Interaktionen von Mikroorganismen und Granulozyten mit Polymer-Oberflächen

Due to an increasing number of biomaterials for clinical applications and more complicated mechanical requirements, there is a growing number of new polymers and polymer modifications. Whereas the physical properties can be varied without great difficulties, biocompatibility is often the limiting factor for the clinical application of polymers. Thus in the present work a novel in vitro method was developed, which makes accessable fast, reliable and reproducible data for determining the hemocompatibility of biomaterials. The method is based upon flowcytometric analysis of polymers in bead form. For the first time, the simultanous measurement of various neutrophil activation parameters (receptor expression, adherence, vitality, interleukin production) in human whole blood, and the determination of microbial adherence onto polymer surfaces as a parameter for estimating the infection riskis possible. The investigation of the expression of various surface molecules after contact with six different polymers revealed one group of polymers (polyisoprene, polyethylene, silicone) which did not induce any significant changes in receptor expression; on the other hand, contact with a group of polymers consisting of polyurethane, polymethyl metacrylate and polylactic acid led to a significantly higher expression of integrins (Mac-1) and PECAM-molecules (CD31), accompanied by a degranulation and the induction of an oxidative burst. This can result in a continous cell activation which can lead to a cell exhaustion and eventually to a local immune defect. The shedding of selectine receptors, which was also observed after contact with the aforementioned polymers, might results in a loss of the ability to migrate to local inflammation sites and thus in a weakened immune defense. As polymers after blood contact are immediately covered with a layer of blood proteins, it is generally believed that the neutrophil activation primarily results from an interaction between this protein layer and the cells. It was demonstrated that all six polymers tested are covered with fibrinogen, IgG and complement proteins. All three groups of proteins are essentially involved into the neutrophil activation process. A working hypothesis was developed which describes the interactions of these blood proteins on the polymer surface. Inhibition of the complement system by application of Compstatin resulted in a drastically reduced neutrophil activation. Thus, further investigation of this oligopeptide is needed, as it might be a useful substance for reducing the inflammatory reaction after contact with biomaterials. The microbial adherence onto polymer surfaces proved to be species-specific. The yeast Candida albicans (ATCC 90028) showed in all media tested significantly less adherence compared to the bacteriae Staphylococcus aureus (DSM 20231) and S. epidermidis (DSM 3269). In the present work it was demonstrated for the first time, that complement proteins increase microbial adherence onto polymer surfaces.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2002

Author dc:creator

• Schmidt, Silke

Contributors dc:contributor

• Haase, Gerhard

• info:eu-repo/classification/ddc/570
• Biowissenschaften, Biologie

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-119222%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:57156