Limits...
Hydraulic fracture during epithelial stretching.

Casares L, Vincent R, Zalvidea D, Campillo N, Navajas D, Arroyo M, Trepat X - Nat Mater (2015)

Bottom Line: Here, we demonstrate that for a variety of synthetic and physiological hydrogel substrates the formation of epithelial cracks is caused by tissue stretching independently of epithelial tension.We show that the origin of the cracks is hydraulic; they result from a transient pressure build-up in the substrate during stretch and compression manoeuvres.Our findings demonstrate that epithelial integrity is determined in a tension-independent manner by the coupling between tissue stretching and matrix hydraulics.

View Article: PubMed Central - PubMed

Affiliation: Institute for Bioengineering of Catalonia, 08028 Barcelona, Spain.

ABSTRACT
The origin of fracture in epithelial cell sheets subject to stretch is commonly attributed to excess tension in the cells' cytoskeleton, in the plasma membrane, or in cell-cell contacts. Here, we demonstrate that for a variety of synthetic and physiological hydrogel substrates the formation of epithelial cracks is caused by tissue stretching independently of epithelial tension. We show that the origin of the cracks is hydraulic; they result from a transient pressure build-up in the substrate during stretch and compression manoeuvres. After pressure equilibration, cracks heal readily through actomyosin-dependent mechanisms. The observed phenomenology is captured by the theory of poroelasticity, which predicts the size and healing dynamics of epithelial cracks as a function of the stiffness, geometry and composition of the hydrogel substrate. Our findings demonstrate that epithelial integrity is determined in a tension-independent manner by the coupling between tissue stretching and matrix hydraulics.

Show MeSH

Related in: MedlinePlus

Cracks seal from apical to basal plane in a myosin dependent fashiona, Live fluorescence images of MDCK cells expressing LifeAct-GFP showing the time evolution of cracks after stretch at different z-planes. Arrowheads point at one representative crack. b, Crack area expressed as a percentage of pattern area at different z-planes and times after stretch cessation (height increases from basal to apical). c, Live imaging of cells expressing LifeAct-Ruby and MHC-GFP during stretch and at different times during crack sealing. d, Time evolution of crack area expressed as a percentage of crack area in untreated controls immediately after stretch cessation. Error bars show SEM of n=4 clusters per condition. e, (left) Clusters of MDCK cells expressing LifeAct-GFP or LifeAct-Ruby before (CT) and after 30 min incubation with 30 μM Y-27632 and 60 μM ML-7 or 80 μM Blebbistatin. (right) Magnified views of regions highlighted on left panels before and after a 10 min 10% biaxial stretch. Note that the same cluster was used successively for control and treatment. Arrowheads point at representative cracks. The acquisition time of each snap shot is marked by a black dot on the time axis (top). Scale bar, 5μm. Epithelial clusters are 80 μm in diameter.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4374166&req=5

Figure 5: Cracks seal from apical to basal plane in a myosin dependent fashiona, Live fluorescence images of MDCK cells expressing LifeAct-GFP showing the time evolution of cracks after stretch at different z-planes. Arrowheads point at one representative crack. b, Crack area expressed as a percentage of pattern area at different z-planes and times after stretch cessation (height increases from basal to apical). c, Live imaging of cells expressing LifeAct-Ruby and MHC-GFP during stretch and at different times during crack sealing. d, Time evolution of crack area expressed as a percentage of crack area in untreated controls immediately after stretch cessation. Error bars show SEM of n=4 clusters per condition. e, (left) Clusters of MDCK cells expressing LifeAct-GFP or LifeAct-Ruby before (CT) and after 30 min incubation with 30 μM Y-27632 and 60 μM ML-7 or 80 μM Blebbistatin. (right) Magnified views of regions highlighted on left panels before and after a 10 min 10% biaxial stretch. Note that the same cluster was used successively for control and treatment. Arrowheads point at representative cracks. The acquisition time of each snap shot is marked by a black dot on the time axis (top). Scale bar, 5μm. Epithelial clusters are 80 μm in diameter.

Mentions: We finally turned to the dynamics of crack healing. Immediately after stretch cessation, the cracks begun to seal and the monolayer quickly regained its original integrity (Fig. 5a,b). Quantification of z-stacks during this process revealed that crack area was initially larger on the basal plane of the clusters than on the apical plane. With time, crack area decreased at a similar rate in all planes, thus implying that sealing proceeded from the apical to the basal planes (Fig. 5a,b). The time evolution of crack area was remarkably similar to that of hydrogel thickness (Fig. 3b, Fig. 5), strongly suggesting that the equilibration of the pressure difference between the cell interior and the crack is a main determinant of the healing rate.


Hydraulic fracture during epithelial stretching.

Casares L, Vincent R, Zalvidea D, Campillo N, Navajas D, Arroyo M, Trepat X - Nat Mater (2015)

Cracks seal from apical to basal plane in a myosin dependent fashiona, Live fluorescence images of MDCK cells expressing LifeAct-GFP showing the time evolution of cracks after stretch at different z-planes. Arrowheads point at one representative crack. b, Crack area expressed as a percentage of pattern area at different z-planes and times after stretch cessation (height increases from basal to apical). c, Live imaging of cells expressing LifeAct-Ruby and MHC-GFP during stretch and at different times during crack sealing. d, Time evolution of crack area expressed as a percentage of crack area in untreated controls immediately after stretch cessation. Error bars show SEM of n=4 clusters per condition. e, (left) Clusters of MDCK cells expressing LifeAct-GFP or LifeAct-Ruby before (CT) and after 30 min incubation with 30 μM Y-27632 and 60 μM ML-7 or 80 μM Blebbistatin. (right) Magnified views of regions highlighted on left panels before and after a 10 min 10% biaxial stretch. Note that the same cluster was used successively for control and treatment. Arrowheads point at representative cracks. The acquisition time of each snap shot is marked by a black dot on the time axis (top). Scale bar, 5μm. Epithelial clusters are 80 μm in diameter.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4374166&req=5

Figure 5: Cracks seal from apical to basal plane in a myosin dependent fashiona, Live fluorescence images of MDCK cells expressing LifeAct-GFP showing the time evolution of cracks after stretch at different z-planes. Arrowheads point at one representative crack. b, Crack area expressed as a percentage of pattern area at different z-planes and times after stretch cessation (height increases from basal to apical). c, Live imaging of cells expressing LifeAct-Ruby and MHC-GFP during stretch and at different times during crack sealing. d, Time evolution of crack area expressed as a percentage of crack area in untreated controls immediately after stretch cessation. Error bars show SEM of n=4 clusters per condition. e, (left) Clusters of MDCK cells expressing LifeAct-GFP or LifeAct-Ruby before (CT) and after 30 min incubation with 30 μM Y-27632 and 60 μM ML-7 or 80 μM Blebbistatin. (right) Magnified views of regions highlighted on left panels before and after a 10 min 10% biaxial stretch. Note that the same cluster was used successively for control and treatment. Arrowheads point at representative cracks. The acquisition time of each snap shot is marked by a black dot on the time axis (top). Scale bar, 5μm. Epithelial clusters are 80 μm in diameter.
Mentions: We finally turned to the dynamics of crack healing. Immediately after stretch cessation, the cracks begun to seal and the monolayer quickly regained its original integrity (Fig. 5a,b). Quantification of z-stacks during this process revealed that crack area was initially larger on the basal plane of the clusters than on the apical plane. With time, crack area decreased at a similar rate in all planes, thus implying that sealing proceeded from the apical to the basal planes (Fig. 5a,b). The time evolution of crack area was remarkably similar to that of hydrogel thickness (Fig. 3b, Fig. 5), strongly suggesting that the equilibration of the pressure difference between the cell interior and the crack is a main determinant of the healing rate.

Bottom Line: Here, we demonstrate that for a variety of synthetic and physiological hydrogel substrates the formation of epithelial cracks is caused by tissue stretching independently of epithelial tension.We show that the origin of the cracks is hydraulic; they result from a transient pressure build-up in the substrate during stretch and compression manoeuvres.Our findings demonstrate that epithelial integrity is determined in a tension-independent manner by the coupling between tissue stretching and matrix hydraulics.

View Article: PubMed Central - PubMed

Affiliation: Institute for Bioengineering of Catalonia, 08028 Barcelona, Spain.

ABSTRACT
The origin of fracture in epithelial cell sheets subject to stretch is commonly attributed to excess tension in the cells' cytoskeleton, in the plasma membrane, or in cell-cell contacts. Here, we demonstrate that for a variety of synthetic and physiological hydrogel substrates the formation of epithelial cracks is caused by tissue stretching independently of epithelial tension. We show that the origin of the cracks is hydraulic; they result from a transient pressure build-up in the substrate during stretch and compression manoeuvres. After pressure equilibration, cracks heal readily through actomyosin-dependent mechanisms. The observed phenomenology is captured by the theory of poroelasticity, which predicts the size and healing dynamics of epithelial cracks as a function of the stiffness, geometry and composition of the hydrogel substrate. Our findings demonstrate that epithelial integrity is determined in a tension-independent manner by the coupling between tissue stretching and matrix hydraulics.

Show MeSH
Related in: MedlinePlus