TY  - JOUR
A1  - Lotz, C.
A1  - Kiesewetter, L.
A1  - Schmid, F. F.
A1  - Hansmann, J.
A1  - Walles, H.
A1  - Groeber-Becker, F.
T1  - Replacing the Draize eye test: impedance spectroscopy as a 3R method to discriminate between all GHS categories for eye irritation
JF  - Scientific Reports
N2  - Highly invasive animal based test procedures for risk assessment such as the Draize eye test are under increasing criticism due to poor transferability for the human organism and animal-welfare concerns. However, besides all efforts, the Draize eye test is still not completely replaced by alternative animal-free methods. To develop an in vitro test to identify all categories of eye irritation, we combined organotypic cornea models based on primary human cells with an electrical readout system that measures the impedance of the test models. First, we showed that employing a primary human cornea epithelial cell based model is advantageous in native marker expression to the primary human epidermal keratinocytes derived models. Secondly, by employing a non-destructive measuring system based on impedance spectroscopy, we could increase the sensitivity of the test system. Thereby, all globally harmonized systems categories of eye irritation could be identified by repeated measurements over a period of 7 days. Based on a novel prediction model we achieved an accuracy of 78% with a reproducibility of 88.9% to determine all three categories of eye irritation in one single test. This could pave the way according to the 3R principle to replace the Draize eye test.
KW  - biological models
KW  - electrical and electronic engineering
KW  - regenerative medicine
KW  - tissue engineering
KW  - toxicology
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-177492
VL  - 8
IS  - 15049
ER  - 
TY  - JOUR
A1  - Kress, Sebastian
A1  - Baur, Johannes
A1  - Otto, Christoph
A1  - Burkard, Natalie
A1  - Braspenning, Joris
A1  - Walles, Heike
A1  - Nickel, Joachim
A1  - Metzger, Marco
T1  - Evaluation of a miniaturized biologically vascularized scaffold in vitro and in vivo
JF  - Scientific Reports
N2  - In tissue engineering, the generation and functional maintenance of dense voluminous tissues is mainly restricted due to insufficient nutrient supply. Larger three-dimensional constructs, which exceed the nutrient diffusion limit become necrotic and/or apoptotic in long-term culture if not provided with an appropriate vascularization. Here, we established protocols for the generation of a pre-vascularized biological scaffold with intact arterio-venous capillary loops from rat intestine, which is decellularized under preservation of the feeding and draining vascular tree. Vessel integrity was proven by marker expression, media/blood reflow and endothelial LDL uptake. In vitro maintenance persisted up to 7 weeks in a bioreactor system allowing a stepwise reconstruction of fully vascularized human tissues and successful in vivo implantation for up to 4 weeks, although with time-dependent decrease of cell viability. The vascularization of the construct lead to a 1.5× increase in cellular drug release compared to a conventional static culture in vitro. For the first time, we performed proof-of-concept studies demonstrating that 3D tissues can be maintained within a miniaturized vascularized scaffold in vitro and successfully implanted after re-anastomosis to the intrinsic blood circulation in vivo. We hypothesize that this technology could serve as a powerful platform technology in tissue engineering and regenerative medicine.
KW  - biological models
KW  - translational research
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-176343
VL  - 8
IS  - 4719
ER  -