Injectable Gel Solidifies into a Therapeutic Matrix

A new study describes a polysaccharide-based hydrogel, designed to be injected into the spinal cord and other tissues, which forms a three-dimensional (3D) matrix that eventually disintegrates as it is replaced by healthy tissue.

The new material, developed by researchers at Purdue University (West Lafayette, IN; USA) and Arizona State University (ASU; Tempe, AZ, USA) mimics an extracellular matrix (ECM) environment. By attaching the polysaccharide-binding peptides (PBP) from antithrombin III to a synthetic material called polyethylene glycol, the basic hydrogel is formed. Mixing this peptide-polyethylene glycol combination with heparin--a natural polysaccharide--instantly solidifies it into a 3D matrix.

The scientists have also shown how gels are strengthened by using polymers that have more functional groups--segments that attach to other molecules to fortify the matrix by forming crosslinks from one molecule to the next. This crosslinking can be used to strengthen the matrix about 10 times, which could be compared to raising consistency of the gel from that of mayonnaise to something closer to that of cartilage. The gel can also be loaded with time-released therapeutic drugs, such as growth factors used in wound healing, bone regeneration, and other medical applications. This same approach could be used to improve drug-eluting stents, making them less prone to clot formation. The study was presented at the American Chemical Society's national meeting, held during March 2007 in Chicago (IL, USA).

"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,” said lead author Dr. Alyssa Panitch, an associate professor of biomedical engineering at Purdue. "So, if you could inject this gel with a therapeutic agent that inhibits inflammation while secreting growth factors within several hours of injury that could potentially be very useful.”

Polysaccharide-based hydrogels have emerged as an intriguing biomaterial for tissue engineering due to their low immunologic response and the biologic importance of polysaccharides throughout the ECM in vivo. Within the ECM, polysaccharides associate with proteins to regulate cell adhesion, migration, and proliferation.


Related Links:
Purdue University
Arizona State University