Nano-messenger opens way for new cancer treatment
A new study from Karolinska Institutet shows that exosomes, nanoparticles that transmit information between cells, constitute a potential new treatment strategy for several cancers. The study, which was conducted on mice, was published recently online in the scientific journal Cancer Research.
Exosomes are nano-sized membrane-enclosed bubbles that carry biological material, such as genetic matter, between cells. While exosomes from immune cells can stimulate a reaction from the body's defence system, exosomes from cancer cells can shut down this process, enabling the tumour cells to evade detection.
In the present study, the researchers used exosomes from the mice's own immune cells (dendritic cells), to which they added both cancer proteins and alpha-galactosylceramide (aGC), a substance that stimulates the immune system's natural killer T (NKT) cells. When this cocktail was injected into mice with extant malignant melanoma, their survival time doubled. This was because the combination of aGC and exosomes stimulated several types of immune cell, which together had a synergistic effect on the other immune cells needed for tumour killing.
Past research found that multiple injections of aGC merely serve to exhaust the NKT cells.
"Interestingly, this didn't happen when aGC was delivered by exosomes", says Dr Susanne Gabrielsson, Docent of experimental immunology, who led the study at the Department of Medicine, Solna. "Instead, we found that two injections produced a stronger immune response and better tumour eradication. This means that exosomes are a possible new therapeutic strategy for several forms of cancer."
The work was supported by the Swedish Research Council, Karolinska Institutet's IMTAC consortium, the Swedish Cancer Society, the Swedish Heart-Lung Association, Hesselman's and David and Astrid Hagelén's Foundations.
Synergistic induction of adaptive antitumor immunity by codelivery of antigen with α-galactosylceramide on exosomes.
Cancer Res. 2013 Jul;73(13):3865-76