| 1. |
- Hansson, Kenny, 1972-, et al.
(författare)
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Surface plasmon resonance detection of blood coagulation and platelet adhesion under venous and arterial shear conditions.
- 2007
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Ingår i: Biosensors & bioelectronics. - : Elsevier BV. - 0956-5663 .- 1873-4235. ; 23:2, s. 261-8
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Tidskriftsartikel (refereegranskat)abstract
- A surface plasmon resonance (SPR) based flow chamber device was designed for real time detection of blood coagulation and platelet adhesion in platelet rich plasma (PRP) and whole blood. The system allowed the detection of surface interactions throughout the 6mm length of the flow chamber. After deposition of thromboplastin onto a section of the sensor surface near the inlet of the flow chamber, coagulation was detected downstream of this position corresponding to a SPR signal of 7 to 8 mRIU (7 to 8 ng/mm2). A nonmodified control surface induced coagulation 3.5 times slower. Platelet adhesion to gold and fibrinogen coated surfaces in the magnitude of 1.25 and 1.66 mRIU was also shown with platelets in buffer, respectively. SPR responses obtained with PRP and whole blood on surfaces that were methylated or coated with von Willebrand factor (vWF), fibrinogen, or collagen, coincided well with platelet adhesion as observed with fluorescence microscopy in parallel experiments. The present SPR detection equipped flow chamber system is a promising tool for studies on coagulation events and blood cell adhesion under physiological flow conditions, and allows monitoring of short-range surface processes in whole blood.
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| 2. |
- Hansson, Kenny, 1972-, et al.
(författare)
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Whole blood coagulation on protein adsorption-resistant PEG and peptide functionalised PEG-coated titanium surfaces.
- 2005
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Ingår i: Biomaterials. - : Elsevier BV. - 0142-9612 .- 1878-5905. ; 26:8, s. 861-72
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate whole blood coagulation on low blood plasma protein adsorbing surfaces. For this purpose, the polycationic graft copolymer poly(L-lysine)-g-poly(ethylene glycol) (PLL-g-PEG), PLL-g-PEG grafted with a cell adhesive peptide containing the amino acid sequence -Arg-Gly-Asp- (RGD), and PLL-g-PEG with a control peptide -Arg-Asp-Gly- (RDG) were adsorbed onto titanium (oxide), forming stable monomolecular adlayers through electrostatic attraction. Free oscillation rheometry and complementary techniques were used to measure the coagulation time (CT) and other interactions of the surfaces with native whole blood, recalcified platelet-rich plasma (PRP), and recalcified citrated platelet-free plasma (PFP). The results show that the uncoated titanium surfaces (reference) activated platelets and quickly triggered the coagulation cascade via the intrinsic pathway, whereas the PLL-g-PEG surfaces displayed a prolonged CT, approximately 2-3 times longer compared to uncoated titanium. We hypothesise that blood coagulates outside the vascular system independent of low protein adsorption to or activation by surfaces, due to the absence of an active down-regulation of procoagulative processes by the vascular endothelium.
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| 3. |
- Pettersson, Sofia, et al.
(författare)
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Cell expansion of human articular chondrocytes on macroporous gelatine scaffolds : — impact of micro carrier selection on cell proliferation
- 2011
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Ingår i: Biomedical Materials. - Bristol, UK : Institute of Physics Publishing Ltd.. - 1748-6041 .- 1748-605X. ; 6:6, s. 065001-
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates human chondrocyte expansion on four macroporous gelatine microcarriers (CultiSpher) differing with respect to two manufacturing processes—the amount of emulsifier used during initial preparation and the gelatine cross-linking medium. Monolayer-expanded articular chondrocytes from three donors were seeded onto the microcarriers and cultured in spinner flask systems for a total of 15 days. Samples were extracted every other day to monitor cell viability and establish cell counts, which were analysed using analysis of variance and piecewise linear regression. Chondrocyte densities increased according to a linear pattern for all microcarriers, indicating an ongoing, though limited, cell proliferation. A strong chondrocyte donor effect was seen during the initial expansion phase. The final cell yield differed significantly between the microcarriers and our results indicate that manufacturing differences affected chondrocyte densities at this point. Remaining cells stained positive for chondrogenic markers SOX-9 and S-100 but extracellular matrix formation was modest to undetectable. In conclusion, the four gelatine microcarriers supported chondrocyte adhesion and proliferation over a two week period. The best yield was observed for microcarriers produced with low emulsifier content and cross-linked in water and acetone. These results add to the identification of optimal biomaterial parameters for specific cellular processes and populations.
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| 4. |
- Pettersson, Sofia, et al.
(författare)
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Human articular chondrocytes on macroporous gelatin microcarriers form structurally stable constructs with blood-derived biological glues in vitro.
- 2009
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Ingår i: Journal of tissue engineering and regenerative medicine. - : Hindawi Limited. - 1932-7005 .- 1932-6254. ; 3:6, s. 450-60
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Tidskriftsartikel (refereegranskat)abstract
- Biodegradable macroporous gelatin microcarriers fixed with blood-derived biodegradable glue are proposed as a delivery system for human autologous chondrocytes. Cell-seeded microcarriers were embedded in four biological glues-recalcified citrated whole blood, recalcified citrated plasma with or without platelets, and a commercially available fibrin glue-and cultured in an in vitro model under static conditions for 16 weeks. No differences could be verified between the commercial fibrin glue and the blood-derived alternatives. Five further experiments were conducted with recalcified citrated platelet-rich plasma alone as microcarrier sealant, using two different in vitro culture models and chondrocytes from three additional donors. The microcarriers supported chondrocyte adhesion and expansion as well as extracellular matrix (ECM) synthesis. Matrix formation occurred predominantly at sample surfaces under the static conditions. The presence of microcarriers proved essential for the glues to support the structural takeover of ECM proteins produced by the embedded chondrocytes, as exclusion of the microcarriers resulted in unstable structures that dissolved before matrix formation could occur. Immunohistochemical analysis revealed the presence of SOX-9- and S-100-positive chondrocytes as well as the production of aggrecan and collagen type I, but not of the cartilage-specific collagen type II. These results imply that blood-derived glues are indeed potentially applicable for encapsulation of chondrocyte-seeded microcarriers. However, the static in vitro models used in this study proved incapable of supporting cartilage formation throughout the engineered constructs.
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| 5. |
- Sjöwall, Christoffer, et al.
(författare)
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Solid-phase classical complement activation by C-reactive protein (CRP) is inhibited by fluid-phase CRP-C1q interaction.
- 2007
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Ingår i: Biochemical and biophysical research communications. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 352:1, s. 251-8
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Tidskriftsartikel (refereegranskat)abstract
- C-reactive protein (CRP) interacts with phosphorylcholine (PC), Fcgamma receptors, complement factor C1q and cell nuclear constituents, yet its biological roles are insufficiently understood. The aim was to characterize CRP-induced complement activation by ellipsometry. PC conjugated with keyhole limpet hemocyanin (PC-KLH) was immobilized to cross-linked fibrinogen. A low-CRP serum with different amounts of added CRP was exposed to the PC-surfaces. The total serum protein deposition was quantified and deposition of IgG, C1q, C3c, C4, factor H, and CRP detected with polyclonal antibodies. The binding of serum CRP to PC-KLH dose-dependently triggered activation of the classical pathway. Unexpectedly, the activation was efficiently down-regulated at CRP levels > 150 mg/L. Using radial immunodiffusion, CRP-C1q interaction was observed in serum samples with high CRP concentrations. We propose that the underlying mechanism depends on fluid-phase interaction between C1q and CRP. This might constitute another level of complement regulation, which has implications for systemic lupus erythematosus where CRP is often low despite flare-ups.
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| 6. |
- Skoglund, Caroline, 1981-, et al.
(författare)
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C-reactive protein and C1q regulate platelet adhesion and activation on adsorbed immunoglobulin G and albumin.
- 2008
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Ingår i: Immunology and cell biology. - : Wiley. - 0818-9641 .- 1440-1711. ; 86:5, s. 466-74
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Tidskriftsartikel (refereegranskat)abstract
- Blood platelets and C-reactive protein (CRP) are both used clinically as markers of ongoing inflammation, and both participate actively in inflammatory responses, although the biological effects are still incompletely understood. Rapidly adhering platelets express receptors for complement factor 1q (C1q) and the Fc part of immunoglobulin G (IgG), and CRP is known to activate/regulate complement via C1q binding, and to ligate FcgammaRs. In the present study, we used normal human IgG pre-adsorbed to a well-characterized methylated surface as a model solid-phase immune complex when investigating the effects of CRP and C1q on platelet adhesion and activation. Protein adsorption was characterized using ellipsometry and polyclonal antibodies, and human serum albumin (HSA) and non-coated surfaces were used as reference surfaces. Platelet adhesion to IgG and HSA was inhibited by both C1q and CRP. Furthermore, CRP (moderately) and C1q (markedly) decreased the spreading of adhering platelets. The combination of C1q and CRP was slightly more potent in reducing cell adhesion to IgG, and also impaired the adhesion to HSA and non-coated surfaces. Platelet production of thromboxane B2 (TXB(2)) was also reduced by C1q both in the presence and absence of CRP, whereas CRP alone had no effect on TXB(2) production. We conclude that CRP and C1q regulate the behaviour of platelets, and that this may be an important immunoregulatory mechanism during inflammatory conditions.
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| 7. |
- Skoglund, Caroline, et al.
(författare)
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C1q induces a rapid up-regulation of P-selectin and modulates collagen- and collagen-related peptide-triggered activation in human platelets
- 2010
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Ingår i: Immunobiology. - Jena, Germany : Elsevier. - 0171-2985 .- 1878-3279. ; 215:12, s. 987-995
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Tidskriftsartikel (refereegranskat)abstract
- Blood platelets are emerging as important immunomodulatory cells, but complement interaction with platelets is not well understood. Several platelet structures have been described as complement protein 1q (C1q) binding receptors, such as C1qRp/CD93 and gC1qR. However, there are conflicting results whether these receptors are C1q binding structures, or even at all expressed on the cell surface. Recently, the collagen-binding integrin alpha II beta I was reported to bind C1q on mast cells, and this receptor is also present on platelets. The aim of this study was to further characterize the effects of C1q on platelets, by quantifying the platelet surface expression of P-selectin (CD62P) and monitoring the formation of platelet-neutrophil aggregates. Using flow cytometry, we found that C1q dose-dependently triggered a rapid but moderate and transient up-regulation of P-selectin already within 5s of C1q exposure. Pre-incubation with an antibody directed against gC1qR significantly inhibited (with 57% compared to control) the up-regulation, whereas an antibody towards the alpha II beta I-integrin showed no effect. Stimulation with C1q did not change the cytosolic calcium-levels, as measured with the fluorescent ratiometric probe Fura-2, however, a protein kinase C inhibitor (GF109203x) blocked the C1q-induced P-selectin expression. Furthermore, pre-incubation of platelets with C1q diminished both the collagen as well as the collagen-related peptide-induced up-regulation of P-selectin, most evident after 90 s of stimulation. This indicates that C1q may regulate platelet activation via the GPVI receptor, which is a novel finding. Moreover, C1q antagonized the collagen-induced formation of platelet-neutrophil aggregates, indicating a reduced interaction between platelet P-selectin and neutrophil P-selectin glycoprotein ligand-1(PSGL-1/CD162). In summary, C1q induces a moderate rapid platelet P-selectin expression, modulates subsequent collagen and collagen-related peptide stimulation of platelets, and inhibits the formation of platelet-neutrophil aggregates. These immuno-regulatory effects of C1q may have a crucial role in innate immunity and inflammation. (C) 2009 Elsevier GmbH. All rights reserved.
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