Recreating the Human Limbal Epithelial Stem Cell Niche with Bioengineered Limbal Crypts

ABSTRACT

Purpose: Creation of an in vitro model incorporating specific features that characterize a particular stem niche would allow researchers to study stem cell behavior in a more physiological environment.

Materials and methods: We have developed a tissue engineering process (RAFT) that rapidly and reliably creates bioengineered limbal crypts (BLCs) in the surface of collagen-based tissue equivalents (TEs). These BLCs mimic the three-dimensional topography of the limbal crypts (LCs), located in the limbal region of the human cornea, which are home to a population of limbal epithelial stem cells (LESCs).

Results: Human limbal epithelial (hLE) cells occupying our BLCs expressed putative LESC markers such as ΔNp63α and Bmi1 and produced basement membrane proteins such as laminin β1 and laminin γ3; expression patterns are very similar to those seen in native LCs. Human limbal stromal cells elongate and align along the edge of native LCs and in our RAFT TEs, human limbal fibroblasts (hLFs) also appeared to exhibit this alignment and elongation behavior in response to the BLC topography.

Conclusions: We have demonstrated that we can maintain an immature population of hLE cells and aligned stromal cells in our BLCs to mimic some elements of the complexity of the human LESC niche.

KEYWORDS:

• Cornea
• epithelial cells
• limbal crypts
• limbal stem cell niche
• tissue engineering

Acknowledgments

We would like to thank all the organ donors and their families who consented to donate their corneas for research as this work would not be possible without their generosity. Thanks to Krishna Patel at Moorfields Eye Hospital for her help with statistical analysis. Thank you to Gordon Imlach from the department of Materials Engineering at the Open University for his assistance with SEM imaging.

Funding

This study was supported by the National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology and a Stem Cell Initiative Award from the Special Trustees of Moorfields Eye Hospital.

Declaration of interest

The authors report no conflicts of interest.

Additional information

Funding

This study was supported by the National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology and a Stem Cell Initiative Award from the Special Trustees of Moorfields Eye Hospital.