The cells at surfaces group aims to understand the mechanisms of how human cells and tissues interact with materials/material surfaces and, in close collaboration with clinics and industry, to use this knowledge for the development of novel materials for unmet clinical needs.

We develop and use tissue-specific advanced in vitro models that more closely mimic the in vivo situation to study cell-material interactions as well as the early events of blood-material interaction and its influence on human cell response governing integration or non-integration of materials into host tissue as well as cellular processes involved in wound healing, mainly focusing on bone, skin and soft tissue. We are also interested in how drug-releasing materials can be used to steer the tissue response. Ultimately, we evaluate the predictive power of our models via correlation with in vivo results and clinical data. For this, we use state of the art techniques including gene- and protein expression analysis as well as microscopy techniques.

When damage to the body occurs, healing processes often lead to fibrosis or tissue scarring, where normal tissue is replaced by permanent scar/fibrotic tissue with impaired functionality.

Our goal is to understand the occurrence of and mechanisms involved in impaired wound healing and tissue scarring for the development of novel, material-based treatment strategies. We explore and develop new materials and fabrication concepts to create tailor-made solutions for different wound pathologies. Furthermore, we develop new advanced in vitro 3D co-culture models and use analytical tools including Microarray-technology, ELISAs, SEM or 2-photon microscopy.

We collaborate with Prof. Brigitte von Rechenberg (University Zurich), Prof. Simon Pot (University Zurich), Prof. Jan Plock (University Hospital Zurich), Prof. Rainer Riedl (ZHAW Wädenswil), Dr. Friedrich von Hahn (Meddrop AG), Prof. Heike Walles (University of Magdeburg), Prof. Sally McArthur (Swinburne University), Dr. David Poxsen (Linköping University) and thankfully acknowledge support by the Gebert Rüf Stiftung, Helmut Horten Foundation, Novartis FreeNovation, Novartis Foundation for Medical-Biological Research and CTI.

• Complex 3D skin models based on a light-sensitive polyvinyl alcohol hydrogel (Skintegrity)

• 3D scaffold based on biodegradable P4HB for the treatment of chronic skin wounds and scar tissue formation (ScarAvoid)

• Near-Infrared Light-Sensitive Polyvinyl Alcohol Hydrogel Photoresist for Spatiotemporal Control of Cell-Instructive 3D Microenvironments.

• Organic ion pump-regulated stimuli-sensitive fibres for biomolecule driven oppression of fibroblast differentiation.

Implantable biomaterials are designed to function either in a transient or permanent manner. Depending on the clinical indication, integration of an implant material into the host tissue is desired or needs to be avoided. Generally, fast and specific protein adsorption and enhanced cell migration towards the implant is beneficial in the former situation, whereas non-fouling is favored in the latter one.  In both cases however, implant surface properties including roughness, surface chemistry or wettability influence the tissue response to the material. Addition of drug-release functionality to a material can be used to further enhance such a response or to add novel properties such as an antibacterial effect to the material.

Our aim is to understand how such material properties influence different stages of the tissue response to implants, ranging from blood-material interaction to immune cell recruitment to cell differentiation processes, and to develop novel materials and material surfaces to either achieve or to avoid tissue integration. For this, we develop in vitro 3D models that mimic the target tissue and that allow to recreate the situation during implantation of a material in vitro.

Fig.2 Confocal Laser Scanning Microscopy (CLSM) image of human bone cells (actin cytoskeleton in green, nuclei in blue) on blood-derived fibrin (red) formed on micro-rough zirconia after 24 hours of culture.

We collaborate with Prof. Marcy Zenobi-Wong (ETH Zurich), Dr. Peter Wahl (Cantonal Hospital Winterthur), Prof. Viola Vogel (ETH Zurich), Prof. Jürgen Brugger (EPFL), Prof. Jörg Löffler (ETH Zurich), Prof. André Bernard (NTB Buchs), Dr. Raphael Wagner (Institut Straumann AG), Prof. Marcela Bilek (University of Sydney), Dr. Stefan Zürcher (SuSoS AG) and thankfully acknowledge support by SFA Additive Manufacturing, OrthoTrauma Foundation and CTI.

• Enhanced endothelialization of electrospun 3D scaffold interlayers on hyperelastic membranes in pulsatile ventricular assist devices by surface functionalization or hybrid scaffold design (Zurich Heart)
   

•  A predictive in vitro model that enables the evaluation of novel dental implant surfaces for their osseointegration potential

• Surface modification of ultrafine‐grained titanium: Influence on mechanical properties, cytocompatibility, and osseointegration potential

The immune response is a key element of wound healing and when the body interacts with implanted materials. Encompassing a complex and coordinated series of events, any disturbance can lead to a variety of pathologies or the development of fibrotic tissue in response to implantation of materials.

Our aim is thus to better understand how we can control the immune cell response (e.g. the switch during macrophage polarization into a pro- or anti-inflammatory phenotype) in wound healing but also in contact with materials via immuno-engineering.

We collaborate with Prof. Marcy Zenobi-Wong (ETH Zurich), Prof. Jan Plock (University Hospital Zurich), Prof. Rainer Riedl (ZHAW Wädenswil), Prof. Simon Pot (University Zurich) and thankfully acknowledge support by the Helmut Horten Foundation.

 

Fig.3 Colorized scanning Electron Microscopy (SEM) image of a macrophage on a fibrin-gel

• Cell-Membrane-Inspired Silicone Interfaces that Mitigate Proinflammatory Macrophage Activation and Bacterial Adhesion

• Anti-oxidant and immune-modulatory properties of sulfated alginate derivatives on human chondrocytes and macrophages

• Convex and concave micro-structured silicone controls the shape, but not the polarization state of human macrophages

Team

Dr. Markus Rottmar

Group leader

In vitro models, osseointegration, skin wound healing, blood-material interaction, immune response, microscopy

Dr. Géraldine Guex

Scientist

Wound healing, bioelectronics, drug delivery, electrospinning

Dr. Eike Müller
Scientist
Dental implants, osseointegration, wound healing, sCO2-foaming

Dr. Berna Sentürk
PostDoc
Dental implants, osseointegration, wound healing, sCO2-foaming

Anne-Sophie Mertgen
PhD student
Endothelialization; surface modification; biomimetic blood-material interface

Ke Yang
PhD Student
Hydrogels, skin tissue engineering, vascularization

Dr.med Matthias Wiesli
PhD student
CaP-Particles, ceramics, osteoblast/macrophage interaction

Chiara Griffoni
guest PhD student
3D skin model, blood-derived macrophages, histology

Stefanie Guimond
Technical Expert
Primary human bone cells, osseointegration, cell-material interaction, microscopy (fluorescence/SEM)

Yvonne Elbs-Glatz
Technician
Primary cell isolation, cell culture, gene-and protein expression analysis

Leonie Bannwart
Intern
Cell culture, wound healing

Natalie Moro
Intern
Wound healing, fibroblast differentiation, orgnic electronic ion pumps

Associated

Dr. Fabian Itel
PostDoc, Lab for Biomimetic Membranes and Textiles
Artificial cells, bone tissue engineering, electrospinning

Dr. Salima Nedjari
PostDoc, Lab for Biomimetic Membranes and Textiles
Endothelialization, electrospinning

Michelle Frei
Master student, Lab for Biomimetic Membranes and Textiles
Endothelialization, electrospinning