Scientists have developed a new hydrogel able to quickly heal animal wounds while minimising scarring, with the immune system's help. It could potentially work as an upgrade on our body's injury-healing abilities.
The microporous annealed particle (MAP) gel had previously shown promise as a structure designed to support tissue growth and speed up wound healing. Here, the MAP gel was modified to trigger a particular immune response too.
So far, the research has only looked at wound healing in mice, but it could potentially help people with burns, cuts, diabetic ulcers, and other types of wounds that would otherwise leave damaged, scarred skin behind.
A repaired wound with hair follicles shown in green. (Duke University)
"This study shows us that activating the immune system can be used to tilt the balance of wound healing from tissue destruction and scar formation to tissue repair and skin regeneration," says biomedical engineer Tatiana Segura, from Duke University.
Scar tissue is formed as part of a rapid reaction to injury by the body: it reduces pain and limits the chance of infection. However, the regrown skin isn't complete, lacking sweat glands and hair follicles, and it's also more susceptible to future injury.
Having already used MAP gels as a way of organising cells to fix wounds faster, here the team tried to keep the biological scaffold in place for longer by flipping the peptide structure of a particular chemical linker in the gel so the body wouldn't see it as being familiar and – in theory – make it more difficult to break down.
"Previously we'd seen that as the wound started to heal, the MAP gel started to lose porosity, which limited how the tissue could grow through the structure," says biomedical engineer Don Griffin from the University of Virginia.
"We hypothesised that slowing down the degradation rate of the MAP scaffold would prevent the pores from closing and provide additional support to the tissue as it grows, which would improve the tissue's quality."
However, in experiments on mice, the team's attempts to prolong the lifetime of the scaffold by making it more alien to the body had the opposite effect: the gel had almost entirely disappeared from the wound site by the time it had healed.
The peptide structure flip did trigger a different immune response, but from the more specialised adaptive immune system – it uses different types of cells and a more regenerative reaction to do its work.
The antibodies and macrophage cells that were triggered in this case were better able to remove traces of the hydrogel, as well as repairing skin in a way that was more like the original skin (including hair follicles).
This process still needs to be adapted for the human body, of course, but we share a lot of the repair mechanisms with other mammals, and the scientists are hopeful that a modified version of their hydrogel could eventually be used to repair wounds faster and more naturally – and perhaps even contribute to vaccine development.
"I am excited about the possibility of designing materials that can directly interact with the immune system to support tissue regeneration," says Segura. "This is a new approach for us."
The research has been published in Nature Materials.