Differences between niche cells and limbal stromal cells in maintenance of corneal limbal stem cells.

PURPOSE

To investigate the differing characteristics of limbal niche cells (LNCs) and limbal stromal cells (LSCs) in the maintenance of limbal epithelial stem/progenitor cells in the cornea.

METHODS

Limbal niche cells were obtained from direct dissection of the human corneal limbus, and LSCs were obtained from explant cultures of limbal stromal tissues under the same culture conditions. The resulting cultures were examined for their ability to support the growth of limbal stem/progenitor cells in colony-forming capacity, stratified epithelial cell sheet formation, maintenance of limbal epithelial stem/progenitor cell characteristics, and gene expression levels of factors that supported the limbal epithelial stem/progenitor cells.

RESULTS

The colony-forming efficiency of limbal epithelial stem/progenitor cells in the LNC group (6.57 ± 1.54%) was significantly higher than that in the LSC group (1.43 ± 0.47%). The epithelial cell sheets in the LNC group stratified into four or five layers compared with two or three stratified layers in the LSC group. Staining of both the colonies and the epithelial cell sheets in the LNC group showed a higher intensity of the limbal stem cell marker ΔNp63 than in the LSC group. Moreover, reverse transcription polymerase chain reaction analysis revealed that compared with the common expression of EGF and so on, the LNCs showed a higher expression level of E-cadherin and a lower expression level of neurotrophin-3 (NT3) than the LSCs.

CONCLUSIONS

LNCs have a different role compared to LSCs in their ability to support epithelial stem/progenitor cells and epithelial cellular sheet formation.