Purified in vitro-expanded ABCB5-positive limbal stem cells possess corneal regenerative capacity.

Abstract

Purpose : We previously demonstrated that freshly isolated human KRT12-negative ABCB5-positive (ABCB5+) limbal stem cells (LSC) produce long-term (13 months) regeneration of a mature KRT12-expressing corneal epithelium when transplanted onto immunodeficient NSG mice with induced limbal stem cell deficiency (LSCD). Here we examined whether purified in vitro-expanded ABCB5+ LSC retain the capacity for corneal regeneration.

Methods : Purified in vitro-expanded human ABCB5+ LSC derived from four separate cadaveric donors were placed into fibrin gels (500 ABCB5+ LSC / gel graft; n= 4-5 mice per group per experiment) and subsequently grafted to immunodeficient NSG mice with mechanically induced LSCD, through removal of the epithelium from limbus to limbus using an Algerbrush. Negative controls were NSG mice with induced LSCD, but treated with grafts containing the gel-carrier only and no cells. Transplants were examined weekly via slit lamp and scored for opacity (0-4) using a standard scoring system.

Results : NSG mice with induced LSCD that received negative control grafts containing no cells developed conjunctivalization and opaque corneas (2.5 ± 0.67 average opacity score ± SD at 5 weeks post transplantation). In contrast, grafts consisting of purified in vitro-expanded ABCB5+ LSC prevented conjunctivalization and regenerated a clear corneal epithelium 5 weeks post transplantation (0.25 ± 0.5 average opacity score ± SD; P < 0.05 versus negative controls by t-test).

Conclusions : Purified in vitro-expanded ABCB5+ LSC retain the corneal regenerative capacity of freshly isolated human ABCB5+ LSC, pointing to therapeutic potential of this novel cell population also for clinical application in treatment of human LSCD.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.