Vaccines that stimulate the immune system to destroy tumor cells are increasingly used in cancer research. Success, however, is not always at the rendezvous. In order to act more effectively on the immune system – and especially on T cells, cells specialized in the detection of cancer cells – researchers from the Universities of Geneva (UNIGE) and Friborg (UNIFR), with their German colleagues from universities from Munich and Bayreuth and the startup AMSilk, have delved into the wonders of nature to create microcapsules in spider silk capable of delivering the vaccine directly to the heart of the immune cells. A process that could also be applied to preventative vaccines to protect against infectious diseases, an important step towards stable vaccines that are easy to use and resistant to the most extreme conservation conditions. This invention is to be discovered in the journalBiomaterials .
Our immune system is essentially based on two types of cells, the B cells – which produce the antibodies that allow us to defend against many infections – and the T cells. In the case of cancer and certain infectious diseases such as tuberculosis, this are precisely the T cells that need to be stimulated. Their activation mechanism is however more complex than that of B lymphocytes: to trigger a response, it is necessary to use a peptide, a small piece of protein which, if injected alone, is rapidly degraded by the body even before d to reach his target. “However, to develop effective immunotherapeutic drugs against cancer, it is essential to generate a significant response of T cells,” says Professor Carole Bourquin, specialist in antitumor immunotherapies at the faculties of medicine and sciences of UNIGE, who led this work. “The vaccines we currently have have only limited action on T cells; it is therefore essential to develop other vaccination methods to circumvent this problem. ”
A virtually indestructible capsule
To do this, scientists have used spider silk diadem scary, a very common garden spider in Europe. This very light, resistant and non-toxic material is also artificially synthesizable. “We have recreated in the laboratory this special silk to insert a peptide with vaccine properties,” says Thomas Scheibel of the University of Bayreuth, global specialist in spider silk, who participated in this study. “Then, the protein chains thus formed are rolled up on themselves to form injectable microparticles.”
The silk microparticles form a sort of transport capsule that not only protects the vaccine peptide so that it is not degraded by the body, but also transports its precious cargo to the heart of the cells of the body. lymph nodes, thus considerably increasing the immune response of T lymphocytes. “Our study has proved the validity of our technique,” says Carole Bourquin. “We are demonstrating the effectiveness of a new vaccination technique that is extremely stable, easy to manufacture and easily customizable.”
Towards a new vaccine model?
The scientists themselves were surprised by the resistance of the spider silk microparticles to heat, which withstands more than 100 ° C for several hours without damage. In theory, this process would provide vaccines that do not require adjuvant or cold chain. An undeniable advantage, especially in developing countries where one of the major difficulties is precisely the conservation of vaccines. One of the limitations of this process, however, lies in the size of the microparticles: if the concept is in principle applicable to any peptide, all of which are small enough to be incorporated into the silk proteins, research must be done. continue to investigate whether it is also possible to incorporate the larger antigens used in standard vaccines,
When scientists mimic nature
“More and more, scientists are trying to imitate nature in what they do best,” says Thomas Scheibel. “This approach even has a name: bioinspiration. That’s exactly what we did here. “The properties of spider silk make it a particularly interesting product: biocompatible, solid, fine, biodegradable, resistant to extreme conditions and even antibacterial, one can imagine multiple applications, including dressings or sutures.
Source : University of Geneva