Fresh Porcine Blood Research Articles

An In Vitro Study of 355‐nm Laser Ablation of Atherosclerotic Lesions Model

ABSTRACTA study of 355 nm laser with high pulse energy across various types of atherosclerotic lesion models is presented. The 355 nm laser pulses (10 ns) are delivered via a single fiber (600 μm diameter), and the ablation of calcified tissue, lipid tissue, and thrombus‐like tissue are studied under varied laser fluence (40–70 mJ/mm2) and repetition rate (5–30 Hz). The contact and noncontact ablation processes of chicken tibia samples (calcified tissue) are compared at 60 mJ/mm2 and 30 Hz, and the size of ablation particles is in the range of 0.1–1 μm. At the same repetition rate, the advancement rate of tricalcium phosphate samples reaches 150 μm/s at 70 mJ/mm2. Calcified and lipid models demonstrate predictable increases in ablation with higher laser fluence and repetition rate. The fresh porcine blood clot samples exhibit high‐quality ablation with good channel effect at 50 mJ/mm2 and 30 Hz.

Abstract 2031: Supramolecularly Fabricated Non-thrombogenic Small Diameter Vascular Graft

Background: Small diameter (<6mm) arterial reconstruction often requires the use of autologous and synthetic vascular substitutes. While autologous conduits are the gold standard, because of their limited availability synthetic conduits are often used. However, synthetic conduits can lead to poor outcomes due to thrombosis and lumen occlusion occluding the lumen and result in graft failure. By modulating the biopolymer properties of the synthetic conduits, graft failure can be prevented. In this study, we present a thromboresistant synthetic vascular graft (zetagraft) fabricated with tunable biopolymers for small diameter arterial reconstructions. Methods: Zetagrafts were fabricated by the solvent extraction driven self-assembly using a concentric tubular assembly device using polyvinyl alcohol dissolved in dimethyl sulfoxide (15% w/v). We characterized the physicochemical and mechanical properties of zetagraft by fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), optical and scanning electron microscopy, and tensiometry. In-vitro studies were performed on the zetagraft using fibroblast, HUVEC and MVEC cell lines. Ex vivo hemocompatibility analysis was performed with fresh porcine blood. The zetagrafts were implanted in a rat aorta replacement model to evaluate its thromboresistance. Results: The zetagraft was uniform, highly stretchable, and self-healing when punctured with a needle. Blood circulation followed by FT-IR and XRD analysis showed no protein adsorption on the luminal surface. Immuno fluorescence staining revealed the absence of platelet and blood cell adsorption on the zetagraft lumen, demonstrating its thromboresistance. In vivo implantation of the zetagraft in rat abdominal aorta replacement model revealed the absence of thrombosis and other blood component adsorption on the zetagraft lumen. Conclusions: Advances in material science allow for fabrication of more tunable biocompatible small vascular grafts. In this study we demonstrated the development of a thromboresistant zetagraft. Our early results are very promising and zetagraft will provide a novel small vascular graft and thus fulfil an important unmet clinical need.

Evaluation of erythrocyte membrane oxidation due to their exposure to shear flow generated by extracorporeal blood pump.

Several similarities have been found between shear stress-induced erythrocyte damage and physiological aging of erythrocytes in terms of elevated mechanical fragility, increased erythrocyte aggregation, and decreased membrane surface charge. Accordingly, we hypothesized that blood pump circulation, which generates shear stress, would accelerate erythrocyte aging, manifesting as oxidation. Therefore, the purpose of this study was to investigate the effect of blood pump circulation on erythrocyte oxidation. Fresh porcine blood was acquired from a slaughterhouse and anticoagulated with sodium citrate. About 500 mL of anticoagulated whole blood was circulated for 180 min in an in vitro test circuit comprising a BP-80 blood pump with a pump speed and a pump pressure head of 100-120 mmHg. A blood sample was taken at the start of the circulation and 180 min afterward. The hemolysis level and oxidation amount of the erythrocyte membrane were analyzed and compared between samples. Hemolysis increased with the prolongation of shear exposure inside the pump circuit. After 180 min of blood pumping in circuit, the oxidation level of the erythrocyte membrane showed an increase of 0.1 nmol/mg protein. Moreover, the membrane oxidation levels of sheared erythrocytes were greater than those of control erythrocytes. These results suggest that blood pump circulation accelerates erythrocyte aging and give us a greater understanding of the effects of blood pump perfusion.

Real-Time Detection of Circulating Thrombi in an Extracorporeal Circuit Using Doppler Ultrasound: In-Vitro Proof of Concept Study.

Thromboembolic stroke continues to be by far the most common severe adverse event in patients supported with mechanical circulatory assist devices. Feasibility of using Doppler ultrasound to detect circulating thrombi in an extracorporeal circuit was investigated. A mock extracorporeal circulatory loop of uncoated cardiopulmonary bypass tubing and a roller pump was setup. A Doppler bubble counter was used to monitor the mean ultrasound backscatter signal (MUBS). The study involved two sets of experiments. In Scenario 1, the circuit was sequentially primed with human blood components, and the MUBS was measured. In Scenario 2, the circuit was primed with heparinized fresh porcine blood, and the MUBS was measured. Fresh blood clots (diameter <1,000 microns, 1,000-5,000 microns, >5,000 microns) were injected into the circuit followed by protamine administration. In Scenario 1 (n = 3), human platelets produced a baseline MUBS of 1.5 to 3.5 volts/s. Addition of packed human red blood cells increased the baseline backscatter to 17 to 21 volts/s. Addition of fresh frozen plasma did not change the baseline backscatter. In Scenario 2 (n = 5), the blood-primed circuit produced a steady baseline MUBS. Injection of the clots resulted in abrupt and transient increase (range: 3-30 volts/s) of the baseline MUBS. Protamine administration resulted in a sustained increase of MUBS followed by circuit thrombosis. Doppler ultrasound may be used for real-time detection of circulating solid microemboli in the extracorporeal circuit. This technology could potentially be used to design safety systems that can reduce the risk of thromboembolic stroke associated with mechanical circulatory support therapy.

Survival and adaptation of Streptococcus phocae in host environments.

Marine mammals are sentinel species representing the "health" of our oceans on which we are dependent. There are many threats to marine mammals including infectious diseases that increase with climate change and pollution of the marine environment. Streptococcus phocae has frequently been isolated from diseased or dead marine mammals. However, its pathogenicity and contribution to disease in marine mammals is still unknown. As bacteria including (potential) pathogens has to deal with different host environments during colonization or infection, we investigated the survival of S. phocae in fresh porcine and phocid blood, in seawater and in the presence of macrophages and (epithelial) cells from harbor seals and pigs. Furthermore, we tested adherence on and invasion of different (marine) mammalian cells by S. phocae. Our results showed that S. phocae can survive in seawater for at least 11 and 28 days at 16°C and 4°C, respectively. It is able to grow in blood of harbor and grey seals, but not in porcine blood. Furthermore, S. phocae is adherent and invasive to cells from seals and pigs, while the portion of invasive cells was higher in seal derived cells. Macrophages of harbor seals were more efficient in killing S. phocae than porcine macrophages. Our results indicate that S. phocae has strategies enabling it to adapt to the marine environment and seal hosts.

A novel lateral flow immunochromatographic assay using a recombinant VP2 antigen for total antibody detection of canine parvovirus-2.

Canine parvovirus-2 (CPV-2) is a viral disease of dogs causing acute hemorrhagic gastroenteritis and myocarditis with high morbidity and mortality rates. The infection is still widespread all over the world. Vaccines developed against infection have great importance in preventing infection. However, it is difficult to recommend a practical vaccination program without knowing the antibody level of a puppy. Despite widespread vaccination, difficulties in detecting the maternal antibodies in puppies remain the main cause of vaccination failure. The hemagglutination inhibition (HAI) test is the gold standard to determine the immune status of dogs for canine parvovirus 2, but the HAI test has several disadvantages such as the need for fresh porcine blood, well-equipped laboratory, and long incubation periods. In this study, for the first time we developed a colloidal gold-based competitive lateral flow assay (cLFA) system for the rapid detection of total antibodies in canine serum using CPV-2b-VP2 derived from field isolates. The recombinantly expressed capsid protein of CPV-2 in the prokaryotic expression system was used as a labeled molecule in cLFA. We carried out studies on our cLFA system using the standard antibody solution and the clinical samples from vaccinated puppy serum. We compared the results of the LFAs with the HAI test. Competitive lateral flow assay results showed good correlation with the gold standard method, the HAI test. In the developed platform, the limit of detection of the standard antibody was determined to be 375 ng mL-1, while the cut-off level of antibodies was observed to be 1 : 40 HAI titer in clinical samples. Our reported system will be a strong alternative for CPV-2 antibody-based detection applications.

Blood Gas Parameters and Acid–Base Balance during Extracorporeal Lung Support with Oxygenators: Semi-Empirical Evaluation

Membrane artificial lungs (oxygenators) are used in cardiopulmonary surgery as well as, in some cases, in severe lung disease to support the natural lung by means of ECMO (extracorporeal membrane oxygenation). The oxygen and carbon dioxide transfer rates of any oxygenator are usually assessed by considering several blood gas parameters, such as oxygen saturation, hemoglobin concentration, partial pressure of oxygen and carbon dioxide, bicarbonate concentration, and pH. Here, we report a set of semi-empirical equations that calculate such parameters directly from their partial pressures and assess the acid–base balance during ECMO. The implementation of this equation set permits the evaluation of any oxygenator, existing or prototypes in development, as well as the development of clinical decision-making tools for predicting the blood gas state and acid–base balance during surgical interventions and ECMO. The predicted results are then compared with experimental data obtained from in vitro gas exchange investigations with a commercial oxygenator using fresh porcine blood. The high correlation, R2&gt;0.95, between the predicted and the experimental data suggests a possibility of using such empirical equations in the simulation of gas transfer in a cardiopulmonary system with an oxygenator for any venous inlet blood gas data and also for estimating the acid–base balance during such therapy.

Noninvasive Image Reconstruction of Flowing Thrombus With Electrical Capacitance Tomography

A method for noninvasive real-time measurement of blood cardiopulmonary bypass is proposed by electrical capacitance tomography (ECT). An eight-electrode sensor ECT data acquisition system is designed, including sensor design and data acquisition module design. The system has a real-time imaging speed of 40 frames per second (FPS) and an average signal-to-noise ratio (SNR) of 64.59 dB per channel, which has been experimentally verified. First, the system is able to detect 6.25%–42.25% of the target area ratio (AR) when the sensor inner diameter is 20 mm, the outer diameter is 25 mm, and the image correlation coefficient (ICC) is not less than 0.7, which obtained by static experiments. Second, the corresponding voltage sum curve is different when different sizes of targets flow through the electrode coverage area. Dynamic experiments have verified that the sum of voltage curve for each frame image is available to further determine the size of the thrombus generated during the circulation process. Finally, dynamic experiments were performed using fresh porcine blood clots to mimic thrombus, which verified the feasibility of using ECT for in vitro thrombus detection.

In vitro hemocompatibility investigation for the development of low-flow centrifugal blood pumps with less platelet clogging.

Low-flow blood pumps rated under 1 L/min are emerging for new medical applications, such as hemofiltration in acute use. In those pumps, platelet adhesion and aggregation have to be carefully considered because of clogging risk in the filter part. To find an acceptable hemocompatibility that can be applied to low-flow centrifugal blood pump design, the platelet aggregation index, clogging on a micromesh filter, and the hemolysis index were investigated using a low-flow blood pump designed for hemofiltration use. We conducted circulation testing in vitro using fresh porcine blood and two centrifugal pumps with different impeller inlet shapes. The Negative Log Platelet Aggregation Threshold Index (NL-PATI), which reflects the ability of residual platelets to aggregate, and flow rate were measured during reflux for 60 min, and the Normalized Index of Hemolysis (NIH (g/20 min)) was calculated. In addition, blood cell clogging after reflux was observed on the micromesh filter by SEM, and the adhesion rate was calculated. Our results showed that the platelet clogging on the micromesh filter occurred when the average NL-PATI was greater than 0.28 and the average NIH (g/20 min) was greater than 0.01. In contrast, platelet clogging on the micromesh was suppressed when NL-PATI was less than 0.17 and the NIH (g/20 min) was less than 0.003. These values might be used as acceptable hemocompatibility of low-flow centrifugal blood pumps with suppressed platelet clogging for hemofiltration pumps.

A Model to Evaluate Effect of Patient-Pump Mismatch on Thrombosis in a Pediatric Pulsatile Ventricular Assist Device

<h3>Purpose</h3> Thromboembolic events remain a common and significant complication of Berlin Heart (BH) EXCOR devices. Retrospective studies have found larger sized pumps in relation to body surface area (BSA) to be a risk factor, but this has not been demonstrated experimentally. We present a model to study the thrombogenic effects of patient-pump mismatch. <h3>Methods</h3> Two flow loops were constructed consisting of cardiopulmonary bypass tubing connecting graduated reservoirs to 10cc and 50cc BH's respectively, which were in turn connected to an Ikus driver (Figure 1A). Fresh (<24 hours post draw) porcine blood anticoagulated with Anticoagulant Citrate Dextrose Solution A was recalcified, heparinized, and instilled into the flow loops. Heparin dose was calculated by incubating latex tubes immersed in various concentrations of heparinized donor blood for 30 minutes to determine the donor-specific threshold for thrombus deposition. The flow loops were then run for 90 minutes at room temperature with driving pressures and heart rates titrated to goal flow of 1.2 l/min (simulating a cardiac index of 2.4 L/m² for 0.5 kg/m² BSA). Thrombus deposits were extracted via irrigation and then dried and weighed. <h3>Results</h3> Goal flow required pressure settings 160/-20 mmHg at 120 bpm for the 10cc BH vs. 120/-20 at 60bpm for the 50cc BH. Incomplete filling and emptying was noted on the 50cc Berlin. Dry thrombus weight was 36mg in the 10cc BH and 156mg in the 50cc BH. Qualitatively, deposits were noted primarily at the polyurethane valves in the 10cc BH. In contrast, the 50cc BH had deposits primarily in the tubing connectors (Figure 1B,C). <h3>Conclusion</h3> We demonstrate an effective model for detecting thrombogenic effects of patient-pump mismatch. This model paves the way for future studies focused on BSA's that are at the cusp of adjacent BH pump sizes.

Species-specific identification of porcine blood plasma in heat-treated chicken meatballs.

This study was conducted to detect the presence of chicken and porcine DNA in meatballs using mitochondria DNA (mtDNA) of cytochrome b (cyt b) and nuclear DNA (nDNA) short interspersed nuclear element (SINE) species-specific primers, respectively. While, the mtDNA primers targeted transfer RNA-ATP8 (tRNA-ATP8) gene was used for 1 and 5% (w/w) chicken meatball spiked with commercial porcine blood plasm. Chicken meatballs spiked with 1% and 5% (v/w) fresh and commercial porcine blood plasma, respectively were prepared and heat-treated using five (n = 5) cooking methods: boiling, pan-frying, roasting, microwaving and autoclaving. Two pairs of mtDNA and nDNA primers used, produced 129 and 161 bp amplicons, respectively. Whereas, tRNA-ATP8 primers produced 212 bp of amplicon. Electrophoresis analysis showed positive results for porcine DNA at 1% and 5% (w/w or v/v) for all of the different cooking techniques, either for fresh or commercial blood plasma using SINE primers but not for tRNA-ATP8 primers. The present study has highlighted the useful of species-specific primers of SINE primers in PCR analysis for detecting porcine DNA blood plasma in heat-treated chicken meatballs.

Real-time, non-invasive thrombus detection in an extracorporeal circuit using micro-optical thrombus sensors

Introduction:Real-time, non-invasive monitoring of thrombus formation in extracorporeal circuits has yet to be achieved. To address the challenges of conventional optical thrombus detection methods requiring large devices that limit detection capacity, we developed a micro-optical thrombus sensor.Methods:The proposed micro-optical thrombus sensor can detect the intensity of light scattered by blood at wavelengths of 660 and 855 nm. Two thrombus sensors were installed on in vitro circuit: one at the rotary blood pump and one at a flow channel. To evaluate the variation in the ratio of incident light intensity at each wavelength of the two sensors, Rfluct (for 660 nm) and Ifluct (for 855 nm) were defined. Using fresh porcine blood as a working fluid, we performed in vitro tests of haematocrit (Hct) and oxygen saturation (SaO2) variation and thrombus detection. Thrombus tests were terminated after Rfluct or Ifluct showed a larger change than the maximum range of those in the Hct and SaO2 variation test.Results:In all three thrombus detection tests, Ifluct showed a larger change than the maximum range of those in the Hct and SaO2 variation test. After the tests, thrombus formation was confirmed in the pump, and there was no thrombus in the flow channel. The results indicate that Ifluct is an effective parameter for identifying the presence of a thrombus.Conclusion:Thrombus detection in an extracorporeal circuit using the developed micro-optical sensors was successfully demonstrated in an in vitro test.

A mock circulation loop to test extracorporeal CO2 elimination setups

BackgroundExtracorporeal carbon dioxide removal (ECCO2R) is a promising yet limited researched therapy for hypercapnic respiratory failure in acute respiratory distress syndrome and exacerbated chronic obstructive pulmonary disease. Herein, we describe a new mock circuit that enables experimental ECCO2R research without animal models. In a second step, we use this model to investigate three experimental scenarios of ECCO2R: (I) the influence of hemoglobin concentration on CO2 removal. (II) a potentially portable ECCO2R that uses air instead of oxygen, (III) a low-flow ECCO2R that achieves effective CO2 clearance by recirculation and acidification of the limited blood volume of a small dual lumen cannula (such as a dialysis catheter).ResultsWith the presented ECCO2R mock, CO2 removal rates comparable to previous studies were obtained. The mock works with either fresh porcine blood or diluted expired human packed red blood cells. However, fresh porcine blood was preferred because of better handling and availability. In the second step of this work, hemoglobin concentration was identified as an important factor for CO2 removal. In the second scenario, an air-driven ECCO2R setup showed only a slightly lower CO2 wash-out than the same setup with pure oxygen as sweep gas. In the last scenario, the low-flow ECCO2R, the blood flow at the test membrane lung was successfully raised with a recirculation channel without the need to increase cannula flow. Low recirculation ratios resulted in increased efficiency, while high recirculation ratios caused slightly reduced CO2 removal rates. Acidification of the CO2 depleted blood in the recirculation channel caused an increase in CO2 removal rate.ConclusionsWe demonstrate a simple and cost effective, yet powerful, “in-vitro” ECCO2R model that can be used as an alternative to animal experiments for many research scenarios. Moreover, in our approach parameters such as hemoglobin level can be modified more easily than in animal models.

T and Small Protrusion (TAP) vs Double-Kissing Crush Technique: Insights From In Vitro Models

BackgroundPercutaneous coronary interventions on complex bifurcation lesions may require implantation of two stents to appropriately treat diffuse side-branch (SB) disease. Comparisons among different bifurcation stenting techniques are continuously attempted by various study designs (bench tests, computer simulations, clinical studies). Among different techniques, double kissing crush (DKC) represents the last evolution for “crushing” while T and small Protrusion (TAP) represents the evolution of “T stenting”. Both techniques are actually gaining popularity, but head-to-head comparisons are lacking. Methods and resultsTwo last generation drug-eluting stents (Synergy™, Boston Scientific, MA, USA and Ultimaster™,Terumo Corp., Japan) were implanted in left main bifurcation bench models using TAP (n = 6 sets) and DKC (n = 6 sets) techniques. A peristaltic pump with fresh porcine blood was used to perfuse the blood through the silicone model at a flow rate of 200 ml/min for 4 min. Optical coherence tomography (OCT) was used to assess stent struts geometry and thrombus formation. SB cross sectional area as well as SB obstruction did not significantly differ between the two techniques. Numerical (but not statistically significant) differences were found in terms of malapposed struts (fewer with TAP) and floating struts (fewer with DKC). Thrombus formation after blood perfusion was similar between TAP and DKC technique (1.53 ± 1.12 vs. 1.20 ± 1.01 mm2, p = 0.6). ConclusionThe result of the present in-vitro study shows the absence of significant difference between TAP and DKC in terms of stent struts apposition and acute thrombus formation potential. Despite the completely different technical steps required, both techniques have similar performance according to such articulated pre-clinical evaluation. What is already known about this subject?Due to its limited complexity, T and Protrusion (TAP) technique is considered the to-go technique for bifurcation lesions with good long-term results. Recently, double kissing crush (DKC) technique has been gaining popularity and demonstrated promising results in randomized clinical trials. What does this study add?This in-vitro bench test study provides a unique detailed OCT comparison and local hemodynamic environment analysis of the two techniques. How might this impact on clinical practice?New insights of acute thrombogenicity and computational flow model simulation may guide percutaneous therapeutic strategies of bifurcation lesions.

Suppressive effects of the neutrophil elastase inhibitor sivelestat sodium hydrate on interleukin-1β production in lipopolysaccharide-stimulated porcine whole blood.

Sivelestat sodium hydrate (Siv) is expected to be an effective therapy for acute respiratory distress syndrome, although its mechanism of action is not understood. In this study, we investigated which myeloid cells-derived cytokines were suppressed by Siv. Continuous hemofiltration was performed by circulating fresh porcine blood through a semi-closed circuit. To ensure that leukocytes survived for 360min, 5% glucose, heparin, and air were continuously injected. The control group received continuous administration of lipopolysaccharide (LPS) only, whereas the Siv group received LPS and Siv. Complete blood count, levels of various cytokines, and other variables were compared between the groups. Interleukin (IL)-1β level was significantly suppressed in the Siv group compared with that in the control group (p<0.05). The results suggested that Siv suppressed the production of IL-1β and possibly other cytokines by myeloid cells. Whether this suppression of cytokine production is caused directly by Siv or mediated via suppression of granulocyte elastase should be evaluated in the future.

Injectable, Non‐Diffusible, and Pre‐Filled Bone Paste Composed of α‐Tricalcium Phosphate and Hydrophobically Modified Poly(Vinyl Alcohol)

Herein, injectable, non‐diffusible, and pre‐filled bone pastes are developed using α‐tricalcium phosphate (α‐TCP) and hydrophobically modified poly(vinyl alcohol)s (hm‐PVAs) with various alkyl chain lengths (3–12). The resulting bone pastes show high injectability (over 90%) when the solid–liquid ratio is lower than 3.5. The non‐diffusion property of α‐TCP/hm‐PVAs bone pastes in water and fresh porcine blood is observed compared with α‐TCP alone, α‐TCP/original PVA (Org‐PVA), and commercial calcium phosphate paste. The compressive strength of α‐TCP/nonanal‐modified PVA (C9‐PVA) bone pastes is 5.4 ± 1.4 MPa within 24 h and reaches 27.5 ± 2.7 MPa after 7 days in water. Young's modulus of α‐TCP/C9‐PVA bone pastes is 0.84 ± 0.02 GPa, which is lower than that of commercial calcium phosphate paste (1.5 ± 0.02 GPa) and poly(methyl methacrylate)‐based bone cement (1.06 ± 0.03 GPa). Furthermore, the surface of α‐TCP/C9‐PVA bone pastes shows excellent cell adhesion of cultured osteoblastic cells. These results demonstrate that α‐TCP/C9‐PVA bone paste is a promising bone filler for percutaneous vertebroplasty (PVP) surgery.

Spectrum analysis for assessing red blood cell aggregation using high-frequency ultrasound array transducer.

The purpose of this study is to investigate a spectrum analysis technique for detecting and monitoring red blood cell (RBC) aggregation using a high-frequency array transducer. To assess the feasibility of this approach, the backscattered radio-frequency signal from non-aggregated and aggregated RBC samples with two hematocrit levels were acquired by using a 30-MHz linear array transducer and analyzed in frequency domain. Three parameters such as spectral slope, midband fit and Y intercept were extracted in a static condition. Fresh porcine blood was used and degrees of aggregation were changed by diluting plasma concentration. From the experiments, it was demonstrated that the spectral slope related to a size of scatterer progressively declined as the level of aggregation increased; its mean values at hematocrit of 40% were 1.10 and -0.22dB/MHz for RBCs suspended in isotonic phosphate buffered saline and solution with 70% plasma concentrations, respectively. For the midband fit and Y intercept, the mean values were increased by 9.1 and 46.4dB, respectively. These results indicated that the spectrum analysis technique is useful for monitoring RBC aggregation and can be potentially developed for assessing aggregation in clinical applications.

Fabrication, Characterization, and Hemocompatibility Investigation of Polysulfone Grafted With Polyethylene Glycol and Heparin Used in Membrane Oxygenators.

Polysulfone (PSF) was grafted chemically with polyethylene glycol (PEG) of different molecular weights (400, 2000, 10 000, and 20 000) and heparin to prepare PSF-PEG-Hep membranes (labeled as PSF-PEG400-Hep, PSF-PEG2000-Hep, PSF-PEG10 000-Hep, and PSF-PEG20 000-Hep). These membranes were synthesized via the following steps: (i) PSF chloromethylation; (ii) PEGylation; and (iii) heparin immobilization process. Water contact angle, critical water permeation pressure, ATR-FTIR, 1 H NMR, UV-visible spectrophotometry, and X-ray photoelectron spectroscopy were conducted to prove grafting success and to fix the optimal reaction parameters during chemical modification processes. To further evaluate the application potential of the PSF-PEG-Hep membrane in a membrane oxygenator, we conducted pure CO2 and O2 gas permeation tests and measured the gas exchange rates of CO2 and O2 through a membrane oxygenator using fresh porcine blood. Meanwhile, the hemocompatibility of the membrane was analyzed and compared by protein adsorption, platelet adhesion, and blood coagulation tests. Results of pure gas permeation experiments indicated that the excellent gas transmission properties through PSF membrane were preserved after modification. Blood oxygenation experiments through the PSF-PEG10 000-Hep membrane showed that when the flow rate of porcine blood was 1.5 L/min, CO2 and O2 exchange rates reached 102 and 110 mL/min, respectively, which could basically satisfy the gas exchange potential of commercial membrane oxygenators. Besides, the PSF-PEG-Hep membrane has demonstrated more prominent blood compatibility than PSF.

Development of an Optical Detector of Thrombus Formation on the Pivot Bearing of a Rotary Blood Pump.

Continuous optical monitoring of thrombus formation in extracorporeal mechanical circulatory support (EMCS) devices will contribute to safe, long-term EMCS. A clinically applicable optical detector must be able to distinguish among the optical characteristics of oxygen saturation (SaO2 ), hematocrit (Hct), and thrombus formation. In vitro studies of spectral changes at wavelengths from 400 to 900 nm associated with SaO2 , Hct, and thrombus formed around the top pivot bearing of a Gyro C1E3 pump were conducted. Fresh porcine blood anticoagulated with sodium citrate was circulated in a mock circuit using the pump. The SaO2 , Hct, and anticoagulation activity were altered using an oxygenator, autologous plasma, and calcium chlorite injection, respectively. Light from a xenon lamp was guided by an incident fiber perpendicularly fixed on the top bearing. This light was scattered by blood pooled between the male and female pivots. The detection fiber was perpendicularly fixed against the incident fiber, and the side-scattered light was detected and guided to a spectrophotometer. As a result, light at two different wavelengths, 420 and 810 nm, was identified as suitable for thrombus detection because it was negligibly influenced by SaO2 and was able to detect the optical characteristics of fibrin. The light at these two wavelengths responded more quickly to thrombus formation than the inlet or outlet pressure, and flow rate change. The optical changes showed the changes in Hct around the top pivot bearing, which is caused by the reduction in density of fibrin-trapped red blood cells (RBCs) due to the RBCs being swept away by the surrounding blood flow. The proposed method was also able to detect fibrin production by extracting subtle differences in the optical characteristics between the Hct and thrombus formation.

Effect of alkyl chain length on the interfacial strength of surgical sealants composed of hydrophobically-modified Alaska-pollock-derived gelatins and poly(ethylene)glycol-based four-armed crosslinker

Surgical sealants are widely used clinically. Fibrin sealant is a commonly used sealant, but is ineffective under wet conditions during surgery. In this study, we developed surgical sealants composed of hydrophobically modified Alaska-pollock-derived gelatins (hm-ApGltns) with different alkyl chain lengths from C3 to C18 and a poly(ethylene)glycol-based 4-armed crosslinker (4S-PEG). The burst strength of the hm-ApGltns-based sealant was evaluated using a fresh porcine blood vessel and was found to increase with increasing alkyl chain length from 167±22 to 299±43mmHg when the substitution ratio of amino groups of ApGltn was around 10mol%. The maximum burst strength was observed when stearoyl-group modified ApGltn (Ste-ApGltn)/4S-PEG-based sealant was used, displaying 3-fold higher burst strength than the original ApGltn (Org-ApGltn)/4S-PEG sealant, and 10-fold higher than the commercial fibrin sealant. Ste-ApGltn/4S-PEG-based sealant was biodegraded in rat subcutaneous tissue within 8 weeks without severe inflammation. By molecular interaction analysis using surface plasmon resonance, the binding constant of Ste-ApGltn to fibronectin was found to be 9-fold higher than that of Org-ApGltn. Therefore, the developed sealant, in particular the Ste-ApGltn/4S-PEG-based sealant, has potential applications in the field of cardiovascular surgery as well as thoracic surgery.