Chapter 9
Transient Adsorption of Fibrinogen from Plasma Solutions Flowing in Silica Capillaries Downloaded by UNIV OF CALIFORNIA SAN DIEGO on January 9, 2017 | http://pubs.acs.org Publication Date: May 5, 1995 | doi: 10.1021/bk-1995-0602.ch009
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M. T. Le , J. N. Mulvihill , J.-P. Cazenave , and P.
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Déjardin
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Institut Charles Sadron, 6 rue Boussingault, 67083 Strasbourg, France Institut National de la Santé et de la Recherche Médicale U311, 10 rue Spielmann, 67085 Strasbourg, France
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The adsorption of fibrinogen on silica capillaries from diluted human plasma was studied under laminar flow conditions using radiolabeled I-fibrinogen. Exchange of fibrinogen at the interface with displacing species in plasma (Vroman effect) was followed by continuous recording of radioactivity during flow and different behavior was observed for a plasma pool as compared to single donor plasma, in particular with regard to the rate of the exchange process. In neither case was an extremum in interfacial fibrinogen concentration detected with increasing dilution above d = 10 . The influence of wall shear rate on the exchange reaction demonstrated the significant role of transport under flow conditions, while temperature was also found to be an important parameter as previously reported for baboon plasma. 125
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Some years ago L . Vroman demonstrated the existence of changes in interfacial populations when human plasma contacted a surface, in particular the transient presence of fibrinogen (1). This resulted from exchange processes at the interface, fibrinogen being detected at short contact times but not at longer times. Several further studies have indicated that high molecular weight kininogen (HK) is responsible for the displacement of fibrinogen (2,3). However, it may not be the only displacer (4). Recently a model of C. Scott (5) proposed a complex of activated kininogen with prekallikrein or factor X I as the main species contributing to the replacement of fibrinogen on contact activating surfaces. Apart from numerous isolated articles, in 1991 two issues of J. Biomater. Sci. were dedicated to the Vroman effect (6). Let us consider fibrinogen adsorption and displacement. It is recognized that hydrophilic surfaces facilitate exchange reactions, an effect which could be related to
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Corresponding author
0097-6156/95/0602-0129$12.00/0 © 1995 American Chemical Society Horbett and Brash; Proteins at Interfaces II ACS Symposium Series; American Chemical Society: Washington, DC, 1995.
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a minimization of protein denaturation and to lower interaction energies than at hydrophobic surfaces. Examination of adsorbed fibrinogen in situ or after desorption by circular dichroism allows quantitation of alterations in the native structure. Whereas no denaturation of adsorbed fibrinogen could be detected on silica beads in situ (7), a significant loss of a-helix content was observed in fibrinogen eluted from glass surfaces (8). The mean residence time on the surface before displacement is also an important parameter (9). Although many different static systems have been employed to study the Vroman effect, quantitative description is not always easy especially at low concentrations where exchange is readily observed, as the depletion due to adsorption can be high and vary with protein type, leading to changes in relative bulk concentrations. Moreover, to start and end an experiment under static conditions, there is an obligation to fill and empty the system. Convection then occurs and hence the interpretation of results from such static models requires corrections (10). Using the "lens-on-slide" method (11,12), similar problems arise with the additional effects of undesirable lateral diffusion under the lens and possible local convection due to small thermal gradients leading to minimize the contact time in experiments (12). Therefore, a study under flow conditions would seem easier to interpret as there is always an arrival of fresh solution in a well defined velocity field. Transport may control the initial interfacial events, while with increasing surface coverage, we would expect a gradual predominance of processes controlled by surface phase reactions. The present work describes application of the CRAFS technique (Continuous Recording of Adsorbance in Flowing Systems) to the adsorption of radiolabeled fibrinogen (13,14) from flowing plasma on hydrophilic silica fibers. Materials and Methods Silica capillaries. High quality fused silica capillaries of diameter 530 urn and length 100 m (SGE, Australia) were purchased from Perichrom (France). An average length of 10m was treated with diluted sulfochromic acid (1/10) at 50°C followed by a mixture of 30% (w/w) aqueous H2O2 and 25% (w/w) aqueous N H 3 with water (respective volume ratios 25 15 I 70) at 80 °C under flow conditions for one hour. This cleaning procedure was completed by thorough rinsing with deionised water (SuperQ, Millipore) at 20°C for 2 hours with a low flow of 1 0 " M Tris buffer overnight. This procedure makes the surface very hydrophilic with a high density of SiO" groups. The capillary was then cut into 22 cm long sections and the streaming potential A E was measured under varying pressure drops AP to deduce the £ potential of the interface from the slope dE /dP. Maximal values of about -80 mV (Tris 10- M ; pH 7.4) were stable only over one to two days and the subsequent decrease in £ potential with time was not accurately reproducible. A chosen number of fibers were assembled in a polystyrene pipet of internal diameter 3 mm by injecting an epoxy type glue at its extremities, which then were cut cleanly before determining the streaming potential of the fiber bundle. In fact the C potential was often smaller (-45 to - 60 mV) than for individual fibers. Flow rate was measured to determine whether Poiseuille's law could be derived from the pressure drop data and to verify that no fiber was plugged. 2
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Horbett and Brash; Proteins at Interfaces II ACS Symposium Series; American Chemical Society: Washington, DC, 1995.
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Fibrinogen and plasma. Purified human fibrinogen was provided by the Centre Regional de Transfusion Sanguine de Strasbourg. A first series of experiments was carried out using a human plasma pool prepared from citrated anticoagulated blood collected from 20 healthy donors, while a second series was performed with plasma from a single donor. Characteristics of the pool and single donor plasma are given in Table I and both preparations were stored at -80°C until use. Plasma dilution was defined by a factor d (0 < d :
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Figure 3: Kinetics of adsorption of fibrinogen on silica capillaries from plasma (single donor) at y = 200 s" and varying dilutions: d = 10" (a) (upper curve y = 360 s' ); d = 2 x 10" (b); d = 4 x 10"? (c); d = 10" (d). Closed symbols refer to passage of plasma, open symbols to rinsing with buffer. T = 37°C. 1
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Figure 4: Adsorption "isotherm" after one hour of contact with plasma at 37°C. Plasma pool (A). Single donor (o). Standard deviation with n=2 (d = 10 ) and n=3 (d = 5 10- andd=10" ) -3
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Horbett and Brash; Proteins at Interfaces II ACS Symposium Series; American Chemical Society: Washington, DC, 1995.
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2.0e-2
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Figure 5: Adsorption "isotherm" after one hour of contact with plasma (pool) at 23°C ( • ) and 37°C (•). Standard deviation with n=2 (d = 10" ) and n=3 (d = 5 10" andd= 10" ) 3
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Time (min) Figure 6: Kinetics of adsorption of fibrinogen from diluted plasma (pool, d = 5 x 10" ) at 23°C ( • ) and 37°C (o). Closed symbols refer to passage of plasma, open symbols to rinsing with buffer. 3
Horbett and Brash; Proteins at Interfaces II ACS Symposium Series; American Chemical Society: Washington, DC, 1995.
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Vroman, L.; Adams, A. L. Surf. Sci.1969,16,438 Schmaier, A. H.; Silver, L.; Adams, A. L.; Fischer, G.C.;Munoz, P. C.; Vroman, L.; Colman, R. W. Thromb.Res.1983,33, 51-67 Poot, A.; Beugeling, T.; Van Aken, W. G.; Bantjes, A. J. Biomed. Mater. Res. 1990, 24, 1021-1036 Brash, J. L. Annals New-York Acad. Sci., 1987, 516, 206-222 Scott, C. F. J. Biomater. Sci.: Polymer Edn., 1991, 2, 173-181 J. Biomater. Sci.: Polymer Edn. 1991, 2, 161-237 ; ibid. 1991, 3, 1-114 Mc Millan, C. R.; Walton, A. C. J. Colloid Interface Sci. 1980, 48, 345-349 Chan, B. M.C.;Brash, J. L. J. Colloid Interface Sci. 1981, 84, 263-265 Slack, S. M.; Horbett, T. A. J. Colloid Interface Sci. 1989, 133, 148-165 Wojciechowski, P.; Brash, J. L. J. Biomater. Sci.: Polymer Edn. 1991, 2, 203216 Vroman, L.; Adams, A. L. J. Colloid Interface Sci. 1986,111,391-402 Elwing, H.; Tengvall, P.; Askendal, A.; Lundstrom, I. J. Biomater. Sci.: Polymer Edn. 1991,3, 7-15 Yan, F.;Déjardin,P. Langmuir 1991, 7, 2230-2235 Boumaza, F.;Déjardin, P.; Yan, F.; Bauduin, F.; Holl, Y. Biophys. Chem. 1992, 42, 87-92 Regoeczi, E. Iodine-labeled Plasma Proteins, CRC Press, Boca Raton, Florida, 1984 pp. 49-56 Brash, J. L.; ten Hove, P. Thromb. Haemostas. 1984,51,326-330 Wojciechowski, P.; ten Hove, P.; Brash, J. L. J. Colloid Interface Sci. 1986, 111, 455-465 Wojciechowski, P. W.; Brash, J. L. Colloids Surfaces B: Biointerfaces 1993, 1, 107-117 Slack, S. M.; Horbett, T. A. J. Biomater. Sci.: Polymer Edn. 1991, 2, 227237 Leonard, E. F.; Vroman, L. J. Biomater. Sci.: Polymer Edn. 1991, 3, 95-117
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Horbett and Brash; Proteins at Interfaces II ACS Symposium Series; American Chemical Society: Washington, DC, 1995.
