Abstract
Purpose: :
Residual lens epithelial cells (LECs) play an important role in posterior capsule opacity (PCO) following intraocular lens (IOL) implantation, although the detailed mechanism is not totally understood. By examining human lens epithelial cell line (AL-LEPI-1) in vitro, we observed continuous morphological changes in cultured cells similar to the spontaneous differentiation of adult stem cells. This investigation is aimed to study whether LECs possess stem cell like properties.
Methods: :
Non-transformed human lens epithelial cells were collected from the anterior equatorial region of a 21 year old male eye donor twenty years ago. The cells were maintained in DMEM completed media. All experiments were carried out at passages between 10 and 12. The potential stem cell markers were then analyzed on a BD FACSArrayTM Bioanalyzer (BD Science). Following incubation with an osteogenic cocktail, osteocytic calcium deposits were detected using 2% Alizarin Red S (pH 4.1-4.3) and alkaline phosphatase activities was detected histologically. The adipogenic properties of LECs were also tested and the adipocytes were stained with 0.3% Oil Red O in 60% isopropanol.
Results: :
We find that 0.1-0.2% of AL-LEPI-1 cells possess mesenchymal stem cell markers (SSEA4+/CD45-) and 1.2-5.8% possess CD34, although the test cells do not have other stem cell markers, including CD44, CD133 and Thy-1. These results suggested that, at least, a small percentage of the LECs may possess the plasticity of progenitor cells. Furthermore, after exposure to an osteogenic differentiation cocktail, many LECs express the mineralization precursor enzyme - alkaline phosphatase (28.0± 7.3% vs. 1.7 ± 0.5% of untreated control). However, no calcium deposition was found in either differentiated or un-differentiated LECs. Furthermore, when cultured in adipogenic media, 15± 6.48% (vs. 1.0± 0.8% of untreated control) of LECs differentiate into lipid droplet-containing adipocytes.
Keywords: differentiation • intraocular lens • wound healing