Tissue fusion over nonadhering surfaces.

Area of Science:

• Cell biology
• Biophysics
• Developmental biology

Background:

• Tissue fusion forms continuous structures, essential for embryonic development and tissue repair.
• In vivo, embryonic tissue fusion often utilizes actomyosin cable purse-string contraction.
• In vitro studies are limited by substrate adhesion, favoring lamellipodial protrusion-driven closure.

Purpose of the Study:

• To investigate purse-string closure as a mechanism for tissue fusion in vitro.
• To explore the role of active epithelial fluctuations in purse-string closure.
• To model the dynamics of tissue closure mediated by purse-string contraction.

Main Methods:

• Culturing epithelial monolayers on nonadherent substrates to control mesoscopic areas.
• Observing and analyzing tissue closure dynamics.
• Developing a stochastic model incorporating contractility, fluctuations, and friction.

Main Results:

• Epithelial monolayers can achieve purse-string closure over large nonadherent areas.
• Active epithelial fluctuations are necessary for purse-string closure.
• A stochastic model accurately describes the observed closure dynamics.

Conclusions:

• Purse-string closure is a viable mechanism for tissue fusion in vitro, independent of substrate adhesion.
• Active tissue fluctuations play a critical role in enabling purse-string closure.
• In vivo, tissue fusion likely integrates purse-string contractions with lamellipodial protrusions for environmental adaptation.