The effect of supplementing the calcium phosphate cement containing poloxamer 407 on cellular activities

Calcium phosphate cement (CPC) is generally used for bone repair and augmentation. Poloxamers are tri-block copolymers that are used as surfactants but have applications in drug and antibiotic delivery. However, their biological effects on bone regeneration systems remain unelucidated. Here, we aimed to understand how supplementing the prototype CPC with poloxamer would impact cellular activity and its function as a bone-grafting material. A novel CPC, modified beta-tricalcium phosphate (mβ-TCP) powder, was developed through a planetary ball-milling process using a beta-tricalcium phosphate (β-TCP). The mβ-TCP dissolves rapidly and accelerates hydroxyapatite precipitation; successfully shortening the cement setting time and enhancing the strength. Furthermore, the addition of poloxamer 407 to mβ-TCP could reduce the risk of leakage from bone defects and improve fracture toughness while maintaining mechanical properties. In this study, the poloxamer addition effects (0.05 and 0.1 g/mL) on the cellular activities of MC3T3-E1 cells cultured in vitro were investigated. The cell viability of mβ-TCP containing poloxamer 407 was similar to that of mβ-TCP. All specimens showed effective cell attachment and healthy polygonal extension of the cytoplasm firmly attached to hydroxyapatite (HA) crystals. Therefore, even with the addition of poloxamer to mβ-TCP, it does not have a negative effect to osteoblast growth. These data demonstrated that the addition of poloxamer 407 to mβ-TCP might be considered a potential therapeutic application for the repair and regeneration of bone defects.

2-methacryloyloxyethyl phosphorylcholine polymer treatment prevents Candida albicans biofilm formation on acrylic resin

PURPOSE

We aimed to evaluate the effectiveness of photoreactive 2-methacryloyloxyethyl phosphorylcholine (MPC) in inhibiting Candida albicans biofilm formation on polymethyl methacrylate (PMMA) and assess its mechanism and need for re-application by evaluating its interaction with salivary mucin and durability during temperature changes.

METHODS

PMMA discs were used as specimens. The MPC coating was applied using the spray and cure technique for the treatment groups, whereas no coating was applied to the control. The MPC treatment (MT) groups were further differentiated based on the number of thermal cycles involved (0, 1000, 2500, and 5000). The optical density was measured to assess mucin adsorption (MA). Contact angle (CA) was calculated to evaluate surface hydrophilicity. The presence of MPC components on the PMMA surface was assessed using X-ray photoelectron spectroscopy (XPS). C. albicans biofilms were evaluated qualitatively (scanning electron microscope images) and quantitatively (colony-forming units (CFUs)). Statistical analysis was conducted using two-way analysis of variance and Tukey's multiple comparison test.

RESULTS

MA rate and CA increased significantly in the MT groups, which exhibited significantly fewer CFUs and thinner biofilms than those of the control group. Based on the XPS, MA, and CFU evaluations, the durability and efficacy of the MPC coating were considered stable up to 2500 thermal cycles. Additionally, a significant interaction was observed between mucin concentration and MPC efficacy.

CONCLUSIONS

The photoreactive MPC coating, which was resistant to temperature changes for approximately 3 months, effectively prevented C. albicans biofilm formation by modifying surface hydrophilicity and increasing mucin adsorption.

Effects of poloxamer additives on strength, injectability, and shape stability of beta-tricalcium phosphate cement modified using ball-milling

A new CPC was developed in this study using a β-TCP powder mechano-chemically modified by ball-milling. The prototype CPC exhibits excellent fluidity for easy injection into bone defects; however, there is a risk of leakage from the defects immediately after implantation due to its high fluidity. The addition of poloxamer, an inverse thermoresponsive gelling agent, into CPC optimizes the fluidity. At lower temperatures, it forms a sol and maintains good injectability, whereas at the human body temperature, it transforms to a gel, reducing the fluidity and risk of leakage. In this study, the effects of poloxamer addition of 3, 5, and 10 mass% on the injectability, shape stability, and strength of the prototype CPC were evaluated. The calculated injectability of the prototype CPC pastes containing three different poloxamer contents was higher than that of the CPC paste without poloxamer for 15 min at 37 °C. Furthermore, the shape stability immediately after injection of the three CPC pastes with poloxamer was higher than that of the CPC paste without poloxamer. After 1 week of storage at 37 °C, the compressive strength and diametral tensile strength of the CPC compacts containing 10 mass% poloxamer were similar to those of the CPC compact without poloxamer. Additionally, the CPC compacts containing 10 mass% poloxamer exhibited clear plastic deformation after fracture. These results indicate that the addition of poloxamer to the prototype CPC could reduce the risk of leakage from bone defects and improve the fracture toughness with maintaining the injectability and strength.

Effect of immersion in NaCl solution on the electrical conductivity and the reduction of the shear bond strength of resin-modified glass-ionomer-cements after current application

Advancements in dental cements have considerably improved their bond strengths. However, high bond strength often makes the removal of restorations difficult. Thus, smart dental cements that show controllable bond strength are required. A conventional resin-modified glass-ionomer-cement demonstrated a significant reduction in the bond strength after current application. However, for this system, the ions in the cement are released into the oral cavity, resulting in a reduction of the electrical conductivity and in losses of the expected on-demand debonding property. Herein, the effects of immersion in 0.9 and 15% NaCl solutions on the electrical conductivity and debonding properties were investigated. The cement immersed in 0.9% NaCl solution from 1 to 28 days maintained similar bond strength reductions after current application, whereas that in 15% NaCl solution initially showed no bond strength reduction after 1 day but exhibited an increase in the bond strength reduction after immersion for 28 days.

Dentin-Pulp Complex Tissue Regeneration via Three-Dimensional Cell Sheet Layering

The dentin-pulp complex is a unique structure in teeth that contains both hard and soft tissues. Generally, deep caries and trauma cause damage to the dentin-pulp complex, and if left untreated, this damage will progress to irreversible pulpitis. The aim of this study was to fabricate a layered cell sheet composed of rat dental pulp (DP) cells and odontogenic differentiation of pulp (OD) cells and to investigate the ability to regenerate the dentin-pulp complex in a scaffold tooth. We fabricated two single cell sheets composed of DP cells (DP cell sheet) or OD cells (OD cell sheet) and a layered cell sheet made by layering both cells. The characteristics of the fabricated cell sheets were analyzed using light microscopy, scanning electron microscope (SEM), hematoxylin-eosin (HE) staining, and immunohistochemistry (IHC). Furthermore, the cell sheets were transplanted into the subrenal capsule of immunocompromised mice for 8 weeks. After this, the regenerative capacity to form dentin-like tissue was evaluated using micro-computed tomography (micro-CT), HE staining, and IHC. The findings of SEM and IHC confirmed that layered cell sheets fabricated by stacking OD cells and DP cells maintained their cytological characteristics. Micro-CT of layered cell sheet transplants revealed a mineralized capping of the access cavity in the crown area, similar to that of natural dentin. In contrast, the OD cell sheet group demonstrated the formation of irregular fragments of mineralized tissue in the pulp cavity, and the DP cell sheet did not develop any hard tissue. Moreover, bone volume/tissue volume (BV/TV) showed a significant increase in hard tissue formation in the layered cell sheet group compared with that in the single cell sheet group (p < 0.05). HE staining also showed a combination of soft and hard tissue formation in the layered cell sheet group. Furthermore, IHC confirmed that the dentin-like tissue generated from the layered cell sheet expressed characteristic markers of dentin but not bone equivalent to that of a natural tooth. In conclusion, this study demonstrates the feasibility of regenerating dentin-pulp complex using a bioengineered tissue designed to simulate the anatomical structure. Impact statement The dentin-pulp complex can be destroyed by deep caries and trauma, which may cause pulpitis and progress to irreversible pulpitis, apical periodontitis, and even tooth loss. Current treatments cannot maintain pulp health, and teeth can become brittle. We developed a three-dimensional (3D) layered cell sheet using dental pulp cells and odontogenic differentiation of pulp cells for dentin-pulp complex regeneration. Our layered cell sheet enables the regeneration of an organized 3D dentin-pulp-like structure comparable with that of natural teeth. This layered cell sheet technology may contribute to dentin-pulp complex regeneration and provide a novel method for complex tissue engineering.

Effects of water immersion on shear bond strength reduction after current application of resin-modified glass-ionomer-cements with and without an ionic liquid

The enhancement in the bonding strength of advanced dental cements has enabled long-lasting dental restorations. However, the high bonding strength can cause difficulty in removing these restorations. Therefore, "smart" dental cements with simultaneous strong bonding and easy on-demand debonding ability are required. A resin-modified glass-ionomer-cement (RMGIC) with an ionic liquid (IL) has demonstrated significant reduction in the bonding strength with current application (CA). This research investigates the effect of immersion in distilled water on the electric conductivity and bonding strength of RMGIC with and without an IL and CA. The RMGIC without the IL exhibited significant electric conductivity after immersion, and a significant decrease in bonding strength with CA. In comparison, the electric conductivity after immersion and the decrease in bonding strength with CA were greater for RMGIC with the IL. Thus, the feasibility of smart dental cements capable of electrically debonding-on-demand is indicated.

Electrical shear bonding strength reduction of resin-modified glass-ionomercement containing ionic-liquid: Concept and validation of a smart dental cement debonding-on-demand

With improvement of bonding strength of recent dental cement, it is difficult nowadays to remove restorations without excessive force or vibration to tooth, occasionally resulting in damage of dentin, enamel, and dental root. Therefore, "smart" dental cement indicating strong bonding and easy debonding-on-demand simultaneously is required. In this research, resin-modified glass-ionomer-cement containing an ionic-liquid, tris(2-hydroxyethyl)methylammonium methylsulfate was produced, and the shear bonding strength before and after direct current application were evaluated. The prototype cement containing 15 to 20 mass% ionic-liquid indicated simultaneously no significant reduction of shear bonding strength from that of the original cement not containing ionic-liquid, and significant reduction of bonding strength to approximately 20% of that of the original cement after direct current application of more than 2 mmC/mm². The prototype cement in this research demonstrated that the concept of smart dental cement electrically debonding-on-demand is feasible.

Effects of powder-to-liquid ratio on properties of β-tricalcium-phosphate cements modified using high-energy ball-milling

The authors have developed a β-tricalcium-phosphate (β-TCP) powder modified mechano-chemically through the application of a ball-milling process (mβ-TCP). The resulting powder can be used in a calcium-phosphate-cement (CPC). In this study, the effects of the powder-to-liquid ratio (P/L ratio) on the properties of the CPCs were investigated, and an appropriate P/L ratio that would simultaneously improve injectability and strength was clarified. The mβ-TCP cement mixed at a P/L ratio of 2.5 and set in air exhibited sufficient injectability until 20 min after mixing, and strength similar to or higher than that mixed at a P/L ratio of 2.0 and 2.78. Although the mβ-TCP cements set in vivo and in SBF were found to exhibit a lower strength than those set in air, it did have an appropriate setting time and strength for clinical applications. In conclusion, P/L ratio optimization successfully improved the strength of injectable mβ-TCP cement.

Bone Ingrowth to Ti Fibre Knit Block with High Deformability

Objectives

The objective of this study is to develop a Ti fibre knit block without sintering, and to evaluate its deformability and new bone formation in vivo.

Material and Methods

A Ti fibre with a diameter of 150 μm was knitted to fabricate a Ti mesh tube. The mesh tube was compressed in a metal mould to fabricate porous Ti fibre knit blocks with three different porosities of 88%, 69%, and 50%. The elastic modulus and deformability were evaluated using a compression test. The knit block was implanted into bone defects of a rabbit’s hind limb, and new bone formation was evaluated using micro computed tomography (micro-CT) analysis and histological analysis.

Results

The knit blocks with 88% porosity showed excellent deformability, indicating potential appropriateness for bone defect filling. Although the porosities of the knit block were different, they indicated similar elastic modulus smaller than 1 GPa. The elastic modulus after deformation increased linearly as the applied compression stress increased. The micro-CT analysis indicated that in the block with 50% porosity new bone filled nearly all of the pore volume four weeks after implantation. In contrast, in the block with 88% porosity, new bone filled less than half of the pore volume even 12 weeks after implantation. The histological analysis also indicated new bone formation in the block.

Conclusions

The titanium fibre knit block with high porosity is potentially appropriate for bone defect filling, indicating good bone ingrowth after porosity reduction with applied compression.

Bone ingrowth of various porous titanium scaffolds produced by a moldless and space holder technique: an in vivo study in rabbits

Porous titanium has long been desired as a bone substitute material because of its ability to reduce the stress shielding in supporting bone. In order to achieve the various pore structures, we have evolved a moldless process combined with a space holder technique to fabricate porous titanium. This study aims to evaluate which pore size is most suitable for bone regeneration using our process. The mixture comprising Ti powder, wax binder and PMMA spacer was prepared manually at 70 °C which depended on the mixing ratio of each group. Group 1 had an average pore size of 60 μm, group 2 had a maximum pore size of 100 μm, group 3 had a maximum pore size of 200 μm and group 4 had a maximum pore size of 600 μm. These specimens were implanted into rabbit calvaria for three and 20 weeks. Thereafter, histomorphometrical evaluation was performed. In the histomorphometrical evaluation after three weeks, the group with a 600 μm pore size showed a tendency to greater bone ingrowth. However, after 20 weeks the group with a pore size of 100 μm showed significantly greater bone ingrowth than the other groups. This study suggested that bone regeneration into porous titanium scaffolds is pore size-dependent, while bone ingrowth was most prominent for the group with 100 μm-sized pores after 20 weeks in vivo.

Silver-catalyzed carboxylation

The recent studies of the silver-catalyzed carboxylation reactions using carbon dioxide are described.

Natural history of bleeding risk in colonic diverticulosis patients: a long-term colonoscopy-based cohort study

BACKGROUND

The natural history of bleeding risk from colonic diverticulosis remains unclear.

AIM

To identify the incidence of bleeding in colonic diverticulosis patients and associated risk factors.

METHODS

A cohort of 1514 patients with colonoscopy-confirmed asymptomatic diverticulosis was selected between 2001 and 2013. Age, sex and location of colonic diverticulosis (right or left side, or bilateral) were assessed. The endpoint was a bleeding event, and data were censored at the time of last colonoscopy. The cumulative and overall incidences of bleeding were estimated using the Kaplan-Meier and person-years methods. The Cox proportional hazards model was used to estimate age- and sex-adjusted hazard ratios (aHRs).

RESULTS

The median follow-up period was 46 months. Bleeding events occurred in 35 patients, and the median time-to-event interval was 50 months. Kaplan-Meier analysis showed that the cumulative incidence of diverticular bleeding was 0.21% at 12 months, 2.2% at 60 months and 9.5% at 120 months. By the person-years method, the overall incidence rate of bleeding was 0.46 per 1000 patient-years. On multivariate analysis, age ≥70 (aHR. 3.7) and bilateral diverticulosis (aHR, 2.4) were significant risk factors for bleeding.

CONCLUSIONS

This long-term follow-up study demonstrated that the cumulative incidence of bleeding from diverticulosis was approximately 2% at 5 years and 10% at 10 years, and the overall incidence was 0.46 per 1000 patient-years. Bilateral diverticulosis increased the risk of bleeding.

Evidence of a sophisticatedly heterogeneous population of human umbilical vein endothelial cells

Induction and promotion of angiogenesis play a role in a diverse range of physiologic and pathophysiologic processes that are especially relevant to the field of regenerative medicine. For assessing vasculogenesis and neo-angiogenesis, identifying angiogenic factors, angiocrine factors, and vascular niche, facilitating tissue-repair and tumor growth, efficiently generating induced pluripotent stem cells, and coculturing with organ-specific stem cells, isolation and characterization of the subpopulation of human umbilical vein endothelial cells (HUVECs) and their endothelial progenitor cells (EPCs) are needed. In this study, primary HUVECs were collected from fresh umbilical cords and fractionated and characterized with the use of flow cytometry. Clonal colony assay showed that endothelial colony-forming units in culture frequently existed in fresh HUVECs. Antigenic profiling demonstrated that undifferentiated EPCs in HUVECs had normal endothelial marker CD31 with a subpopulation of cells positive for hematopoietic stem cell marker CD34 and c-Kit. With continuing passages, EPC markers CD34 and vascular endothelial growth factor receptor 2 expression decreased dramatically. Moreover, a distinct subpopulation with different proliferative capability and angiogenesis from the early-passage HUVECs was shown. In conclusion, it is possible to isolate accurately and to enrich EPCs or hematoangioblast-like cells from a heterogeneous population of HUVECs, and to explore the differential process with flow cytometry for further investigations.

Fluorescent labeling and visualization of human induced pluripotent stem cells with the use of transcription activator-like effector nucleases

BACKGROUND

The visualization of induced pluripotent stem (iPS) cells with the use of fluorescent techniques is useful for the in vivo evaluation of iPS-derived functional cells following differentiation and distribution of the transplanted cells. The data obtained from the fluorescently labeled iPS cells would lead to amelioration and validation of protocols directing the differentiation of iPS cells into functional cells. In this study, we established enhanced green fluorescent protein (EGFP)-labeled iPS cells to enable their easy visualization.

METHODS

Human iPS cells were transfected with (a) 2 transcription activator-like effector nuclease (TALEN) vectors targeted to the adeno-associated virus integration site 1 (AAVS1) locus and (b) the targeting vector carrying the homology arms, EGFP gene, and a drug-selection marker.

RESULTS

Several puromycin-resistant clones were obtained after transfection of the targeting vector and corresponding TALEN-expressing vectors. EGFP expression in these clones was observed with the use of a fluorescent microscope. Clones were examined for specific recombination, which revealed precise targeting at the AAVS1 locus. Furthermore, EGFP protein expression was sustained after directed differentiation into a hepatic lineage.

CONCLUSIONS

We were successful in evaluating the behavior of iPS-derived hepatic cells. The data suggest that genomic knock-in at the AAVS1 locus is suitable for long-term observation of iPS-derived cells. Manipulation of the iPS genome can also be applied for the purification of hepatic cells during iPS cell differentiation by introducing the fluorescent protein under the regulation of a hepatic cell-specific promoter. Another application involves gene correction of iPS cells from patients with hepatic disease for regenerative medicine.

Identification of proliferating human hepatic cells from human induced pluripotent stem cells

Mass-scale production of hepatocytes from human induced pluripotent stem cells (iPSCs) with functional properties of primary hepatocytes is of great value in clinical transplantation for liver failure as well as in facilitating drug development by predicting humanized drug metabolism profiles. In this report, we generated human hepatocyte-like cells from human iPSCs with the use of a stepwise protocol. Aiming at future clinical and industrial application, it is important to determine the suitable stage of iPSC-derived hepatic cells that possess high proliferative capacity to intensively expand the hepatic cells. Ki67 immunostaining showed that human iPSC-derived hepatic endoderm cells contained Ki67(+) cells at the highest level in the middle stage of hepatic differentiation, suggesting that the abundance of proliferating hepatic progenitor cells exists in this stage. Extensive expansion and differentiation of human iPSC-derived hepatic progenitors will provide future perspectives in transplantation therapy and drug development.

Diagnostic performance of plasma biomarkers in patients with acute intestinal ischaemia

BACKGROUND

The aim of this study was to evaluate the use of intestinal fatty acid binding protein (I-FABP) and traditional biomarkers in the early diagnosis of acute intestinal ischaemia of different causes.

METHODS

I-FABP, white blood cell (WBC) count, C-reactive protein, base deficit, lactate, lactate dehydrogenase, aspartate aminotransferase, creatine kinase and D-dimer were measured prospectively in consecutive patients suspected of having acute intestinal ischaemia. Biomarker levels were compared in patients with vascular and non-vascular ischaemia.

RESULTS

Two hundred and eight patients with a clinical suspicion of acute intestinal ischaemia were enrolled. Vascular intestinal ischaemia was diagnosed in 24 patients (11·5 per cent), non-vascular ischaemia in 62 (29·8 per cent) and non-ischaemic disease in 122 (58·7 per cent). The levels of most biomarkers (except WBC count and creatine kinase) were significantly higher in the vascular ischaemia group than in the other groups (P < 0·010). However, none of the biomarker levels differed between patients with non-vascular intestinal ischaemia and those with non-ischaemic disease. Receiver operating characteristic (ROC) curve analysis suggested that I-FABP was best at diagnosing vascular intestinal ischaemia (area under the curve 0·88).

CONCLUSION

Serum biomarkers may be useful in the diagnosis of vascular, but not non-vascular, intestinal ischaemia. Among them, I-FABP shows promise for detecting vascular ischaemia.

Bovine milk contains microRNA and messenger RNA that are stable under degradative conditions

We previously reported that microRNA (miRNA) is present in human breast milk. Recently, other groups have reported that bovine milk also contains miRNA; however, these reports are few. We therefore investigated bovine milk miRNA using microarray and quantitative PCR analyses to identify the differences between colostrum and mature milk. The RNA concentration in a colostrum whey fraction was higher than that in a mature milk whey fraction. In total, 102 miRNA were detected in bovine milk by microarray analysis (100 in colostrum and 53 in mature milk; 51 were common to both). Among these miRNA, we selected several immune- and development-related miRNA, including miR-15b, miR-27b, miR-34a, miR-106b, miR-130a, miR-155, and miR-223. These miRNA were detected in bovine milk by quantitative PCR, and each of these miRNA was significantly more highly expressed in colostrum than in mature milk. We also confirmed the presence of some mRNA in bovine milk. Nevertheless, synthesized miRNA spiked in the raw milk whey were degraded, and naturally existing miRNA and mRNA in raw milk were resistant to acidic conditions and RNase treatment. The RNA molecules in milk were stable. We also detected miRNA and mRNA in infant formulas purchased from Japanese markets. It is still unknown whether milk-derived RNA molecules play biological roles in infants; however, if milk-derived RNA do show functions in infants, our data will help guide future studies.

Evaluation of strontium introduced apatite cement as the injectable bone substitute developments

We have developed bone cement introducing Strontium (Sr) to promote early bone regeneration. To prolong the release duration of Sr, we applied inorganic Sr filler for containing into the cement powder. The purpose of this study is to evaluate the mechanical properties, crystallinic properties, and ion release activities, especially Sr anion, of this cement. Alpha-TCP powder was mixed with Sr filler, with 0.1wt%, 0.5wt%, 1.0wt%, and 5.0wt%. These were mixed with mixing liquid and formed for each test. They were incubated and crystalized in 95% moisture for 1 week. The mechanical properties were studied by the compression, the diametral tensile strength and 4-point vending. Tested specimens were evaluated by X-ray diffraction(XRD) and scanning electron microscopic(SEM) imaging. The ion release behaviors were measured by inductively coupled plasma mass spectrometry(ICP-MS). The mechanical properties were increased in consistency of filler, but decreased in some samples because of declining the apatite matrix. And the Sr release showed interesting results as the sequential resource of Sr. By adjusting the mixing ratio or considering the application of these Sr releasable cements, this material would show good performance by its strength and longer Sr release for bone regeneration.

Highly efficient generation of definitive endoderm lineage from human induced pluripotent stem cells

BACKGROUND

Although hepatocytes can be an option for liver transplantation, the shortage of donor organs continues to worsen. Since the development of induced pluripotent stem (iPS) cell technology, it is eagerly anticipated to produce functional elements from pluripotent stem cells. These functional cells differentiated from iPS cells could be used for transplantation, drug screening, and in vitro toxicology.

METHODS

Human iPS cells are maintained on Mitomycin C-treated mouse embryonic fibroblast layers in DMEM-Ham F12-based medium supplemented with Knockout Serum Replacement, nonessential amino acids, 2-mercaptoethanol, and Glutamax. Differentiation of human iPS cells into a definitive endodermal lineage was induced with PRMI 1640 medium supplemented with B27 and 100 ng/mL human activin A. Two B27 supplements were examined with and without insulin. Furthermore, the PI3 kinase inhibitor LY294002 was used to examine the effect of inhibiting insulin signaling.

RESULTS AND DISCUSSION

We established efficient induction of definitive endodermal differentiation from iPS cells. Quantitative analysis revealed efficient (93.03 ± 2.74%) differentiation of human iPS cells into definitive endoderm cells using B27 minus insulin. This protocol may contribute as a fundamental technique to promote human iPS studies to develop cellular sources for transplantation.

Self-organization of human hepatic organoid by recapitulating organogenesis in vitro

BACKGROUND

Careful orchestration among endodermal epithelial, endothelial, and mesenchymal cells initiate liver organogenesis prior to vascular function. Nonparenchymal endothelial or mesenchymal cells not only form passive conduits, but also establish an organogenic stimulus. Herein, we have evaluated the potential roles of primitive endothelial and mesenchymal cells toward hepatic organization in vitro.

METHODS

To track the cellular movements and localization, we retrovirally transduced enhanced green fluorescence protein and kusabira orange into human fetal liver cells (GFP-hFLCs) and human umbilical vein endothelial cells (KO-HUVECs), respectively. GFP-hFLCs were cocultivated with KO-HUVECs and human mesenchymal stem cells (hMSCs) under conventional two-dimensional (2D) conditions.

RESULTS

Even under 2D culture, fetal liver, endothelial, and mesenchymal cells self-organized into a macroscopically visible three-dimensional (3D) organoid. Time-lapse confocal imaging showed dynamic cellular organizations of GFP-hFLCs and KO-HUVECs. Endothelial cells organized into patterned clusters wrapping fetal liver cells, forming vessel-like lumens inside. Mesenchymal cells supported the generated organoid from outside.

CONCLUSION

Generation of whole organ architecture remains a great challenge so far. Our preliminary results showed that recapitulation of primitive cellular interactions during organogenesis elicit the intrinsic self-organizing capacity to form hepatic organoids. Future studies to define precise conditions mimicking organogenesis may ultimately lead to the generation of a functional liver for transplantation and for other applications such as drug development.

Generation of functional human vascular network

BACKGROUND

One of the major obstacles in regenerating thick, complex tissues such as the liver is their need for vascularization, which is essential to maintain cell viability during tissue growth and to induce structural organization. Herein, we have described a method to engineer a functional human vascular network.

METHODS

Enhanced green fluorescence protein-labeled human umbilical vein endothelial cells (GFP-HUVECs) were cocultivated with kusabira orange-labeled human mesenchymal stem cells (KO-hMSCs) inside a collagen/fibronectin matrix. Premature vascular network formation was visualized by fluorescence microscopy imaging. Furthermore, constructs prevascularized in vitro were implanted into a transparency window in immunodeficient mice.

RESULTS

Following several days of cultivation, GFP-HUVECs formed vessel-like structures that were stabilized by pericytes differentiated from KO-hMSCs. After implantation in vivo, the patency of human vascular structures was proved by rhodamine dextran infusion. These functional vascular structures remained for over 2 months.

DISCUSSION

Vascularization is the key challenge to organ generation. We successfully generated human vascular networks inside a matrix. Integration of parenchymal cells using our engineering technique should facilitate future efforts to reconstitute vascularized human organ systems in vitro.

A Novel Method for Obtaining a High Performance Carbon Anode for Li-Ion Secondary Batteries

Entire surfaces of the pitch-based well graphitized and poorly graphitized carbon fibers were covered with an evaporated metallic film of Au, Ag, Sn, or Zn, whose thickness was varied from 100 to 600 Å. Li dope and undope characteristics as the anode of Li-ion secondary battery were compared for the samples with and without evaporated film. Not only high rate charge/discharge characteristics but cycleability have been realized to be improved remarkably for the sample whose surface was covered with a thin metal film.

Effects of Milk Casein-derived Peptides on Absolute Oxyhaemoglobin Concentrations in the Prefrontal Area and on Work Efficiency after Mental Stress Loading in Male Students

This study examined the influence of milk casein-derived peptides on cerebral activity after mental stress loading. In a crossover study, 16 male students were given a drink containing peptides (peptide group), or water (control group) before stress loading. The oxyhaemoglobin (HbO2) concentration in the prefrontal area of the brain and work efficiency were measured as indicators of cerebral activity and differences in these parameters were examined according to type A or type B personality. Type A behaviour was defined as: aggression–hostility, hard-driving—time-urgency and speed–power, whereas type B behaviour did not have these characteristics. Peptide intake resulted in a significant increase in both HbO2 concentration and work efficiency, whilst a similar increase was not seen in the control group. When divided into type A or type B personality, the changes in HbO2 concentration for the control group differed significantly in the right prefrontal area. Moreover, in type A subjects the HbO2 concentration in the right prefrontal area following intake was significantly different between the peptide and control groups.

Application of a magnetic fluid seal to rotary blood pumps

A magnetic fluid seal enables mechanical contact-free rotation of a shaft without frictional heat and material wear and hence has excellent durability. However, the durability of a magnetic fluid seal decreases in liquid. The life of a seal applied to a rotary blood pump is not known. We have developed a magnetic fluid seal that has a shield mechanism minimizing the influence of the rotary pump on the magnetic fluid. The developed magnetic fluid seal worked for over 286 days in a continuous flow condition, for 24 days (on-going) in a pulsatile flow condition and for 24 h (electively terminated) in blood flow. The magnetic fluid seal is promising as a shaft seal for rotary blood pumps.

Biochemical evaluation of an artificial anal sphincter made from shape memory alloys

Severe anal incontinence is a socially incapacitating disorder and a major unresolved clinical problem that has a considerable negative impact on quality of life. In this study, we developed a new artificial anal sphincter using shape memory alloys (SMAs) in order to improve the quality of life of such patients and evaluated the influence of this sphincter on blood serum chemistry in animal experiments. The artificial anal sphincter was driven by two Ti-Ni SMA actuators sandwiching the intestine and was implanted in three female goats. Blood was collected from the jugular vein on days 1 and 4; at weeks 1 and 2; and at months 1, 2, and 3, postoperatively. Biochemical parameters including total protein, albumin, total bilirubin, aspartate amino-transferase, blood urea nitrogen, creatinine, and C-reactive protein were examined. The time courses of total bilirubin and aspartate amino transferase of the three goats were within the baseline levels after 1 week of implantation and remained normal, demonstrating no liver function complications. The blood urea nitrogen and creatinine levels remained within the normal range, indicating no renal function complications. The total protein and albumin fluctuated within the normal range throughout the duration of this study. In these goats, it was also found that the level of C-reactive protein did not increase and that there was no stricture of the intestine where the artificial sphincter was attached. Our findings indicate that the artificial sphincter SMA demonstrated no adverse influence on blood serum chemistry and exhibited an effective system performance.

A Hydrodynamically Suspended, Magnetically Sealed Mechanically Noncontact Axial Flow Blood Pump: Design of a Hydrodynamic Bearing

To overcome the drive shaft seal and bearing problem in rotary blood pumps, a hydrodynamic bearing, a magnetic fluid seal, and a brushless direct current (DC) motor were employed in an axial flow pump. This enabled contact-free rotation of the impeller without material wear. The axial flow pump consisted of a brushless DC motor, an impeller, and a guide vane. The motor rotor was directly connected to the impeller by a motor shaft. A hydrodynamic bearing was installed on the motor shaft. The motor and the hydrodynamic bearing were housed in a cylindrical casing and were waterproofed by a magnetic fluid seal, a mechanically noncontact seal. Impeller shaft displacement was measured using a laser sensor. Axial and radial displacements of the shaft were only a few micrometers for motor speed up to 8500 rpm. The shaft did not make contact with the bearing housing. A flow of 5 L/min was obtained at 8000 rpm at a pressure difference of 100 mm Hg. In conclusion, the axial flow blood pump consisting of a hydrodynamic bearing, a magnetic fluid seal, and a brushless DC motor provided contact-free rotation of the impeller without material wear.

Development of an Artificial Myocardium using a Covalent Shape-memory Alloy Fiber and its Cardiovascular Diagnostic Response

The authors have been developing a newly-designed totally-implantable artificial myocardium using a covalent shape-memory alloy fibre (Biometal&#174;, Toki Corporation), which is attached onto the ventricular wall and is also capable of supporting the natural ventricular contraction. This mechanical system consists of a contraction assistive device, which is made of Ti-Ni alloy. And the phenomenon of the martensitic transformation of the alloy was employed to achieve the physiologic motion of the device. The diameter of the alloy wire could be selected from 45 to 250&#956;m. In this study, the basic characteristics of the fiber of 150&#956;m was examined to design the sophisticated mechano-electric myocardium. The stress generated by the fiber was 400gf under the pulsatile driving condition (0.4W, 1Hz). Therefore it was indicated that the effective assistance might be achieved by using the Biometal shape-memory alloy fiber.

An innovative approach to evaluate a cardiac function based on surface measurement

Major function of the heart is to pump blood flow up to all tissues or organs in the body, and it is generally recognized that cardiac function under various diseased conditions are mainly represented by a relationship between blood flow and pressure inside of the heart. In this report, an original proposal of evaluation method on cardiac function is introduced through a simultaneous measurement of various points of cardiac muscular surface. An optical three-dimensional location sensor was employed to measure a displacement change of anatomically specific points on heart surface. Then, changes in strain in each regional surface area were quantitatively obtained. This result indicated similar tendency obtained from echocardiogram. It was also indicated that there was a difference in displacements and phrases between control and arrhythmia. Moreover, strain change in regional area was coincident with a contraction of natural heart. It was found that an attempt to superimpose the data of strain change onto the video images of natural heart was extremely helpful to understand a cardiac function visually.

Impact of Type A Behavior on Brachial-Ankle Pulse Wave Velocity in Japanese

Pulse wave velocity (PWV) is the velocity of a pulse wave traveling a given distance between 2 sites in the arterial system, and is a well-known indicator of arteriosclerosis. Brachial-ankle PWV (baPWV) is a parameter more simple to obtain, compared with the conventional PWV, and is an easy and effective means of evaluating arteriosclerosis. BaPWV can be obtained by only wrapping the four extremities with blood pressure cuffs, and it can be easily used to screen a large number of subjects. Type A behavior has been confirmed as an independent risk factor for the development of coronary heart disease. To examine the relationship between Type A behavior and arteriosclerosis, 307 normal Japanese subjects were classified into either a Type A group (n = 90) or a non-Type A group (n = 217) by using Maeda's Type A Scale. BaPWV was evaluated using a PWV diagnosis device. The baPWV in the Type A group was significantly higher than that obtained in the non-Type A group. The baPWV showed a positive correlation with age both in the Type A group and in the non-Type A group; however, the straight-line regression slope of baPWV versus age in the Type A group was significantly larger than that in the non-Type A group. Therefore, our results suggest that arteriosclerosis might be promoted earlier in subjects expressing the Type A behavior pattern. Type A behavior pattern is confirmed as a risk factor for arteriosclerosis, and may increase the risk of the cardiovascular disease related to arteriosclerosis.

Evaluation of cardiac function based on ventricular pressure-volume relationships during assistance with a rotary blood pump

Nowadays, a rotary blood pump can be used as not only for a bridge to transplantation (BTT) but also for a bridge to recovery (BTR) and a destination therapy (DT). In such cases, evaluation of the recovery level of the native heart provides useful information to improve the clinical strategy and decide adequate timing for removing of the RBP. In contrast, the indices for cardiac function have been studied. However, most of them do not consider the assistance with the RBP. In this study, we aimed at evaluating whether Emax, which is an index for cardiac function based on the pressure-volume relationships, is still valid during assistance with the RBP from an animal experiment. In the acute animal experiment with an adult goat, we measured pressure-volume (P-V) loops while cardiac function was normal, augmented or diminished. The experimental results revealed that there were typical differences in the shapes of P-V loops when the cardiac function was altered, and Emax can still be used as an index for the cardiac function even if the assistance with the RBP is ongoing.

Comparison of brachial-ankle pulse wave velocity in Japanese and Russians

Pulse wave velocity (PWV) is a well-known indicator of arterial stiffness and a marker of the presence of vascular lesions. Cardiovascular mortality in Russia has become the highest in the world. The Japanese are enjoying long lives, and the mortality caused by cardiovascular diseases has thus far remained at lower levels than that in Russia. In this study, we focused on brachial-ankle pulse wave velocity (baPWV) obtained from normal human subjects in Russia as well as in Japan, and compared their respective cardiovascular risks. We evaluated baPWV in 337 Japanese and 138 Russian healthy subjects. The baPWV was recorded using a PWV diagnosis device. BaPWV was measured between 2 locations of the arterial tree. The baPWV in the Russian group was significantly higher than that obtained in the Japanese of two groups categorized by age (40-59 years and 60- years). Further, body mass index (BMI), systolic blood pressure (SBP) and diastolic blood pressure in the Russian group were significantly higher than those obtained in Japanese in three age groups (under 39 years, 40-59 years, and 60- years). Moreover, the baPWV indicated a positive correlation with age, BMI and SBP in both Japanese and Russians, although the increasing trend of the baPWV against age of the Russian group had a larger value than that of the Japanese. Therefore, we suggest that arterial stiffness might be promoted earlier in the Russian group, which might be the main cause of the increased cardiovascular risk in Russia.

Effect of the alternative magnetic stimulation on peripheral circulation for regenerative medicine

Regenerative medicine for patients with peripheral atherosclerosis attracts considerable attention around the world. However, ethical problems persist in gene therapy. This study evaluates the effect of alterative magnetic stimulation on peripheral circulation. The effect of magnetic stimulation as a medical treatment was examined using a thermograph for 11 healthy volunteers. The thermograph was used to measure the rise in skin temperature. The experimental results suggested an improvement in the peripheral circulation. The results of our study suggest the effectiveness of alternative magnetic stimulation on atherosclerosis. We intend to extend our study in order to establish a methodology for regenerative medical treatment for patients with peripheral atherosclerosis. Further, we wish to advance the current research in the field of angiogenesis.

Cardio-ankle vascular index (CAVI) for the monitoring of the atherosclerosis after heart transplantation

Atherosclerosis has been reported to progress rapidly after heart transplantation. A quantitative diagnosis is required for the diagnosis of atherosclerosis after heart transplantation. In this study, we compared brachial-ankle pulse wave velocity (baPWV) and cardio-ankle vascular index (CAVI) for the diagnosis. The average values of both baPWV and CAVI in the seven cases after heart transplantation were found to be signif-icantly large in comparison to the average values of the normal healthy people of the same age group. When comparisons were made before and after the heart transplantation in a particular case, CAVI was stable and baPWV changed sharply. A lot of parameters such as blood pressure, blood volume, etc. have been reported to influence baPWV. The results of this study suggested that CAVI was a stable parameter in comparison to baPWV even after heart transplantation. Thus, CAVI may be useful in the diagnosis of arteriosclerosis after heart transplantation.

Development of the Pulsation Device for Rotary Blood Pumps

A rotary blood pump (RP) is desirable as a small ventricular assist device (VAD). However, an RP is nonpulsatile. We tried to develop a device that attaches a pulse to the RP. We also tried to develop a pulse-generating equipment that was not air-pressure driven. The ball screw motor was considered a candidate. The application of a small-sized shape memory alloy was also attempted. An electrohydraulic system was adopted, and actuator power was connected to the diaphragm. The diaphragm was placed on the outer side of the ventricle. Most RPs that have been developed all over the world drain blood from the ventricle. The wave of a pulse should be generated if a pulse is added by the drawn part. The output assistance from the outer side of the ventricle was attempted in animal experiments, and the device operated effectively. This device can be used during implantable operation of RP. This may serve as an effective device in patients experiencing problems in peripheral circulation and in the function of internal organs.

Chaos analysis of electro encephalography and control of seizure attack of epilepsy patients

In order to evaluate the EEG of patients with epilepsy, chaos analysis was performed for the subdural EEG time series data. The chaos attractor was reconstructed in the phase space and the correlation dimension. KS entropy calculated from the Lyapunov exponents was evaluated. Before the seizure attack, the KS entropy showed a lower value when compared with the time series data recorded during healthy condition. The results of our study suggest that it is possible to predict the seizure attack by the chaos analysis of the EEG signal. Further, we aim at developing an automatic control system for predicting a seizure attack by the use of local cooling of the focus with Peltier elements.

Artificial esophagus with peristaltic movement

In this study, we have developed an artificial esophagus simulating peristaltic movement with the use of a nickel-titanium shape memory alloy (NiTi-SMA) actuator. Serial pairs of NiTi-SMAs were placed around a Gore-Tex vascular graft in a helical position such that they obliterated the lumen of the vessel when they contracted. In an animal experiment using a goat, the cervical esophagus was resected over a length of approximately 20 cm. The artificial esophagus was anastomosed with the remaining cervical esophagus. When a direct current of 500 mA at 5 V was applied to the NiTi-SMAs, the first pair of the NiTi-SMA contracted. The following pairs of the NiTi-SMAs contracted consecutively. The entire contraction of the artificial esophagus was similar to the esophageal peristaltic movement observed by x-ray examination in humans. The results showed the possibility that the artificial esophagus could function as an artificial esophagus having peristaltic movement.

Addition of rhythm to non-pulsatile circulation

The development of a rotary blood pump (RP) is desirable as it can be used as a small ventricular assistance device (VAD). However, a RP does not generate any pulse. It may be physiologically better for the patient if the RP could generate a pulse. We have attempted to develop a device that produces a pulse in the RP. Intra-aortic balloon pumping (IABP) is effective in producing a pulse. However, the IABP cannot be implanted inside the body. Therefore, an attempt was made to develop pulse-generating equipment that was not driven by air pressure. The ball screw motor was considered as a possible candidate. In the future, we plan to apply small shape memory alloys. An electrohydraulic system was adopted, and actuator power output was connected to the diaphragm. The diaphragm was placed outside the ventricle. Most RPs developed throughout the world drain blood from the ventricle. The pulse wave should be generated if a pulse is added by the part from which blood is being drawn. In this study, animal experiments were conducted and the output assistance was tested from outside the ventricle. The device operated effectively in the animal experiment. The RP can easily be equipped with this device at the time of performing the implant operation. For a patient with problems of peripheral circulation and the internal organ function, it may prove to be an effective device.

Natural course of the remission of vertigo in patients with benign paroxysmal positional vertigo

The authors assessed the natural course of benign paroxysmal positional vertigo (BPPV) in 108 patients who were not treated with canalith repositioning procedure. The average number of days from onset to remission of positional vertigo in patients with posterior canal BPPV (P-BPPV) (39 days) was longer than in those with horizontal canal BPPV (H-BPPV) (16 days). The ratio of patients with H-BPPV to those with BPPV was 33%.

Estimation of plasma and saliva levels of coenzyme Q10 and influence of oral supplementation

Coenzyme Q10 (CoQ(10)) levels in human saliva were measured by HPLC with a highly sensitive electrochemical detector (ECD) and a special concentration column. This HPLC system showed satisfactory analytical results within the standard range of 0.78-50 ng/ml. We also found a significant correlation between CoQ(10) levels in plasma and in saliva from parotid glands, while this correlation was lacking between plasma CoQ10 and CoQ10 in whole saliva. Unlike in plasma, there are some fluctuations of saliva CoQ(10) levels throughout the day. A good correlation was obtained by collecting parotid gland saliva at times between meals. The mean saliva CoQ(10) level for 55 healthy volunteers was 17.0 ng/ml (S.D. 6.8 ng/ml); approximately one fiftieth of that in plasma. Regarding the influence of oral supplementation, CoQ(10) was analyzed in plasma and parotid gland saliva from 20 healthy volunteers supplemented daily with 100 mg of CoQ(10) for the first week and 200 mg for the second. The plasma CoQ(10) levels of all volunteers increased to different extents in accordance with the CoQ(10) daily intake and the corresponding change in saliva showed almost the same trend.

Long term effects of exposure to automobile exhaust on the pulmonary function of female adults in Tokyo, Japan

AIMS

To investigate the chronic effects of air pollution caused mainly by automobiles in healthy adult females.

METHODS

Respiratory symptoms were investigated in 5682 adult females who had lived in the Tokyo metropolitan area for three years or more in 1987; 733 of them were subjected to pulmonary function tests over eight years from 1987 to 1994. The subjects were divided into three groups by the level of air pollution they were exposed to during the study period. The concentrations of nitrogen dioxide and suspended particulate matter were the highest in group 1, and the lowest in group 3.

RESULTS

The prevalence rates of respiratory symptoms in group 1 were higher than those in groups 2 and 3, except for wheezing. Multiple logistic regression analysis showed significant differences in persistent phlegm and breathlessness. The subjects selected for the analysis of pulmonary function were 94, 210, and 102 females in groups 1, 2, and 3, respectively. The annual mean change of FEV(1) in group 1 was the largest (-0.020 l/y), followed by that in group 2 (-0.015 l/y), and that in group 3 (-0.009 l/y). Testing for trends showed a significant larger decrease of FEV(1) with the increase in the level of air pollution.

CONCLUSIONS

The subjects living in areas with high levels of air pollution showed higher prevalence rates of respiratory symptoms and a larger decrease of FEV(1) compared with those living in areas with low levels of air pollution. Since the traffic density is larger in areas with high air pollution, the differences among the groups may reflect the effect of air pollution attributable to particulate matter found in automobile exhaust.

Development of a magnetic fluid shaft seal for an axial-flow blood pump

A rotating impeller in a rotary blood pump requires a supporting system in blood, such as a pivot bearing or magnetic suspension. To solve potential problems such as abrasive wear and complexity of a supporting system, a magnetic fluid seal was developed for use in an axial-flow blood pump. Sealing pressures at motor speeds of up to 8,000 rpm were measured with the seal immersed in water or bovine blood. The sealing pressure was about 200 mm Hg in water and blood. The calculated theoretical sealing pressure was about 230 mm Hg. The seal remained perfect for 743 days in a static condition and for 180+ days (ongoing test) at a motor speed of 7,000 rpm. Results of measurement of cell growth activity indicated that the magnetic fluid has no negative cytological effects. The specially designed magnetic fluid shaft seal is useful for an axial-flow blood pump.