Summary The Mesenchymal Stromal Cell (MSC) Secretome Study is designed to assess the safety of allogeneic bone marrow-derived MSC secreted factors on the ocular surface, and also obtain a preliminary observation on 1) epithelial healing; 2) development of scarring; and 3) final visual acuity; with the objective of improving clinical outcomes in significant non-healing corneal epithelial disease. To achieve these goals, the MSC Secretome Study will include a Phase 1 safety and maximum tolerated dose study (Specific Aim #1) and a Phase 2a double- masked vehicle-controlled study to assess preliminary evidence of efficacy while identifying patient subgroups most likely to benefit from the treatment (Specific Aim#2).