γ-Propoxy-Sulfo-Lichenan Induces In Vitro Cell Differentiation of Human Keratinocytes

As non-cellulosic β-d-glucans are known to exert wound-healing activity by triggering keratinocytes into cellular differentiation, the functionality of a semisynthetic lichenan-based polysaccharide on skin cell physiology was investigated.

γ-Propoxy-sulfo-lichenan (γ-PSL, molecular weight 52 kDa, β-1,3/1,4-p-d-Glucose, degree of substitution 0.7) was prepared from lichenan. Differentiation of primary human keratinocytes was assayed by the protein analysis of differentiation specific markers and by gene expression analysis (qPCR). The gene array gave insight into the cell signaling induced by the polysaccharide.

γ-PSL (1 to 100 μg/mL) triggered keratinocytes, in a concentration-dependent manner, into the terminal differentiation, as shown by the increased protein expression of cytokeratin 1 (KRT1). Time-dependent gene expression analysis proved differentiation-inducing effects, indicating strong and fast KRT1 gene expression, while KRT10 expression showed a maximum after 12 to 24 h, followed by downregulation to the basal level. Involucrin gene expression was only changed to a minor extent, which was similar to loricrin and transglutaminase. Gene array indicated the influence of γ-PSL on MAP kinase and TGF-β mediated signaling towards keratinocyte differentiation.

The propoxylated lichenan may improve wound healing by topical application to promote the terminal barrier formation of keratinocytes.