Medication in the matrix

Researchers are developing scaffold-like materials designed to be injected into the body where they will quickly solidify to fit any space, repairing damaged bones, spinal cords, arteries and other tissues.

Because the material starts out as a liquid, it fills in the gaps between damaged or missing tissue before hardening into a gel, or ‘three-dimensional matrix’ that eventually disintegrates as it is replaced by healthy tissue, according to Alyssa Panitch, an associate professor in Purdue University's Weldon School of Biomedical Engineering.

This gel could be loaded with time-released therapeutic drugs, such as ‘growth factors’ needed to enhance healing. The approach also could be used to improve ‘drug-eluting stents,’ which are metal scaffolds inserted into arteries to keep them open after surgeries to treat clogs. Once in place, the stents release therapeutic agents, but scientists have recently learned that the stents can cause new clogs, leading to heart attacks.

The method harnesses natural interactions in the body between molecules called polysaccharides and protein building blocks called peptides to control the assembly of the three-dimensional matrices. The polysaccharides interact with proteins and help the proteins come together and assemble scaffolds. Researchers have used the interaction between a polysaccharide called heparin and a peptide fragment of a protein called antithrombin III, which is contained in the bloodstream to control clotting.