BIOPRINTING FOR SKIN - 3D Bioprinting and Nanotechnology in Tissue Engineering and Regenerative Medicine - page 291

FIGURE 13.9 E-cadherin expression detected by immunohistochemistry.
Printed skin constructs were cultivated in the dorsal skin fold chamber in mice for 11 days. E-cadherin expression
can be detected in normal mouse skin (A) as well as in the skin constructs (B, D). Normal mouse skin without first
antibody constitutes the negative control (C). All scale bars represent 100 m m. Reprint from Michael et al. (2013b) .
13.3.5 DISCUSSION OF THE DIFFERENT BIOPRINTING TECHNIQUES AND CLINICAL
APPLICABILITY
13.3.5.1 Optimization of the Skin Equivalents
So far, different bioprinting techniques have been used to print fibroblast and keratinocyte skin cells in
a bilayered 3D structure. The formation of tissue with intercellular junctions could be observed in vitro
and in vivo ( Koch et al., 2012; Michael et al., 2013b ). Implantation of ex vivo printed skin equivalents
( Michael et al., 2013b ) and printing skin cells in wounds in situ ( Binder, 2011 ), both result in an in-
growth of the printed tissue into the surrounding natural skin. Thus, the printed skin is capable of cover-
ing wounds for preventing liquid or protein loss or infections.
However, these skin equivalents lack the important functions of natural skin, such as effective
barrier function, regulation of body temperature by sweat glands, and immune competence. Also,
printed skin's function as a sensory organ is very constricted. The appearance of printed skin differs
fundamentally from natural skin, particularly in the absence of hair. Moreover, high mechanical stabil-
ity for printed skin equivalents is needed. Perhaps, some of these functions might be regenerated by
immigrating cells from the patient's organism.