Abstract
Purpose :
Vimentin/CD44-rich leader cells, which we now identify as resident immune cells, are immediate responders to cataract surgery wounding and can mediate either a wound healing or a fibrotic response to injury depending upon the wound environment they encounter. The purpose of this study is to investigate the impact of two distinct wound environments on the transforming growth factor-beta (TGFβ)-mediated fibrotic response of leader cells with properties of resident immune cells.
Methods :
An ex vivo mock cataract surgery wound healing chick embryo model was used to follow the injury response within two distinct wound environments: 1) cell-denuded posterior lens capsule basement membrane and 2) the rigid tissue culture substrate surrounding the explant (extracapsular zone (ECZ)). To determine the effect of the distinct wound microenvironments on the TGFβ-mediated fibrotic response of leader cells, ex vivo cataract surgery explant cultures were incubated +/- 10ng/ml TGFβ, fixed, and labeled for the leader cell protein CD44 and/or markers of fibrosis. Proliferation was assessed by EdU labeling. Immunolabeling was analyzed by confocal microscopy imaging.
Results :
In contrast to untreated ex vivo cataract surgery explants, the addition of TGFβ induced leader cells located on the lens capsule to produce and deposit a fibrotic matrix that included tenascin-C and was rich in fibronectin EDA (FN-EDA). On day 3 post-injury, when wound healing on the lens capsule has completed, TGFβ induced the appearance of pro-collagen I producing cells without an increased presence of alpha-smooth muscle actin (αSMA) stress-fiber+ myofibroblasts. Lens epithelial cells retained their cuboidal epithelial phenotype. In the environment of the ECZ, exogenous TGFβ induced an accelerated and exacerbated fibrotic response by leader cells compared to controls. Exogenous TGFβ also promoted CD44+ leader cell proliferation and the earlier transition of leader cells to αSMA+ myofibroblasts. Furthermore, TGFβ treatment in the ECZ wound environment accelerated the appearance and the amount of pro-collagen I-producing cells as well as led to the increased accumulation of a FN fibrillar matrix network.
Conclusions :
The wound microenvironment that resident immune cells encounter shapes their TGFβ-mediated fibrotic response to injury.
This is a 2021 ARVO Annual Meeting abstract.