Design and fabrication of full-thickness vascularized human skin with 3d bioprinting technology

Tânia Daniela Calaveiras Baltazar

Key information

Authors:

Tânia Daniela Calaveiras Baltazar (Tânia Daniela Calaveiras Baltazar)

Supervisors:

Pankaj Karande; Frederico Castelo Alves Ferreira (Frederico Castelo Alves Ferreira)

Published in

03/21/2019

Abstract

Treatment of chronic skin wounds (e.g. diabetic ulcers and venous ulcers) remains a significant clinical challenge. Autologous split-thickness skin grafts represent the ‘gold standard of care’ but are limited by the pain and discomfort associated with harvesting skin from donor sites, limited availability of donor sites, and the need for multiple surgeries. To overcome this challenge, many bioengineered skin substitutes using biological and artificial matrices and/or allogeneic cells have been developed and are beneficial in conditions when urgent care is needed. However, the use of foreign or synthetic materials to cover the wounded area is only a temporary solution, and sub-optimal engraftment often leads to unsatisfactory clinical results. When the clinical situation allows for a delayed reconstruction of the defects such as chronic wounds, tissue engineered skin constructs are the ideal choice. Nevertheless, current artificial skin grafts do not include dermal vascular networks important for graft survival and integration with the native tissue. To date, the construction of tissue-engineered skin substitutes for clinical use has involved self-assembly of various constituents, resulting in homogenous or bilayered structures without specific instructions for organization normally provided by the extracellular matrix. Three-dimensional (3D) bioprinting, an adaptation from tools developed for non-living systems, has enabled the precise fabrication of living systems, which can be organized over multiple and relevant length scales. Here, using a 3D bioprinting platform, we have successfully fabricated a multilayered bioengineered skin construct that consists of human keratinocytes in the epidermis and dermal fibroblasts in the dermis to mimic the morphology and function of human skin. Second, we have developed a method to generate functional endothelial networks of physiologically relevant size in vitro. Bioprinted vascular endothelial cells and fibroblasts formed dense interconnected capillary networks with open lumens mimicking the dermal microvasculature. Third, we shown successful integration of a vascularized bed in a 3D bioprinted skin model. 3D bioprinted vascularized skin substitutes formulated with human endothelial colony forming cells (HECFC) derived from cord blood were implanted on the dorsal part of immunodeficient mice, showing human vascular structures that were perfused. These data illustrate the feasibility of studying 3D printed skin comprised of human primary cells in immunodeficient mice and the ability of HECFC to produce vasculature in the grafted 3D printed bioengineered skin. These advances will allow the fabrication of more complex skin tissues suitable for clinical translation.