Left: A fully collapsed square-shaped cryogel rapidly regains its original memorized shape, size, and volume upon hydration. Right: Photos show the placement of a cryogel inside a 1-mL syringe, and the recovery of a square gel after injection through a normal 16-gauge needle. (Images courtesy of Sidi Bencherif.)
Bioengineers at Harvard School of Engineering and Applied Sciences have come up with a compressible gel-based sponge which can be delivered into the human body via injection. The material can be made into any shape and loaded with drugs or stem cells, before being compressed and injected. After injection it will form its original shape, release its substances and degrade. The new technology was described in this week’s Proceedings of the National Academy of Sciences.
Principal investigator of the project David Mooney explains that their finding will also make it possible to introduce materials into the body to replace tissue that has been lost. The structure they have created can be used to influence cells in the tissue surrounding the gel-based sponge and maybe promote tissue formation.
The sponge-like injectable is mainly made of a seaweed-based jelly, called alginate. Liquids and large molecules can flow through the sponge because the sponge contains networks of large pores. It is made through cryogelation, a freezing process. By freezing the alginate solution, pure ice crystals are formed, which leads to a more concentrated gel. After melting of the ice crystals, the more concentrated gel stays behind, and thus the injectable cryogel is formed.
The researchers also hint towards numerous other applications like cell therapy, tissue engineering, dermal filler in cosmetics, drug delivery, and scaffold-based immunotherapy. The ability of recreating a pre-defined shape after injection will also be useful in other situations in which one requires a certain shape and size of patches or gap-filling material. What’s next for the research is to tweak the rate of degradation of the injectable structure in such a way that is will degenerate at the same rate as newly grown tissue will replace it.
Video of the gel released from a syringe…
Harvard press release: Injectable Sponge Delivers Drugs, Cells and Structure: Compressable Bioscaffold Pops Back to Its Molded Shape Once Inside the Body
Article abstract in PNAS: Injectable Preformed Scaffolds with Shape-Memory Properties