Abstract
Abstract: :
Purpose: Transforming growth factor ß2 (TGFß2) plays a critical role in posterior capsule opacification (PCO) and in transdifferentiation of the epithelial cells in particular. This study investigated the time-course of changes in normal lens epithelial and also transdifferentiation marker genes in response to TGFß2 exposure. Methods: Human capsular bags were dissected from donor eyes (age 50-80 years) and cultured in serum free EMEM either in the absence or presence of 10ng/ml TGFß2 for 2 or 28 days. Freshly isolated capsular bags (t=0) served as a baseline for gene expression. At the experimental end point, bags were snap-frozen and mRNA extracted. Following reverse transcription, cDNA was amplified for the following genes: GAPDH, αA and ßB2 crystallins, α smooth muscle actin (αSMA) and connective tissue growth factor (CTGF). PCR products were isolated by agarose gel electrophoresis and quantified using image analysis software. Results: Freshly isolated capsular bags expressed significant message for αA and ßB2 crystallins, and CTGF but very little αSMA. Message for all of these was detected after culture for 2 or 28 days in serum-free medium. Relative to serum-free controls, exposure to TGFß2 had little effect on α crystallin or CTGF expression after 2 days, but induced a significant reduction in ß crystallin message, while stimulating αSMA expression. After 28 days culture, TGFß2 induced a further reduction in ß crystallin expression, while maintaining the stimulus in αSMA level. CTGF was increased at this time, but α crystallin expression remained relatively unaffected throughout. Conclusions: Exposure to TGFß2 increased expression of transdifferentiation marker genes and this was accompanied by reduced expression of the normal lens early differentiation gene ßB2 crystallin. Expression of the ubiquitous lens gene αA crystallin was unchanged.
Keywords: gene/expression • growth factors/growth factor receptors • posterior capsular opacification (PCO)