Clin Res Cardiol (2022). https://doi.org/10.1007/s00392-022-02002-5
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Atrial tissue slices: a model to study mechanically-induced fibrosis
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T. Schiatti1, J. Greiner1, E. Rog-Zielinska1, T. Seidel2, P. Kohl1, U. Ravens1, R. Peyronnet1
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1Institut für Experimentelle Kardiovaskuläre Medizin, Universitäts-Herzzentrum Freiburg - Bad Krozingen GmbH, Freiburg im Breisgau; 2Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen;
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Fibrosis is a common phenotype of a number of cardiac diseases. This excess
accumulation of extracellular matrix proteins can be both the cause and the
consequence of electrophysiological or/ and mechanical remodelling. In the
context of atrial fibrillation (AF), fibrosis constitutes a substrate
contributing to the maintenance and progression of the arrhythmia. Since atrial
fibrosis and mechanical overload are typically both associated with AF in the
majority of patients, we postulate that mechanical overload applied to atrial
tissue from patients in sinus rhythm (SR) can induce fibrosis patterns that resemble
those found in AF. The aim of our study is to gain deeper insight into atrial
fibrosis development in order to limit ‘domestication’ of AF. To this purpose
we have developed an in-vitro model replicating
key features of mechanically-induced fibrosis.
Rabbit and human atrial slices, 400 µm thickness and 3-5 mm
length and width, were cultured in biomimetic chambers for up to 5 days. The
tissue was paced at 2 Hz and a controlled preload was applied chronically
from the beginning of the culture. Tissue quality over time was assessed by
monitoring functional parameters: (i) systolic and diastolic forces; (ii)
responses to mechanical stimuli (Frank-Starling mechanism, slow force response);
(iii) responses to changes in stimulation frequency (force-frequency relationship,
post-rest potentiation). Live staining of collagen and cell membranes was used
to analyse tissue structure.
Our results show that slice contractility was stable over time for up to
5 days and cardiac canonical mechanically-induced responses (Frank-Starling and
slow force response) were maintained. Cardiomyocyte shape as well as tranverse
tubules were also conserved. Expected responses to well-known modulators of
cardiomyocyte contractility such as isoproterenol were also observed. Tissue
was mechanically stressed by the application of a constant preload of 2 mN
over 3 days in order to mimic the mechanical overload observed in patients. This
mechanical stimulation resulted in an increased deposition of collagen which was
analysed using a tailor-made automated image analysis method.
Our work demonstrates that
atrial tissue can be maintained in culture over 5 days with preserved
contractile properties and typical mechanically-induced responses, making this
model suitable for medium-term investigations of mechanical load effects on
atrial functional and structural remodelling. The mechanical induction of
fibrosis in these conditions will allow to monitor over time and in parallel
both the organisation of collagen deposition and the consequences for active/ passive
forces as well as for electrical conduction. Based on the changes in passive
mechanics, it will also be interesting to explore to what extend collagen
contributes to protect cardiomyocytes and nonmyocytes from excess diastolic
strain. We envision that such a platform will facilitate drug testing and the
identification of molecular targets which can potentially reduce, slow down, or
stop fibrosis.
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https://dgk.org/kongress_programme/jt2022/aP1998.html
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