Thanks to the proliferation of bioengineering advances in recent years, the fight against cancer has seen the development of a number of promising new tools that take a novel approach to tackling this challenging disease, and which could prove significantly more effective than current treatment methods. One of these innovations, which received a great deal of attention when it was introduced in late 2014, is a 3D vaccine that is capable of harnessing the body’s own immune cells in a unique way to combat cancerous growth. Read on to learn more about how the vaccine works, what it can do, and where it’s headed.
The challenge for cancer-fighting vaccines
The reason why cancer is such a challenging disease to fight is that it has an uncanny ability to evade the body’s immune system. Cancer cells may be mutated and misplaced, but they originally spring from cells that do belong in the body—unlike, for example, viruses or bacterial cells. Because of this, the immune system has trouble differentiating these malignant cancer cells from normal, healthy cells, and therefore is usually unable to mount an effective defense against cancer on its own.
Some cancer vaccines work to help the body recognize cancer cells as foreign, and thus provoke an immune response, by manipulating dendritic cells. Acting as coordinators of immune system behavior, these cells identify foreign cells by sampling antigens, or bits of protein, from the surfaces of cells or viruses they come in contact with. If a dendritic cell encounters a foreign antigen, it will instruct the immune system to attack anything else in the body that also contains that antigen.
Some immunotherapy techniques take advantage of the properties of dendritic cells by removing white blood cells from a patient’s blood, artificially stimulating them to turn into dendritic cells, and then incubating those cells with the corresponding antigen for a patient’s tumor. The idea is that when these “programmed” cells are infused back into the patient’s bloodstream, they will instruct the immune system to attack the tumor antigen.
Why the 3D vaccine could be more effective
The dendritic cell therapy described above has had some clinical success, but has so far not been able to consistently initiate a long-term, robust immune system response. That’s the gap that researchers at the Wyss Institute for Biologically Inspired Engineering at Harvard University are hoping their 3D vaccine will fill.
A research team led by bioengineering professor Dr. David Mooney began experimenting several years ago with techniques for employing implantable biomaterials—essentially any type of matter, construct, or surface that interacts with biological systems—to reprogram immune cells from within the body. Their original proposition was to create a biodegradable scaffold that would serve as a kind of “infection-mimicking microenvironment” in which millions of dendritic cells could be housed and reprogrammed over a period of several weeks. The porous scaffold would be loaded with tumor antigens, and would use a blend of biological and chemical components to attract and activate dendritic cells once implanted.
While original trials with the scaffold proved highly successful in mice, it is the next step in the team’s research that has the medical community excited. The researchers developed a 3D vaccine, essentially a deconstructed version of the original scaffold, which can spontaneously and independently assemble itself into a scaffold once injected. The vaccine is made up of mesoporous silica rods (MSRs), or micro-sized silica tubes, dispersed in liquid.
When injected, the liquid diffuses and the tubes are left forming a 3D structure similar to a haystack or a pile of sticks, with plenty of spaces between the tubes where dendritic cells can be drawn in. The MSRs also have nanopores throughout their structures, which are holes that can be filled with drugs and antigens. When these drugs are delivered from the nanopores, the dendritic cells then have the power to trigger the appropriate immune response. Over the course of a few months, the MSR scaffold slowly dissolves into the patient’s body.
Next steps for the vaccine
The potential advantage of the 3D vaccine is not only that it may elegantly and effectively harnesses the natural behavior of dendritic cells to trigger the desired immune response, but also that it could be simple to administer and does not require costly or invasive surgery. So far, the vaccine has had impressive success rates in animal trials, with 90% of mice with lymphoma living for at least 30 days after receiving the 3D vaccine, compared with 60% of mice who received a traditional bolus injection.
The 3D vaccine could also have significant potential for fighting other diseases beyond cancer. Because the nanopores in the scaffold structure could be loaded with any combination of antigens and drugs, the vaccine could also be a new tool to treat infectious diseases that may be resistant to other therapies.