Hydrogels to potentially make chemotherapy and tissue regeneration more convenient and safe

Dec 15 2005

Scientists at the Institute of Bioengineering and Nanotechnology (IBN) have invented an injectable and biodegradable gel that can deliver drugs at targeted sites or act as a scaffold for tissue repair.

This “hydrogel” is formed by simple injections at the desired site, where drugs or cells contained in the gel can be released at a controlled rate. No surgery is required, and the gel will degrade after the disease is treated or when the tissue has regenerated.

IBN’s hydrogel is almost 90 percent composed of water. Another unique feature of the invention is the ease with which the hydrogel can be formed in the body without the need for surgery. Conventional hydrogels are normally manufactured in the labs before they are surgically implanted into a specific location in the body. IBN scientists, however, have devised a simple method of forming the hydrogel directly at the target site through the injection of two types of solution – a fluid drug-loaded biodegradable polymer and an enzyme which acts as the gelation catalyst.

Previous efforts in this area have been unsuccessful at addressing a number of problems, including the conventional use of toxic catalysts and chemicals, which affect the bioactivity of the drugs and cells, causing tissue damage. IBN’s hydrogel, however, is formed using hyaluronic acid-tyramine conjugates with enzyme – both of which are non-toxic in nature.

The chemically cross-linked hydrogel is also better than those produced using physical interactions, such as ionic and hydrophobic reactions, because it can retain its stability for a long time in the body. As this chemical cross-linkage can be achieved by an injected enzyme, this system does not need any harsh gelation trigger such as high temperature and toxic chemicals. In addition, IBN’s hydrogel is biodegradable. It does not need to be surgically removed after treatment, as it can decompose safely in the body.

“Our hydrogel system can be effectively applied in cancer therapy, drug delivery and tissue engineering because it is convenient and safe, and it can deliver therapeutic proteins and cells without loss in their bioactivity,” said Dr Motoichi Kurisawa, the lead scientist of the project.

“For example, in the area of tissue engineering, we can develop injectable hydrogel systems for bone and cartilage regeneration with the hydrogel acting as a scaffold and drug or cell delivery reservoir. In addition, this hydrogel is ideal for tissue regeneration as it offers a benign environment that is close to conditions in a body due to its high biocompatibility and water content,” said Dr Kurisawa.

“For chemotherapeutic treatment, we can load the hydrogel with chemotherapeutics, which can be released only at the targeted malignant site, thus minimizing potential side effects on normal cells or tissues,” he added.