Vitronectin: a matrix support factor for human limbal epithelial progenitor cells.

PURPOSE The authors recently developed a therapeutic technique for patients with limbal stem cell deficiency by harvesting ocular surface stem cells (SCs), expanding them on therapeutic contact lenses (CLs), and applying them to diseased corneas. The present study determined the proteins that bind to CLs and whether such factors, along with transplanted cells, are critical determinants for corneal rehabilitation using this method. METHODS Therapeutic CLs were exposed to human serum, and adherent proteins were analyzed by proteomics. The distribution of vitronectin (VN) on the ocular surface was determined with specific antibodies. Cadaveric human corneas were chemically wounded, and cell transfer by CLs was assessed in organ culture. RESULTS VN was identified as a serum factor that binds and desorbs from CLs. VN localized to the limbal and basement membranes (BM) of other SC-harboring organs. Clonogenic assays demonstrated higher colony-forming efficiency on VN compared with uncoated surfaces. Cell transfer from CLs was achieved through in vitro models and was abrogated by RGD peptides and inhibitory antibodies to VN and its receptor. CONCLUSIONS Identification of VN within the limbal BM, its effect on limbal SC activity, and the discovery of this factor on serum-exposed CL polymers implies a role in supporting progenitor cells and facilitating corneal regeneration.