DISTRIBUTION OF SPARC PROTEIN (OSTEONECTIN) IN NORMAL AND WOUNDED FELINE CORNEA

The purpose of this study was to determine the distribution of SPARC p rotein, also known as osteonectin or BM-40, in normal and wounded cat cornea. Indirect immunohistochemistry was used to study the distributi on of SPARC protein. The following types of corneal wounds were perfor med: - 5.0-diophic excimer laser photorefractive keratectomy, mechanic al keratectomy, and epithelial scrape wounds. The cats (n = 9) were ki lled 1-30 days after the operation and corneas prepared for immunohist ochemistry using polyclonal rabbit anti-murine SPARC antibody and avid in-biotin complex. Weak immunoreaction for SPARC protein was observed in the cytoplasm of epithelial and endothelial cells but not in the ke ratocytes of both normal and wounded corneas. Unwounded extracellular matrix was negative in the control cornea. Following experimental woun ding, an intense immunoreaction for SPARC appeared transiently at the basal aspect of the basal epithelial cells of multilayered, recently h ealed epithelium. The SPARC immunoreaction began from the wound edge b ut was not observed subjacent to the Battened single-layered epithelia l cells of the leading edge. The immunoreaction for SPARC was found on Days 1-6 following wounding and subsequently withdrew. The transient appearance of SPARC under the healing corneal epithelium suggests its involvement in the regulation of epithelial cell migration or shape du ring the healing process. (C) 1996 Academic Press Limited