Applying controlled shear stress on cell covered microprobes

Appropriate coating of any artificial device meant for implantation in the body is thought to reduce long term foreignbody- reaction and thus is of particular interest for chronic implants into the brain e.g. for Deep Brain Stimulation. We assume a beneficial coverage may be reached by using multipotent adult stem cells as surface coating. These cells give rise to a multilineage progeny with a strong tendency to neuronal cells. So we hypothesise that they will provide the competence to the microprobe to become a part of the target tissue and excellent integration may be reached by this strategy. Unfortunately, any insertion of a probe into body tissue exerts shear stress on the surrounding tissue and on the probe itself. In order to evaluate the stability of confluent cell layers on micro probes, we established a test system to simulate the forces exerted upon mechanical tissue penetration. This enables us to develop protection mechanisms for our target application, brain microstimulation. In this study we present the test system consisting of a micromanipulator dragging test substrates with defined speed and force through tissue-resembling bio-gels. The simple experimental design has the potential to simulate insertion conditions for the testing of biomolecule or cellular coating of such devices prior to animal experiments to ensure the maintenance of the coating after insertion