Antigen-laden disks rally immune system against tumours in mice

January 23rd, 2009 - 4:57 pm ICT by ANI  

London, January 23 (ANI): Harvard University researchers have shown that small plastic disks, when impregnated with tumour-specific antigens and implanted under the skin, can coax the mammalian immune system to attack tumours.
The researchers claim that their research represents the most effective demonstration to date of a cancer vaccine.
They have revealed that the study involved mice with an aggressive form of melanoma that would usually kill them within 25 days.
“Our immune systems work by recognizing and attacking foreign invaders, allowing most cancer cells — which originate inside the body — to escape detection,” Nature Materials quoted Mooney, Gordon McKay Professor of Bioengineering in Harvard’’s School of Engineering and Applied Sciences, as saying.
“This technique, which redirects the immune system from inside the body, appears to be easier and more effective than other approaches to cancer vaccination,” the researcher added.
A recent study on cancer vaccines focused on removing immune cells from the body, reprogramming them to attack malignant tissues, and re-injecting the altered cells back into the body.
Mooney said that that approach should theoretically work, but over 90 per cent of the re-injected cells died before having any effect in experiments.
The scientist described the new implant developed by the research team as slender disks measuring 8.5 millimetres across, which are made of an FDA-approved biodegradable polymer.
According to the researchers, these disks can be inserted subcutaneously, much like the implantable contraceptives that can be placed in a woman’’s arm.
The disks are 90 percent air, making them highly permeable to immune cells. They release cytokines, powerful attractants of immune-system messengers called dendritic cells.
The researchers say that these cells enter an implant’’s pores, where they are exposed to antigens specific to the type of tumour being targeted.
They add that the dendritic cells report to nearby lymph nodes, where they activate the immune system’’s T cells to hunt down and kill tumour cells throughout the body.
“Much as an immune response to a bacterium or virus generates long-term resistance to that particular strain, we anticipate our materials will generate permanent and body-wide resistance against cancerous cells, providing durable protection against relapse,” says Mooney, a core member of the recently established Wyss Institute for Biologically Inspired Engineering at Harvard.
Loading the implants with bacterial or viral antigens may help protect against an array of infectious diseases, and even redirect the immune system to combat autoimmune diseases such as type 1 diabetes, which occurs when immune cells attack insulin-producing pancreatic cells.
“This study demonstrated a powerful new application for polymeric biomaterials that may potentially be used to treat a variety of diseases by programming or reprogramming host cells,” Mooney and his co-authors write.
“The system may be applicable to other situations in which it is desirable to promote a destructive immune response (for example, eradicate infectious diseases) or to promote tolerance (for example, subvert autoimmune disease),” the researchers add. (ANI)

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