Chun Wang and colleagues, writing in the March issue of Nature Materials, have incorporated DNA in a new formulation of biocompatible poly(ortho ester) micro-particles, the opening of which can be timed to occur with a specific delay, and only inside the sentry cells of the immune system. The delay gives the sentries the time they need to move from the tissue to the lymph nodes where they stimulate an immune response.
This sequence of events is crucial to the efficacy of DNA vaccines, because only in the lymph nodes can the antigens encoded by the DNA trigger the killer cells that defend the body. What's worse is that, if the antigens are made available before the sentries reach the lymph node, immune tolerance, the opposite of vaccination, could occur. Animal experiments show that this first attempt at timing the release of DNA has proved that poly(ortho ester) particles make for more potent vaccines that can even work against cancer.
As Daniel Pack notes in an accompanying News and Views article, these poly(ortho ester) particles are an important starting point, now that DNA vaccination is heralded as a means of treating several types of diseases. These microparticles could be developed into more complex systems capable of multiple delivery at predefined times, and their use would be particularly advantageous in developing countries where safe injection practices are problematic.
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Daniel W. Pack
University of Illinois
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Abstract available online.
(C) Nature Materials press release.
Message posted by: Trevor M. D'Souza