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SPARC from corneal epithelial cells modulates collagen contraction by keratocytes
1Department of Ophthalmology, Kinki University School of Medicine, Osaka-Sayama City, Osaka, Japan.
Investigative Ophthalmology & Visual Science
|December 18, 1998
Summary
Corneal epithelial cells secrete a factor that stimulates scar tissue contraction. This factor was identified as secreted acidic rich cysteine (SPARC), which plays a role in corneal wound healing.
Area of Science:
- Ophthalmology
- Cell Biology
- Biochemistry
Background:
- Corneal wound healing involves scar tissue contraction, altering corneal shape and refraction.
- Corneal epithelial cells previously identified as secreting a factor that stimulates keratocyte collagen gel contraction in vitro.
Purpose of the Study:
- To purify and identify the specific contraction-stimulating factor secreted by corneal epithelial cells.
- To elucidate the role of this factor in corneal scar tissue modulation.
Main Methods:
- Collected conditioned medium from cultured rabbit corneal epithelial cells (ECCM).
- Purified the contraction-stimulating factor using sequential chromatography (acetone precipitation, heparin Sepharose, gel filtration, reversed-phase).
- Analyzed the amino acid sequence and confirmed identity using Western blot.
Main Results:
- ECCM enhanced keratocyte collagen gel contraction in a dose-dependent manner.
- The purified factor was identified as secreted acidic rich cysteine (SPARC), a 32-kDa glycoprotein.
- Purified SPARC dose-dependently enhanced collagen gel contraction and was localized to wound sites in vivo.
Conclusions:
- Corneal epithelial cells secrete SPARC.
- SPARC modulates corneal scar tissue contraction during wound healing.