Alyssa Panitch, an associate professor at Purdue University (West Lafayette, IN, USA), holds a sample of an organic compound that solidifies upon injection in the body.
Natural interactions between heparin polysaccharide and a peptide derived from the antithrombin III protein molecule are responsible for the compound’s ability to form a three-dimensional matrix. “Assembly is very rapid and the matrix can have any shape you want,” Panitch says. “If you had a defect in a bone, you could inject it there. It would solidify immediately to fill the defect and release bone morphogenic proteins to enhance healing.”
The discovery occurred during a study of formulations for the controlled release of heparin-binding growth factors. “We discovered in the laboratory—purely by serendipity—that interactions between the polysaccharides and some of the peptide sequences from proteins of the extracelluar matrix will come together to form gel-like materials.” By controlling how strongly peptides bind to polysaccharides, the researchers can develop gels that release therapeutic peptides over a given length of time. Through cross-linking molecules in the material, the researchers can fortify the matrix to approximate the strength of cartilage.
The properties of the gel also can be influenced through temperature. When heated, the solidified gel returns to a liquid state, while cooling has the opposite effect. “This characteristic could be important for controlled release for drug therapy,” Panitch explains.
When used for the controlled release of drugs and growth factors, the biomaterial could support wound healing and bone regeneration. Consequently, the material has potential in treating spinal cord injuries. “It is thought that most of the damage caused in spinal cord injury is not caused by the initial injury but by the inflammation that occurs later,” Panitch notes. “If you could inject this gel with a therapeutic agent that inhibits inflammation while secreting growth factors within several hours of injury, that could be potentially very useful,” she adds. “In any case, we hope to get this into humans in 2–3 years.”