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@PHDTHESIS{Kozyrina:996968,
author = {Kozyrina, Aleksandra},
othercontributors = {Di Russo, Jacopo and Leube, Rudolf and Zimmer-Bensch,
Geraldine Marion},
title = {{U}nravelling extracellular matrix impact on retinal
pigment epithelium mechanical homeostasis and functionality:
a multidimensional approach with stem cell-derived models},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2024-10960},
pages = {1 Online-Ressource : Illustrationen},
year = {2024},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, RWTH Aachen University, 2024},
abstract = {Epithelial cells are interconnected, whereby they acquire
mesoscale mechanical properties to accomplish specific
tissue functions. In a homeostatic state, these mechanical
properties rely on a balance between intercellular tension
and adhesion to the underlying extracellular matrix (ECM).
This balance is crucial for tissue function, particularly in
postmitotic epithelium like retinal pigment epithelium
(RPE), which due to lack of cell division, must undergo
constant remodelling events to compensate for natural cell
loss. The ECM, composed of a multitude of proteins, plays a
pivotal role in regulating this force balance, influencing
cell mechanics and behaviour. However, how changes in the
ECM composition influence the ability of RPE to maintain
their essential functions remains poorly understood.
Overall, RPE is a vital component of the retina, responsible
for maintaining photoreceptor homeostasis and supporting
vision. Daily, RPE cells phagocyte and recycle fragments of
photoreceptor cells called photoreceptor outer segments
(POS), to ensure their proper renewal and overall health of
the tissue. In this research, I hypothesized that the
biochemical and physical properties of the ECM, particularly
the variations in laminin isoforms, which are key
biochemical regulators within the ECM, directly influence
RPE cell mechanics and functionality.To study this, I
developed several reductionist models using human stem
cell-derived RPE cells. One model involved retinal spheroids
in suspension culture, which allowed for the biochemical
stimulation of cells with specific ECM components without
mechanical interference from the environment. Another model
included RPE cells cultured on soft hydrogels coated with
different concentrations of laminins. This setup simulated
the natural ECM environment of the retina and allowed
control over the ECM cues. The mechanical properties of RPE
cells were quantified using traction force microscopy,
monolayer stress microscopy, and nanoindentation. Further, I
explored how cellular contractility—an indicator of
mechanical stress—affects their ability to phagocyte POS,
a function essential for retinal health and vision.The
research revealed that the functionality of RPE cell is
significantly influenced by laminin density and composition.
Particularly, lower laminin 511 concentrations led to
increased cellular strain and reduced phagocytic ability,
which was conversely the case with laminin 332. I
demonstrated that the ratio between specific integrin
receptors (β1 and β4) modulated these interactions,
altering the balance between actin and keratin cytoskeletal
networks, which in turn determined the overall mechanical
stability of the tissue. In vivo data supported these
findings, showing that laminin density decreases towards the
retinal periphery, aligning with reduced functional demand
and indicating the presence of ECM-defined mechanical
gradient within the RPE.In conclusion, my work highlights
the importance of ECM diversity in maintaining the
mechanical homeostasis and functionality of RPE cells. The
findings presented in this work highlight the crucial role
of mechanics in visual function and offer valuable insights
into retinal health and disease. This research provides a
novel perspective on how ECM variations, particularly
age-related remodelling, may disrupt cellular adhesion and
mechanical balance, potentially leading to retinal disorders
such as age-related macular degeneration. Further studies
are needed to fully understand the extent to which these
ECM-induced changes in RPE mechanical status contribute to
retinal diseases and to explore potential treatments.},
cin = {900003 / 511001-4 ; 921110 / 164620 / 160000},
ddc = {570},
cid = {$I:(DE-82)529500-2_20161213$ / $I:(DE-82)511001-4_20140620$
/ $I:(DE-82)164620_20181217$ / $I:(DE-82)160000_20140620$},
pnm = {GRK 2415 - GRK 2415: Mechanobiology in Epithelial 3D Tissue
Constructs (363055819)},
pid = {G:(GEPRIS)363055819},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2024-10960},
url = {https://publications.rwth-aachen.de/record/996968},
}
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