Abstract
Purpose: :
To examine the role of SPARC in scarring response of the Tenon capsule. The main reason for bleb failure in glaucoma filtering surgery is a scarring response of human tenon fibroblasts (hTF). The matricellular protein SPARC is involved in embryonic development, remodeling and wound healing response. SPARC deficient mice have an accelerated wound healing and altered dermal extracellular matrix deposition. Its role in the conjunctival scarring response remains unclear.
Methods: :
Expression of SPARC was assessed by immunohistochemistry of primary and scarred Tenon’s capsules and by Western and Northern blot analyses from cultured hTF after incubation with TGF–ß. In addition, proliferation of hTF after incubation with SPARC protein at 1–100 ng/ml for 3 days was quantified using BrdU labeling. The effect of SPARC on collagen contraction by hTF was analysed with free floating collagen gels.
Results: :
By immunohistochemistry, SPARC was markedly expressed in Tenon scars. After incubation of hTF for 3 days with TGF–ß1 and –ß2 a marked increase of SPARC protein and mRNA was observed. In addition, incubation of hTF with SPARC protein induced a significant cell proliferation and enhancement of the contraction of collagen gels.
Conclusions: :
SPARC is expressed in human Tenon scars in situ. In vitro, SPARC induces cell proliferation of hTF and enhances collagen gel contraction, both markers of the wound healing reactions. Therefore, SPARC could play an important role in the scarring response of Tenon’ capsule after glaucoma filtering surgery.
Keywords: wound healing • conjunctiva • extracellular matrix