Scientists have had some success activating the body's immune system to take the fight to cancer and other diseases, a process known as immunotherapy. Now, a new method developed by researchers at the Wyss Institute for Biologically Inspired Engineering at Harvard University could advance this form of treatment even further. The technique involves the injection of biomaterials that assemble into 3D scaffolds inside the body to accommodate huge amounts of immune cells, a process that could trigger an attack on deadly infections ranging from HIV to cancer to Ebola.

The technique involves very small, rod-shaped devices known as mesoporous silica rods (MSRs) that can carry drugs being administered by needle beneath the skin. Made from silica, these rods are in the micron-sized range and are biodegradable, meaning that they dissolve naturally after around three months. The rods bear nanopores, or tiny holes, which can be filled with cytokines, oligonucleotides, large protein antigens or other drugs, depending on the type of infection at hand.

Once injected, they form a scaffold, likened by the researchers to a pile of matches, with the spaces in between attracting the body's dendritic cells by the tens of millions. It is the responsibility of these dendritic cells to surveil the body for the presence of harmful infections and trigger an immune response if needed. Once they are gathered within the scaffold, the rods prompt the release of the drugs, causing the dendritic cells to move to the lymph nodes and enact an immune response.

The researchers tested the 3D vaccine in mice and observed very promising results, describing the immune response as "powerful." They say the vaccine is easily manufactured and can carry different drugs, meaning it could be widely accessible should a fast-spreading infectious disease emerge.

"Although right now we are focusing on developing a cancer vaccine, in the future we could be able to manipulate which type of dendritic cells or other types of immune cells are recruited to the 3D scaffold by using different kinds of cytokines released from the MSRs," says study co-lead author Aileen Li, a graduate student in bioengineering at Harvard. "By tuning the surface properties and pore size of the MSRs, and therefore controlling the introduction and release of various proteins and drugs, we can manipulate the immune system to treat multiple diseases."

The method also shows promise as a preventative measure and could serve to boost the body's immune system before an infection has taken hold.

"Injectable immunotherapies that use programmable biomaterials as a powerful vehicle to deliver targeted treatment and preventative care could help fight a whole range of deadly infections, including common worldwide killers like HIV and Ebola, as well as cancer," says Wyss Institute Founding Director Donald Ingber.

The research findings were published in the journal Nature Biotechnology.

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