The Effect of Corneal-Derived Versus Bone Marrow-Derived Mesenchymal Stromal Cell Secretome on Corneal Epithelial Wound Healing

Abstract

Purpose : The corneal epithelium protects the eye against pathogen invasion and plays an essential role in preserving corneal clarity. Mesenchymal stromal cells (MSCs) have been shown to modulate the wound healing response in some tissues. The regenerative effects of MSCs appear to be mostly mediated through paracrine mechanisms via their secretome. We investigated the effect of secretome from corneal MSCs (cMSCs) and bone marrow MSC (BMSC) on corneal epithelial wound healing.

Methods : Human cMSC were isolated from cadaver limbus. BMSCs were isolated from healthy donors. MSCs were cultured in MEM-alpha supplemented with 10% serum. Passage 4 to 6 MSCs were used for the experiments. All experiments were repeated with at least five different donors. After reaching confluency, the media was changed to serum-free MEM-alpha. The secretome was collected after 48 hours. It was normalized based on total protein content. Scratch assay was performed on telomerase-immortalized human corneal epithelial cells (HCEC) to evaluate in vitro wound closure in presence of either cMSC secretome (cMSC^S), BMSC secretome (BMSC^S) or MEM- alpha. Six-month-old C57BL/6J mice were used to study corneal wound healing in vivo. A 1.5-mm area of the central epithelium was demarcated and removed by gentle scraping using a blunt corneal scraper, and the cornea was subsequently treated with MSC secretome or MEM-alpha for 30 minutes. The eyes were serially photographed under a slit lamp microscope every 12 hours.

Results : Mechanically wounded HCECs that were incubated with cMSC^S had 9.1 ± 0.05 percent remaining wound area (RWA) after 24 hours which was significantly smaller than 34.9 ± 0.16 percent in BMSC^S (P<0.001). Both cMSC^S and BMSC^S significantly accelerated wound closure compared to unconditioned media with a mean of 63.1 ± 0.24 percent RWA (P<0.001). Twenty-four hours after corneal epithelial debridement, corneal epithelial defect completely healed in 93.34 ± 11.54 percent of cMSC^S treated mice whereas 66.67 ± 11.54 percent of BMSC^S treated and 13.34 ± 11.54 percent of unconditioned media treated mice (P<0.001 for all comparisons).

Conclusions : Secretome from cMSC and BMSC can promote corneal epithelial wound healing. However, cMSC^S is more potent compared to BMSC^S and can be a better therapeutic alternative for ocular surface diseases such as persistent corneal epithelial defects.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.