"We can create 3D structures using minimally–invasive delivery to enrich and activate a host's immune cells to target and attack harmful cells in vivo," said the study's senior author David Mooney, who is the Robert P. Pinkas Professor of Bioengineering at Harvard. The study was published in Nature Biotechnology earlier this month.
Tiny biodegradable rod–like structures made from silica, known as mesoporous silica rods (MSRs), which are built with nanopores and can be loaded with biological and chemical drug components and then delivered via injection. The rods spontaneously assemble at the vaccination site to form a 3D scaffold, which can recruit and fill up with dendritic cells.
"Nano–sized mesoporous silica particles have already been established as useful for manipulating individual cells from the inside, but this is the first time that larger particles, in the micron–sized range, are used to create a 3D in vivo scaffold that can recruit and attract tens of millions of immune cells," said co-lead author Jaeyun Kim, Assistant Professor of Chemical Engineering at Sungkyunkwan University.
The nanopores can be filled with specific cytokines, oligonucleotides, large protein antigens, or any variety of drugs of interest to allow a vast number of possible combinations to treat a range of infections.
"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," said 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."
So far, researchers have only tested the 3D vaccine in mice, but have found that the scaffold recruited and attracted millions of dendritic cells in a host mouse, before dispersing the cells to the lymph nodes and triggering a powerful immune response.
According to Harvard, the vaccines are easily and rapidly manufactured so that they could potentially be widely available quickly in the face of an emerging infectious disease.
"We anticipate 3D vaccines could be broadly useful for many settings, and their injectable nature would also make them easy to administer both inside and outside a clinic," said Mooney.