(Understanding Interactions of Human Tissue with Medical Devices)
The main goals of this FP7 Marie Curie Industry-Academia Partnership are to:
- explore and develop design strategies and guidelines for improved catheter-based medical devices to minimise tissue damage, medical complications, patient trauma and discomfort
- develop appropriate in-vitro testing methods that reliably simulate in-vivo conditions, thus avoiding the need for animal testing
Project partners are:
- Philips Research, The Netherlands
- The University of Sheffield, UK
- The West Pomeranian University of Technology, Poland
The Scientific and technological vision of UNITISS is to meet the needs of today’s healthcare industry and social expectations in minimizing the invasiveness of catheter-based procedures, thus reducing clinical complications, patient discomfort and total healthcare costs.
The project aims to develop advanced design strategies for catheter-based medical devices that lead to reduced clinical catheterization complications and patient trauma caused by or relating to mechanical interactions with the human tissue. The project started in March 2012 and good progress is being made with the specific technical objectives:
More reliable in vitro test methods for simulating in vivo behaviour, thereby reducing the need for animal- and human-based testing:
- Different test protocols using ex-vivo porcine aorta (fresh from an abattoir) have been developed for simulating the contact between catheters and guidewires and the human tissue. This has been done by in-house design and fabrication of special holders for the catheter tip or guidewire and the porcine tissue that fit together with the tribological test equipment available within the partner's laboratories.
- A set of test conditions has been developed that correspond to the conditions in practice. The evaluation of the nature and severity of the damage done to the tissue during the test is challenging and work is continuing in this area to assess the limitations of the various analysis techniques available to the UNITISS partners (including various confocal microscopy techniques, FTIR, Raman Spectroscopy, OCT, etc.) and to find the most appropriate techniques.
Greater understanding of the response of human tissue to physical interactions:
- Tests carried out using the tests mentioned above, in addition to advanced tensile testing of ex-vivo human skin, human dermis and tissue-engineered skin, complemented by histology, have already provided valuable insights into the mechanical response of human tissue to physical interactions. Some of this work has already been presented at conferences. Evaluating the biochemical response of the tissue is more challenging and work is continuing in this area using various spectroscopic techniques. The use of biomarkers is also being investigated. It has become clear however that “non-living” (ex-vivo, tissue engineered) tissue cannot be used to simulate the true body response which is dependent on the blood flow. For this reason, work is being carried out in parallel on evaluating the potential of miniature spectroscopic and imaging devices that are under development at Philips and that may be used in the future for in-situ evaluation in living patients by placement on e.g. a catheter tip. Actual trials on living patients are however outside the scope of the UNITISS project.
Improved materials and coatings for device applications and for the simulation of human tissue:
- Improved coatings for medical devices that are hydrophilic, lubricious and anti-bacterial are under development at ZUT. The tribological behaviour of these coatings and the application on catheters is being tested within the UNITISS project and some of this work will be presented at the International Conference on Biotribology, Toronto, May 2014. Also newly-available commercial and experimental bulk materials for medical device applications are being evaluated within UNITISS, including new commercial hydrophilic polymers and experimental silicone composites for pressure-sensing at the catheter tip.
- Several synthetic materials for the simulation of human tissue have been evaluated; some of this work has been or will be presented at conferences: Euromat 2013 (Seville, Sept. 2013), IMoBT 2013 (Sitges, Dec. 2013), ICoBT 2014 (Toronto, May 2014). So far it has not been possible to find synthetic materials that satisfactorily simulate the tribological and damage behaviour of human blood vessels. It is for this reason that our work has continued using ex-vivo porcine aorta. Synthetic materials have been found that at least partially simulate the tribological response of human skin. Work is continuing in this area and the development of an own synthetic skin material is not ruled out.
- In addition, finite element modelling of a catheter in mechanical contact with a blood vessel, as well as further numerical modelling of the elasto-hydrodynamic behaviour of the catheter-blood-blood vessel system, are providing valuable insights into the effectiveness and optimisation of catheter design features for reducing local surface pressures and therefore the risk of tissue damage.
The project has received funding from the European union Seventh funding Framework Programme (FP7/2007-2013) under grant agreement no. 285969.