| dc.contributor.advisor | Janshoff, Andreas Prof. Dr. | |
| dc.contributor.author | Bodenschatz, Jonathan Francis Edward | |
| dc.date.accessioned | 2022-06-29T11:31:07Z | |
| dc.date.available | 2022-07-05T00:50:12Z | |
| dc.date.issued | 2022-06-29 | |
| dc.identifier.uri | http://resolver.sub.uni-goettingen.de/purl?ediss-11858/14131 | |
| dc.identifier.uri | http://dx.doi.org/10.53846/goediss-9326 | |
| dc.language.iso | eng | de |
| dc.subject.ddc | 540 | de |
| dc.title | Epithelial Cells under Mechanical Strain: an Investigation | de |
| dc.type | doctoralThesis | de |
| dc.contributor.referee | Janshoff, Andreas Prof. Dr. | |
| dc.date.examination | 2021-07-08 | de |
| dc.description.abstracteng | Cells are the minimal living unit of the body. Each cell plays a vital role that must
withstand various stresses, from chemical environments to mechanical strain and
temperature variations. One of these vital cell types in the mammalian body is the
epithelial cell, which lines the inner and outer surfaces of organs and cavities. These
form tightly connected cell monolayers that produce a barrier that allows for directed
transport in the body.
In this cell resolved study, confluent epithelial cells (MDCK II) were investigated under
uniaxial strain. Since little is known about the combined effect of temperature and
strain on epithelial cell layers, measurements were performed at 25 °C, 37 °C, and 39 °C
under strain. For this purpose, a uniaxial cell stretcher with elastic polydimethylsiloxane
membranes was designed, built, characterized, and used for studies at axial strains
up to 45 %. The stretcher allowed for both geometric characterization with optical
microscopy and mechanical characterization with atomic force microscopy of single
cells in a confluent layer, before, during the 30 minute strain application, and directly
after strain release.
With strain application, the cell geometry changed with an increase in cell area and shift
of the cell orientation in the direction of strain. These changes were temperature and
strain-dependent, with smaller geometric changes at 25 °C and low strain. After strain
release, the cells returned largely to their before strain values. Atomic force microscopy
indentation experiments at 37 °C showed that during strain, the pre-stress and area
compressibility modulus increased while the cell fluidity remained constant.
After strain release all parameters except tension returned to the before strain values. This increase in
stiffness at constant fluidity can also be observed in the treatment of cells with methyl-
beta-cyclodextrin, which reduced the excess membrane area of the cells. Therefore
the changes in mechanical properties can be largely attributed to a reduction in excess
membrane area. When cooling the cells to 25 °C at low strains, a shift in the scaling of
stiffness and fluidity can be observed, which disappears at high strains. This change
might be attributed to a lipid membrane phase transition at 27 °C which restricts the
recruitment of excess membrane area at low strains. When the stain is increased, a
shear-induced phase transition might occur, resulting in similar properties as at 37 °C.
Overall, these results point to a passive reaction of the cells to external stress, namely
recruitment of the excess surface area in response to strain. | de |
| dc.contributor.coReferee | Enderlein, Jörg Prof. Dr. | |
| dc.contributor.thirdReferee | Großhans, Jörg Prof. Dr. | |
| dc.contributor.thirdReferee | Betz, Timo Prof. Dr. | |
| dc.contributor.thirdReferee | Köster, Sarah Prof. Dr. | |
| dc.contributor.thirdReferee | Rizzoli, Silvio Prof. Dr. | |
| dc.subject.eng | atomic force microscopy | de |
| dc.subject.eng | epithelial cells | de |
| dc.subject.eng | cell stretcher | de |
| dc.subject.eng | cell mechanics | de |
| dc.identifier.urn | urn:nbn:de:gbv:7-ediss-14131-5 | |
| dc.affiliation.institute | Fakultät für Chemie | de |
| dc.subject.gokfull | Chemie (PPN62138352X) | de |
| dc.description.embargoed | 2022-07-05 | de |
| dc.identifier.ppn | 1808732820 | |