Abstract
Purpose::
Primary mouse keratinocytes derived from the syndecan-1 (sdc-1) null mouse have altered TGFß1 signaling with increased endogenous signaling and a reduced response to addition of TGFß1. The goal of the current study was to examine whether TGFß1 altered migration during corneal wound repair in the sdc-1 mouse.
Methods::
Adult BALB/c and sdc-1 null mice on a BALB/c genetic background were used in all experiments. 1.5 mm debridement wounds were created centrally on wt and sdc-1 null corneas after sacrifice and corneas were placed in organ culture media for 18 hr at 36°C and 7% CO2. The size of each study group was from 11-16 corneas; experiments were repeated twice. For each treatment group, 1.25 ng/ml TGFß1 was added to organ culture media at the start of the incubation. The size of the remaining wound area was determined by staining corneas with Richardson’s stain, taking photographs, and using Image Pro Plus software to calculate the area of the remaining wound. Corneas were then processed for whole mount indirect immunofluorescence microscopy to localize pSMAD-2. Unwounded mouse corneas served as controls.
Results::
For wt corneas, the size of the remaining wound at 18 hr was 573 +/ 76 µm2 which was significantly (p< 0.05) less than 864 +/- 67 µm2 for sdc-1 null corneas. After TGFß1 treatment, the size of the remaining wounds for wt mice increased to 637 +/- 83 µm2 and 884 +/- 64 µm2 for sdc-1 null mouse corneas. The delay in wound closure was significant for the wt mice after TGFß1 addition (p< 0.08) using the Mann-Whitney test but was not significant for the sdc-1 null mice. No differences were seen in the localization of pSMAD2 between wt and sdc-1 null corneas with or without TGFß1 treatment.
Conclusions::
TGFß1 delays sheet migration and the overall rate of reepithelialization in wt BALB/c corneas. While sdc-1 null corneas appear to have a reduced response to the addition of TGFß1, more experiments need to be conducted to confirm the role of TGFß1 signaling in the delayed healing seen in the sdc-1 null mouse cornea.
Keywords: cornea: epithelium • wound healing • cell adhesions/cell junctions