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M. Stepp, S. Pal-Ghosh, G. Tadvalkar, R. A. Jurjus, A. Sekaran, W. P. Daley, M. Larsen; Stromal Cells Derived from the Syndecan-1 (sdc-1) Null Mouse Cornea Migrate Faster, and Have Altered Integrin Expression and Function. Invest. Ophthalmol. Vis. Sci. 2009;50(13):5696.
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Mice lacking sdc-1 have delayed corneal and skin wound healing. We have shown that dermal fibroblasts (DFs) isolated from the sdc-1 null mouse migrate faster and have altered integrin expression and activity. Here we determine whether cells isolated from the sdc-1 null mouse corneal stroma have similar phenotypes as DFs.
At 8 weeks of age, Balb/c wt and sdc-1 null mice were sacrificed, eyes removed, and corneas dissected to remove the iris and conjunctival rim. Corneas were digested with collagenenase, digests filtered to separate cells from stromal components, and cells placed in culture in 10% serum containing DMEM and used within 3-4 passages. We assessed migration rates using time-lapse microscopy. Integrin expression and function were assessed using immunoblots and immunofluorescence and by collagen gel contraction and fibronectin fibrillogenesis assays.
wt Balb/c corneal stromal cells (CSCs) migrate at similar velocities as wt DFs. Also, like the DFs, the sdc-1 null CSCs migrate significantly faster than wt CSCs. Replating the CSCs onto surfaces coated with FN did not alter the velocity of the wt cells but decreased that of the sdc-1 null cells by 26%. In contrast, replating cells onto VN-coated surfaces decreased the rates of migration of wt cells by 24% and of the sdc-1 null cells by 46%. Despite the reduced migration rates after replating, sdc-1 CSCs still migrated faster than similarly treated wt cells. The expression of both total β1 and v integrins is 2.0 fold greater in the sdc-1 null stromal cells; 5 integrin is slightly but significantly enhanced in expression in the sdc-1 null cells whereas 7 integrin is downregulated by 66%. SMA expression is elevated by 32% in the sdc-1 null cells. MnCl2 enhances integrin activity of cells and MnCl2 treatment decreased the migration rate of the wt cells 17% whereas it decreased the migration rate of the sdc-1 null 41% consistent with data on DFs showing that the integrins expressed on the surfaces of sdc-1 null cells are less active compared to those on wt cells.
The loss of sdc-1 on the surface of cells in the sdc-1 null mouse has a profound impact on the regulation of expression and function of integrins. Corneal stromal cells from sdc-1 null mice, like dermal fibroblasts, migrate faster and show enhanced integrin expression and altered regulation of integrin function. These differences are likely to impact the healing of corneal and skin wounds in these mice.
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