Activation of Wnt signaling to improve in vitro human limbal stem cell maintenance

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PROJECT SUMMARY Limbal epithelial stem/progenitor cells (LSCs) in the human corneal epithelium are the front line of defense to maintain transparency of the cornea. Loss or dysfunction of the LSCs leads to limbal stem cell deficiency (LSCD), which causes pain, inflammation, and loss of corneal transparency in patients. Cultivated LSCs from a patient’s healthy LSCs can be transplanted into the diseased cornea to replenish the LSCs, but maintaining sufficient LSCs and preventing LSC differentiation in culture to allow for a successful transplant remain a major challenge in the field. A canonical Wnt mimic small molecule and the expression of the Wnt co-receptor and putative LSC marker Fzd7 have separately been shown to improve the cultivation of LSCs while preventing differentiation. The goal of this proposal is to use a novel hybrid small molecule, termed Fzd7-ND, that specifically binds Fzd7 and the Wnt co-receptor LRP5/6, to activate canonical Wnt signaling. The kinetics of Fzd7-ND of Wnt activation will be investigated using a TopFlash assay first. The function and population of cultivated LSCs following Fzd7-ND treatment will be evaluated as described using biomarkers in the parent grant. The proposed project will inform further development of Wnt mimic small molecule Fzd7-ND to maximize the population of undifferentiated LSCs in culture. The knowledge gained from the proposed project will allow continued improvement of patient-specific LSCD treatment.