Fabrication of In Vitro 3D Human Dermal Model

In vitro 3D human skin models have been used as suitable semi in vivo models for in vitro diagnostics and cosmetics testing [1], for evaluating the potential of various vitamins [2], and drugs such as antibiotics [3], anti-cancer [4] and anti-viral molecules and for studying the carcinogenic biomarkers [5]. In developing these models, the presence of a dermal component with vessel may increase the similarity to native human skin and therefore, more accurate analyses results can be achieved when used as an in vitro 3D model. In this study, an in vitro 3D human dermal model consisting of dermis and hypodermis with vessel-like structures was developed. The methacrylated gelatin (GelMA) hydrogel (8% w/v) was produced by photocrosslinking and the results of its swelling ratio (16.14 ± 1.51 %), degradation ratio (2.98 ± 1.52 %) and compressive modulus (8.25 ± 2.26 kPa) was proved that the hydrogel was a suitable material for fabricating of an in vitro 3D human dermal model. For hypodermis, human adipose-derived mesenchymal stem cells (hAT MSCs) at passage 3 (2x106 cells/mL) and human umbilical vein endothelial cells (HUVECs, 4x106 cells/mL, passages 2-5) were suspended in GelMA prehydrogel solution (8% w/v) and exposed to UV A lamp for 5.5 min. The dermis consisting of dermal fibroblasts (4x106 cells/mL, passages 2-5) and HUVECs (2.25x106 cells/mL, passages 2-5) was constructed over the hypodermis by photocrosslinking for 11 min. HUVECs (6.3x104 cells/cm2, passages 2-5) were seeded on both of layers to increase the formation of vessel. After 35 days of incubation, the fluorescent micrographs showed that the dermal layer had homogeneously spread cells while the hypodermis contained well-differentiated adipocytes and hAT MSCs. Moreover, the dermal and hypodermal layers had vessel-like structures, especially in the regions close to the surface of hydrogel. It can be concluded that developed in vi