Swiss researchers have developed a type of hydrogel that could help hand transplant patients at risk of a compromised immune system by delivering drugs locally into the new limb.
The scientists at the University of Bern encapsulated the immunosuppressive drug FK506 tacrolimus within a water-soluble hydrogel, which they then injected under the skin of a rat's transplanted hind limb. The delivery system allowed for a more controlled concentration of the drug, and the graft survived for 100 days, which is more than three times the median survival period for rats with the same dose directly, according to a report in The Nation.
The self-assembled nanofibrous hydrogels, which have been used to treat rheumatoid arthritis, react to an enzyme that concentrates in areas of inflammation and split to release the immunosuppressant.
Immunosuppressive drugs are rapidly absorbed into the bloodstream and reach a peak concentration before being cleared, the team explained in the report. This limits the possibilities of the drug by shortening the window of acceptability, but by loading the drugs into hydrogels, higher concentrations can last much longer without causing an initial overload.
The first successful hand transplant took place in 1998 and is a very difficult procedure, particularly in terms of protecting the immune response at the site.
- here's the Nation report