Abstract
Purpose:
The mesenchymal cells involved in regulating repair of injured epithelial are now being considered as likely agents of various disease states from fibrosis to cancer. We have previously identified a role for a vimentin-rich mesenchymal subpopulation in the lens in our studies with a clinically relevant mock cataract surgery wound healing model. Our studies show that these repair cells play a requisite role in directing the wound healing process that is dependent on their vimentin intermediate filament cytoskeleton. Here, we extend our studies to the functional properties of these vimentin-rich repair cells that confer them with the ability to perform their role as the immediate responders to injury to coordinate the wound healing process, and poise them to acquire disease-promoting phenotypes.
Methods:
Using an ex vivo wound healing model that mimics the response to cataract surgery in lenses from E15 chick embryos and recapitulates features of the fibrotic lens disease, PCO, we examined the properties associated with the mesenchymal vimentin-rich repair cell population that would give them the ability to alter their matrix environment. These studies used a combination of biochemical and cell imaging approaches. Invasion potential of repair cells was determined with a matrigel matrix-coated transwell assay and a 3D matrigel assay.
Results:
Molecules required for degradation of the ECM and cell invasion were induced in vimentin-rich repair cells that function as the directors of epithelial wound healing in response to a mock cataract surgery, including the hyaluronic acid receptor CD44 and the matrix metalloproteinases MMP2/9. These findings led to the discovery that these repair cells have innate invasive capabilities, which was confirmed by their ability to degrade and invade through an extracellular matrix environment in both the matrigel transwell and 3D matrigel matrix assays. Repair cell invasion appeared to occur in a vimentin-dependent manner since treatment with the vimentin inhibitor WIthaferin A suppressed repair cell invasion.
Conclusions:
Our studies reveal a novel involvement of repair cells in modulating the tissue environment, with a capability to degrade and remodel matrix, and that this process relies on vimentin function. Elucidation of the mechanisms involved during invasion in a normal wound healing response is a pivotal step toward understanding how this process becomes dysregulated and hijacked to promote disease.