Repellent rings at titanium cylinders against overgrowth by fibroblasts

Peter Fosodeder,Camilo Florian,Achim Walter Hassel,Johannes Heitz,Werner Baumgartner,Clemens Steinwender,Jörn Bonse

doi:10.1515/aot-2019-0070

Abstract

Abstract The invention of new miniaturized and smart medical implants continues in all medical fields, including miniaturized heart pacemakers. These implants often come with a titanium (Ti) casing, which may have to be removed after several months or years and shall therefore not be completely overgrown by cells or scar tissue after implantation. Scar tissue is mainly formed by fibroblast cells and extracellular matrix proteins like collagen produced by them. Suppression of fibroblast growth at Ti surfaces could be achieved by 800 nm femtosecond laser-ablation creating self-organized sharp spikes with dimensions in the 10 μm-range which are superposed by fine sub-μm parallel ripples. On flat Ti control samples, the best results regarding suppression of cell growth were obtained on spike-structures which were additionally electrochemically anodized under acidic conditions. When Ti cylinders with a diameter of 8 mm (similar as the pacemakers) were placed upright in a culture of murine fibroblasts, a multi-layer cell growth up to a height of at least 1.5 mm occurred within 19–22 days. We have demonstrated that a laser-structured and anodized ring around the Ti cylinder surface is an effective way to create a barrier that murine fibroblasts were not able to overgrow within this time.

Highlights

Controlled cell-adhesion on titanium (Ti) surfaces due to femtosecond-laser induced micro- and nanostructures have been investigated by several groups in the last years [1,2,3]
The major aim of this work was to expand the applicability of femtosecond laser-processing for cell-repellence from flat samples to cylindric samples
We aimed to process a ring around cylindric samples that would ideally act as a barrier for upgrowing cells and stop cell growth at a given height

Summary

Introduction

Controlled cell-adhesion on titanium (Ti) surfaces due to femtosecond-laser induced micro- and nanostructures have been investigated by several groups in the last years [1,2,3]. This interest is triggered by the fact that Ti and Tialloys are often used materials for medical implants, for instance in dentistry, orthopedics, and for cardio-vascular applications. One example are the new miniaturized leadless intracardiac transcatheter pacing systems [5], marketed under the trademark Micra® (Medtronic plc, Dublin, Ireland) The advantage of this device over a traditional pacemaker system is the possibility to fully implant it into the right ventricle of the heart via the usage of a catheter. The average lifespan of the built-in battery allows the device to operate for 10–12 years, after which the device with the battery has to be exchanged again

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