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Applications of 3D bioprinted iPSCs
any tissue in its native architecture by preserving cosmetics testing (Figure 5). At present, the
the complexity of cellular pathways, cell-cell human skin models required for cosmetic testing
interactions, and cellular-microenvironment are manufactured by layering fibroblasts in a
interactions. The tissue microenvironment is collagen hydrogel, then adding keratinocytes on
critical for the understanding of drug acting top. The cells are allowed to differentiate and
mechanisms in humans [141] . The use of 3D mature into the different epidermal layers. This
bioprinted tissue is predicted to be an integral part type of artificial skin models is simple and would
of future drug discovery research for improved not exactly reflect the complexity of the native
in vitro assays with better predictive value. skin. Advanced bioprinting technology and iPSCs
as cell source allow fabrication of more realistic
4.4.2 Cosmetics testing
artificial skin models for drug testing as well as
The European Union Cosmetics Directive for regenerative medicine [143] . This would help
was introduced in 1976 to enforce high safety develop skin models with different skin types with
standards for cosmetics across the EU member respect to race (Asian, Caucasian, etc.), character
states. In 2009, the EU commission has introduced (dry, oily, etc.), or other specific skin types
new directives to phasing out animal testing for depending on the intended use of the cosmetic
cosmetic products. The directive bans the testing of as these models incorporate iPSC-derived cells.
the cosmetic products and cosmetic ingredients on Collagen-based skin construct reinforced with
animals. The law even prohibits the marketing of biocompatible materials such as polycaprolactone
finished cosmetic products and ingredients tested (PCL) mesh prevented the contraction of collagen
on animals in the European Union [142] . Hence, during tissue maturation and enable manufacturing
the cosmetic industry is looking for methods to of biomimetic human skin models [144,145] . Other
replace the animal testing. Bioprinted artificial biomaterials such as polylactic acid, Pluronic,
skin tissue can substitute the use of animals for alginate, chitosan, hyaluronic acid, fibrin, and

Figure 5. Bioprinting of human skin tissue models for cosmetic testing to replace the animal testing
procedures. Use of induced pluripotent stem cell-derived skin cells would help develop skin models
with different skin types (Asian, Caucasian, etc.), character (dry, oily, etc.), or other specific skin types
depending on the intended use of the cosmetic.

70 International Journal of Bioprinting (2020)–Volume 6, Issue 4