Biomedical subjects

Stephanie Nagel-Heyer

Publications and source records attributed to Stephanie Nagel-Heyer.

4 recordsLinked to original sources

PubMed2005

Cultivation of three-dimensional cartilage-carrier-constructs under reduced oxygen tension.

Three-dimensional cartilage-carrier-constructs were produced according to a standard protocol from chondrocytes of an adult mini-pig. Experiments with different oxygen concentrations (21, 10 and 5%, v/v O(2)) were performed and the constructs were compared qualitatively and quantitatively. The appearance of the cartilage obtained under reduced oxygen tension seemed to be closer to native cartilage with respect to shape of the cells, distribution of the cells within the matrix, smoothness of the surface, etc. The thickness of the cartilage formed by free swelling was always in the same range as for native cartilage (approximately 1mm). Qualitatively the most stable attachment of the cartilage on top of the carrier was found for 10% O(2) (v/v). Especially at 5% O(2) (v/v) the attachment between cartilage and carrier was not sufficient. The constructs generated at lower oxygen tensions had a significantly higher amount of glycosaminoglycan per DNA, but still significantly less when compared to native cartilage. Furthermore, the cultivated cartilage contained a large amount of collagen type II. The experiments proved the applied concept for generation of cartilage-carrier-constructs and the usefulness of cultivation under reduced oxygen tension.

Animals↗

PubMed2005

Bioreactor cultivation of three-dimensional cartilage-carrier-constructs.

A flow-chamber bioreactor was designed for generation of three-dimensional cartilage-carrier-constructs. A specific attribute of the flow-chamber is a very thin medium layer for improved oxygen supply and a counter current flow of medium and gas. Three-dimensional cartilage-carrier-constructs were produced according to a standard protocol from chondrocytes of an adult mini-pig. The final step of this protocol was performed either in the bioreactor or in 12-well plates. The bioreactor experiments showed a significantly higher matrix thickness but a lower ratio of glycosaminoglycan to DNA. For both culture methods the constructs contained a high amount of collagen II. Appearance of the cartilage obtained in the bioreactor seemed to be closer to native cartilage with respect to distribution of the cells within the matrix, smoothness of the surface etc. All results considered the flow-chamber bioreactor is a very useful tool for generation of three dimensional cartilage-carrier constructs.

Bioreactors↗

PubMed2005

Relationship between physical, biochemical and biomechanical properties of tissue-engineered cartilage-carrier-constructs.

Three-dimensional cartilage-carrier-constructs were produced according to a standard protocol from chondrocytes of an adult mini-pig. Physical parameters (height and weight) correlated very well with total DNA content (r2 = 0.86, re. 0.94). The relation between DNA content and glycosaminoglycan content was less but still significant. No significant relationship was found between the elasticity module and the DNA content, even if the elasticity module increased slightly at higher DNA content. With respect to later implantation, selection of a construct for implantation based on the weight, which can be determined non-invasive and under sterile conditions, seems to be justifiable.

Animals↗

PubMed2005

Bioreactor design for tissue engineering.

Bioreactor systems play an important role in tissue engineering, as they enable reproducible and controlled changes in specific environmental factors. They can provide technical means to perform controlled studies aimed at understanding specific biological, chemical or physical effects. Furthermore, bioreactors allow for a safe and reproducible production of tissue constructs. For later clinical applications, the bioreactor system should be an advantageous method in terms of low contamination risk, ease of handling and scalability. To date the goals and expectations of bioreactor development have been fulfilled only to some extent, as bioreactor design in tissue engineering is very complex and still at an early stage of development. In this review we summarize important aspects for bioreactor design and provide an overview on existing concepts. The generation of three dimensional cartilage-carrier constructs is described to demonstrate how the properties of engineered tissues can be improved significantly by combining biological and engineering knowledge. In the future, a very intimate collaboration between engineers and biologists will lead to an increased fundamental understanding of complex issues that can have an impact on tissue formation in bioreactors.

Animals↗