Development of a Static Avascular and Dynamic Vascular Human Skin Equivalent Employing Collagen/Keratin Hydrogels

TL;DR

Researchers developed a skin model with blood vessels that better mimics real skin function and structure compared to traditional models.

Contribution

A novel vascularized human skin equivalent with a collagen/keratin hydrogel ECM that improves barrier function and vessel development.

Findings

The vascularized skin model had a thicker epidermis and higher resistance, indicating better barrier function.

Keratin in the hydrogel increased keratinocyte differentiation and reduced permeability.

Endothelial cells in collagen/keratin ECM showed improved growth and tighter vessels.

Abstract

One of the primary complications in generating physiologically representative skin tissue is the inability to integrate vasculature into the system, which has been shown to promote the proliferation of basal keratinocytes and consequent keratinocyte differentiation, and is necessary for mimicking representative barrier function in the skin and physiological transport properties. We created a 3D vascularized human skin equivalent (VHSE) with a dermal and epidermal layer, and compared keratinocyte differentiation (immunomarker staining), epidermal thickness (H&E staining), and barrier function (transepithelial electrical resistance (TEER) and dextran permeability) to a static, organotypic avascular HSE (AHSE). The VHSE had a significantly thicker epidermal layer and increased resistance, both an indication of increased barrier function, compared to the AHSE. The inclusion of keratin in our collagen hydrogel extracellular matrix (ECM) increased keratinocyte differentiation and barrier function, indicated by greater resistance and decreased permeability. Surprisingly, however, endothelial cells grown in a collagen/keratin extracellular environment showed increased cell growth and decreased vascular permeability, indicating a more confluent and tighter vessel compared to those grown in a pure collagen environment. The development of a novel VHSE, which incorporated physiological vasculature and a unique collagen/keratin ECM, improved barrier function, vessel development, and skin structure compared to a static AHSE model.

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