from full-thickness wounds or burn injuries or microbial disease. Although topical wound healing substances could promote rapid wound healing by preventing or reducing the consequences of inflammation, there still remains a need for the development of novel substances that can effectively reduce infection and inflammation in initial wound healing phase. In this study, collagen was combined with asiaticoside (AS) and ε-poly-l-lysine (εPLL). This complex was then applied to in vitro models of infection and inflammation. Collagen-AS coatings inhibited the initial inflammatory response to LPS through a sustained release of AS, and a bilayer coating-εPLL showed a notable antimicrobial effect using microbial infection test. In this study, we determined whether asiaticoside and εPLL have anti-inflammatory and antibacterial effects through different mechanisms. Collectively, the collagen-AS/εPLL complex indicated great therapeutic potentials for accelerate wound healing and the complex may be considered as a artificial scaffold substitute product to full-thickness wound healing.

Hydrogel cross-linking-programmed release of nitric oxide regulates source-dependent angiogenic behaviors of human mesenchymal stem cell.

Angiogenesis is stimulated by nitric oxide (NO) production in endothelial cells (ECs). Although proangiogenic actions of human mesenchymal stem cells (hMSCs) have been extensively studied, the mechanistic role of NO in this action remains obscure. Here, we used a gelatin hydrogel that releases NO upon crosslinking by a transglutaminase reaction ("NO gel"). Then, the source-specific behaviors of bone marrow versus adipose tissue-derived hMSCs (BMSCs versus ADSCs) were monitored in the NO gels. NO inhibition resulted in significant decreases in their angiogenic activities. The NO gel induced pericyte-like characteristics in BMSCs in contrast to EC differentiation in ADSCs, as evidenced by tube stabilization versus tube formation, 3D colocalization versus 2D coformation with EC tube networks, pericyte-like wound healing versus EC-like vasculogenesis in gel plugs, and pericyte versus EC marker production. These results provide previously unidentified insights into the effects of NO in regulating hMSC source-specific angiogenic mechanisms and their therapeutic applications.

Effective stacking and transplantation of stem cell sheets using exogenous ROS-producing film for accelerated wound healing.

Extensive skin loss caused by burns or diabetic ulcers may lead to major disability or even death. Therefore, cell-based therapies that enhance skin regeneration are clinically needed. Previous approaches have been applied the injections of cell suspensions and the implantation of biodegradable three-dimensional scaffolds seeded cells. However, these treatments have limits due to poor localization of the injected cells and insufficient delivery of oxygen and nutrients to cells. Recently, cell sheet-based tissue engineering has been developed to transplant cell sheets, which are cell-dense tissues without scaffolds. Because cell density is one of the important factors for improving the therapeutic effect of cell transplantation, transplanting layered cell sheet constructs can promote the recovery of tissue function and tissue regeneration compared with a single cell sheet. Thus, this study designed ROS-induced cell sheet stacking method with newly fabricated hematoporphyrin-incorporated polyketone film (Hp-PK film) to enhance cell sheet delivery efficiency and application in wound healing. We have demonstrated the therapeutic effect of a multi-layered mesenchymal stem cell sheets onto a full-thickness wound defect in nude mice. Consequentially, three-layered cell sheets transplanted and stacked by ROS-induced method promoted angiogenesis and skin regeneration at the wound site. Thus, our strategy based on Hp-PK film, which allows for easy stacking and transplantation of cell sheets, could be applied to enhance tissue regeneration. STATEMENT OF SIGNIFICANCE: We herein report exogenous ROS-induced cell sheet stacking method with newly fabricated hematoporphyrin-incorporated polyketone film (Hp-PK film) to enhance cell sheet transplantation efficiency and application in wound healing. Although there are several ways to stack-up cell sheets, all of these methods have limitations in transplanting the cell sheet directly to the target site. The method is simple and takes a relatively short time compared to previously reported methods for stacking and transplanting cell sheets. Thus, our study will provide a scientific impact because the method of applying exogenous ROS generated from Hp-PK film on cell detachment can transplant the cell sheet through a process of putting a cell sheet-cultured film on the lesion, irradiating with light, and then removing only the film.

Influence of Biomimetic Materials on Cell Migration.

In recent tissue engineering applications, the advance of biomaterials has focused on the devising of biomimetic materials that are directing new tissue formation and capable of causing specific cellular responses. These advances can be controlled by modifying the devising parameters of the materials. The biomimetic materials potentially mimic many roles of ECM in tissues. For the homogeneous distribution and biocompatibility of scaffolds by cell migration with biomimetic materials, cell migration is studied because it has a important role in physiological phenomenon and in pathologies; cancer metastasis, immune response or embryonic development. This review discusses the migration of cells with biomimetic materials for tissue engineering. It is also summarized that the recent advances of cell migration with biomimetic materials in 2-D and 3-D for tissue engineering.

Author Correction: Homogeneity evaluation of mesenchymal stem cells based on electrotaxis analysis.

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Suppression of T24 human bladder cancer cells by ROS from locally delivered hematoporphyrin-containing polyurethane films.

Systemic injection of a photosensitizer is a general method in photodynamic therapy, but it has complications due to the unintended systemic distribution and remnants of photosensitizers. This study focused on the possibility of suppressing luminal proliferative cells by excessive reactive oxygen species from locally delivered photosensitizer with biocompatible polyurethane, instead of the systemic injection method. We used human bladder cancer cells, hematoporphyrin as the photosensitizer, and polyurethane film as the photosensitizer-delivering container. The light source was a self-made LED (510 nm, 5 mW cm-2) system. The cancer cells were cultured on different doses of hematoporphyrin-containing polyurethane film and irradiated with LED for 15 minutes and 30 minutes each. After irradiating with LED and incubating for 24 hours, cell viability analysis, cell cycle analysis, apoptosis assay, intracellular and extracellular ROS generation study and western blot were performed. The cancer cell suppression effects of different concentrations of the locally delivered hematoporphyrin with PDT were compared. Apoptosis dominant cancer cell suppressions were shown to be hematoporphyrin dose-dependent. However, after irradiation, intracellular ROS amounts were similar in all the groups having different doses of hematoporphyrin, but these values were definitely higher than those in the control group. Excessive extracellular ROS from the intended, locally delivered photosensitizer for photodynamic treatment application had an inhibitory effect on luminal proliferative cancer cells. This method can be another possibility for PDT application on contactable or attachable lesions.

Recombinant batroxobin-coated nonwoven chitosan as hemostatic dressing for initial hemorrhage control.

The choice of hemostat is determined by the situation and the degree of hemorrhage. One common hemostat, the nonwoven dressing, is easy to handled and controls severe bleeding on wider wounds. In this study, chitosan-based nonwoven dressings with recombinant batroxobin (rBat) were used as efficacious hemostatic dressing agents. Hemostatic agents need to absorb blood quickly in the early stages of blood coagulation cascade to rapidly and effectively control of excessive hemorrhages. To date, most studies of hemostatic agents focused on a single material and hemostats composed of multiple materials have not been studied sufficiently. Thus, we made a chitosan dressing coated with rBat and investigated the microstructure, mechanical properties, hemostatic efficacy, and clotting properties of the coated dressing. Our results showed that the rBat had a synergetic effect on chitosan that improved blood coagulation. Furthermore, the dressing had excellent bleeding control in an Sprague-Dawley (SD) rat femoral artery hemorrhage model. In conclusion, hemostasis can be improved by combining a chitosan-based nonwoven dressing with other agents, and rBat-coated chitosan-based nonwoven dressings have enormous potential to improve blood coagulation.

Exogenous ROS-induced cell sheet transfer based on hematoporphyrin-polyketone film via a one-step process.

To date, most of invasive cell sheet harvesting methods have used culture surface property variations, such as wettability, pH, electricity, and magnetism, to induce cell detachment. These methods that rely on surface property changes are effective when cell detachment prior to application is necessary, but of limited use when used for cell sheet transfer to target regions. The study reports a new reactive oxygen species (ROS)-induced strategy based on hematoporphyrin-incorporated polyketone film (Hp-PK film) to transfer cell sheets directly to target areas without an intermediate harvesting process. After green LED (510 nm) irradiation, production of exogenous ROS from the Hp-PK films induces cell sheet detachment and transfer. The study suggests that ROS-induced cell detachment property of the Hp-PK film is closely related to conformational changes of extracellular matrix (ECM) proteins. Also, this strategy with the Hp-PK film can be applied by regulating production rate of exogenous ROS in various types of cells, including fibroblasts, mesenchymal stem cells and keratinocytes. In conclusion, ROS-induced method using the Hp-PK film can be used for one-step cell sheet transplantation and has potential in biomedical applications.

Design of Polymeric Culture Substrates to Promote Proangiogenic Potential of Stem Cells.

Stem cells are a promising cell source for regenerative medicine due to their differentiation and self-renewal capacities. In the field of regenerative medicine and tissue engineering, a variety of biomedical technologies have been tested to improve proangiogenic activities of stem cells. However, their therapeutic effect is found to be limited in the clinic because of cell loss, senescence, and insufficient therapeutic activities. To address this type of issue, advanced techniques for biomaterial synthesis and fabrication have been approached to mimic proangiogenic microenvironment and to direct proangiogenic activities. This review highlights the types of polymers and design strategies that have been studied to promote proangiogenic activities of stem cells. In particular, scaffolds, hydrogels, and surface topographies, as well as insight into their underlying mechanisms to improve proangiogenic activities are the focuses. The strategy to promote angiogenic activities of hMSCs by controlling substrate repellency is introduced, and the future direction is proposed.

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.

Control of neonatal human dermal fibroblast migration on poly(lactic-co-glycolic acid)-coated surfaces by electrotaxis.

Many types of cells respond to applied direct current electric fields (dcEFs) by directional cell migration, a phenomenon called galvanotaxis or electrotaxis. In this study, electrotaxis was used to control cell migration. We designed a new electrotaxis incubator and chamber system to facilitate long-term (> 12 h) observation and to allow for alterations to the direction of the current. Poly(lactic-co-glycolic acid) (PLGA) was coated onto surfaces to mimic a commonly used tissue-engineering scaffolding environment. Neonatal human dermal fibroblasts (nHDFs) were grown on PLGA-coated surfaces and exposed to EFs at increasing currents in the range 0-1 V/cm. These cells migrated toward the cathode during 3 h of dcEF stimulation; however, the migration speed decreased with increasing electric fields. Cells exposed to dcEFs in the range 1-2 V/cm showed no changes to migration speed or x forward migration indices (xFMIs) and the cells continued to move toward the cathode. nHDFs showed directional migration towards the cathode in direct current (dc) EFs (1 V/cm) and they moved in the opposite direction when the polarity of the dcEF was reversed. Reorganization of the actin cytoskeleton and polarization of the Golgi apparatus were evaluated by immunostaining, which showed that the actin cytoskeleton elongated towards the cathode and the Golgi apparatus polarized in the direction of the dcEF. This study revealed that cell migration could potentially be controlled on PLGA scaffolds through electrotaxis. Copyright © 2015 John Wiley & Sons, Ltd.

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.

Controlled Delivery of Extracellular ROS Based on Hematoporphyrin-Incorporated Polyurethane Film for Enhanced Proliferation of Endothelial Cells.

The principle of photodynamic treatment (PDT) involves the administration of photosensitizer (PS) at diseased tissues, followed by light irradiation to produce reactive oxygen species (ROS). In cells, a moderate increase in ROS plays an important role as signaling molecule to promote cell proliferation, whereas a severe increase of ROS causes cell damage. Previous studies have shown that low levels of ROS stimulate cell growth through PS drugs-treating PDT and nonthermal plasma treatment. However, these methods have side effects which are associated with low tissue selectivity and remaining of PS residues. To overcome such shortcomings, we designed hematoporphyrin-incorporated polyurethane (PU) film induced generation of extracellular ROS with singlet oxygen and free radicals. The film can easily control ROS production rate by regulating several parameters including light dose, PS dose. Also, its use facilitates targeted delivery of ROS to the specific lesion. Our study demonstrated that extracellular ROS could induce the formation of intracellular ROS. In vascular endothelial cells, a moderated increase in intracellular ROS also stimulated cell proliferation and cell cycle progression by accurate control of optimum levels of ROS with hematoporphyrin-incorporated polymer films. This modulation of cellular growth is expected to be an effective strategy for the design of next-generation PDT.

Ethyl-2, 5-dihydroxybenzoate displays dual activity by promoting osteoblast differentiation and inhibiting osteoclast differentiation.

The interplay between bone-forming osteoblasts and bone-resorbing osteoclasts is essential for balanced bone remodeling. In this study, we evaluate the ability of ethyl-2, 5-dihyrdoxybenzoate (E-2, 5-DHB) to affect both osteoblast and osteoclast differentiation for bone regeneration. Osteogenic differentiation of human mesenchymal stem cells (hMSCs) was quantified by measuring alkaline phosphatase (ALP) activity and calcium deposition. To evaluate osteoclast differentiation, we investigated the effect of E-2, 5-DHB on RANKL-activated osteoclastogenesis in RAW 264.7 cells. E-2, 5-DHB enhanced ALP activity and inhibited RAW 264.7 cell osteoclastogenesis in vitro. To assess the in vivo activity of E-2, 5-DHB, hMSCs were delivered subcutaneosuly alone or in combination with E-2, 5-DHB in an alginate gel into the backs of nude-mice. Histological and immunohistochemical evaluation showed significantly higher calcium deposition in the E-2, 5-DHB group. Osteocalcin (OCN) was highly expressed in cells implanted in the gels containing E-2, 5-DHB. Our results suggest that E-2, 5-DHB can effectively enhance osteoblast differentiation and inhibit osteoclast differentiation both in vitro and in vivo. Understanding the dual function of E-2, 5-DHB on osteoblast and osteoclast differentiation will aid in future development of E-2, 5-DHB as a material for bone tissue engineering.

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.

Exovascular application of epigallocatechin-3-O-gallate-releasing electrospun poly(L-lactide glycolic acid) fiber sheets to reduce intimal hyperplasia in injured abdominal aorta.

Intimal hyperplasia is an excessive ingrowth of tissue resulting in chronic structural lesions commonly found at sites of atherosclerotic lesions, arterial angioplasty, vascular graft anastomoses, and other vascular abnormalities. Epigallocatechin-3-O-gallate (EGCG) was shown to elicit antioxidant, anti-proliferative, and anti-thrombogenic effects. In this study, we used an electrospinning technique to synthesize EGCG-eluting biodegradable poly(L-lactide glycolic acid) (PLGA) fiber sheets for local delivery of EGCG and investigated the effect of their exovascular application on intimal hyperplasia following balloon-induced abdominal aorta injury in a rabbit experimental model. The morphology of the composite sheets was characterized using scanning electron microscopy and Fourier transform-infrared spectroscopy. EGCG was loaded and dispersed into the PLGA-based electrospun fibers. The EGCG-loaded PLGA sheets exhibited sustained EGCG release following the initial 24 h of burst release in phosphate-buffered saline. In vivo studies demonstrated significant inhibition of intimal hyperplasia following the application of the EGCG-eluting electrospun PLGA fiber sheets, compared with vehicle PLGA controls. In conclusion, our results show that exovascular application of EGCG-eluting PLGA electrospun fiber sheets may provide a useful system for the effective local delivery of drugs for the prevention of intimal hyperplasia.

Enhancement of human mesenchymal stem cell infiltration into the electrospun poly(lactic-co-glycolic acid) scaffold by fluid shear stress.

The infiltration of the cells into the scaffolds is important phenomenon to give them good biocompatibility and even biodegradability. Fluid shear stress is one of the candidates for the infiltration of cells into scaffolds. Here we investigated the directional migration of human mesenchymal stem cells and infiltration into PLGA scaffold by fluid shear stress. The human mesenchymal stem cells showed directional migrations following the direction of the flow (8, 16 dyne/cm(2)). In the scaffold models, the fluid shear stress (8 dyne/cm(2)) enhanced the infiltration of cells but did not influence on the infiltration of Poly(lactic-co-glycolic acid) particles.

Golgi polarization plays a role in the directional migration of neonatal dermal fibroblasts induced by the direct current electric fields.

Directional cell migration requires cell polarization. The reorganization of the Golgi apparatus is an important phenomenon in the polarization and migration of many types of cells. Direct current electric fields (dc (EF) induced directional cell migration in a wide variety of cells. Here nHDFs migrated toward cathode under 1 V/cm dc EF, however 1 µM of brefeldin A (BFA) inhibited the dc EF induced directional migration. BFA (1 µM) did not cause the complete Golgi dispersal for 2 h. When the Golgi polarization maintained their direction of polarity, the direction of cell migration also kept toward the same direction of the Golgi polarization even though the dc EF was reversed. In this study, the importance of the Golgi polarization in the directional migration of nHDf under dc EF was identified.

Ethyl-3,4-dihydroxybenzoate with a dual function of induction of osteogenic differentiation and inhibition of osteoclast differentiation for bone tissue engineering.

The current approach in biomaterial design of bone implants is to induce in situ regeneration of bone tissue, thus improving integration of the implants and reducing their failure. Therefore, ethyl-3,4-dihydroxybenzoate (EDHB), which stimulates differentiation of osteoblasts and the resultant bone formation, should be studied. In this study, the osteoinductive ability of EDHB in preosteoblasts and human mesenchymal stem cells was examined. EDHB for future use in bone tissue engineering was evaluated by examination of early markers of differentiation (such as alkaline phosphatase [ALP] activity and collagen type I expression) and late markers of osteoblast differentiation (bone nodule formation). As bone remodeling and implant osteointegration depend not only on osteoblast response but also on interaction of the biomaterial with bone-resorbing osteoclasts, differentiation of osteoclasts in response to the compounds was also observed. For in vivo study, alginate gel comprised of EDHB and cells was transplanted into the back subcutis of mice. Our results show that EDHB might have beneficial effects through regulation of both osteoblast and osteoclast differentiation. Therefore, we suggest that EDHB could be a strong candidate for dual regulation to increase osteoblast differentiation and decrease osteoclast differentiation.