Three-dimensional (3D) bioprinting, a flexible automated on-demand platform for 
the free-form fabrication of complex living architectures, is a novel approach 
for the design and engineering of human organs and tissues. Here, we demonstrate 
the potential of 3D bioprinting for tissue engineering using human skin as a 
prototypical example. Keratinocytes and fibroblasts were used as constituent 
cells to represent the epidermis and dermis, and collagen was used to represent 
the dermal matrix of the skin. Preliminary studies were conducted to optimize 
printing parameters for maximum cell viability as well as for the optimization 
of cell densities in the epidermis and dermis to mimic physiologically relevant 
attributes of human skin. Printed 3D constructs were cultured in submerged media 
conditions followed by exposure of the epidermal layer to the air-liquid 
interface to promote maturation and stratification. Histology and 
immunofluorescence characterization demonstrated that 3D printed skin tissue was 
morphologically and biologically representative of in vivo human skin tissue. In 
comparison with traditional methods for skin engineering, 3D bioprinting offers 
several advantages in terms of shape- and form retention, flexibility, 
reproducibility, and high culture throughput. It has a broad range of 
applications in transdermal and topical formulation discovery, dermal toxicity 
studies, and in designing autologous grafts for wound healing. The 
proof-of-concept studies presented here can be further extended for enhancing 
the complexity of the skin model via the incorporation of secondary and adnexal 
structures or the inclusion of diseased cells to serve as a model for studying 
the pathophysiology of skin diseases.