Generation of human epidermal constructs on a collagen layer alone

Area of Science:

• Tissue Engineering
• Dermatology
• Cell Biology

Background:

• Clinical applications of engineered tissues face contamination issues from allogenic molecules used in stem cell culture.
• Current methods for in vitro epidermal equivalents often rely on irradiated murine fibroblasts as feeder layers for keratinocytes.

Purpose of the Study:

• To develop a simplified procedure for generating human epidermal constructs in vitro.
• To evaluate the feasibility of growing human keratinocytes on a collagen layer without feeder cells.

Main Methods:

• Human keratinocytes were isolated from adult skin and seeded at high density onto collagen-coated flasks in a low-calcium epithelial growth medium.
• No human or murine feeder layers were utilized for cell amplification.
• The resulting constructs were analyzed for morphological, immunochemical, and cytokinetic characteristics.

Main Results:

• Keratinocyte colonies grown on collagen exhibited typical morphological and immunochemical features, comparable to those grown on feeder layers.
• Stratified 3D epidermal constructs were generated, showing tissue architecture similar to natural epidermis.
• Epithelial cells expressed key differentiation markers like involucrin and filaggrin.
• However, the constructs had fewer cell layers and poorer overall organization compared to natural epidermis, likely due to the absence of epithelial-mesenchymal interactions.

Conclusions:

• A feeder-layer-free method using a collagen substrate enables the generation of human epidermal constructs from adult keratinocytes.
• While this method simplifies epidermal tissue engineering, further optimization is needed to fully replicate the complex maturation and organization of natural epidermis.
• The absence of epithelial-mesenchymal interactions is a key factor limiting the complete maturation of these engineered skin constructs.