A team of researchers at the Intelligent Polymer Research Institute at the University of Wollongong in Australia have developed a 3D bioprinting platform that they have demonstrated can be used to grow full-thickness skin in the lab.
The skin forms a natural barrier to protect inner tissues from harmful substances, radiation, and temperature fluctuations and has remarkable regeneration properties. Human skin contains up to 7 different layers, and while researchers have successfully grown the outer layer of skin – the epidermis – in the lab, efforts to grow full-thickness skin complete with blood vessels, that has a similar level of flexibility and strength as human skin has proved to be a major challenge.
The Australian researchers turned to 3D printing to solve the problem and developed a 3D bioprinted scaffold to support cell growth that they demonstrated could be used to grow a skin-like structure that supports the growth of dermal fibroblasts. To achieve that, the researchers developed an ink consisting of a polymer called catechol-hyaluronic acid (HACA) and alginate found in the cell walls of brown algae. Both materials are nontoxic to cells, have the required biomechanical properties, and can be printed into a hydrogel scaffold. Once printed, the scaffolds were checked using nuclear magnetic resonance and ultraviolet-visible spectroscopy to verify their structure.
The 3D-printed scaffolds are highly elastic and retain their original form after bending to mimic the elasticity of human skin. The scaffolds contain microchannels made of gelatin that allow nutrients to flow to support cell growth, akin to the vasculature in real skin. The researchers then added skin cells encapsulated in fibrin gel to the scaffolds and were able to build up their artificial skin to the same thickness as human skin. The researchers validated the self-assembly of fibrinogen using scanning electron microscopy and analyzed the differentiation of the epidermis and extracellular matrix through histology analyses and immunostaining.
“These biomaterials work together to produce a tough and elastic hydrogel framework with built-in microchannels, to support cells in their specific environment as dictated by the targeted application,” said Zhilian Yue, senior author of the study. The researchers believe their 3D printing platform could be used to generate skin in the lab suitable for skin regeneration in clinical settings by incorporating other types of cells into the 3D printing process.
You can read more about the study in the paper – Catechol functionalized ink system and thrombin-free fibrin gel for fabricating cellular constructs with mechanical support and inner microchannels – which was recently published in Biofabrication. DOI: 10.1088/1758-5090/ac2ef8