eCM Meeting Abstracts 2001, Collection 1

Abstracts of European Cells and Materials I
Bone & Soft tissue Biomaterial interactions
August 22nd- 24th 1999, Congress Centre, Davos, Switzerland

Summary of the meeting

From August 22 - 24, 1999, the first European Cells and Materials meeting for was held in Davos, Switzerland, on the theme "Bone & Soft Tissue Biomaterial Interactions". The 50 oral presentations and several posters addressed pressing issues in the field such as surface microtopography and chemistry, biodegradeable implants as well as fundamental presentations in hard tissues and implants. Medical applications in these areas and the problems of producing an animal model with osteoporotic like bone were also considered.
The conference was organised by Dr. Geoff Richards, AO Research Institute of Davos. Tel. 0041 (0)81 4142 397 Fax :288 e-mail: geoff.richards@aofoundation.org
There were 6 main sessions followed at the end of the conference with poster presentations and a summary of each session (speaker in bold) from the session chairs.

Final summaries of sessions and general comments given at the meeting:

Chair: Hanns Plenk, University of Vienna, Austria. Hard tissue: structure, mechanics & interactions with biomaterials.
The ultrastructure of a hard tissue was elegantly demonstrated for the different types of dental cementum. Cementum attachment to dentine during tooth development or periodontal regeneration can also serve as a model for hard tissue interfaces with biomaterials. New insights into the three-dimensional structure and micromechanical properties of bone are provided by confocal laser and atomic force microscopy.
With most of the presently used macro- and microstructured metallic implant surfaces bone tissue can form a mechanical interlocking which can withstand functional loading by long-time interfacial and periimplant remodelling. Laser structuring of metallic implant surfaces may be a new approach which will first have to prove its possible advantages. Finite element analyses show favourable stress distributions around elastomer-coated hip endoprotheses, but histomorphology of the tissue reactions must show whether this represents an alternative to direct mechanical interlocking with bone.

Co-chair: SimonTurner, Colorado University, USA. Fracture treatment & diagnostics in osteoporosis.
Chair: Erich Schneider, AO Research Institute Davos.
Osteoporosis is a significant health problem as can be seen here on the streets of Davos in the elderly female population. There is no perfect animal model for osteoporosis. The researcher should start with the rat, in some cases with the mouse for manipulation of the genome, the sheep is the next most practical animal, followed by the use of primates before clinical trials. Dexa and high resolution micro-CT are important tools for measuring bone density and showing its architecture. When making animal models with severe bone loss one should be aware of the complications of long-term administration of cortico-steroids and the possibility of infections. Vertebroplasty was mentioned here and in the previous session. Initially there was a trend towards injecting with PMMA but bioactive ceramics are being used more and more to fix implants. When using markers diurnal variation should be taken into account.

Chair: Marcus Textor, Swiss Federal Institute of Technology, CH-Zürich. Surface characterisation of biomaterials
Co-chair: Ann Wennerberg, Göteborg University, Sweden
Surface properties were seen to be important throughout the sessions showing there is a great need for quantification of topography using the six orders of magnitude between nm to mm. There may be no lower limit to the size of surface features that influence surface–protein and surface–cell interactions. The use of atomic force microscopy and scanning electron microscopy are all important in this aspect. Surface probe and scanning techniques are important for topographical roughness and mechanical techniques at the nano scale. In the area of fretting, the quantitative description of particle shapes and their distribution (morphometrics) must be worked on. We have seen an extension to real time optical microscopy showing local properties on the sub-micron scale. When working on surface interfaces, biologists, engineers, chemists and physicists come together bringing livelier discussions - though their terms for description may differ. Help for the young scientists should be available during preparation of their presentations possibly preventing harsh criticism later.

Chair: Geoff Richards, AO Research Institute Davos. Cell interactions at the soft tissue-biomaterial interface.
Co-chair: Adam Curtis, University of Glasgow, Scotland.
Surface topography and chemistry were seen to be very important for the cell and tissue interactions. Though we had no presentations from the microbiology community this should also hold true for bacteria on implant surfaces. For roughness measurements it is clearly evident that standardisation methods should be updated to areas since in biology areas are important not single lines. Though there is no clear definition of an osteoblast, simple marking with alkaline phosphatase or looking for mineralisation is not enough. Fibroblasts and myocytes may come up positive with these methods. Standard published tests using osteopontin and osteocalcin markers of 'osteoblasts like cells' should be used, though culture conditions must be considered such as serum, media and cell seeding concentration which may all alter the phenotype.
On a general note I would like to defend the strong criticism of several presentations from the audience. There are no experts in science, but there is experience and knowledge gained with time which should be imparted onto others. It has been observed many times in this conference that people have not read publications in the area of their research before carrying out their work leading to repetition of published work or mistaken conclusions of results. Though publications should also be questioned, not everything should be believed as fact. We have had many expensive technical machines shown at this conference and should bear in mind that the machines are there to solve a problem not to search for one. Iolo ap Gwynn from The University of Wales also added to the general comment that specimen preparation is very important for the new instruments being used and that old methods can not just be applied for this. Results depend on good preparation techniques.

Chair: Berton Rahn, AO Research Institute Davos. Medical applications
Co-chair: Jean-Marc Meyer, University of Geneva, Switzerland.
The keynote lecture on dental materials revealed, in comparison to orthopaedic surgery, an extremely wide spectrum of materials, and highly developed technologies for chair-side material processing, and it gave an overview over the dramatic developments during the last two decades, and into the future. The topics of this session were less homogeneous, but some of the presentations can be grouped under the general heading of medical problems with an increasingly aging population. In fracture treatment, fixation of implants in critical situations could eventually be improved by the use degradable materials, e.g. in osteoporotic bone. The use of degradable scaffolds for tissue engineering would be extremely welcome in situations where prolonged overuse has led to destruction of joint surfaces. So far, in spite of nice histological results, the functionality of cartilage replacements still seems to be problematic.

Chair: Sylwester Gogolewski, AO Research Institute Davos. Non metallic materials in bone regeneration.
Co-chair: Marcus Glatt, Novartis, Basel, Switzerland.
To make progress in implant design, brave imaginative surgeons are needed to introduce these innovations into the clinic. This statement also applies to the area of resorbable implants. This session showed the great success of current pioneering surgeons using resorbable implants. One of the new applications of biodegradable materials would be the adhesives/glues. These could be used in areas of low loads, e.g. maxillofacial surgery, small fragments, intra-articular defects, and possibly also in combination with standard fixation devices. Medical carbon materials have not been popular over the last ten years but new avenues are opening up. Closer collaboration between various specialists in basic research and medical practice is required for successful development in this area.

General Conference Summary
Hanns Plenk, University of Vienna, Austria.
The imaging of cell functions, intercellular matrix composition, and biomaterials structures can profit from new technologies, but only in combination with the established and proven light and electron microscopical methods. Further prerequisites are appropriate sample preparation and selection of the most suitable instrumentation. The truly interdisciplinary nature of this meeting and the fruitful discussions improved the understanding between the biological and engineering sciences, but also showed that exchange of basic information in the respective fields should precede project planning and interpretation of results. I would like to thank the attendees for their discussions which made this meeting of the highest standard. We (He referred to the attendees who have been in the field for a long time) are always open for questions and to give help.

Student Award
A student award was established in order to give young scientists a recognition of their scientific performance which could be documented in their curriculum vitae and to encourage them to continue their research career in the field of materials and tissue interaction. A small cash prize was donated by Saphirwerk Industry, Brügg, Switzerland, and by the AO Research Institute, Davos. Three reviewers assessed the presentations of all the eligible candidates and independently judged their performance.
Professor Hanns Plenk, University of Vienna, Austria.
Professor Adam Curtis, University of Glasgow, Scotland.
Professor Berton Rahn, AO Research Institute Davos
Evaluation criteria included the importance of the topic, and the contribution of the presented work to the field, the clarity and the didactic aspects of the presentation, and the appropriate use of visual aids. The ability to interact with the audience was assessed during the discussion as was the presentor's knowledge of the research field and the specific project, i.e. the candidate's involvement in the entire project.

Two candidates were identified who both deserved the award and the committee came to the conclusion that splitting the prize would be a fair solution. The award was thus presented to
Christine Dupont from the Institute of Chemical Interfaces, Catholic University Louvain, Belgium, and to
Andreas Laib from the Institute of Biomedical Technology, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland.
We congratulate both prize winners on their success.