Presented here is a protocol for a standardized in vitro hemodynamic loop model. This model allows to test the hemocompatibility of perfusion tubes or vascular stents to be in accordance with ISO (International Organization for Standardization) standard 10993-4.
In this study, the hemocompatibility of tubes with an inner diameter of 5 mm made of polyvinyl chloride (PVC) and coated with different bioactive conjugates was compared to uncoated PVC tubes, latex tubes, and a stent for intravascular application that was placed inside the PVC tubes. Evaluation of hemocompatibility was done using an in vitro hemodynamic loop model that is recommended by the ISO standard 10993-4. The tubes were cut into segments of identical length and closed to form loops avoiding any gap at the splice, then filled with human blood and rotated in a water bath at 37 °C for 3 hours. Thereafter, the blood inside the tubes was collected for the analysis of whole blood cell count, hemolysis (free plasma hemoglobin), complement system (sC5b-9), coagulation system (fibrinopeptide A), and leukocyte activation (polymorphonuclear elastase, tumor necrosis factor and interleukin-6). Host cell activation was determined for platelet activation, leukocyte integrin status and monocyte platelet aggregates using flow cytometry. The effect of inaccurate loop closure was examined with x-ray microtomography and scanning electron microscopy, that showed thrombus formation at the splice. Latex tubes showed the strongest activation of both plasma and cellular components of the blood, indicating a poor hemocompatibility, followed by the stent group and uncoated PVC tubes. The coated PVC tubes did not show a significant decrease in platelet activation status, but showed an increased in complement and coagulation cascade compared to uncoated PVC tubes. The loop model itself did not lead to the activation of cells or soluble factors, and the hemolysis level was low. Therefore, the presented in vitro hemodynamic loop model avoids excessive activation of blood components by mechanical forces and serves as a method to investigate in vitro interactions between donor blood and vascular medical devices.
Hemocompatibility testing of medical devices is a crucial step in the development of new devices such as vascular stents or perfusion tubes for extracorporeal membrane oxygenation. Until today, animal models are considered as standard tools to finalize the procedure for testing the medical devices prior to its implementation in humans. Henceforth, it is necessary to find alternative in vitro models that further aid in minimizing investigations on animals. In this study, we, therefore, have explored a miniature in vitro hemodynamic loop model. The goal of this presented method is to test the in vitro blood compatibility of medical devices in accordance to the ISO 10993-4 standard.
The ISO 10993-4 standard describes standardized sets of clinical parameters to be investigated on blood specimen1. Briefly, these are thrombosis (platelet aggregation and count), coagulation (fibrinopeptide A, FPA), hematological analysis (whole blood cell count), hemolysis index (free plasma hemoglobin) and the complement system (terminal complement complex, sC5b9). However, additional markers, such as neutrophil polymorphonuclear elastase (PMN), interleukin 6 (IL-6) and tumor necrosis factor - alpha (TNF) reflecting the activation status of leukocytes can also be accounted for measurements. To determine and to quantify the circulating cell free proteins that are present in blood plasma, sandwich enzymatic linked immunosorbent assay (ELISA) represents a conventional and most reliable method2,3. Likewise, the phenotype and activation status of the host cells (e.g., leukocytes) can be quantified by detecting the cell surface expression of molecules by flow cytometry (FACS) that provides single cell suspension based readouts, where fluorescent labeled specific antibodies bind to the targeted cell surface molecules4. Scanning electron microscopy (SEM) is also recommended to determine thrombus formation on the tested material by the ISO 10993-4 standard1. This method can be complemented with X-ray microtomography (μCT), to perform structural analysis of the thrombus e.g., its thickness, size and localization in a 3D rendered image5.
The rationale behind using this in vitro hemodynamic model is to screen for the best performing and compatible medical devices by understanding the basic physiological dynamics of blood components such as platelets, that are involved in the primary hemostasis or leukocytes and their interaction with different types of vascular devices. Such in vitro systems are highly demanded as they reduce the need for animal studies.
The here presented loop model fulfills these demands. This model was first described by A.B. Chandler in 1958 for the production of blood thrombi and is, therefore, also called Chandler Loop model6. Until now, this model has been used in a series of experiments and modifications to investigate the blood biocompatibility of medical devices7,8,9,10,11,12,13,14. It consists of polymer tubes, which are partly filled with blood and shaped into re-closable loops. These loops rotate in a temperature-controlled water bath to simulate vascular flow conditions with its hemorheological effects. Alternative methods such as pump driven models or models that use mechanical ball valves inside the loops to induce a blood flow inside the polymer tubes have already been described15,16. However, the overall advantage of the here presented method is that the mechanical force applied to the blood cells and proteins is low, avoiding hemolysis, and there is no contact between blood and connectors, that could possibly lead to flow turbulences and activation of blood components. The main activating factors inside the loop are the test material itself and the air that is trapped inside. This helps to minimize sources of measuring error and to deliver a high reproducibility, even if the blood-air interface can lead to protein denaturation17. It is also possible to investigate varieties of tubing materials and stent diameters without length or size restrictions thereby allowing the use of tubes of different length and inner diameter. Moreover, host hemocompatibilities on inaccurate loop closure and exposure to the uncoated tube surface are also possible to investigate. Other similar medical applications of this in vitro hemodynamic loop model is that it could also be used to study the interactions between immunotherapeutics (drugs) and blood components during either preclinical development or individual drug safety screening prior to first-in-man phase I clinical trial, or for the generation of thrombus material that can be used in further experiments18,19,20.
This study describes a detailed protocol for testing the hemocompatibilities of perfusion tubes and/or stents. Here, the comparison between uncoated and coated PVC tubes (hepPVC: heparin coating, polyPVC: coating with an bioactive polymer). Lowered activation of platelets, but a higher activation of the coagulation system (FPA) were found for both coated tubes in comparison to the uncoated tubes. The hepPVC tubes used here are modified with covalently bound heparin to make them thromboresistant21 and have already been employed in a loop model to optimize and characterize different parameters22. The polyPVC tubes used in this study are commercially available tubes used in clinical settings of extracorporeal blood perfusion and are coated with a heparin polymer to reduce their thrombogenicity23. Sometimes, in clinical applications even uncoated PVC tubes are used. Therefore, we included latex tubes as a positive control group that showed excessive activation of platelets, coagulation system, and soluble factors like IL-6, TNF and PMN elastase. Thrombus formation was noticed when inaccurate loop closure was simulated. This led to the activation of coagulation and complement system as well as leukocytes and platelets compared to the baseline conditions. Furthermore, blood contact to the here used stent material (bare metal nitinol stent, covered with carbon-impregnated expanded polytetrafluoroethylene) led to higher platelet and leukocyte activation in terms of PMN elastase. Overall, the presented model did not induce hemolysis in any of the tested vascular devices as they were comparable to the baseline or static conditions, except for the latex tubes, where red blood cell (RBC) hemolysis was obvious. Moreover, these perfusion tubes can be examined either by imaging or by histology. Though histological evaluations might be feasible, we mainly focused on ELISA and flow cytometry to perform these experiments and thereby enabling the feasibilities of conducting experiments based on the here presented model for many laboratories. Thus, this method represents a feasible method to test the blood biocompatibility of vascular medical devices in accordance with the recommendations of the ISO 10993-4 standard. Furthermore, this method can be used whenever an interaction between blood and materials should be tested under flow conditions, mimicking the in vivo conditions.
This study was approved by the Ethics Committee of the medical faculty of the University Hospital Magdeburg (application number 88/18) and the subjects provided written informed consent prior to the blood drawing procedure.
1. Heparin stock preparation and blood sampling
2. In vitro hemodynamic loop assembly
3. Blood sample processing
4. Scanning electron microscopy and µCT images
5. Blood cell count
6. Measurement of free hemoglobin (fHb) in plasma
7. Measurement of FPA
8. Measurement of sC5b9
9. Measurement of PMN
10. Measurement of TNF
11. Measurement of IL-6
12. FACS analyses
All presented data, except FACS plots, were analyzed with a statistics software. The FACS plots were analyzed using flow cytometry software.
The analysis of whole blood cell count did not show any significant differences with respect to erythrocytes between all tested conditions (Figure 2). But, platelets and leukocytes were drastically reduced in the latex group, indicating a very poor biocompatibility of latex. This is further underlined by increased levels of free hemoglobin in the latex group, indicating the fact that except for the latex group, none of the other vascular devices or conditions led to extensive hemolysis (Figure 2). Further, the coated PVC tubes, polyPVC and hepPVC, as well as the tested stent did not lead to thrombosis by means of platelet and leukocyte loss, while latex exhibited the highest platelet and leukocyte loss, followed by uncoated PVC tubes that showed a decreased trend.
While all the tested vascular devices led to increased activation of the coagulation system (FPA) and complement component (sC5b-9), the hepPVC loops exhibited a trend for decreased levels of FPA and sC5b-9 when compared specifically to polyPVC loops (Figure 3). Interestingly, uncoated PVC and Gap loops showed lower levels of FPA compared to polyPVC, though not reaching the level of statistical significance. Nevertheless, latex loops exhibited significantly increased levels of FPA when compared to baseline and static conditions.
In accordance with the whole blood cell counts, latex loops exhibited highest levels of TNF, IL-6 and PMN elastase (Figure 4), reaching the level of statistical significance when compared to rest of the groups in terms of TNF and IL-6 (Figure 4A,B), whereas to static and baseline conditions in terms of PMN elastase (Figure 4C). These results indicate the potent activation of leukocytes by latex. The baseline levels of activation markers were always comparable to static conditions, indicating a proper heparinization of the blood.
Interestingly, it was shown that platelet and leukocyte counts for gap induced loops were only slightly reduced with moderate activation of the coagulatory system (FPA) and leukocytes (PMN elastase), though improper loop closure with resulting flow turbulences and blood contact to the uncoated, rough cutting surface led to macroscopically visible clots at the splice (Figure 1F). The clots and its distribution over the whole splice surface were evident with µCT and SEM images, while no clot was found when the loops were closed with the external closing device leaving no gap between the loop endings (Figure 5).
Flow cytometric analysis of host blood cells that were stained with platelet specific markers, CD41 and platelet activation marker CD62P, are shown in Figure 6A,B. Here, the latex tubes exhibited exceedingly high median fluorescence intensity (MFI) for CD62P on blood platelets, followed by stent, whereas heparin coated polyPVC tubes exhibited minimal activation of platelets depicting anti-thrombogenic property of polyPVC tubes. Furthermore, leukocytes were classified based on the CD45 and SSC (side scatter) based granularity into (i) granulocytes; (ii) monocytes and (iii) lymphocytes (Figure 7), and the expression of CD162+ integrin was detected on each subpopulation of leukocytes that are known to interact with the CD62P on platelets24. It was noticed that the integrin expressions were drastically reduced on granulocytes and lymphocytes in latex loops. This result was in line with lowered levels of total frequencies of leukocytes in the latex loops (Figure 2). In general, the integrin levels were higher among monocytes when compared to granulocytes and lymphocytes, indicating the likelihood for the monocyte interaction with activated platelets. In this regard, monocyte platelet aggregates were also evaluated by staining the blood cells with CD14 (as monocyte marker) and CD41 (as platelet marker) and ultimately to identify double positive cells i.e. CD14+CD41+MPA (Figure 8). Here, we noticed that the stent group exhibited the highest levels of CD41 expression on the MPA, followed by the latex group, indicating an increased tendency to form MPA, despite the reduced frequency of monocyte (<1 %) in the latex loops.
Figure 1: Overview of the in vitro hemodynamic loop model and its modifications. (A) Loop for the gap experiment with external loop closing system, leaving no gap at the splice. (B) Loop made of polyPVC coated PVC tube and stent inside (arrow). (C) Loop made of latex tube. (D) Loop for the gap experiment without the external loop closing system leaving a gap between the tube endings (arrow). (E) Loops placed in the loop cradle inside the water bath and filled with blood. (F) Thrombus resulting in a gap at the splice (arrow) after rotation. Please click here to view a larger version of this figure.
Figure 2: Results for blood cell count and plasma hemoglobin. (A) Erythrocytes count. (B) Platelets count. (F) Leukocytes count. (D) Free plasma hemoglobin. The results indicate the poor biocompatibility of latex, leading to excessive hemolysis. Data are presented as mean value; error bars indicate SEM. n=1. Please click here to view a larger version of this figure.
Figure 3: Results for activation of the coagulation and complement system. (A) Coagulation system activation, measured by levels of Fibrinopeptide A (FPA) (B) Complement system activation, measured by levels of sC5b-9. While latex tubes evoked significant elevated levels of the FPA, the complement activation was strong for all tested materials. Data are presented as mean value, error bars indicate SEM. *p<0.05, n=1. Please click here to view a larger version of this figure.
Figure 4: Leukocyte activation markers. (A) Tumor necrosis factor alpha (TNF). (B) Interleukin 6 (IL-6) (C) PMN Elastase. The results indicate increased activation of leukocytes due to elevated levels of the analyzed markers, followed by stent loops, that only led to increased levels for PMN Elastase but not TNF or IL-6. Data are presented as mean value, error bars indicate SEM. *p<0.5; **p<0.01, n=1. Please click here to view a larger version of this figure.
Figure 5: Imaging of the splice of the loops. (A) µ-computer tomography (µCT) of loops with improper closing (gap). The red areas indicate thrombus material. (B) Rendering of the luminal side of the tube. The rectangular selection indicates the area for scanning electron microscopy (SEM) (C). (D) µCT of loops with external loop closing device and no gap at the splice, and (E) rendering and view of the luminal surface. No thrombus material was found. (F) SEM image of the rectangular selection in (E). No thrombus material was found on the cutting surface. Please click here to view a larger version of this figure.
Figure 6: FACS plot for platelet activation (CD62P). (A) Representative FACS plot (basic condition) showing the blood CD41+ platelets. (B) Graph showing the platelet activation status reflected by the mean fluorescence intensity (MFI) of the different types of vascular devices in comparison to the static RT and baseline conditions. The data bars present data from single measurements. Please click here to view a larger version of this figure.
Figure 7: FACS plot for leukocyte integrin (CD162). (A) Representative FACS plot (basic condition) showing the blood CD45+ leukocytes and subgroups (B) Graph showing the leukocyte CD162+ integrin mean fluorescence intensity (MFI) of the different types of vascular devices in comparison to the static and baseline conditions. The data bars present data from single measurements. Please click here to view a larger version of this figure.
Figure 8: FACS plot for platelet monocyte aggregates (CD41/CD14). (A) Representative FACS plot (basic condition) showing the gating for blood monocytes (CD45+/CD14+), platelets (CD41+) and monocyte platelet aggregates (CD41+/CD14+) (B) Graph showing the CD41+ mean fluorescence intensity (MFI) on monocyte platelet aggregates for the various vascular devices compared to the static and baseline conditions. The data bars present data from single measurements. Please click here to view a larger version of this figure.
This study has shown that the presented in vitro hemodynamic loop model offers a reliable method for testing the in vitro blood compatibility of medical devices in accordance to the ISO 10993-4 standard.
Critical steps in the protocol include the drawing of blood and filling the tubes with blood, where excessive vacuum or agitation should be avoided to prevent the blood components from activation by the handling procedure. Furthermore, it is very important to immediately freeze the plasma samples and keep them on ice after thawing, as the complement and coagulation system activation can be tampered by keeping the samples on room temperature for a longer time.
Since this model has both merits and demerits when compared to other in vitro models, several factors have to be taken into account while designing the experiments.
First, the loops can be varied in length and diameter to fit various experimental setups. In case the setup includes contrasting tubes of varying inner diameters, it should be kept in mind that the differences in diameter will result in different shear forces, thereby affecting the coagulation and complement cascade7. Second, the rotation speed was set to 30 rpm in this experiment. This will result in a blood flow of approximately 25 cm/s, which is comparable to the blood flow velocity in human coronary artery bypass grafts25. The strain rate, generated by the rotation of the loops, is the major parameter that will initiate biochemical cascades of blood components, including cells and cell-free proteins. But as blood is a non-Newtonian fluid, the strain rate will also be influenced by the tube curvature, respectively the length of the tubes that are closed to loops10. Whenever the rotation speed or loop size is changed, it is important to consider that the correlation between strain rate and rotation speed is not linear. The correlation between the rotation speed and strain rate is not sufficiently examined until today and further studies are required to investigate these particular parameters10,26,27. However, based on a model for laminar boundary layer, the given tube diameter of 5 mm and the rotation speed of 25 cm/s, a rough estimation of the wall shear stress (WSS) would indicate values between 2.20-22.00 pascal for a distance of 1,00-0,01 mm to the wall of the tube when the blood density is estimated to be 1060 kg*m-3 and the kinetical viscosity is set to 0.0025 pascal*s28,29. Interestingly, also a more detailed computational analysis of flow dynamics in the curvature of human coronary arteries showed WSS values ranging from 11.33 to 16.77 pascal at roughly comparable parameters for the velocity, density and viscosity of the blood30.
Beside this limitation, the presented loop model is a pressure less system, that does not mimic the intravascular blood pressure ratios of the human vascular system.
Next important limitation is that the blood is in contact with air inside the loops, which brings additional interferences. Such a blood-air contact is impacted by two parameters, which includes the gas permeability of the tubes and the retainment of air inside the loops while filling them with blood. Every tube material possesses a certain gas permeability that can lead to significant changes in gas concentrations inside the tubes. While some authors state that the resultant effect of the gas permeability on activation of blood components remains unclear31, it is known that the function of the blood coagulators is highly sensitive to a pH-shift, that may be caused by CO2 diffusion32,33,34. Here, we have tested the biocompatibility of blood perfusion tubes under indoor air conditions, comparable to clinical scenarios of extracorporeal blood perfusion. For future improvements of the presented model, incubation of the whole model in a CO2 incubator and performing blood pH validation before and after incubation might be useful to further standardize this model.
Also, the blood-air interface inside the loops can lead to activation of plasma proteins and cell fractions of the blood35,36. The roller pump driven devices without air inside the tubes may avoid the issue of blood-air interface, but they certainly induce damage to blood cells with significant elevated levels of hemoglobin compared to the here presented loop model, and the hemoglobin in plasma can interfere with the sensitivity of tested analytes in ELISA16. In this study we have shown that the hemolytic effect of the loop model itself remains minimal while using biocompatible materials such as heparin coated PVC tubes. Thus, the model is, on the one hand, not causing excessive cell damage compared to pump driven models, but on the other hand inducing plasma proteins due to blood air contact. Of note, van Oeveren et al. developed a ball-valve based loop model avoiding air inside the loops16. This promising alternative to the here presented loop model may overcome the problem of the blood-air interface, however, compared to the model presented here, platelet adhesion is still higher for the ball-valve based loop model.
With regard to the static control, it is of note that glass itself has been shown to be a potent activator of the coagulatory system37. However, in the presented setup, incubation in a glass beaker (static control) did not lead to excessive host cell activation or activation of the coagulatory system compared to the baseline levels directly after drawing the blood. In conclusion, it might be helpful to use for example polypropylene tubes, if the static control shows high levels of activation.
Regardless of whether it is a loop based or a pump-driven model, these in vitro models completely lack the authentic biological interactions that are mainly contributed by an intact endothelium, which is an ideal blood contacting surface. The rationale behind this issue is more evident when a medical device like a stent is being tested, which might impart different outcomes, in terms of activation and plasma proteins, during its interaction with blood components in the presence of endothelium. This declares to be a major drawback of all discussed in vitro systems mimicking the circulatory system. Hence, to overcome this issue, new microfluidic systems that are completely covered with endothelium are gaining immense interest, but nevertheless in comparison to the loop model presented here, they are still limited to accommodate smaller blood volumes and minimal flow rates38,39
Thus, we conclude that the Chandler Loop model remains to be a robust model for conducting standardized tests on the blood biocompatibility of vascular medical devices in the field of cardiovascular research.
The authors are thankful to Ms. Elena Denks for her technical assistance.
Name | Company | Catalog Number | Comments |
5 ml tube, K3 EDTA | Sarstedt | 32332 | |
Anti-Mouse Ig, κ/Negative Control Compensation Particles Set | Becton Dickinson BioSciences | 552843 | |
APC anti-human CD45 Antibody | BioLegend | 368512 | |
BD LSR Fortessa II cell analyzer | Becton Dickinson | 647465 | |
BD Vacutainer Citrate Tubes | Becton Dickinson | 369714 | |
BD Vacutainer one-use holder | Becton Dickinson | 364815 | |
BD Vacutainer Safety-Lok butterfly canula 21 G | Becton Dickinson | 367282 | |
Beaker glass ROTILABO short 10 ml | Carl Roth GmbH + Co. KG | X686.1 | |
Beaker glass ROTILABO short 50 ml | Carl Roth GmbH + Co. KG | X688.1 | |
Brilliant Violet 421 anti-human CD162 Antibody | BioLegend | 328808 | |
Brilliant Violet 421 anti-human CD41 Antibody | BioLegend | 303730 | |
Centrifuge ROTINA 420 | 420 R | Hettich Zentrifugen | 4701 | 4706 | |
Centrifuge tubes, 50 ml | Greiner Bio-One GmbH | 227261 | |
CHC Super modified, 5mm PVC tubing | Corline Sweden | 1807-148 | Referred to as hepPVC tube |
Circular Precision Cutter | ebo kunze industriedesign, Neuffen, Germany | CLS 007-20 | |
Closing Unit (complete with tension bands) | ebo kunze industriedesign, Neuffen, Germany | CLS 008-20 | |
Electric tape Scotch Super 33+ | VWR | MMMA331933 | |
ELISA MAX Deluxe Set Human IL-6 | BioLegend | 430504 | |
ELISA MAX Deluxe Set Human TNF-a | BioLegend | 430204 | |
Eppendorf Pipette Research plus, single channel, inkl. epT.I.P.S. box, 0,1 – 2,5 µL, gray | Eppendorf AG | 3123000012 | |
Eppendorf Pipette Research plus, single channel, inkl. epT.I.P.S. box, 0,5 – 10 µL, gray | Eppendorf AG | 3123000020 | |
Eppendorf Pipette Research plus, single channel, inkl. epT.I.P.S. box, 10 – 100 µL, yellow | Eppendorf AG | 3123000047 | |
Eppendorf Pipette Research plus, single channel, inkl. epT.I.P.S. box, 100 – 1,000 µL, blue | Eppendorf AG | 3123000063 | |
Eppendorf Pipette Research plus, single channel, inkl. epT.I.P.S. box, 20 – 200 µL, yellow | Eppendorf AG | 3123000055 | |
Eppendorf Pipette Research plus, single channel, inkl. epT.I.P.S. sample bag, 0,5 – 5 mL, violet | Eppendorf AG | 3123000071 | |
Ethylenediaminetetraacetic acid solution | Sigma-Aldrich | 03690-100ML | |
FACS tubes polystyrene 5.0 ml round bottom | Corning BV | 352052 | |
Fetal bovine serum Gold Plus | Bio-Sell | FBS.GP.0500 | |
FITC anti-human CD14 Antibody | BioLegend | 367116 | |
Fluency plus stent 13.5 x 60 mm | Angiomed GmbH & Co | FVM14060 | |
Free Hemoglobin fHb Reagent | Bioanalytics GmbH | 004001-0250 | |
Gibco PBS Tablets | Thermo Fisher Scientific | 18912014 | |
Gloves Vasco Nitril white L | B. Braun Deutschland GmbH & Co.KG | 9208437 | |
Gloves Vasco Nitril white M | B. Braun Deutschland GmbH & Co.KG | 9208429 | |
Glutaraldehyde 25% aequous solution | Sigma Aldrich | G6257-100ML | |
Heparin, 25.000 IE in 5 ml | Rotexmedica, Trittau, Germany | PZN 3862340 | |
Human Fibrinopeptide A (FPA) ELISA Kit | Hölzel Diagnostika | abx253234 | |
Kodan tincture forte colourless | Schülke & Mayr GmbH | 104012 | |
Latex tube, ID 5 mm | Laborhandel24 GmbH | 305 0507 | |
Loop Stand | ebo kunze industriedesign, Neuffen, Germany | CLS 009-20 | |
Medimex venous tourniquet classic | ROESER Medical GmbH | 310005 | |
Microplate reader Infinite 200 Pro M Plex | Tecan | TEC006418I | |
Microplate shaker PMS-1000i | VWR | 444-0041 | |
Nalgene Metric non-phthalate PVC tubing, ID 5 mm | VWR | NALG8703-0508 | Referred to as PVC tube |
NexTemp (Standard) Single-Use Clinical Thermometer | Medical Indicators | 2112-20 | |
Nunc MaxiSorp ELISA Plates, uncoated | BioLegend | 423501 | |
Osmium tetroxide solution | Fisher Scientific | 10256970 | |
Paraformaldehyde Solution, 4% in PBS | Thermo Fisher Scientific | AAJ19943K2 | |
PE anti-human CD16Antibody | BioLegend | 302008 | |
PE anti-human CD62P (P-Selectin) Antibody | BioLegend | 304906 | |
Pipette controller, pipetus | VWR | 612-1874 | |
Pipette tips epT.I.P.S. 0.2 - 5 ml | OMNILAB-LABORZENTRUM GmbH & Co. KG | 5186480 | |
Pipette tips epT.I.P.S. standard 0,1 - 10µl | Th. Geyer GmbH & Co. KG | 9409410 | |
Pipette tips epT.I.P.S. standard 2 - 200µl | Th. Geyer GmbH & Co. KG | 0030 000.870 | |
Pipette tips epT.I.P.S. standard 50 - 1000µl blue | Th. Geyer GmbH & Co. KG | 0030 000.919 | |
PMN (Neutrophil) Elastase Human ELISA Kit | Fisher Scientific | BMS269 | |
Probe stand ROTILABO combi | CARL ROTH | K082.1 | |
Rack for rotation unit (12 slots 3/8 '' with variable slot width) | ebo kunze industriedesign, Neuffen, Germany | CLS 011-20 | |
RBC Lysis Buffer (10X) | BioLegend | 420301 | |
Reagent reservoirs | VWR | 613-1184 | |
Rotation Unit | ebo kunze industriedesign, Neuffen, Germany | CLS 010-20 | |
Safe-Lock micro test tubes 0.5 ml | OMNILAB-LABORZENTRUM GmbH & Co. KG | 5409320 | |
Safe-Lock micro test tubes 1.5 ml | OMNILAB-LABORZENTRUM GmbH & Co. KG | 5409331 | |
sc5b9 Human ELISA KIT | TECOmedicalGroup | A029 | |
Scalpel no 10 | Fisher Scientific | NC9999403 | |
Scanning electron microscope XL30 ESEM-FEG | Philips | n.a. | |
Screw top bottle ROTILABO Clear glass, 1000 ml, GL 45 | Carl Roth GmbH + Co. KG | X715.1 | |
Screw top bottle ROTILABO Clear glass, 500 ml, GL 45 | Carl Roth GmbH + Co. KG | X714.1 | |
Semi-micro cuvette 1.6 ml | Sarstedt | 67.746 | |
Serological pipette 10.0 ml | Corning BV | 4488 | |
Serological pipette, 25.0 ml | Corning BV | 4489 | |
Serological pipette, 5.0 ml | Corning BV | 4487 | |
Silicon tube, inner diameter 8 mm, outer diameter 12 mm | VWR | BURK8803-0812 | |
Sprout mini centrifuge | Biozym | 552034 | |
Stop Solution for TMB Substrate | BioLegend | 77316 | |
Swabs, sterile | Fuhrmann GmbH | 32055 | |
Syringe, 10 ml | Becton Dickinson | 300296 | |
Temperature controlled water basin | ebo kunze industriedesign, Neuffen, Germany | CLS 020-20 | |
tert-Butanol, 99.5%, extra pure, ACROS Organics | Fisher Scientific | 10000730 | |
TMB Substrate Set | BioLegend | 421101 | |
Trillium PVC tube, 5 mm ID | Medtronic | 161100107100103 | Referred to as polyPVC tube |
Tween 20 | AppliChem | A4974,0250 | |
UV-Vis Spektrometer Lambda 2 | Perkin Elmer | 33539 | |
Vornado Mini Vortexer | Biozym | 55BV101-B-E | |
XN-3000 workstation blood analyzer | Sysmex Europe | n.a. | |
μ-CT Phoenix Nanotom S | GE Sensing & Inspection, Wunstorf, Germany | n.a. |
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