[Evolving concepts on limbal stem cells and their niche].

As a concentrated location for adult somatic stem cells, the niche plays a crucial role on maintaining the high proliferative ability and the inducing the particular differentiation of the stem cells by providing the special microenvironment containing definite extracellular matrix and niche cells. Nowadays limbal stem cells (LSCs) are the acknowledged adult somatic stem cells of corneal epithelium. Rapid progress has been accomplished in the theory and clinical practice on LSCs. However, the understanding on its niche has obviously fallen behind. This review summarized and analyzed the status quo of the study on niche of LSCs, mainly through the following aspects: the precise location of the niche was described as limbal epithelial crypts; the blood-derived and stroma-derived cytokine could regulate the proliferation, differentiation and apoptosis of LSCs by triggering particular intracellular information pathway; the survival and function of LSCs could be influenced by damaged niche microenvironment, while the differentiation of LSCs could be veered by another type of niche; in ex vivo LSCs expansion, reconstruction of the niche is needed and could be achieved by 3T3 cells or using amniotic membrane as the carrier.