PhD Position in Advanced 3D Organotypic Bone Models for In Vitro Osteosynthesis Research

The Laboratory for Bone Biomechanics (LBB) at the Institute for Biomechanics at ETH Zurich is offering a PhD position in 3D bone tissue engineering. This position is embedded within the SNF Interdisciplinary Project '' Facilitating a paradigm shift in osteosynthesis: Controlling biodegradation of magnesium alloys an their local effect on surrounding tissue'' (Nr. 10007007; project start 01.10.2025: collaboration partners: J. Löffler, ETH Zürich; K. Klein, Universität Zürich; R. Müller, ETH Zürich, B. Schaller, Universitätsspital Bern) focusing on the development of advanced organotypic in vitro bone models to study degradable osteosynthesis systems based on magnesium (Mg) alloys. Degradable magnesium implants provide temporary fixation during bone healing and gradually resorb afterward, reducing the need for implant removal and promoting natural bone regeneration. However, their degradation rate and biological effects remain insufficiently understood, and existing in vitro models fail to accurately reproduce the dynamic in vivo environment of bone healing, leading to significant in vitro-in vivo discrepancies (IVIVD).

Osteosynthesis systems are designed to stabilize fractured bones in their correct anatomical alignment, but conventional implants often require removal once healing is complete, which can lead to complications. Mg-based biodegradable systems could overcome this limitation by resorbing naturally after bone repair. Yet, most current Mg alloys contain rare earth elements (REEs) to improve mechanical stability and corrosion resistance, raising concerns about biocompatibility. Moreover, Mg degradation products, such as ions and hydrogen gas, can alter the local microenvironment - affecting pH, pressure, and cellular activity - and may influence bone regeneration outcomes differently in vitro and in vivo.

The overall goal of this project is to bridge this gap by engineering an advanced organotypic 3D bone culture system that better replicates the biophysical and biochemical conditions of bone healing. The doctoral researcher will develop and apply models incorporating mechanical stimulation and cocultures of human bone forming stem cells and monocytes to capture both inflammatory and regenerative aspects of healing. These models will enable systematic evaluation of material-cell interactions under physiologically relevant conditions, helping to reduce the IVIVD and advance the clinical translation of REE-free Mg-based osteosynthesis systems.

Project team and setup: Within this SNSF-funded project, we will follow a multidisciplinary collaborative approach involving multiple doctoral and postdoctoral researchers on material surface development, in vivo small-animal studies, in vitro organotypic bone models and in vivo large animal. The research will be conducted collaboratively across four laboratories at three leading Swiss institutions, all with an excellent international reputation and state-of-the-art research facilities.

This multidisciplinary team setup integrates the development and characterization of magnesium alloys and their surface modifications, in vivo analysis of magnesium biodegradation and the associated biophysicochemical microenvironment, advanced in vitro modeling to reduce IVIVD, and small-animal testing in rabbits and large-animal testing in mini pigs to evaluate biocompatibility and translational potential of modified magnesium implants.

Job description

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• Access to state-of-the-art research infrastructure, including bioprinters, imaging platforms, and advanced cell culture facilities
• Working in a highly committed multidisciplinary team
• Regular meetings and close collaboration with the project partners
• Enrolment in the PhD program of ETH Zürich
• ETH Zürich is a family-friendly employer with excellent working conditions with an exciting working environment, cultural diversity and attractive offers and benefits