The material builds an instantaneous scaffold which enables new tissue to hook on and grow in the cavities created between linked gel spheres.
“Achieving a biomaterial that promotes rapid regeneration while maintaining structural support has been a holy grail in the field of tissue engineering,” principal investigator Dino Di Carlo said. “Our team has achieved this in an injectable form by combining tailored material chemistry and microfluidic fabrication of uniform spherical building blocks, each about the width of a human hair.”
Physicians treating skin wounds strive to keep the area moist, since dry wounds heal much less quickly than wet ones. To achieve this, they often use topically applied hydrogel dressings or films, to seal over or cap the wound and provide moisture.
To fill in the wound, in other cases, ointments are used, similar to filling a pothole with new asphalt.
The problem is none of the current materials provide an ideal scaffold to allow new tissue to grow as they degrade. As a result, the new tissue growth is relatively slow and fragile.
Jar of Gumballs
“Our technology is beautifully simple, as it utilizes any available chemistry to generate tiny gels that can be assembled into a large unit, leaving behind a path for cellular infiltration,” co-principal investigator Tatiana Segura said.
The process creates a packed cluster of microscopic synthetic polymer spheres attached at their surfaces, analogous to a jar of gumballs that are stuck together.
The cluster results in a scaffold of microporous annealed particles, or a MAP gel, that fills in the wound. New tissue rapidly grows into the voids between the microspheres.
A matrix of newly grown tissue is left where the wound once was, as the spheres degrade into the body. New tissue continues to grow until the wound is totally healed.
“The beauty of the MAP gel is that there are no other added growth factors that other technologies require to attract cells into the material,” co-lead author Westbrook Weaver said. “The geometry of the MAP gel networks entices cells to migrate into the gel without the need for anything other than a cell adhesive peptide, so that the cells can grab onto the gels.”
In in vivo tests, the researchers saw significant tissue regeneration in the first 48 hours, with much more healing over five days compared to materials in use today.
“We envision this material being useful for a wide range of wound applications, from acute damage, like lacerations and surgical wound closures, to more chronic applications like diabetic ulcers and large-area burn wounds,” co-lead author Donald Griffin.
He added the hydrogel scaffolds could be helpful in trauma situations, such as emergency rooms or battlefields.
Donald R. Griffin, Westbrook M. Weaver, Philip O. Scumpia, Dino Di Carlo & Tatiana Segura
Accelerated wound healing by injectable microporous gel scaffolds assembled from annealed building blocks
Nature Materials (2015) doi:10.1038/nmat4294
Illustration: Lux Virtual for UCLA