GMA News Online

RNA-coated bandages help heal chronic wounds

May 28, 2013 7:22pm
This isn’t your regular band-aid.
Scientists and engineers from the Massachusetts Institute of Technology have developed a way of coating bandages with siRNA (short interfering RNA) to help speed up the healing of chronic wounds, usually associated with diseases like diabetes and cancer.
siRNAs have long been used as a way to block protein expression. They work by binding to the RNAs responsible for translating the gene into protein, effectively stopping protein production. In this case, the researchers used siRNA to block a protein known as MMP-9, a protein that destroys collagen needed in the wound healing process.
But the problem with using siRNAs is that they’re easily degraded by enzymes. What they did to circumvent that problem is to deliver the siRNAs directly to the wound by nanocoating the bandages.
The bandages (commercially available nylon woven dressing) were coated using a peptide called protamine sulphate and calcium phosphate nanoparticles bound to the siRNAs. These two solutions are water soluble and all that was required to coat the bandages was to dip them alternately in the two different solutions. The differing polarities of the solutions cause them to bind tightly to each other once the water evaporates. And when the bandage is placed on the wound and exposed to the body’s humidity, the peptide releases the nanoparticles onto the cells and delivers the siRNA directly into the wound.
The treated bandages have proven to be effective in human and animal culture tests. In one of their experiments, a bandage loaded with 19µg of siRNA per square centimetre was able to unload two thirds of its RNA load in 10 days.  
Paula Hammond, a chemical engineer and the lead of the study, said in her statement to Chemical and Engineering News that they are on their way to animal testing. And according to Sarah C. Heilshorn, a materials scientist at Stanford University, the chances of this study reaching clinical trials quickly are very good since the materials used have already been approved by the US Food and Drug Administration.
Hammond states in their paper that, “this coating can be easily applied to a medically relevant device and requires no externally delivered transfection agents for effective delivery of siRNA.” If this passes trials, their simple process would help make it easier for medical devices to be coated with therapeutic siRNA easier and at lower cost. — TJD, GMA News
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