A novel culture system included a self-designed bi-layer 3-D collagen scaffold with different pore size on both sides and
specific culture media for different culture stages. This skin equivalent culture model provides a new investigating system
to study the role of extracellular matrix and growth factors including epidermal growth factor (EGF), keratinocyte growth
factor (KGF), transforming growth factor beta 1 (TGF-β1), in the cell–cell and cell–matrix interactions. Keratinocytes were
seeded onto the dermal equivalent and incubated under submerged condition for 5 days then proceeding to air–liquid interface
cultured either with or without EGF addition. In this study, EGF has a positive effect on the keratinocyte migration and proliferation
in the submerged stage. However, when 10 ng per ml of EGF was continual added in the air-lifted stage, a less organized and
thin differentiated keratinocyte layers were found. Continual 10 ng per ml of EGF addition in the air-lifted stage resulted
in uneven cell–matrix interface, and disorganization of the suprabasal layers. On the contrary, in the air-lifted stage without
excess EGF, the epithelium cells will stratify, differentiate, and form an epidermis completed with basal, spinous, granular,
and cornified layers. The results showed that time scale modulation of EGF on keratinocyte cell behavior depend on the expression
of paracrine or autocrine growth factors (e.g. KGF and TGF-β1).
Key words collagen - EGF - keratinocyte - skin equivalent