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Medicine and Health

Improving the performance of medical-grade polymers

   
 
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This project brought together Medtronic, the world's largest manufacturer of implantable biomedical devices, with the University of Maastricht and CSMA Limited, Europe's leading independent surface analysis organisation - to develop commercially feasible methods of modifying the surfaces of biomaterials in order to improve the body's response to biomedical implants.
Previously unknown aspects of biomaterial behaviour affecting performance were identified. Results include approval for human clinical trials for a wound dressing and an intravascular stent used in conjunction with Percutaneous Translumenal Coronary Angioplasty (PCTA). New products and applications in the fields of wound dressing, intravascular stents and blood compatible surfaces for oxygenators were developed.

The main objective was to develop commercially feasible methods of modifying the surfaces of biomaterials in order to improve the body's response to biomedical implants. These new methods had to be applicable to any design of medical devices, and suitable for the most common biomaterials. Emphasis was placed on processes that had manufacturing feasibility.
The partnership was led by Medtronic's Bakken Research Centre (BRC) in Maastricht in the Netherlands. Medtronic is the world's largest manufacturer of implantable biomedical devices. Its partners were the Dutch University of Maastricht and the Centre for Surface and Materials Analysis (CSMA), a UK-based company with 15 years experience serving the biomedical device industry, offering state-of-the-art capability in surface analysis.
This project enabled these three partners to help each other improve the compatibility of medical grade polymers. Performance wise, these polymers have had a mixed history, especially with respect to their interaction with blood. The performance of medical devices used in invasive surgery depends on the coatings used. In a wide range of medical applications from transplants and bypass surgery to the use of catheters, artificial limbs and stents (the springs used to keep arteries open), surgeons are faced with the problem of the patient's body rejecting foreign entities. Coatings help make the polymers used in medical devices 'biocompatible' or rejection proof, and in the case of contact with blood 'haemocompatible'.

Project roles and research tasks

In exploring the variations in performance of medical biomaterials and devices, the three project partners shared complementary experience and skills. Medtronic's expertise as product developer centred on the coating and engineering chemistries involved. CSMA looked at the characterisation of the coating structure, while the University of Maastricht examined in vitro characterisation and tested for contact with blood.
Several research tasks were undertaken. The physical and chemical methods of activating and functionalising the most common biomaterials were examined and their surface characterisation was evaluated. Chemistries for coupling bioactive molecules to functionalised and activated surfaces were also developed. These methods were then applied to different biomedical devices and materials and tested for complete in vitro and in vivo biocompatibility. Next, the manufacturing costs of the modification process were analysed.

Results

Research results were impressive. Approval for human clinical trials was gained for a wound dressing and an intravascular stent used in conjunction with Percutaneous Translumenal Coronary Angioplasty (PCTA). Other key accomplishments include the development of proprietary processes for attachment of heparin - an anti coagulant molecule - to all materials and devices, state of the art analytical methods for analysing heparin activity on surfaces, and development of an infection-resistant surface modification.
The project has led to new products and applications in the fields of wound dressing, intravascular stents and blood compatible surfaces for oxgenators. Further products relating to infection-resistant surfaces, alternative tissue fixation methods and protective coatings for implantable sensors are currently in the pipeline.

Important new insights

As a result of the research, the project partners were able to identify crucial but previously unknown aspects of biomaterial behaviour affecting performance. Not only did the medical grade polymers need to be treated prior to the coating process, but the way in which the coating process itself was undertaken turned out to be very important. The same coating applied in different ways had substantially different impacts on the device's subsequent performance.
This has substantial implications for the production of medical devices and the techniques being developed in various applications of invasive surgery. While state-of-the- art technology is still ahead of much clinical practice, the results of Project BE-5972 research can already be seen. One consequence, for example, has been the development of safer implants and a better quality of life for patients who no longer need to undergo as much post-operative immuno repression via drugs.

Benefits of collaboration

For all of the project partners, the collaborative experience was very positive. For Medtronic, the main advantages were the much better quality of European university/ industry cooperation by contrast with the US and the networking opportunities across a wide range of products and applications. Medtronic has maintained ongoing research and commercial agreements with the all the partners beyond the life of the project, and additional contracts for continued R&D work on device modifications have been signed with the Universities of Twente and Groningen in The Netherlands and Compiegne in France.
For Maastricht University the project provided financial stability, the opportunity to develop state of the art technology with a major global industrial player and new business opportunities in Europe. For CMSA Limited, the project was a springboard for developing in-house expertise in the characterisation of biomaterials' surfaces, resulting in CSMA's present position as a leading European service for industrial surface analysis in this field. The knowledge gained in the project is being used to plan further cooperative research projects in areas such as surface modification for hybrid synthetic organs and alternative new technologies for collagen and tissue fixation. In the meantime, Medtronic is increasing its investment and employment in European centred research and development efforts, including a 60% rise in R&D expenditures at BRC for next generation stents for coronary and other applications.

 

Project Title:  
Surface modification of biomaterials for biomedical implants

Programmes:
Industrial and Materials Technologies (BRITE-EURAM/CRAFT/SMT)

Contract Reference: BE-5972

Cordis DatabaseFor more information on this project,
go to the CORDIS Database Record

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