Biofabrication of biomimetic undulating microtopography at the dermal-epidermal junction and its effects on the growth and differentiation of epidermal cells

Abstract

The undulating microtopography located at the junction of the dermis and epidermis of the native skin is called rete ridges (RRs), which plays an important role in enhancing keratinocyte function, improving skin structure and stability, and providing three-dimensional (3D) microenvironment for skin cells. Despite some progress in recent years, most currently designed and manufactured tissue-engineered skin models still cannot replicate the RRs, resulting in a lack of biological signals in the manufactured skin models. In this study, a composite manufacturing method including electrospinning, 3D printing, and functional coating was developed to produce the epidermal models with RRs. Polycaprolactone (PCL) nanofibers were firstly electrospun to mimic the extracellular matrix environment and be responsible for cell attachment. PCL microfibers were then printed onto top of the PCL nanofibers layer by 3D printing to quickly prepare undulating microtopography and finally the entire structures were dip-coated with gelatin hydrogel to form a functional coating layer. The morphology, chemical composition, and structural properties of the fabricated models were studied. The results proved that the multi-process composite fabricated models were suitable for skin tissue engineering. Live and dead staining, cell counting kit-8 (CCK-8) as well as histology (haematoxylin and eosin (HE) methodology) and immunofluorescence (primary and secondary antibodies combination assay) were used to investigate the viability, metabolic activity, and differentiation of skin cells for in vitro culturing. In vitro results showed that each model had high cell viability, good proliferation, and the expression of differentiation marker. It was worth noting that the sizes of the RRs affected the cell growth status of the epidermal models. In addition, the unique undulation characteristics of the epidermal-dermal junction can be reproduced in the developed epidermal models. Overall, these in vitro human epidermal models can provide valuable reference for skin transplantation, screening and safety evaluation of drugs and cosmetics.

A Novel Method for Fabricating the Undulating Structures at Dermal—Epidermal Junction by Composite Molding Process

“…Biological experiments such as histological and immunofluorescence testing were performed on the microstructural skin model after a period of air-liquid interface culture. The results showed that the rete ridge structure played a positive role in cell proliferation, viability, and differentiation [29]. However, extrusion-based 3D printing still makes it difficult to directly shape microstructures with a certain curvature.…”

Strain sensor on a chip for quantifying the magnitudes of tensile stress on cells

“…Microfluidic systems have been utilized in cell culture more frequently in recent years 17 – 20 , particularly in dynamic cell culture systems that imitate the intricate movements of bodily organs 21 – 24 . Microfluidic devices allow human manipulation to mimic intricate movements and possess precise dimensions that simplify the process of structural design.…”