Dr. sc. nat. Martin Ehrbar, Head of Research
Main Field of Research, Abstract
of fully synthetic modular designed biomaterials. Although naturally
occurring biomaterials are well suitable for tissue regeneration
approaches, they contain matrix inherent properties that limit their use
in engineering applications. In collaboration with the laboratories of
Prof. Franz Weber, University Hospital Zürich, Prof. Matthias Lütolf
EPFL Lausanne and Prof. Wilfried Weber Bioss Freiburg Germany, we
develop a fully synthetic hydrogel platform that can be designed towards
specific matrix engineering applications in vitro and in vivo.
Building blocks are developed that will allow the combination of
features such as mechanical properties, proteolytic susceptibility,
integrin binding, and growth factor presentation within the otherwise
inert poly (ethylene glycol) PEG hydrogels. Ongoing studies with this
materials platform focus on: the study of cell-extracellular matrix
interactions, the establishment of in vitro tissue-like constructs, the recruitment and characterization of bone precursor cells, and bone healing in vivo.
Major topics of research
- Development of adult stem cell implants: Exploration of stem /
progenitor cells from human umbilical cord blood, amniotic fluid, and
placenta for tissue healing applications other than hematopoietic
applications. The objective is to develop cell-based therapeutics for
healing of diseased cardiovascular tissue, chronic skin wounds,
cartilage or bone. Transplantation of such cells may require their
fixation in the treated tissue. We seek the development of implants
comprised of adult stem cells in biomaterials that support engraftment
and differentiation of adult stem cells.
- Healing of premature preterm rupture of the fetal membrane (PPROM).
PPROM represents a devastating complication in obstetrics for which no
treatment exists yet. We seek to develop implant prepared from
resorbable biomatrices and human amnion cells that permit to immediately
plug the leak in the ruptured membrane and guide wound healing in the
following (a concept of sealing and healing). Cell biological and
biochemical studies and proteomics are used to identify protein
substances that will promote growth of native human amnion tissue in
bioengineered healing devices.
- Development of biomaterial-protein therapeutics for biological
revascularization of ischemic tissues or chronic wounds: One implant
matrix from our research and development (see below), fibrin matrix
formulated with covalently affixed vascular endothelial growth factor,
has recently completed safety studies such that it has become approved
by the ethical committee of the Kanton of Zurich for clinical studies of
treatment of patients with fingertip ulcers. Ongoing studies concern
tissue angiogenesis response to implants on the transcriptional level.
To this end, we apply Xenogen biophotonic imaging technology and
genetically engineered mice in which a luciferase reporter is driven by
the promoter of the VEGF receptor 2 to non-invasively monitor the
transcriptional response over weeks in the animal.
- Growth factor-loaded matrix coatings that promote prosthetic graft
endothelialization. Synthetic small-diameter blood vessel replacements
have a high failure rat, but early endothelialization of the lumenal
surface may improve graft patency. In vivo endothelialization of
synthetic grafts may be achieved by pretreatment of synthetic graft
implants with angiogenic substrates that recruit endothelial cells
across the anastomis, from the blood stream, or transmurally.
- Cell sheet engineering. In collaboration with the laboratory of
Prof. Janos Voeros, ETH Zurich, we seek development of
three-dimensionally designed composite materials consisting of
cell-sheets and polymer hydrogel films for tissue engineering. The basis
of the project is a new method of the Voeros laboratory at ETH Zurich
that allows for the harvesting of cell sheets by electrochemical means.
Such 3D cell/polymer multilayers will be used as a new platform to
spatially pattern different cell types for the analysis of complex
physiology in vitro and for drug screening applications. Target models
are the cellular situation of an adult blood vessel, and instruction of
differentiation of stem cells by enddifferentiated cells.