Association of ENAM, TUFT1, MMP13, IL1B, IL10 and IL1RN gene polymorphism and dental caries susceptibility in Chinese children.

OBJECTIVE: To investigate the association between single nucleotide polymorphisms (SNPs) in six candidate genes (enamelin [ ENAM]; tuftelin 1 [ TUFT1]; matrix metallopeptidase 13 [ MMP13]; interleukin 1 beta [ IL1B]; interleukin 10 [ IL10]; interleukin 1 receptor antagonist [ IL1RN]) and dental caries in children from northwest China. METHODS: This case-control study enrolled children (12-15 years) who underwent routine dental examinations. The children were divided into two groups based on the presence of dental caries. A saliva sample was collected and seven SNPs (rs3806804A/G in ENAM, rs3811411T/G in TUFT1, rs2252070A/G and rs597315A/T in MMP13, rs1143627C/T in IL1B, rs1800872A/C in IL10 and rs956730G/A in IL1RN) were genotyped. RESULTS: A total of 357 children were enrolled in the study: 161 with dental caries and 196 without dental caries. No significant difference was found in the alleles and genotypes of five genes ( ENAM, TUFT1, MMP13, IL10 and IL1RN) between those with and without dental caries. A significant relationship was found between the IL1B rs1143627C/T polymorphism and dental caries susceptibility with those carrying the rs1143627CT genotype having a lower risk of dental caries compared with those carrying the CC genotype (odds ratio 0.557; 95% confidence interval 0.326, 0.952). CONCLUSION: The IL1B rs1143627C/T polymorphism may be associated with dental caries susceptibility in children from northwest China.

Numerical investigation of the influence of a bearing/shaft structure in an axial blood pump on the potential for device thrombosis.

Adverse events caused by flow-induced thrombus formation around the bearing/shaft of an axial blood pump remain a serious problem for axial blood pumps. Moreover, excessive anticoagulation with thrombosis around the bearing potentially increases the risk of postoperative gastrointestinal bleeding. The purpose of this study is to analyze the influence of the bearing structure on the thrombosis potential of an axial blood pump. The bearing/shaft structure was embedded into an axial blood pump numerical model. The numerical simulation and analysis are focused on the low wall shear stresses, recirculation, and residence time close to the bearing region to evaluate the potential for thrombosis around the bearing. Then, the flow field near the blood pump bearing was tested via in vitro particle image velocimetry experiments to verify the numerical results. The simulation results showed that after embedding the bearing/shaft structure a recirculation zone appeared in the outlet guide vane bearing/shaft region, the residence time increased 11-fold in comparison to the pump without the bearing/shaft structure, the scalar shear stress in the shaft surface was less than 7.8 Pa, and the stress accumulation was less than 0.10 Pa s. The numerical results showed that platelets that flow through the bearing region are exposed to significantly lower wall shear stress and a longer residence time, leading to activated platelet adhesion. The reduced stress accumulation and increased time in the bearing region lead to increased platelet activation.

Numerical Investigation of the Influence of Blade Radial Gap Flow on Axial Blood Pump Performance.

The gaps between the blades and the shroud (or hub) of an axial blood pump affect the hydraulics, efficiency, and hemolytic performance. These gaps are critical parameters when a blood pump is manufactured. To evaluate the influence of blade gaps on axial blood pump performance, the flow characteristics inside an axial blood pump with different radial blade gaps were numerically simulated and analyzed with special attention paid to the hydraulic characteristics, gap flow, hydraulic efficiency, and hemolysis index (HI). In vitro hydraulic testing and particle image velocimetry testing were conducted to verify the numerical results. The simulation results showed that the efficiency and pressure rise decreased when the gap increased. The efficiency of the axial blood pump at design point decreased from 37.1% to 27.1% and the pressure rise decreased from 127.4 to 71.2 mm Hg when the gap increased from 0.1 to 0.3 mm. Return and vortex flows were present in the outlet guide vane channels when the gap was larger than 0.2 mm. The HI of the blood pump with a 0.1 mm gap was 1.5-fold greater than that with a 0.3 mm gap. The results illustrated poor hydraulic characteristics when the gap was larger than 0.15 mm and rapidly deteriorated hemolysis when the gap was larger than 0.1 mm. The numerical and experimental results demonstrated that the pressure rise, pump efficiency, and scalar shear stress decreased when the gap increased. The HI did not strictly decrease with gap increases. The preliminary results encourage the improvement of axial blood pump designs.

Design and numerical evaluation of an axial partial-assist blood pump for Chinese and other heart failure patients.

A fully implantable axial left ventricular assist device LAP31 was developed for Chinese or other heart failure patients who need partial support. Based on the 5-Lpm total cardiac blood output of Chinese without heart failure disease, the design point of LAP31 was set to a flow rate of 3 Lpm with 100-mmHg pressure head. To achieve the required pressure head and good hemolytic performance, a structure that includes a spindly rotor hub and a diffuser with splitter and cantilevered main blades was developed. Computational fluid dynamics (CFD) was used to analyze the hydraulic and hemodynamic performance of LAP31. Then in vitro hydraulics experiments were conducted. The numerical simulation results show that LAP31 could generate a 1 to 8 Lpm flow rate with a 60.9 to 182.7 mmHg pressure head when the pump was rotating between 9,000 and 12,000 rpm. The average scalar shear stress of the blood pump was 21.7 Pa, and the average exposure time was 71.0 milliseconds. The mean hemolysis index of LAP31 obtained using Heuser's hemolysis model and Giersiepen's model was 0.220% and 3.89 × 10-5% respectively. After adding the splitter blades, the flow separation at the suction surface of the diffuser was reduced. The cantilever structure reduced the tangential velocity from 6.1 to 4.7-1.4 m/s within the blade gap by changing the blade gap from shroud to hub. Subsequently, the blood damage caused by shear stress was reduced. In conclusion, the hydraulic and hemolytic characteristics of the LAP31 are acceptable for partial support.

Numerical and In Vitro Experimental Investigation of the Hemolytic Performance at the Off-Design Point of an Axial Ventricular Assist Pump.

The ventricular assist pumps do not always function at the design point; instead, these pumps may operate at unfavorable off-design points. For example, the axial ventricular assist pump FW-2, in which the design point is 5 L/min flow rate against 100 mm Hg pressure increase at 8,000 rpm, sometimes works at off-design flow rates of 1 to 4 L/min. The hemolytic performance of the FW-2 at both the design point and at off-design points was estimated numerically and tested in vitro. Flow characteristics in the pump were numerically simulated and analyzed with special attention paid to the scalar sheer stress and exposure time. An in vitro hemolysis test was conducted to verify the numerical results. The simulation results showed that the scalar shear stress in the rotor region at the 1 L/min off-design point was 70% greater than at the 5 L/min design point. The hemolysis index at the 1 L/min off-design point was 3.6 times greater than at the 5 L/min design point. The in vitro results showed that the normalized index of hemolysis increased from 0.017 g/100 L at the 5 L/min design point to 0.162 g/100 L at the 1 L/min off-design point. The hemolysis comparison between the different blood pump flow rates will be helpful for future pump design point selection and will guide the usage of ventricular assist pumps. The hemolytic performance of the blood pump at the working point in the clinic should receive more focus.

[Microbial Community Structure on the Root Surface of Patients with Periodontitis.]

OBJECTIVES: To study the microbial community structure on the root surface of patients with periodontitis. METHODS: Bacterial plaque and tissues from the root neck (RN group),root middle (RM group) and root tine (RT group) of six teeth with mobility 3 in one patient with periodontitis were sampled.The V3V4 region of 16S rRNA was sequenced on the Illumina MiSeq platform.The microbial community structure was analyzed by Mothur,Qiime and SPSS software. RESULTS: The principal component analysis (PCoA) results indicated that the RM samples had a similar microbial community structure as that of the RT samples,which was significant different from that of the RN samples.Thirteen phyla were detected in the three groups of samples,which included 7 dominant phyla.29 dominant genera were detected in 184 genera.The abundance of Bacteroidetes_[G-6] and Peptostre ptococcaceae_[XI][G-4] had a positive correlation with the depth of the collection site of samples (P<0.05),while the abundance of Prevotella,Selenomonas,Corynebacterium and Olsenella had a negative correlation with the depth of the collection site of samples (P<0.05). CONCLUSIONS: There is region-specificity of microbial community structure on the root surface of patients with periodontitis.

A novel vascularized patch enhances cell survival and modifies ventricular remodeling in a rat myocardial infarction model.

OBJECTIVE: Although stem cells hold a great therapeutic potential for injured tissues, limited survival of transplanted stem cells has hindered the clinical application of this technology. We hypothesized that an omentum-based stem cell-supporting patch could provide adequate nutrients and microenvironment to prolong cell survival. We examined this hypothesis in rats with experimental myocardial infarction. METHODS: The omentum-based supporting patch was constructed by stitching polylactic acid-co-glycolic acid polymer seeded with mesenchymal stem cells from male Sprague-Dawley rats. Eight weeks after the experimental myocardial infarction, which was created by ligating the left coronary artery of female Sprague-Dawley rats, mesenchymal stem cells were transplanted with (n = 16) or without (n = 14) the supporting patch. After 4 weeks, transplanted mesenchymal stem cell survival, ventricular remodeling, and cardiac performance were examined. RESULTS: Significantly more cells survived after 4 weeks in rats transplanted with mesenchymal stem cells on the supporting patch assessed by means of polymerase chain reaction detection of the Sry gene than seen in those without the supporting patch (2.61 ± 0.40 vs 1.19 ± 0.12, P < .05). Rats with myocardial infarction that received mesenchymal stem cells with the patch also had significantly improved ventricular remodeling and cardiac function than those without the patch. Wrapping infarcted myocardium with omentum alone did not change the myocardial function. CONCLUSIONS: The omentum-based cell-supporting patch provided a favorable microenvironment for transplanted mesenchymal stem cell survival, which resulted in favorable ventricular remodeling and restoration of cardiac function in rats with experimental myocardial infarction. Further validation of the technique in human subjects could make mesenchymal stem cell transplantation a viable therapeutic option for patients with cardiac disease.

[Effects of mobilization of bone marrow stem cells on regenerative potential of cardiac tissues after myocardial infarction].

OBJECTIVE: To test the potential of bone marrow stem cells mobilized by granulocyte macrophage colony stimulating factor (GM-CSF) to promote regeneration of myocyte and neovascularization in a rat model of myocardial infarction. METHODS: A myocardial infarction model was created by ligation of the left anterior descending coronary artery in adult Sprague-Dawley rats. Then the infracted rats were randomly assigned to receive GM-CSF injection subcutaneously 50 microg x kg(-1) x day(-1) as experimental group or receive saline injection as control group. Enumeration of CD(34)(+) stem cells in peripheral blood and bone marrow was performed by flow cytometric analysis. Histologic and immunohistological staining such as Factor VIII, Ki67 and PTAH staining (phosphotungstic acid hematoxylin) was performed to assess angiogenesis and myogenesis, calculate myocardial infarction size in the heart. RESULTS: The CD(34)(+) stem cells in the blood and bone marrow increased from Day 3, peaked between Day 7 (0.350% +/- 0.026%, 2.250% +/- 0.140%) and Day 14 (0.260% +/- 0.022%, 2.060% +/- 0.110%) in experimental group compared with control group (0.170% +/- 0.015%, 1.240% +/- 0.064%) (P < 0.01), declined on Day 28 and no difference versus control group (P > 0.05). Immunohistological staining showed apparent neovasculature formation and much more Ki67 expression in the infracted regions in experimental group (313 +/- 10, 275 +/- 5) compared with control group (264 +/- 10, 207 +/- 10) (P < 0.05). The Ki67 positive cells in the experimental hearts were significantly positively correlated with CD(34)(+) stem cells in the blood and bone marrow (r = 0.961, P = 0.019, r = 0.975, P = 0.005). Ki67 and PTAH double staining showed that the Ki67 positive nucleoli overlay the lymphocytes, fibroblasts and endothelial cells but not myocytes. No significant decrease of infracted size occurred in experimental group (P > 0.05). CONCLUSIONS: Bone marrow and peripheral blood stem cells could be mobilized effectively by GM-CSF after myocardial infarction which could only promote neovascularization without myogenesis.

[Effect of tannic acid treatment on the physico-chemical properties of glutaraldehyde-fixed bovine jugular vein].

OBJECTIVE: To evaluate the effects of tannic acid (TA) treatment on the physico-chemical properties of glutaraldehyde (Glut)-fixed bovine jugular vein (BJV). METHODS: Fresh BJVs were treated with Glut or Glut/TA, respectively. The shrinkage temperature, resistance to collagenase or elastase digestion, bio-mechanical properties, and molecular structure of these prepared BJVs were evaluated by Fourier transform infrared spectroscopy. RESULTS: TA treatment resulted in higher shrinkage temperature (P < 0.01), higher resistance to collagenase or elastase digestion (P < 0.01), slightly increased tensile strength (P < 0.01), and elongation at break (P < 0.05) in Glut/TA BJV walls when compared with those of Glut group. Chemical bonds existed between TA and JBV tissue. CONCLUSION: TA treatment can effectively improve the physicochemical properties of Glut-fixed BJVs.

Off-pump pulmonary valve implantation of a valved stent with an anchoring mechanism.

PURPOSE: The purpose of this study was to evaluate the longitudinal performance and anti-migration effect of a bovine valved stent equipped with an anchoring mechanism implanted off-pump in the pulmonary position. DESCRIPTION: Through a delivery system, the bell-shaped pulmonary valved stents were implanted off-pump in the pulmonary valve position into six sheep by the transventricular approach. Hemodynamic, angiographic, and echocardiographic evaluations were carried out before, immediately after, and 2 months after implantation. Macroscopic and radiographic examination were performed for evaluation. EVALUATION: The valved stents were all successfully implanted off-pump in the pulmonary position on six sheep. Early and late angiographic, echocardiographic, hemodynamic, and macroscopic studies confirmed firm anchoring and good positions of the stents. All valved stents were potent, except one mild stenosis with a 24 mm Hg transvalvular pressure gradient that developed and one mild insufficiency that were discovered at the end of the study. CONCLUSIONS: Transventricular implantation of the bell-shaped pulmonary valved stents was evaluated during a 2-month period in the sheep in the present study and showed a good structural and functional outcome with no migration.

In vivo experimental testing of the FW axial blood pump for left ventricular support in Fu Wai Hospital.

A fully implantable, axial flow blood pump has been developed in Fu Wai Hospital aiming for clinical use. This ventricular assist device (VAD), which was developed after numerous CFD analyses for the flow characteristics of the pump, is 58.5-mm long, 30-mm wide (including DC motor), and weighs 240 g. The pump can deliver 5 L/min for pressures of 100 mm Hg over 8,000 rpm. In this study, short-term hemocompatibility effects of the axial left ventricular assist device (LVAD) (FW blood pump) were evaluated in four healthy sheep. The device was implanted into the left ventricular apex of beating hearts. The outflow graft of each device was anastomosed to the descending aorta. The hemolysis, which was evaluated in vivo by free hemoglobin value, was below 30 mg/dL. Evaluation of serum biochemical data showed that implantation of the FW blood pump in sheep with normal hearts did not impair end organ function. Gross and microscopic sections of kidney, liver, and lung revealed no evidence of microemboli. Performance of the pump in vivo was considered sufficient for a LVAD, although further design improvement is necessary in terms of hemolysis and antithrombosis to improve biocompatibility of the pump.

[Hemodynamic performance of newly developed composite stentless porcine aortic valve: in vitro testing and in vivo experiment with sheep].

OBJECTIVE: To investigate the effects of a newly developed composite stentless porcine aortic valve constructed from noncoronary leaflets of three porcine aortic valves. METHODS: Fresh porcine hearts with ascending aorta were obtained from a slaughterhouse. The porcine aortic roots with ascending aorta and anterior leaflet of mitral valve and partial ventricular septum were dissected out and were pressurized to maintain their natural anatomical shapes with the leaflets floating freely at zero-pressure. Three noncoronary leaflets fixed in 0.6% glutaraldehyde were carefully matched for size and symmetry to construct a novel composite stentless porcine aortic valve. The lower margin and outside of the valve was covered with a piece of bovine pericardium. The novel stentless valves were tested in vitro pulsatile flow to detect the effective orifice area (EOA) and mean pressure difference (DeltaP) of the valve compared with the stented bovine pericardial bioprostheses of the same size. Sixteen male juvenile sheep underwent implantation of the novel valves in the supra-annular position in under cardio-pulmonary bypass. The intraoperative and postoperative echocardiography and pathological specimen were given to evaluate the hemodynamic performance and observed in the respects of a long-term survival, function of valve and pathological specimen. RESULTS: Since novel valves had the unfavorable muscle-based right coronary leaflet characteristic of porcine valve removed it had larger EOA. Pulsatile flow testing indicated that the EOA of the 3 novel valves was (3.47 +/- 0.15), (3.69 +/- 0.11), and (3.92 +/- 0.18) cm2 respectively, all significantly greater than those of the stented bovine pericardial bioprosthesis [(2.00 +/- 0.16), (2.21 +/- 0.26), and (2.37 +/- 0.42) cm2 respectively] at each integral simulated cardiac output between 3 - 6 L/min (all P < 0.05), while the DeltaP levels of the novel valves were (2.35 +/- 0.41), (3.10 +/- 0.20), and (3.56 +/- 0.16) mm Hg respectively, all significantly lower than those of the stented bovine pericardial bioprosthesis [(4.98 +/- 0.46), (6.82 +/- 1.27), and (8.40 +/- 1.83) mm Hg respectively, all P < 0.05]. Twelve of the sixteen sheep survived after operation. Five of them had lived for more than 90 days, 3 more than 180 days, and 2 more than 360 days. The intra-operative echocardiographic analyses showed low DeltaP [(3.90 +/- 0.78) mm Hg] and no regurgitation in all sheep. After 15 to 360 days, all valves performed excellently. The sheep were postoperatively sacrificed in 5 d, 15 d, 45 d, 90 d, 180 d, or 300 d respectively. Necropsy revealed the valves had a low to mild level of calcification, without periprosthetic leakage and overgrowth of fibrous tissue. CONCLUSION: The newly developed composite stentless porcine aortic valves show excellent hemodynamic performance with lower transvalvular pressure gradient and are relatively easy to implant.

Mitigated calcification of glutaraldehyde-fixed bovine pericardium by tannic acid in rats.

BACKGROUND: Bioprosthetic heart valves derived from glutaraldehyde (Glut)-fixed xenografts have been widely used to replace diseased cardiac valves. However, calcification and degeneration are common following their implantation. Inflammation is closely associated with calcification of Glut-fixed xenografts via macrophage infiltration. Tannic acid (TA) possesses anti-inflammatory effects. This study was designed to investigate the anti-calcification of TA treatment on the Glut-fixed bovine pericardium (BP) in a rat subdermal model. METHODS: Fresh BP was divided into two groups (10 in each group) and separately subjected to different fixation procedures as follows: (1) Glut group: fixation with 0.6% Glut alone; (2) Glut/TA group: fixation with 0.6% Glut and subsequent 0.3% TA. Then the BP samples were subdermally implanted in juvenile male Sprague-Dawley rats and explanted 21 days after implantation. Each explanted BP sample was divided into three parts for calcium content analysis, von Kossa's staining and immunohistochemical staining, and reverse transcription-polymerase chain reaction study. RESULTS: The data from quantitative calcium analysis and von Kossa's staining showed that Glut-fixed BP developed significantly more calcification than Glut/TA-fixed BP ((90.3 +/- 32.5) mg/g dry weight vs (6.4 +/- 1.3) mg/g dry tissue, P < 0.01). Immunostaining demonstrated lower matrix metalloproteinase-9 and tenascin-C expression as well as macrophage infiltration into Glut/TA-fixed BP than in its Glut-fixed counterpart (P < 0.01 for all). Additionally, the reverse transcription-polymerase chain reaction study showed that higher levels of expression of matrix metalloproteinase-9 and tenascin-C mRNA occurred within Glut-fixed BP than within the Glut/TA-fixed ones (P < 0.01 for all). CONCLUSION: TA exerts excellent anti-calcification effects on Glut-fixed BP via inhibiting macrophage infiltration and expression of matrix metalloproteinase-9 and tenascin-C.

Design optimization of an axial blood pump with computational fluid dynamics.

A fully implantable, axial flow blood pump has been developed in our hospital. Both in vitro and in vivo tests showed that the hemolysis and thrombus characteristics of the pump were in an acceptable but not in an ideal range. Computational fluid dynamics (CFD) and in vitro test results showed that the pump worked at off-design point with a low hydraulic efficiency; CFD analysis also showed regions of reverse flow in the diffuser, which not only decreases the pump's hydrodynamic efficiency, but also increases its overall potential for blood trauma and thrombosis. To make a blood pump atraumatic and nonthrombogenic, several methods were taken to reach a final model of the optimized blood pump using CFD, which decreased the rotational speed from 9,000 to 8,000 rpm, and the design flow rate from 11 to 6 L/min. More significantly, the flow separation and recirculation in the diffuser region were eliminated, which mitigated the traumatic and thrombus effect on blood. The acceptable results of the numerical simulations encourage additional in vitro and in vivo studies.

[Hemocompatibility of bovine pericardium with additional sodium bisulfite treatment].

OBJECTIVE: To evaluate the hemocompatibility of glutaraldehyde (GA)-tanned bovine pericardium additionally treated by sodium bisulfite (SOB) solution. METHODS: The hemocompatibility of GA-tanned bovine pericardium treated by SOB solution is evaluated by using dynamic clotting time test, blood platelet adhension test, D-dimeride determination, and complement activation test. The GA-tanned bovine pericardium was used as control. RESULTS: The curve of absorbance-clotting time of two kinds of bovine pericardium was similar in dynamic clotting time test. There was no significant difference between SOB-treated and control groups in blood platelet adhension test. The D-dimeride contents of all bioprostheses were at normal level, and the D-dimeride content of GA-tanned bovine pericardium treated by SOB solution was significantly lower than that of control group (P < 0.05). In complement activation test, the level of complement C3a in SOB-treated group was significantly lower than that in control group (P < 0.05). CONCLUSION: GA-tanned bovine pericardium treated by SOB solution meets the demands of cardiac interstitial implanted materials in hemocompatibility.

Adult endothelial progenitor cells from human peripheral blood maintain monocyte/macrophage function throughout in vitro culture.

Mononuclear cells (MNCs) isolated from peripheral blood by density gradient centrifugation were plated on human fibronectin-coated culture plates and cultured in EGM-2 medium. Attached spindle-shaped cells, reported as endothelial progenitor cells (EPCs) by some investigators, had elongated from adherent round cells, but had not proliferated from a small number of cells as supposed previously. The growth curve of the primary EPCs showed that the cells had little proliferative capacity. Flow cytometry analysis showed that the cells could express some of the endothelial lineage markers, while they could also express CD14, which is considered a marker of monocyte/macrophage lineages throughout culture. In endothelial function assays, the cells demonstrated a lower level of expression of eNOS than mature endothelial cells in the reverse transcription-polymerase chain reaction and did not show an ability to develop tube-like structures in angiogenesis assay in vitro. In this study, we identified the monocytoid function of EPCs by the combined Dil-labeled acetylated low-density lipoprotein (Dil-Ac-LDL) and Indian ink uptake tests. All the cells were double positive for Dil-Ac-LDL and Indian ink uptake at days 4, 14 and 28 of culture, which means the EPCs maintained monocytoid function throughout the culture. Therefore, although adult EPCs from peripheral MNCs have some endothelial lineage properties, they maintain typical monocytic function and have little proliferative capacity.

[Crosslinking bovine pericardial bioprosthetic heart valves by phthalocyanine sensitized photooxidation reaction].

OBJECTIVE: To crosslink bovine pericardial valves by phthalocyanine sensitized photooxidation reaction. METHODS: Fresh bovine pericardial tissues were immersed in PBS solution containing 0.01% cupreous sulfonatophthalocyanine and exposed to a broad wavelength light source for 20-120 h. Using sodium dodecyl sulfate-polyarylamide gel electrophoresis (SDS-PAGE) to analyze the cross-linking extent of pericardial tissue. With the help of attenuated total reflection-fourier transform infrared (ATR-FTIR), explained the change of protein structure after photooxidation reaction. Differential scanning calorimetry (DSC) was used to measure the change of shrinkage temperature. Tissue water content experiment method was also used. RESULTS: Photooxidized tissue was resistant to extraction when it was compared with untreated tissue and had similar crosslinking extent over glutaraldehyde-treated tissue. The three dimension structure of collagen were changed but not seriously destroyed and the model of photooxidation reaction was validated. Phthalocyanine-treated tissue was much more flexible than glutaraldehyde-treated tissue. CONCLUSION: Bovine pericardial tissue can be successfully crosslinked by phthalocyanine-mediated photooxidation reaction.

[Using chemical methods to crosslink xenogeneic heart valves: the progress of bioprosthetic heart valves].

Glutaraldehyde clinically is the most commonly accepted crosslinking reagent for bioprosthetic valves preparation. Glutaraldehyde-treated tissue is stable against chemical and enzymatic degradation; however, its calcification and cytotoxicity are severe. Dye-mediated photooxidation is an alternative tissue preservation method that oxidizes the protein with visible light in the presence of a suitable photosensitizer. This article reviews chemical mechanism, research progress, clinical applications future development of these two methods.