Abstract
Purpose: :
Posterior capsular opacification (PCO) is the most common complication after cataract surgery and the cellular mechanisms responsible for PCO remain to be characterized. In this study, the effect of TGF–ß2 in the presence and absence of SPARC (Secreted Protein, Acidic and Rich in Cysteine), on proliferation, migration, and epithelial–mesenchymal transition (EMT) of lens epithelial cell (LEC) was investigated.
Methods: :
LEC was cultured from wild–type (WT) and SPARC–null (SP–null) mice. Intraocular lens (IOL) (VA60BB) (HOYA, JAPAN) was placed on cell culture inserts coated with collagen type IV in 12–well culture plates. 45,000 cells were plated into each culture well and were incubated in 10% FBS/DMEM in the presence or absence of porcine TGF–ß2 (10ng/ml) and recombinant human SPARC (20µg/ml) at 37ºC and in 5% CO2, for 6 days. The proliferation and migration of LEC were examined by staining with 0.1% crystal violet. Expression of the EMT markers collagen type I and fibronectin was assessed by immunocytochemistry.
Results: :
TGF–ß2 inhibited the proliferation and stimulated the migration of WT and SP–null LEC. TGF–ß2 increased the production of collagen type I and fibronectin in LEC of all groups. Rates of proliferation and migration, as well as the synthesis of EMT markers, were enhanced in SP–null compared to WT LEC cultured under the IOL in the presence or absence of TGF–ß2. The responses of SP–null LEC were rescued by the addition of recombinant SPARC.
Conclusions: :
These data confirm that the action of TGF–ß2 on proliferation and migration of LEC is influenced by SPARC. The results predict a functional intersection between pathways activated by TGF–ß2 and those including the matricellular protein, SPARC, in the formation of PCO.
Keywords: posterior capsular opacification (PCO) • EMT (epithelial mesenchymal transition) • extracellular matrix