Human skin pigmentation can be achieved by using 3D bioprinting technology, a novel method that allows distribution of melanin-producing cells (melanocytes) on a biomimetic tissue substrate, to appear like original human skin. The method was developed by a research team from A*STAR's Singapore Institute of Manufacturing Technology (SIMTech) and the Singapore Centre for 3D Printing (SC3DP) at Nanyang Technological University.
The findings published in Biofabrication show how the scientists utilize 3D bioprinting to control the distribution of melanin-producing skin cells (melanocytes) on a biomimetic tissue substrate, to produce human-like skin pigmentation.
While current engineered skin constructs are successfully used in skin repair and grafting, toxicology, and chemical testing, they lack complex features such as skin pigmentation, sweat glands or hair follicles.
"Our aim with this project was to use this method to demonstrate the feasibility of making 3D in-vitro pigmented human skin constructs, with uniform skin pigmentation."
To make the pigmented skin constructs, the team used three different types of skin cells - keratinocytes, melanocytes, and fibroblasts - and a two-step 'drop on demand' bioprinting method.
Wei Long Ng explained: "The two-step bioprinting strategy involves the fabrication of hierarchical porous collagen-based structures (that closely resembles the skin's dermal region), and deposition of epidermal cells such as keratinocytes and melanocytes at pre-defined positions on top of the biomimetic dermal skin constructs, to create 3D in-vitro pigmented human skin constructs.
"When we compared the 3D bioprinted skin constructs to those made using a manual-casting method, we found two distinct differences between the two fabrication approaches - the cell distribution on top of the dermal regions, and the microstructures within the dermal regions. The two-step bioprinting strategy enables the standardized distribution of printed cells in a highly-controlled way, as compared to the manual casting approach."
He added: "Furthermore, the bioprinting technique allows the manipulation of pore sizes within the 3D collagen-fibroblast matrices, to fabricate hierarchical porous structures that are clearly seen in the native skin tissues. In contrast, tuning the skin microstructure within the 3D collagen-fibroblast matrices using the manual-casting approach is extremely challenging."
As well as the potential to produce pigment-correct skin grafts, the team's 3D bioprinting method could also be used to develop skin constructs for toxicology testing and fundamental cell biology research.