Figure 7. Identification of Lumikines (Lum C-terminal peptide(s) capable of stimulating wound healing in vitro and in vivo.

(A) Amino acid sequences of synthetic LumC peptides, LumC₃₃Δ_C20, LumC₁₈Δ_C5, Lum_C13 and LumC_13C-A (substitution of C with A). (B) In vitro analysis of the function of LumC peptides on the healing of HTCE cells. Healing followed biphasic kinetics in cells treated with CM, BM+GST-Lum, BM+Lum_C13 and BM+LumC_13C-A; whereas those of BM, BM+LumC₃₃Δ_C20 and BM+LumC₁₈Δ_C5 followed monophasic kinetics. The R² values were as follows: full_Lum 0.993; LumC_18ΔC5 0.970; LumC_33ΔC20 0.936; LumC₁₃ 0.952; LumC_13c-a 0.902. These data suggest that the last C-terminal 13 amino acids have wound healing activity. (C–G) In vivo wound healing activity of Lumican peptides. To confirm LumC_13C-A can also promote corneal epithelium wound healing in vivo, Lum^-/- mice were subjected to epithelium debridement. C–F are representative cut view images showing the migration distance. Migration distance was measured between the original wound edge and the wound front. In LumC_13C-A treated corneas, the wound front moved ∼144 µm. The control peptide, LumC₃₃Δ_C20, did not promote epithelium wound healing. (G) Summary of epithelium migration. The average epithelium migration (µm) and standard deviation were calculated from five corneas of two separate experiments. In PBS and peptide LumC₃₃Δ_C20 peptide treated cornea, the epithelium moved ∼38 µm, while corneas treated with LumC_13C-A migrated ∼140 µm. Injured corneal epithelium of wild type mice migrated about 100 µm.