TY  - JOUR
A1  - Lange, Maik
A1  - Braune, Steffen
A1  - Luetzow, Karola
A1  - Richau, Klaus
A1  - Scharnagl, Nico
A1  - Weinhart, Marie
A1  - Neffe, Axel T.
A1  - Jung, Friedrich
A1  - Haag, Rainer
A1  - Lendlein, Andreas
T1  - Surface functionalization of poly(ether imide) membranes with linear, methylated oligoglycerols for reducing thrombogenicity
JF  - Macromolecular rapid communications
N2  - Materials for biomedical applications are often chosen for their bulk properties. Other requirements such as a hemocompatible surface shall be fulfilled by suitable chemical functionalization. Here we show, that linear, side-chain methylated oligoglycerols (OGMe) are more stable to oxidation than oligo(ethylene glycol) (OEG). Poly(ether imide) (PEI) membranes functionalized with OGMes perform at least as good as, and partially better than, OEG functionalized PEI membranes in view of protein resistance as well as thrombocyte adhesion and activation. Therefore, OGMes are highly potent surface functionalizing molecules for improving the hemocompatibility of polymers.
KW  - hemocompatibility
KW  - poly(ethylene glycol)
KW  - polyglycerol
KW  - polyimides
KW  - surface chemistry
Y1  - 2012
U6  - https://doi.org/10.1002/marc.201200426
SN  - 1022-1336
VL  - 33
IS  - 17
SP  - 1487
EP  - 1492
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Neffe, Axel T.
A1  - von Rüsten-Lange, Maik
A1  - Braune, Steffen
A1  - Lützow, Karola
A1  - Roch, Toralf
A1  - Richau, Klaus
A1  - Jung, Friedrich
A1  - Lendlein, Andreas
T1  - Poly(ethylene glycol) grafting to Poly(ether imide) membranes - influence on protein adsorption and Thrombocyte adhesion
JF  - Macromolecular bioscience
N2  - The chain length and end groups of linear PEG grafted on smooth surfaces is known to influence protein adsorption and thrombocyte adhesion. Here, it is explored whether established structure function relationships can be transferred to application relevant, rough surfaces. Functionalization of poly(ether imide) (PEI) membranes by grafting with monoamino PEG of different chain lengths (M-n=1kDa or 10kDa) and end groups (methoxy or hydroxyl) is proven by spectroscopy, changes of surface hydrophilicity, and surface shielding effects. The surface functionalization does lead to reduction of adsorption of BSA, but not of fibrinogen. The thrombocyte adhesion is increased compared to untreated PEI surfaces. Conclusively, rough instead of smooth polymer or gold surfaces should be investigated as relevant models.
KW  - biomaterials
KW  - poly(ethylene glycol)
KW  - protein adsorption
KW  - surface functionalization
KW  - thrombocyte adhesion
Y1  - 2013
U6  - https://doi.org/10.1002/mabi.201300309
SN  - 1616-5187
SN  - 1616-5195
VL  - 13
IS  - 12
SP  - 1720
EP  - 1729
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Braune, Steffen
A1  - Walter, M.
A1  - Schulze, F.
A1  - Lendlein, Andreas
A1  - Jung, Friedrich
T1  - Changes in platelet morphology and function during 24 hours of storage
JF  - Clinical hemorheology and microcirculation : blood flow and vessels
N2  - For in vitro studies assessing the interaction of platelets with implant materials, common and standardized protocols for the preparation of platelet rich plasma (PRP) are lacking, which may lead to non-matching results due to the diversity of applied protocols. Particularly, the aging of platelets during prolonged preparation and storage times is discussed to lead to an underestimation of the material thrombogenicity. Here, we study the influence of whole blood-and PRP-storage times on changes in platelet morphology and function.
 Whole blood PFA100 closure times increased after stimulation with collagen/ADP and collagen/epinephrine. Twenty four hours after blood collection, both parameters were prolonged pathologically above the upper limit of the reference range. Numbers of circulating platelets, measured in PRP, decreased after four hours, but no longer after twenty four hours. Mean platelet volumes (MPV) and platelet large cell ratios (P-LCR, 12 fL - 40 fL) decreased over time. Immediately after blood collection, no debris or platelet aggregates could be visualized microscopically. After four hours, first debris and very small aggregates occurred. After 24 hours, platelet aggregates and also debris progressively increased. In accordance to this, the CASY system revealed an increase of platelet aggregates (up to 90 mu m diameter)with increasing storage time.
 The percentage of CD62P positive platelets and PF4 increased significantly with storage time in resting PRP. When soluble ADP was added to stored PRP samples, the number of activatable platelets decreased significantly over storage time. The present study reveals the importance of a consequent standardization in the preparation of WB and PRP. Platelet morphology and function, particularly platelet reactivity to adherent or soluble agonists in their surrounding milieu, changed rapidly outside the vascular system. This knowledge is of crucial interest, particularly in the field of biomaterial development for cardiovascular applications, and may help to define common standards in the in vitro hemocompatibility testing of biomaterials.
KW  - Platelet
KW  - platelet function
KW  - platelet rich plasma
KW  - whole blood
KW  - platelet aging
KW  - platelet storage
KW  - hemocompatibility
KW  - biomaterials
Y1  - 2014
U6  - https://doi.org/10.3233/CH-141876
SN  - 1386-0291
SN  - 1875-8622
VL  - 58
IS  - 1
SP  - 159
EP  - 170
PB  - IOS Press
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Neffe, Axel T.
A1  - von Rüsten-Lange, Maik
A1  - Braune, Steffen
A1  - Lützow, Karola
A1  - Roch, Toralf
A1  - Richau, Klaus
A1  - Krüger, Anne
A1  - Becherer, Tobias
A1  - Thünemann, Andreas F.
A1  - Jung, Friedrich
A1  - Haag, Rainer
A1  - Lendlein, Andreas
T1  - Multivalent grafting of hyperbranched oligo- and polyglycerols shielding rough membranes to mediate hemocompatibility
JF  - Journal of materials chemistry : B, Materials for biology and medicine
N2  - Hemocompatible materials are needed for internal and extracorporeal biomedical applications, which should be realizable by reducing protein and thrombocyte adhesion to such materials. Polyethers have been demonstrated to be highly efficient in this respect on smooth surfaces. Here, we investigate the grafting of oligo- and polyglycerols to rough poly(ether imide) membranes as a polymer relevant to biomedical applications and show the reduction of protein and thrombocyte adhesion as well as thrombocyte activation. It could be demonstrated that, by performing surface grafting with oligo-and polyglycerols of relatively high polydispersity (>1.5) and several reactive groups for surface anchoring, full surface shielding can be reached, which leads to reduced protein adsorption of albumin and fibrinogen. In addition, adherent thrombocytes were not activated. This could be clearly shown by immunostaining adherent proteins and analyzing the thrombocyte covered area. The presented work provides an important strategy for the development of application relevant hemocompatible 3D structured materials.
Y1  - 2014
U6  - https://doi.org/10.1039/c4tb00184b
SN  - 2050-750X
SN  - 2050-7518
VL  - 2
IS  - 23
SP  - 3626
EP  - 3635
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Braune, Steffen
A1  - Gross, M.
A1  - Walter, M.
A1  - Zhou, Shengqiang
A1  - Dietze, Siegfried
A1  - Rutschow, S.
A1  - Lendlein, Andreas
A1  - Tschoepe, C.
A1  - Jung, Friedrich
T1  - Adhesion and activation of platelets from subjects with coronary artery disease and apparently healthy individuals on biomaterials
JF  - Journal of biomedical materials research : an official journal of the Society for Biomaterials, the Japanese Society for Biomaterials; the Australian Society for Biomaterials
N2  - On the basis of the clinical studies in patients with coronary artery disease (CAD) presenting an increased percentage of activated platelets, we hypothesized that hemocompatibility testing utilizing platelets from healthy individuals may result in an underestimation of the materials' thrombogenicity. Therefore, we investigated the interaction of polymer-based biomaterials with platelets from CAD patients in comparison to platelets from apparently healthy individuals. In vitro static thrombogenicity tests revealed that adherent platelet densities and total platelet covered areas were significantly increased for the low (polydimethylsiloxane, PDMS) and medium (Collagen) thrombogenic surfaces in the CAD group compared to the healthy subjects group. The area per single platelet—indicating the spreading and activation of the platelets—was markedly increased on PDMS treated with PRP from CAD subjects. This could not be observed for collagen or polytetrafluoroethylene (PTFE). For the latter material, platelet adhesion and surface coverage did not differ between the two groups. Irrespective of the substrate, the variability of these parameters was increased for CAD patients compared to healthy subjects. This indicates a higher reactivity of platelets from CAD patients compared to the healthy individuals. Our results revealed, for the first time, that utilizing platelets from apparently healthy donors bears the risk of underestimating the thrombogenicity of polymer-based biomaterials.
KW  - platelets
KW  - biomaterials
KW  - hemocompatibility
KW  - cardiovascular disease
KW  - cardiovascular implant
Y1  - 2016
U6  - https://doi.org/10.1002/jbm.b.33366
SN  - 1552-4973
SN  - 1552-4981
VL  - 104
SP  - 210
EP  - 217
PB  - Wiley-Blackwell
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Braune, Steffen
A1  - Froehlich, G. M.
A1  - Lendlein, Andreas
A1  - Jung, Friedrich
T1  - Effect of temperature on platelet adherence
JF  - Clinical hemorheology and microcirculation : blood flow and vessels
N2  - BACKGROUND: Thrombogenicity is one of the main parameters tested in vitro to evaluate the hemocompatibility of artificial surfaces. While the influence of the temperature on platelet aggregation has been addressed by several studies, the temperature influence on the adherence of platelets to body foreign surfaces as an important aspect of biomedical device handling has not yet been explored. Therefore, we analyzed the influence of two typically applied incubation-temperatures (22 degrees C and 37 degrees C) on the adhesion of platelets to biomaterials. MATERIAL AND METHODS: Thrombogenicity of three different polymers - medical grade poly(dimethyl siloxane) (PDMS), polytetrafluoroethylene (PTFE) and polyethylene terephthalate (PET) - were studied in an in vitro static test. Platelet adhesion was studied with stringently characterized blood from apparently healthy subjects. Collection of whole blood and preparation of platelet rich plasma (PRP) was carried out at room temperature (22 degrees C). PRP was incubated with the polymers either at 22 degrees C or 37 degrees C. Surface adherent platelets were fixed, fluorescently labelled and assessed by an image-based approach. RESULTS AND DISCUSSION: Differences in the density of adherent platelets after incubation at 22 degrees C and 37 degrees C occurred on PDMS and PET. Similar levels of adherent platelets were observed on the very thrombogenic PTFE. The covered surface areas per single platelet were analyzed to measure the state of platelet activation and revealed no differences between the two incubation temperatures for any of the analyzed polymers. Irrespective of the observed differences between the low and medium thrombogenic PDMS and PET and the higher variability at 22 degrees C, the thrombogenicity of the three investigated polymers was evaluated being comparable at both incubation temperatures.
KW  - Biomaterial
KW  - thrombogenicity
KW  - platelet adhesion
KW  - platelet activation
KW  - temperature
Y1  - 2016
U6  - https://doi.org/10.3233/CH-152028
SN  - 1386-0291
SN  - 1875-8622
VL  - 61
SP  - 681
EP  - 688
PB  - IOS Press
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Krüger-Genge, A.
A1  - Braune, S.
A1  - Walter, M.
A1  - Krengel, M.
A1  - Kratz, K.
A1  - Küpper, J. H.
A1  - Lendlein, Andreas
A1  - Jung, Friedrich
T1  - Influence of different surface treatments of poly(n-butyl acrylate) networks on fibroblasts adhesion, morphology and viability
JF  - Clinical hemorheology and microcirculation : blood flow and vessels
N2  - BACKGROUND: Physical and chemical characteristics of implant materials determine the fate of long-term cardiovascular devices. However, there is still a lack of fundamental understanding of the molecular mechanisms occurring in the material-tissue interphase. In a previous study, soft covalently crosslinked poly(n-butyl acrylate) networks (cPnBA) were introduced as sterilizable, non-toxic and immuno-compatible biomaterials with mechanical properties adjustable to blood vessels. Here we study the influence of different surface treatments in particular oxygen plasma modification and fibrinogen deposition as well as a combinatorial approach on the adhesion and viability of fibroblasts. RESULTS: Compared to non-treated cPnBAs the advancing water-contact angles were found to be reduced after all surface modifications (p<0.05, each), while lowest values were observed after the combined surface treatment (OPT+FIB). The latter differed significantly from the single OPT and FIB. The number of adherent fibroblasts and their adherence behavior differed on both pristine cPnBA networks. The fibroblast density on cPnBA04 was 743 +/- 434 cells. mm(-2), was about 6.5 times higher than on cPnBA73 with 115 +/- 73 cells. mm(-2). On cPnBA04 about 20% of the cells were visible as very small, round and buckled cells while all other cells were in a migrating status. On cPnBA73, nearly 50% of fibroblasts were visible as very small, round and buckled cells. The surface functionalization either using oxygen plasma treatment or fibrinogen coating led to a significant increase of adherent fibroblasts, particularly the combination of both techniques, for both cPnBA networks. It is noteworthy to mention that the fibrinogen coating overruled the characteristics of the pristine surfaces; here, the fibroblast densities after seeding were identical for both cPnBAnetworks. Thus, the binding rather depended on the fibrinogen coating than on the substrate characteristics anymore. While the integrity of the fibroblasts membrane was comparable for both polymers, the MTS tests showed a decreased metabolic activity of the fibroblasts on cPnBA. CONCLUSION: The applied surface treatments of cPnBA successfully improved the adhesion of viable fibroblasts. Under resting conditions as well as after shearing the highest fibroblast densities were found on surfaces with combined post-treatment.
KW  - Biomaterial
KW  - poly(n-butyl acrylate)
KW  - fibroblast
KW  - oxygen plasma
KW  - fibrinogen
KW  - cell adhesion
KW  - focal adhesion
KW  - actin cytoskeleton
KW  - viability
Y1  - 2018
U6  - https://doi.org/10.3233/CH-189130
SN  - 1386-0291
SN  - 1875-8622
VL  - 69
IS  - 1-2
SP  - 305
EP  - 316
PB  - IOS Press
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Krüger-Genge, Anne
A1  - Schulz, Christian
A1  - Kratz, Karl
A1  - Lendlein, Andreas
A1  - Jung, Friedrich
T1  - Comparison of two substrate materials used as negative control in endothelialization studies
BT  - Glass versus polymeric tissue culture plate
JF  - Clinical hemorheology and microcirculation : blood flow and vessels
N2  - The endothelialization of synthetic surfaces applied as cardiovascular implant materials is an important issue to ensure the anti-thrombotic quality of a biomaterial. However, the rapid and constant development of a functionallycon-fluent endothelial cell monolayer is challenging. In order to investigate the compatibility of potential implant materials with endothelial cells several in vitro studies are performed. Here, glass and tissue culture plates (TCP) are often used as reference materials for in vitro pre-testing. However, a direct comparison of both substrates is lacking. Therefore, a comparison of study results is difficult, since results are often related to various reference materials. In this study, the endothelialization of glass and TCP was investigated in terms of adherence, morphology, integrity, viability and function using human umbilical vein endothelial cells (HUVEC). On both substrates an almost functionally confluent HUVEC monolayer was developed after nine days of cell seeding with clearly visible cell rims, decreased stress fiber formation and a pronounced marginal filament band. The viability of HUVEC was comparable for both substrates nine days after cell seeding with only a few dead cells. According to that, the cell membrane integrity as well as the metabolic activity showed no differences between TCP and glass. However, a significant difference was observed for the secretion of IL-6 and IL-8. The concentration of both cytokines, which are associated with migratory activity, was increased in the supernatant of HUVEC seeded on TCP. This result matches well with the slightly increased number of adherent HUVEC on TCP. In conclusion, these findings indicate that both reference materials are almost comparable and can be used equivalently as control materials in in vitro endothelialization studies.
KW  - Negative control
KW  - endothelial cells
KW  - glass
KW  - TCP
KW  - reference
Y1  - 2018
U6  - https://doi.org/10.3233/CH-189904
SN  - 1386-0291
SN  - 1875-8622
VL  - 69
IS  - 3
SP  - 437
EP  - 445
PB  - IOS Press
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Reinthaler, Markus
A1  - Johansson, Johan Backemo
A1  - Braune, Steffen
A1  - Al-Hindwan, Haitham Saleh Ali
A1  - Lendlein, Andreas
A1  - Jung, Friedrich
T1  - Shear-induced platelet adherence and activation in an in-vitro dynamic multiwell-plate system
JF  - Clinical hemorheology and microcirculation : blood flow and vessels
N2  - Circulating blood cells are prone to varying flow conditions when contacting cardiovascular devices. For a profound understanding of the complex interplay between the blood components/cells and cardiovascular implant surfaces, testing under varying shear conditions is required. Here, we study the influence of arterial and venous shear conditions on the in vitro evaluation of the thrombogenicity of polymer-based implant materials. Medical grade poly(dimethyl siloxane) (PDMS), polyethylene terephthalate (PET) and polytetrafluoroethylene (PTFE) films were included as reference materials. The polymers were exposed to whole blood from healthy humans. Blood was agitated orbitally at low (venous shear stress: 2.8 dyne. cm(-2)) and high (arterial shear stress: 22.2 dyne .cm(-2)) agitation speeds in a well-plate based test system. Numbers of non-adherent platelets, platelet activation (P-Selectin positive platelets), platelet function (PFA100 closure times) and platelet adhesion (laser scanning microscopy (LSM)) were determined. Microscopic data and counting of the circulating cells revealed increasing numbers of material-surface adherent platelets with increasing agitation speed. Also, activation of the platelets was substantially increased when tested under the high shear conditions (P-Selectin levels, PFA-100 closure times). At low agitation speed, the platelet densities did not differ between the three materials. Tested at the high agitation speed, lowest platelet densities were observed on PDMS, intermediate levels on PET and highest on PTFE. While activation of the circulating platelets was affected by the implant surfaces in a similar manner, PFA closure times did not reflect this trend. Differences in the thrombogenicity of the studied polymers were more pronounced when tested at high agitation speed due to the induced shear stresses. Testing under varying shear stresses, thus, led to a different evaluation of the implant thrombogenicity, which emphasizes the need for testing under various flow conditions. Our data further confirmed earlier findings where the same reference implants were tested under static (and not dynamic) conditions and with fresh human platelet rich plasma instead of whole blood. This supports that the application of common reference materials may improve inter-study comparisons, even under varying test conditions.
Y1  - 2019
U6  - https://doi.org/10.3233/CH-189410
SN  - 1386-0291
SN  - 1875-8622
VL  - 71
IS  - 2
SP  - 183
EP  - 191
PB  - IOS Press
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Kuhnla, A.
A1  - Reinthaler, Markus
A1  - Braune, Steffen
A1  - Maier, A.
A1  - Pindur, Gerhard
A1  - Lendlein, Andreas
A1  - Jung, Friedrich
T1  - Spontaneous and induced platelet aggregation in apparently healthy subjects in relation to age
JF  - Clinical hemorheology and microcirculation : blood flow and vessels
N2  - Thrombotic disorders remain the leading cause of mortality and morbidity, despite the fact that anti-platelet therapies and vascular implants are successfully used today. As life expectancy is increasing in western societies, the specific knowledge about processes leading to thrombosis in elderly is essential for an adequate therapeutic management of platelet dysfunction and for tailoring blood contacting implants. This study addresses the limited available data on platelet function in apparently healthy subjects in relation to age, particularly in view of subjects of old age (80-98 years). Apparently healthy subjects between 20 and 98 years were included in this study. Platelet function was assessed by light transmission aggregometry and comprised experiments on spontaneous as well as ristocetin-, ADP- and collagen-induced platelet aggregation. The data of this study revealed a non-linear increase in the maximum spontaneous platelet aggregation (from 3.3% +/- 3.3% to 10.9% +/- 5.9%). The maximum induced aggregation decreased with age for ristocetin (from 85.8% +/- 7.2% to 75.0% +/- 7.8%), ADP (from 88.5% +/- 4.6% to 64.8% +/- 7.3%) and collagen (from 89.5% +/- 3.0% to 64.0% +/- 4.0%) in a non-linear manner (linear regression analysis). These observations indicate that during aging, circulating platelets become increasingly activated but lose their full aggregatory potential, a phenomenon that was earlier termed "platelet exhaustion". In this study we extended the limited existing data for spontaneous and induced platelet aggregation of apparently healthy donors above the age of 75 years. The presented data indicate that the extrapolation of data from a middle age group does not necessarily predict platelet function in apparently healthy subjects of old age. It emphasizes the need for respective studies to improve our understanding of thrombotic processes in elderly humans.
Y1  - 2019
U6  - https://doi.org/10.3233/CH-199006
SN  - 1386-0291
SN  - 1875-8622
VL  - 71
IS  - 4
SP  - 425
EP  - 435
PB  - IOS Press
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Zhou, Shuo
A1  - Xu, Xun
A1  - Ma, Nan
A1  - Jung, Friedrich
A1  - Lendlein, Andreas
T1  - Influence of sterilization conditions on sulfate-functionalized polyGGE
JF  - Clinical hemorheology and microcirculation : blood flow and vessels
N2  - Sulfated biomolecules are known to influence numerous biological processes in all living organisms. Particularly, they contribute to prevent and inhibit the hypercoagulation condition. The failure of polymeric implants and blood contacting devices is often related to hypercoagulation and microbial contamination. Here, bioactive sulfated biomacromolecules are mimicked by sulfation of poly(glycerol glycidyl ether) (polyGGE) films. Autoclaving, gamma-ray irradiation and ethylene oxide (EtO) gas sterilization techniques were applied to functionalized materials. The sulfate group density and hydrophilicity of sulfated polymers were decreased while chain mobility and thermal degradation were enhanced post autoclaving when compared to those after EtO sterilization. These results suggest that a quality control after sterilization is mandatory to ensure the amount and functionality of functionalized groups are retained.
KW  - Sulfated polymer
KW  - sulfation
KW  - sterilization
KW  - ethylene oxide
Y1  - 2021
U6  - https://doi.org/10.3233/CH-211241
SN  - 1386-0291
SN  - 1875-8622
VL  - 79
IS  - 4
SP  - 597
EP  - 608
PB  - IOS Press
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Tartivel, Lucile
A1  - Blocki, Anna M.
A1  - Braune, Steffen
A1  - Jung, Friedrich
A1  - Behl, Marc
A1  - Lendlein, Andreas
T1  - An Inverse shape-memory hydrogel scaffold switching upon cooling in a tissue-tolerated temperature range
JF  - Advanced materials interfaces
N2  - Tissue reconstruction has an unmet need for soft active scaffolds that enable gentle loading with regeneration-directing bioactive components by soaking up but also provide macroscopic dimensional stability. Here microporous hydrogels capable of an inverse shape-memory effect (iSME) are described, which in contrast to classical shape-memory polymers (SMPs) recover their permanent shape upon cooling. These hydrogels are designed as covalently photo cross-linked polymer networks with oligo(ethylene glycol)-oligo(propylene glycol)-oligo(ethylene glycol) (OEG-OPG-OEG) segments. When heated after deformation, the OEG-OPG-OEG segments form micelles fixing the temporary shape. Upon cooling, the micelles dissociate again, the deformation is reversed and the permanent shape is obtained. Applicability of this iSME is demonstrated by the gentle loading of platelet-rich plasma (PRP) without causing any platelet activation during this process. PRP is highly bioactive and is widely acknowledged for its regenerative effects. Hence, the microporous inverse shape-memory hydrogel (iSMH) with a cooling induced pore-size effect represents a promising candidate scaffold for tissue regeneration for potential usage in minimally invasive surgery applications.
KW  - active scaffold
KW  - critical micellation temperature
KW  - hydrogel
KW  - inverse
KW  - shape-memory effect
KW  - platelet-rich plasma
Y1  - 2022
U6  - https://doi.org/10.1002/admi.202101588
SN  - 2196-7350
VL  - 9
IS  - 6
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Lau, Skadi
A1  - Gossen, Manfred
A1  - Lendlein, Andreas
A1  - Jung, Friedrich
T1  - Differential sensitivity of assays for determining vein endothelial cell senescence
JF  - Clinical hemorheology and microcirculation : blood flow and vessels
N2  - In vivo endothelialization of polymer-based cardiovascular implant materials is a promising strategy to reduce the risk of platelet adherence and the subsequent thrombus formation and implant failure. However, endothelial cells from elderly patients are likely to exhibit a senescent phenotype that may counteract endothelialization. The senescence status of cells should therefore be investigated prior to implantation of devices designed to be integrated in the blood vessel wall. Here, human umbilical vein endothelial cells (HUVEC) were cultivated up to passage (P) 4, 10 and 26/27 to determine the population doubling time and the senescence status by four different methods. Determination of the senescence-associated beta-galactosidase activity (SA-beta-Gal) was carried out by colorimetric staining and microscopy (i), as well as by photometric quantification (ii), and the expression of senescence-associated nuclear proteins p16 and p21 as well as the proliferation marker Ki67 was assessed by immunostaining (iii), and by flow cytometry (iv). The population doubling time of P27-cells was remarkably greater (103 +/- 65 h) compared to P4-cells (24 +/- 3 h) and P10-cell (37 +/- 15 h). Among the four different methods tested, the photometric SA-beta-Gal activity assay and the flow cytometric determination of p16 and Ki67 were most effective in discriminating P27-cells from P4- and P10-cells. These methods combined with functional endothelial cell analyses might aid predictions on the performance of implant endothelialization in vivo.
KW  - Ageing
KW  - population doubling time
KW  - senescence-associated
KW  - beta-galactosidase
KW  - cell cycle inhibitors
KW  - p16
KW  - p21
KW  - Ki67
Y1  - 2022
U6  - https://doi.org/10.3233/CH-211294
SN  - 1386-0291
SN  - 1875-8622
VL  - 81
IS  - 3
SP  - 191
EP  - 203
PB  - IOS Press
CY  - Amsterdam
ER  -