About 25,000 organ transplants are performed in the
T cells, the white blood cells that identify and attack foreign bodies, are one of the main culprits behind organ rejection. The most potent of these, known as effector memory T cells, are activated by a group of proteins known as human leukocyte antigens (HLAs) on the surface of endothelial cells lining the donated organ's blood vessels. Researchers can silence the proteins with small interfering RNA (siRNA), a double-stranded RNA that hinders the expression of targeted genes. When delivered conventionally, however, the effects of siRNA last only a few days. A transplanted organ from a deceased donor typically needs weeks to "heal" and reduce the risk of rejection. The siRNA can also cause side effects in endothelial cells of other organs, which don't need treatment, when administered to the whole body.
To give the siRNA more staying power, the researchers developed a drug delivery system in which polymer-based nanoparticles carry siRNA to the site of the graft and slowly release the drug. They also developed methods for introducing the nanoparticles into the donor organ before it is transplanted, so that only the organ is treated, not the whole body. The results of their work are published in the journal Nature Communications.
The particles—made in the Yale lab of Mark Saltzman, the Goizueta Foundation Professor of Chemical and Biomedical Engineering—can be tuned for specific properties. Saltzman, who is also a member of the Yale Cancer Center, said these nanoparticles were designed to have a slight positive charge to interact with the negative charge of the siRNA's nucleic acid. This affinity between the two materials makes the particle a natural carrier for the drug, unlike commercially available nanoparticles that can hold only a limited amount of the drug.
Read more at: https://phys.org/news/2017-08-nanoparticles-body-transplants.html#jCp
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