At the National Institute of Biomedical Imaging and Bioengineering (NIBIB), a part of the National Institutes of Health, scientists have developed a “nanovaccine” for safer delivery of immunotherapies. DNA strings need to be carefully introduced near the target in order to activate the immune system to kill nearby cancer cells, but enzymes easily break them up if the delivery is poorly focused.
The team used DNA sequences obtained from bacteria, called unmethylated cytosine-guanine oligodeoxynucleotides (CpG), which have previously been trialed by injecting them directly into tumors. The body recognizes them as foreign and mounts a immune response, but additionally they help the immune system remember how to fight back against same kind of tumors near where the CpG was delivered. The problem is CpG doesn’t stay inside the tumor long enough to work as intended, which is why NIBIB researchers worked on encapsulating them inside a safe delivery vehicle.
Magnified image of nannovaccine complexes showing flower-like structure. Each complex is about a micron in diameter, which is equivalent to 1/100 the thickness of a human hair. Image taken with a scanning electron microscope and colored purple.
Called DNA-inorganic hybrid nanovaccines (hNVs), these particles contain multiple CpG DNA strings in a flowery shape that make them easy for the immune cells to grab onto. The size of the particles can be varied so that they can easily enter a tumor while sticking around longer without being washed away.
The team tested these on mice with melanoma and showed that the nNVs not only stayed inside the tumor much longer than naked CpG molecules, but also that mice treated with nNVs responded much better to the immunotherapy.
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In addition to boosting the immune response induced by CpGs, the hNVs also reduced side effects associated with administration of CpG by decreasing the amount of CpG that leaked out of the tumor and into the bloodstream. One indication of the side effects of CpG immunotherapy is an enlarged spleen. The researchers showed that mice injected with hNVs had spleens that weighed nearly half as much as mice injected with CpG molecules.
According to the researchers, an additional benefit of the hNVs is that they stabilize the CpGs so that they don’t need to be refrigerated while stored or being transported. This is important because refrigeration requirements can significantly increase the price of vaccines and limit who has access to them.
Study in journal Nanoscale: DNA-inorganic hybrid nanovaccine for cancer immunotherapy…
Via: NIBIB…
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