Isolation and Identification of Limbal Niche Cells.

Abstract

Here we report a standard procedure for the isolation and identification of limbal niche cells (LNCs). Limbus tissue obtained from an eye bank was used for LNCs isolation. The tissue was divided into 12 pieces under aseptic conditions and digested for 18 h at 37 °C in the cell culture incubator using collagenase A to obtain cell clusters with LNCs and limbalepithelial progenitor cells. The cell clusters were further digested for 15 min at 37 °C using 0.25% trypsin-EDTA to obtain single cells and then cultured in modified embryonic stem cell medium (MESCM) on a plastic surface coated with 5% Matrigel. Cells were passaged upon 70% confluence, and LNCs were identified using immunofluorescence, real-time quantitative PCR (qPCR), and flow cytometry. Primary LNCs were isolated and passaged more than 12 times. The proliferation activity of LNCs from P4 to P6 was the highest. LNCs expressed higher stem cell markers than BMMSCs (SCF, Nestin, Rex1, SSEA4, CD73, CD90, MSX1, P75NTR, and PDGFRβ). Furthermore, results showed that P4 LNCs uniformly expressed VIM, CD90, CD105, and PDGFRβ, but not Pan-CK, which could be used as a marker for the identification of LNCs. Flow cytometric analysis showed that approximately 95%, 97%, 92%, and 11% of LNCs expressed CD73, CD90, CD105, and SCF respectively, while they were68%, 99%, 20%, and 3% inBMMSCs. The standard process for LNCisolation and identification could providea reliable laboratory basis for the widespread use of LNCs.