Direct 3D bioprinted full-thickness skin constructs recapitulate regulatory signaling pathways and physiology of human skin

Abstract

Currently available tissue engineered skin-equivalents fail to replicate anatomically relevant features, e.g. undulated morphology of the dermal-epidermal junction, resulting in inadequate recapitulation of biologically meaningful cellular signaling pathways. This study reports fabrication of 3D bioprinted, human cell-based full thickness skin model possessing anatomically relevant structural, mechanical and biochemical features akin to human skin. The unique undulated feature of the epidermis-dermis junction could be recapitulated in the 3D bioprinted skin-equivalents. Extensive migration of the keratinocytes within the construct along with differentiation events reminded reepithelialisation. Cell-cell interaction along with diffusible factors promoted expression of differentiation and cornification markers in region-specific manner. Architectural features and silk bioink microenvironment triggered deposition of basement membrane specific-proteins at the interface. Most interestingly, extensive transcriptomics and proteomics analysis accentuated striking similarity of the 3D bioprinted full thickness skin model to the native human skin, with involvement of a number of pathways related to skin development and physiology, such as skin development, extracellular matrix organization, keratinization/cornification and collagen fibril organization. Such bioprinted in vitro human skin models would offer tremendous potential for screening cosmetic products and drugs, as well as to understand the complex physiological processes relevant to human skin thereby bridging the gap between conventional monolayer or 3D cultures and animal models.