Feature Article

By: J. Vienken, Fresenius Medical Care, Bad Homburg, Germany

The development of medical devices during the past 20 years has been a real success story. The medtech realm represents, by far, the largest number of patent applications submitted to the European Patent Office in Strasbourg, France. In 2006 alone, 15  723 medtech-related patents were submitted, exceeding the number of patents filed for other innovative sectors such as telecommunications or the automotive industry. The innovative power of medical technology has resulted in more efficient treatments and better therapies. In 2003, the British Medical Journal reported that “… advances in medical technology account for a third of the reduction in road traffic deaths.”¹

 

Setting aside mechanical or electrical components and devices such as pacemakers and inhalers, a major contributor to this success story has been the development of appropriate polymers and biomaterials. In recent years, the definition of a biomaterial has undergone major changes. In his landmark article in 1987, D.F. Williams defined a biomaterial as “… a nonviable material used in a medical device, intended to interact with biological systems.”² Recent innovations and a better understanding of the underlying mechanisms of interaction between biomaterials and living tissue have led to a more complex, but possibly more precise, definition of a biomaterial, which opens new perspectives for individualised therapeutic applications. The following definition is suggested as a basis for the establishment of a consensus definition:

 

“A biomaterial is a technically fabricated state of matter, usually a solid of defined structure, surface properties and function for a species-adapted biocompatible interaction with living organisms.”³

 

When describing the advances of biomaterial applications in medical devices, three major steps or developmental periods can be observed (Figure 1).

 

In the early days of biomaterial application, research and development mainly focused on identifying appropriate polymers. Empirical analyses of biomechanics and sometimes even casual observations of biofunctions were applied in favour or in opposition of the application of a polymer as a biomaterial. During that first period, which I call “the period of understanding” between 1970 and 1990, scientists and engineers tried to elucidate the basic mechanisms of biomaterial and tissue interactions and identify those polymers or metals that offer the least pronounced interaction with liquids, tissue or organs in animal or human organisms.

 

This era was followed by the “period of parameters,” which lasted approximately another 20 years from 1990 to 2010. That is when medical device scientists tried to find out how to characterise the interaction between biomaterials and body parts. During this period, ISO 10993 Biological Evaluation of Medical Devices and innumerable publications appeared that targeted biocompatibility parameters and their manipulation and optimisation. In addition, at that time the biocompatibility properties of biomaterials were already used to discriminate among polymers for marketing purposes. This often happened without an in-depth understanding of the underlying mechanisms and possible related clinical consequences. Simultaneously, sterilisation issues arose and polymer and device stability following gas sterilisation with ethylene oxide or a high-energy intake by steam or irradiation had to be assessed. Furthermore, the long-term performance of medical devices that are implanted or attached to the body needed attention, because cost constraints led to the idea of reusing medical devices. All of those investigations produced a better understanding of the results of repeated exposure of a biomaterial, whether under the extreme situation of contact with protein-containing body fluids (whole blood or serum) or to oxidising cleansing agents. As an example, Fresenius Medical Care, a manufacturer of dialyzers for blood purification and haemodialysis, decided to stop the reuse of filters in its dialysis clinics based on observations of adverse clinical events in patients after reuse.

 

“How the Sum of Its Parts Gets Greater Than the Whole” is the title of a paper published in Nature Methods in 2008.⁴ This notion exactly describes the intention of the third period, which I call “the period of quality,” and which may relate to the years between 2010 and 2030.

 

As a result of improved, precise imaging technologies, direct analysis of the effects of the device and related therapies is feasible. Magnetic resonance tomography and related electromagnetic techniques, combined with considerable improvement in the reduction of the signal-to-noise ratio, allow for the application of noninvasive sensors and thus a comfortable analysis of patient data.

 

Therapies dedicated to the specific and individual pathological condition of patients are currently in development. Patients with chronic diseases such as diabetes, chronic obstructive pulmonary disease and uraemia and those with cardiovascular problems will profit.

 

Medical devices of this period will be characterised increasingly by a “systems approach” that takes into account the effects of polymers and biomaterials and their active or inactive surface properties at the nano-level. Synergistic effects between administered drugs and polymer properties and the specific conditions of device applications also will play a role.

 

These aspects will be accompanied by new therapy standards that may facilitate the application of complex devices and consequently lead to reduced morbidity and mortality of patients whilst maintaining a reasonable quality of life for them.

 

The expected demographic changes, which will lead to increasing numbers of elderly people in the population (including their higher morbidity), will require medical devices that offer individualised therapies. System solutions for medical devices, which incorporate feedback loops between analytical sensors and adaptable therapy parameters, as well as noninvasive sensors based on electromagnetic effects will be the basis for individualised therapies of the future and, thus, provide a quantum leap beyond the current application of medtech components or products (Figure 2). 

 

 

is Vice President, BioSciences,

Fresenius Medical Care Deutschland GmbH, Else-Kröner-Straße 1, D-61352 Bad Homburg
tel. +49 6172 609 2463
e-mail: joerg.vienken@fmc-ag.com
www.fmc-ag.com