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Sökning: hsv:(MEDICIN OCH HÄLSOVETENSKAP) hsv:(Medicinsk bioteknologi) hsv:(Medicinsk bioteknologi med inriktning mot cellbiologi inklusive stamcellsbiologi molekylärbiologi mikrobiologi biokemi eller biofarmaci)

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  • Fürsatz, Marian, et al. (författare)
  • Functionalization of bacterial cellulose wound dressings with the antimicrobial peptide ε-poly-L-Lysine
  • 2018
  • Ingår i: Biomedical Materials. - : Institute of Physics Publishing (IOPP). - 1748-6041 .- 1748-605X. ; 13
  • Tidskriftsartikel (refereegranskat)abstract
    • Wound dressings based on bacterial cellulose (BC) can form a soft and conformable protective layer that can stimulate wound healing while preventing bacteria from entering the wound. Bacteria already present in the wound can, however, thrive in the moist environment created by the BC dressing which can aggravate the healing process. Possibilities to render the BC antimicrobial without affecting the beneficial structural and mechanical properties of the material would hence be highly attractive. Here we present methods for functionalization of BC with ε-Poly-L-Lysine (ε-PLL), a non-toxic biopolymer with broad-spectrum antimicrobial activity. Low molecular weight ε-PLL was cross-linked in pristine BC membranes and to carboxymethyl cellulose (CMC) functionalized BC using carbodiimide chemistry. The functionalization of BC with ε-PLL inhibited growth of S. epidermidis on the membranes but did not affect the cytocompatibility to cultured human fibroblasts as compared to native BC. The functionalization had no significant effects on the nanofibrous structure and mechanical properties of the BC. The possibility to functionalize BC with ε-PLL is a promising, green and versatile approach to improve the performance of BC in wound care and other biomedical applications.
  • Georgiou, Melanie, et al. (författare)
  • Engineered neural tissue with aligned, differentiated adipose-derived stem cells promotes peripheral nerve regeneration across a critical sized defect in rat sciatic nerve
  • 2015
  • Ingår i: Biomaterials. - 0142-9612 .- 1878-5905. ; 37, s. 242-251
  • Tidskriftsartikel (refereegranskat)abstract
    • Adipose-derived stem cells were isolated from rats and differentiated to a Schwann cell-like phenotype in vitro. The differentiated cells (dADSCs) underwent self-alignment in a tethered type-1 collagen gel, followed by stabilisation to generate engineered neural tissue (EngNT-dADSC). The pro-regenerative phenotype of dADSCs was enhanced by this process, and the columns of aligned dADSCs in the aligned collagen matrix supported and guided neurite extension in vitro. EngNT-dADSC sheets were rolled to form peripheral nerve repair constructs that were implanted within NeuraWrap conduits to bridge a 15 mm gap in rat sciatic nerve. After 8 weeks regeneration was assessed using immunofluorescence imaging and transmission electron microscopy and compared to empty conduit and nerve graft controls. The proportion of axons detected in the distal stump was 3.5 fold greater in constructs containing EngNT-dADSC than empty tube controls. Our novel combination of technologies that can organise autologous therapeutic cells-within an artificial tissue construct provides a promising new cellular biomaterial for peripheral nerve repair. 
  • Halling Linder, Cecilia, 1975- (författare)
  • Biochemical and functional properties of mammalian bone alkaline phosphatase isoforms during osteogenesis
  • 2016
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • The human skeleton is a living and dynamic tissue that constantly is being renewed in a process called bone remodeling. Old bone is resorbed by osteoclasts and new bone is formed by osteoblasts. Bone is a composite material made up by mineral crystals in the form of hydroxyapatite (calcium and phosphate) that provides the hardness of bone, and collagen fibrils that provides elasticity and flexibility. Alkaline phosphatase (ALP) is a family of enzymes that is present in most species and catalyzes the hydrolysis of various phosphomonoesters at alkaline pH. Despite the generalized use of ALP as a biochemical marker of bone formation, the precise function of bone ALP (BALP) is only now becoming clear. Three circulating human BALP isoforms (B1, B2, and B/I) can be distinguished in healthy individuals and a fourth isoform (B1x) has been discovered in patients with chronic kidney disease and in bone tissue.Paper I. Three endogenous phosphocompounds, (i.e., inorganic pyrophosphate (PPi), pyridoxal 5′-phosphate (PLP) and phosphoethanolamine (PEA)), have been suggested to serve as  physiological substrates for BALP. The BALP isoforms display different catalytic properties towards PPi and PLP, which is attributed to their distinct N-linked glycosylation patterns. The catalytic activity, using PEA as substrate, was barely detectable for all BALP isoforms indicating that PEA is not a physiological substrate for BALP.Paper II. Mouse serum ALP is frequently measured and interpreted in mammalian bone research. However, little is known about the circulating ALPs in mice and their relation to human ALP. We characterized the circulating and tissue-derived mouse ALP isozymes and isoforms from mixed strains of wild-type and knockout mice. All four BALP isoforms (B/I, B1x, B1, and B2) were identified in mouse serum and bone tissues, in good correspondence with those found in human bones. All mouse tissues, except liver, contained significant ALP activities. This is a notable difference as human liver contains vast amounts of ALP.Paper III. The objective of this study was to investigate the binding properties of human collagen type I to human BALP, including the two BALP isoforms B1 and B2, together with ALP from human liver, human placenta and E. coli. A surface plasmon resonance-based analysis showed that BALP binds stronger to collagen type I in comparison with ALPs expressed in non-mineralizing tissues. The B2 isoform binds significantly stronger to collagen type I in comparison with the B1 isoform, indicating that glycosylation differences in human ALPs are of crucial importance for protein–protein interactions with collagen type I.Paper IV. Tartrate-resistant acid phosphatase (TRAP) is highly expressed in osteoclasts and frequently used as a marker of bone resorption. Intriguingly, recent studies show that TRAP is also expressed in osteoblasts and osteocytes. TRAP displays enzymatic activity towards the endogenous substrates for BALP, i.e., PPi and PLP. Both TRAP and BALP can alleviate the inhibitory effect of osteopontin on mineralization by dephosphorylation, which suggests a novel role for TRAP in skeletal mineralization.
  • Huang, Shan, et al. (författare)
  • Reciprocal relationship between contact and complement system activation on artificial polymers exposed to whole human blood.
  • 2016
  • Ingår i: Biomaterials. - : Elsevier. - 0142-9612 .- 1878-5905. ; 77, s. 111-119
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Inappropriate and uncontrolled activation of the cascade systems in the blood is a driving force in adverse inflammatory and thrombotic reactions elicited by biomaterials, but limited data are available on the activation of the contact system by polymers and the present study was undertaken to investigate these mechanisms in established models.METHODS: Polymer particles were incubated in (1) EDTA-plasma (10 mM) to monitor the adsorption of 20 selected proteins; (2) lepirudin-anticoagulated plasma to evaluate contact system activation, monitored by the formation of complexes between the generated proteases factor[F]XIIa, FXIa and kallikrein and the serpins C1-inhibitor [C1INH] and antithrombin [AT]; (3) lepirudin-anticoagulated whole blood to determine cytokine release.RESULTS: Strong negative correlations were found between 10 cytokines and the ratio of deposited FXII/C1INH, generated FXIIa-C1INH complexes, and kallikrein-C1INH complexes. Formation of FXIIa-C1INH complexes correlated negatively with the amount of C3a and positively with deposited IgG.CONCLUSIONS: A reciprocal relationship was found between activation of the contact system and the complement system induced by the polymers studied here. The ratios of FXII/C1INH or C4/C4BP, adsorbed from EDTA-plasma are useful surrogate markers for cytokine release and inflammatory response to materials intended for blood contact.
  • Pulkkinen, Hertta, et al. (författare)
  • Recombinant human type II collagen as a material for cartilage tissue engineering.
  • 2008
  • Ingår i: International Journal of Artificial Organs. - : Wichtig Editore Srl. - 0391-3988 .- 1724-6040. ; 31:11, s. 960-969
  • Tidskriftsartikel (refereegranskat)abstract
    • PURPOSE: Collagen type II is the major component of cartilage and would be an optimal scaffold material for reconstruction of injured cartilage tissue. In this study, the feasibility of recombinant human type II collagen gel as a 3-dimensional culture system for bovine chondrocytes was evaluated in vitro.METHODS: Bovine chondrocytes (4x106 cells) were seeded within collagen gels and cultivated for up to 4 weeks. The gels were investigated with confocal microscopy, histology, and biochemical assays.RESULTS: Confocal microscopy revealed that the cells maintained their viability during the entire cultivation period. The chondrocytes were evenly distributed inside the gels, and the number of cells and the amount of the extracellular matrix increased during cultivation. The chondrocytes maintained their round phenotype during the 4-week cultivation period. The glycosaminoglycan levels of the tissue increased during the experiment. The relative levels of aggrecan and type II collagen mRNA measured with realtime polymerase chain reaction (PCR) showed an increase at 1 week.CONCLUSION: Our results imply that recombinant human type II collagen is a promising biomaterial for cartilage tissue engineering, allowing homogeneous distribution in the gel and biosynthesis of extracellular matrix components.
  • Arfvidsson, Berndt, et al. (författare)
  • S100B concentrations increase perioperatively in jugular vein blood despite limited metabolic and inflammatory response to clinically uneventful carotid endarterectomy
  • 2015
  • Ingår i: Clinical Chemistry and Laboratory Medicine. - : Walter de Gruyter. - 1434-6621 .- 1437-4331. ; 53:1, s. 111-117
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Our aim was to test the hypothesis that metabolic and inflammatory responses of the brain perioperatively during carotid endarterectomy (CEA) might affect blood brain barrier (BBB) integrity.Methods: Twenty patients with >70% stenosis of internal carotid artery (ICA) were prospectively included. Surgery was performed under general anaesthesia. Blood was sampled from ipsilateral internal jugular vein and radial artery: just before, during, and after ICA clamping S100B protein, glucose, lactate, 20 amino acids, and key cytokines were analysed.Results: Jugular vein S100B increased during clamping and reperfusion, while a marginal systemic increase was recorded, unrelated to stump pressure during clamping. Glucose increased during clamping in jugular vein blood and even more systemically, while jugular lactate values were higher than systemic values initially. Most amino acids did not differ significantly between jugular vein and systemic levels: glutamic acid and aspartic acid decreased during surgery while asparagine increased. Jugular vein interleukin (IL)-6 showed a transient non-significant increase during clamping and decreased systemically. IL-8 and IL-10 increased over time.Conclusions: Rising jugular vein S100B concentrations indicated reduced BBB integrity, and marginal secondary increase of S100B systemically. Limited ischaemic effects on the brain during cross-clamping, unrelated to S100B concentrations, were confirmed by lower brain glucose levels and higher lactate levels than in systemic blood. The lack of increased jugular vein glutamic acid disproves any major ischaemic brain injury following CEA. The inflammatory response was limited, did not differ greatly between jugular and systemic blood, and was unrelated to S100B.
  • Cholujová, Dana, et al. (författare)
  • Comparative study of four fluorescent probes for evaluation of natural killer cell cytotoxicity assays
  • 2008
  • Ingår i: Immunobiology. - : Elsevier. - 0171-2985 .- 1878-3279. ; 213:8, s. 629-640
  • Tidskriftsartikel (refereegranskat)abstract
    • Cytotoxicity is one of the major defence mechanisms against both virus-infected and tumor cells. Radioactive 51chromium (51Cr) release assay is a “gold standard” for assessment of natural killer (NK) cytolytic activity in vitro. Several disadvantages of this assay led us to design alternative tools based on flow cytometry analysis. Four different fluorescent dyes, calcein acetoxymethyl ester (CAM), carboxyfluorescein succinimidyl ester (CFSE), Vybrant DiO (DiO) and MitoTracker Green (MTG) were tested for labeling of NK target K-562 cells. Target staining stability, spontaneous release of fluorochromes and subsequent accumulation in bystander unstained cells were measured using fluorimetry and flow cytometry. Healthy donor peripheral blood mononuclear cells and affinity column purified NK cells were used as effectors coincubated with target K-562 cells at different E:T ratios for 3h and 90min, respectively. Fluorescent probe 7-amino-actinomycin D was used for live and dead cell discrimination. Bland–Altman statistical method was applied to measure true agreement for all CAM–51Cr, CFSE–51Cr, DiO–51Cr and MTG–51Cr pairs analyzed. Based on the data, none of the four proposed methods can be stated equivalent to the standard 51Cr release assay. Considering linear relationships between data obtained with four fluorochromes and 51Cr release assay as well as linear regression analysis with R2=0.9393 value for CAM–51Cr pair, we found the CAM assay to be the most closely related to the 51Cr assay.
  • Christoffersson, Jonas, 1986-, et al. (författare)
  • A Cardiac Cell Outgrowth Assay for Evaluating Drug Compounds Using a Cardiac Spheroid-on-a-Chip Device
  • 2018
  • Ingår i: Bioengineering. - 2306-5354. ; 5:2, s. 1-13
  • Tidskriftsartikel (refereegranskat)abstract
    • Three-dimensional (3D) models with cells arranged in clusters or spheroids have emerged as valuable tools to improve physiological relevance in drug screening. One of the challenges with cells cultured in 3D, especially for high-throughput applications, is to quickly and non-invasively assess the cellular state in vitro. In this article, we show that the number of cells growing out from human induced pluripotent stem cell (hiPSC)-derived cardiac spheroids can be quantified to serve as an indicator of a drug’s effect on spheroids captured in a microfluidic device. Combining this spheroid-on-a-chip with confocal high content imaging reveals easily accessible, quantitative outgrowth data. We found that effects on outgrowing cell numbers correlate to the concentrations of relevant pharmacological compounds and could thus serve as a practical readout to monitor drug effects. Here, we demonstrate the potential of this semi-high-throughput “cardiac cell outgrowth assay” with six compounds at three concentrations applied to spheroids for 48 h. The image-based readout complements end-point assays or may be used as a non-invasive assay for quality control during long-term culture.
  • Cros, Olivier (författare)
  • Structural properties of the mastoid using image analysis and visualization
  • 2017
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • The mastoid, located in the temporal bone, houses an air cell system whose cells have a variation in size that can go far below current conventional clinical CT scanner resolution. Therefore, the mastoid air cell system is only partially represented in a CT scan. Where the conventional clinical CT scanner lacks level of minute details, micro-CT scanning provides an overwhelming amount of ne details. The temporal bone being one of the most complex in the human body, visualization of micro-CT scanning of this boneawakens the curiosity of the experimenter, especially with the correct visualization settings.This thesis first presents a statistical analysis determining the surface area to volume ratio of the mastoid air cell system of human temporal bone, from micro-CT scanning using methods previously applied for conventional clinical CT scans. The study compared current results with previous studies, with successive downsampling the data down to a resolution found in conventional clinical CT scanning. The results from the statistical analysis showed that all the small mastoid air cells, that cannot be detected in conventional clinical CT scans, do heavily contribute to the estimation of the surface area, and in consequence to the estimation of the surface area to volume ratio by a factor of about 2.6. Such a result further strengthens the idea of the mastoid to play an active role in pressure regulation and gas exchange.Discovery of micro-channels through specific use of a non-traditional transfer function was then reported, where a qualitative and a quantitative pre-analysis were performed and reported. To gain more knowledge about these micro-channels, a local structure tensor analysis was applied where structures are described in terms of planar, tubular, or isotropic structures. The results from this structural tensor analysis suggest these microchannels to potentially be part of a more complex framework, which hypothetically would provide a separate blood supply for the mucosa lining the mastoid air cell system.The knowledge gained from analysing the micro-channels as locally providing blood to the mucosa, led to the consideration of how inflammation of the mucosa could impact the pneumatization of the mastoid air cell system. Though very primitive, a 3D shape analysis of the mastoid air cell system was carried out. The mastoid air cell system was first represented in a compact form through a medial axis, from which medial balls could be used. The medial balls, representative of how large the mastoid air cells can be locally, were used in two complementary clustering methods, one based on the size diameter of the medial balls and one based on their location within the mastoid air cell system. From both quantitative and qualitative statistics, it was possible to map the clusters based on pre-defined regions already described in the literature, which opened the door for new hypotheses concerning the effect of mucosal inflammation on the mastoid pneumatization.Last but not least, discovery of other structures, previously unreported in the literature, were also visually observed and briefly discussed in this thesis. Further analysis of these unknown structures is needed.
  • Grannas, Karin, 1983- (författare)
  • Improvements and Applications of in situ Proximity Ligation Assays
  • 2015
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • The cells building up the human body is in constant communication with each other. This communication is done through large complex networks of signaling pathways for inter- and intracellular signal transduction. The signaling activity regulates many important processes, for example cell death, proliferation and differentiation. Information within the signaling networks is communicated over the cell membrane, through the cytoplasm and entering the nucleus by protein activities such as protein-protein interactions (PPIs) and post translation modifications (PTMs). The cells adapts to their own environment, responding to multiple stimuli from their surroundings. This in combination with memory of previous responses, difference in cell cycles stages and sometimes altered genetic background generates heterogeneous cell populations in which every cell is slightly different from its neighbor. This calls for methods to study the activity of endogenous proteins in individual cells within a population.In situ proximity ligation assay (in situ PLA) was originally developed to visualize interaction between endogenous proteins in fixed cells and tissue and can also be applied to detect PTMs. This thesis describe the application of in situ PLA to study PPIs in signaling pathways and the work to further develop and improve techniques for proximity dependent detection. In paper I in situ PLA is used to study cross talk between the Hippo and the TGFβ signaling pathways. The study shows the complex formation by the transcription co-factors of the Hippo pathway, Yap and Taz, and the main effectors of the TGFβ pathway Smad2/3. Furthermore the density dependent localization of the interaction is described.Paper II presents a new version of the in situ PLA probes for simultaneous detection of multiple complexes. Visualization of various complexes involving EGFR, Her2 and Her3 is presented as a proof of concept.The efficiency of in situ PLA is limited by several factors, one being the design of PLA probes and oligonucleotide systems. Even upon proximal binding of the probes there is a risk of formation of non-circular ligation products, which cannot be amplified and detected. In Paper III two new PLA probes are presented aiming to reduce the formation of non-circular ligation product and hence increase the detection efficiency of in situ PLA.Paper IV presents a new method for detection of protein complexes and phosphorylation; proxHCR. ProxHCR combines signal amplification by enzyme free hybridization chain reaction (HCR) with the requirement of proximal binding of two affinity probes. As a proof of principle the method is used to detect multiple complexes and protein phosphorylation in fixed cells and tissue.  
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