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RESEARCH ARTICLE

Pilot Study of the Biological Properties and

Vascularization of 3D Printed Bilayer Skin Grafts

Yige Huyan, Qin Lian*, Tingze Zhao, Dichen Li, Jiankang He
State Key Laboratory for Manufacturing System Engineering, School of Mechanical Engineering, Xi’an Jiaotong University,
Xi’an, China

Abstract: The skin is the largest human organ, and defects in the skin with a diameter greater than 4 cm do not heal
without treatment. Allogeneic skin transplantation has been used to allow wound healing, but many grafts do not survive
after implantation, due to multiple complications in the procedure. In the present study, the vascularization of three-
dimensional (3D) printed full-thickness skin grafts was investigated. Dermal-epithelial grafts were transplanted into a
nude mouse model to evaluate integration with the host tissue and the extent of wound healing. To create microvessels in
the skin grafts, a bilayer structure consisting of human dermal fibroblasts, keratinocytes, and microvascular endothelial
cells was designed and fabricated using an extruded 3D printer. Human dermal fibroblasts and human microvascular
endothelial cells were mixed with gelatin-sodium alginate composite hydrogel as the dermis, and human keratinocytes
were mixed with gel as the epithelium. Confocal imaging allowed visualization of the location of the cells in the double-
layer skin grafts. A full-thickness wound was created on the backs of nude mice and then covered with a double-layer
skin graft. Various groups of mice were tested. Animals were euthanized and tissue samples collected after specified
time points. Compared with the control group, wound contraction improved by approximately 10%. Histological
analysis demonstrated that the new skin had an appearance similar to that of normal skin and with a significant degree
of angiogenesis. The results of the immunohistochemical analysis demonstrated that the transplanted cells survived and
participated in the healing process.

Keywords: Three-dimensional printing, Bilayer skin graft, Gelatin-alginate complex hydrogel, Vascularization

*Corresponding Author: Qin Lian, State Key Laboratory for Manufacturing System Engineering, School of Mechanical Engineering, Xi’an
Jiaotong University, Xi’an, China; lqiamt@mail.xjtu.edu.cn

Received: November 11, 2019; Accepted: January 02, 2020; Published Online: January 21, 2020
Citation: Huyan Y, Lian Q, Zhao T, et al., 2020, Pilot study of the biological properties and vascularization of 3D printed
bilayer skin grafts. Int J Bioprint, 6(1):246. DOI: 10.18063/ijb.v6i1.246

1 Introduction epidermis and subcutaneous tissue, consisting
principally of fibroblasts .
[3]
As the largest human organ, skin protects the At present, large-area skin defects and chronic
[1]
body from poisons, pathogens, microorganisms, [4]
and other invaders. It can also regulate homeostasis skin injury remain major problems in clinics .
of body fluids, regulate body temperature, immune Autologous skin transplantation is limited by
monitoring, and self-healing, in addition to, donor insufficiency, and allografts suffer immune
physiological functions such as external sensory rejection. Tissue-engineered skin is an effective
[5]
stimulation. Human skin consists of epidermis solution . It can be used not only as a skin
and dermis . The epidermis is the outermost substitute in the clinic but also as an infiltration and
[2]
layer of the skin, of which 90 – 95% of cells screening model for basic research. Great progress
are keratinocytes. The dermis lies between the has been made in the study of tissue-engineered

© 2020 Huyan, et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International
License (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the
original work is properly cited.
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