- A systematic approach to improve blood compatibility of biomaterials for cardiovascular applications

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	Biocompatible Materials » Project survey » Main projects » A systematic approach to improve blood compatibility of biomaterials for cardiovascular applications

Background and description

Blood compatible materials relate to construction materials used in devices intended to be in contact with circulating blood, either as externally communicating temporary devices or as permanent implants. In both situations numerous applications involve critical life support, as e.g. vascular grafting and coronary stenting. Although the choice of materials used in today’s devices to a large extent have been made empirically, or even by accident, the widespread use of such devices demonstrate that they may be used clinically with good results. There are still significant clinical problems, which are poorly understood but likely to be related to biocompatibility aspects. It is anticipated that the solution of these problems could substantially improve the quality of medical care with blood-contacting devices.

The vision of the project was to establish a comprehensive knowledge of the molecular and cellular mechanisms that regulates biocompatibility, in particular blood compatibility, of biomaterials in contact with blood and other bodily fluids. This knowledge will be utilised in designing materials with improved performance characteristics in combination with protocols for selective inhibition to be used in cardiovascular applications.

Scientific results

Three doctoral dissertations have been presented (see Publications 5:1-3) including 12 original papers. Twenty-one additional papers and four review papers have been published separately (see Publications). Two in vitro test models designed for evaluation of biomaterials using fresh human blood have been documented and widely used to study heparin modified surfaces (5:10, 5:13 ), stent grafts modified with immobilised heparin (5:15), surfaces with immobilised factor H (5:9), titanium and other interesting metals (5:5, 5:26), the effect of specific inhibition of complement (5:6) and further interactions with complement (5:7-8, 5:10, 5:15 ), different aspects of activation of coagulation (5:4-5, 5:10, 5:13, 5:16, 5:18) including cellular interactions (5:4-5, 5:10, 5:13-15). SEM images of stent grafts after blood contact

SEM images of stent grafts after blood contact

A clinical study has shown less activation of coagulation and inflammation during coronary bypass grafting, using a heparin coated extracorporeal circuit compared with a regular non-modified circuit (5:11-12). Photon electron spectroscopy and QCM-D have been utilised to characterise a new heparin surface (5:17). QCM-D has also been used to describe the formation of a complement convertase (5:7-8), which has also been studied using surface plasmon resonance (5:25). Phosphorylation of plasma proteins such as C3, fibrinogen, vitronectin, and factor XI, by a protein kinase released by activated platelets has been thoroughly described and shown to effect biological activity with respect to both complement and coagulation (5:19-24). The in vitro test models have proven useful to study blood compatibility of islets of Langerhans, which has resulted in a number of interesting papers (5:27-29, 5:33-34).

We conclude that all seven long-term goals which were put forward in the original application have been fulfilled: all aspects have been addressed and discussed in original peer-review papers and in review articles.

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	SSF research programme: Biocompatible Materials Fysik och teknisk fysik Chalmers tekniska högskola och Göteborgs universitet 412 96 Göteborg Besöksadress: Fysikgränd 3 Tel 031-772 1000 \| Fax 031-772 xxxx

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