New hydrogel for drug delivery developed

MIT chemical engineers have designed a new type of hydrogel that could be injected through a syringe to deliver drugs to treat cancer, heart attack and macular degeneration.
Scientists are interested in using gels to deliver drugs because they can be molded into specific shapes and designed to release their payload over a specified time period.
However, current versions are not always practical because they must be implanted surgically.
The new hydrogel can be injected through a syringe and carry one or two drugs at a time. It could be useful for treating cancer, macular degeneration, or heart disease, among other diseases, the researchers said.

The new gel consists of a mesh network made of two components: nanoparticles made of polymers entwined within strands of another polymer, such as cellulose.
"Now you have a gel that can change shape when you apply stress to it, and then, importantly, it can re-heal when you relax those forces," said Mark Tibbitt, a postdoc at Massachusetts Institute of Technology's Koch Institute for Integrative Cancer Research.

"That allows you to squeeze it through a syringe or a needle and get it into the body without surgery," he said.
Scientists have previously constructed hydrogels for biomedical uses by forming irreversible chemical linkages between polymers.

These gels, used to make soft contact lenses, among other applications, are tough and sturdy, but once they are formed their shape cannot easily be altered.
The MIT team set out to create a gel that could survive strong mechanical forces, known as shear forces, and then reform itself.
The team relies on a combination of two readily available components. One is a type of nanoparticle formed of PEG-PLA copolymers, commonly used to package and deliver drugs.
To form a hydrogel, the researchers mixed these particles with a polymer - in this case, cellulose.
Using two components to form the gel also allows delivery of two different drugs at the same time.

In the study, the researchers showed that the gels survived injection under the skin of mice and successfully released two drugs, one hydrophobic and one hydrophilic, over several days.
The researchers are now looking into using the gel to deliver anti-angiogenesis drugs to treat macular degeneration.
Currently, patients receive these drugs, which cut off the growth of blood vessels that interfere with sight, as an injection into the eye once a month.
The MIT team envisions that the new gel could be programmed to deliver these drugs over several months, reducing the frequency of injections.
Another potential application for the gels is delivering drugs, such as growth factors, that could help repair damaged heart tissue after a heart attack.

The gel is described in the journal Nature Communications.