New printing skin method helps heal chronic wounds

“We used a stain that allowed us to quantify the integration we got between original material and tissue. We were able to demonstrate some integration even after a short period of time.”Liam Grover

A new material that simulates all three predominant layers of skin, the hypodermis, the dermis and the epidermis, has been developed by a team from the University of Birmingham and University of Huddersfield in the UK. They devised a printing technique that produces an effective skin equivalent that could be key to the healing of chronic wounds.

Deep and chronic wounds are major trauma to skin and are challenging to repair in the longer term, with the top of such injuries tending to heal ahead of the bottom, which means the wound can collapse in on itself, leaving scar tissue and a reduction in skin function. To develop an approach that mimicked this kind of tri-layered structure, the main problem was to provide the requirements of each different layer. Although a range of skin replacements already exist, none of them are able to that simulate the chemical, mechanical and biological aspects of skin.

However, as detailed in the journal APL Bioengineering [Moakes et al. APL Bioeng. (2021) DOI: 10.1063/5.0061361], here the researchers used a technique called suspended layer additive manufacturing (SLAM) to produce a gel-like material to support the skin equivalent, and then twisted and changed the structure of the gel as it formed to provide an array of particles to support a second phase of gel injection.

Depositing the skin layers within a support gel in the printing process keeps all elements in place. Once printing was complete, the support material was washed away to leave the layered skin equivalent. When a needle was moved through the supporting gel, it was shown to repair itself quicker than in other similar methods, offering higher resolution printing and the subsequent printing of complicated skin structures.

The team tested the skin substitute by cutting a hole in pig tissue and printing a skin equivalent to fill the hole, before culturing the model system for two weeks before there were signs of wound repair. As author Liam Grover said “We used a stain that allowed us to quantify the integration we got between original material and tissue. We were able to demonstrate some integration even after a short period of time.”

Unfortunately, the team were not able to examine chronic wound healing using the skin substitute as the process would take longer than allowed by their model, ie, just 14–21 days, but they now hope to investigate longer, appropriate models for chronic deep wounds with the aim of being able to repair human skin and reduce scarring in all scenarios.