Scientists developed a new vaccine based on spider silk microcapsules

Engineered hybrid spider silk particles as delivery system for peptide vaccines.

Immune cells that ingested spider silk nanoparticles (in green). The endosomes - the part of the cell in which the nanoparticles release the vaccine - appear in blue. (Illustration © Laboratoire Bourquin – UNIGE.)
Immune cells that ingested spider silk nanoparticles (in green). The endosomes - the part of the cell in which the nanoparticles release the vaccine - appear in blue. (Illustration © Laboratoire Bourquin – UNIGE.)

Scientists from the universities of Geneva (UNIGE), Freiburg (UNIFR), Munich, and Bayreuth, in collaboration with the German company AMSilk, have developed spider silk microcapsules to strengthen the efficacy of vaccines on the immune system – and in particular, on T lymphocytes, specialized in the detection of cancer cells.

The potential benefit of this microcapsule is, stable, easy to use, and resistant to the most extreme storage conditions. In addition, it could deliver the vaccine directly to the heart of immune cells. Scientists additionally suggest that could also be applied to preventive vaccines to protect against infectious diseases.

Professor Carole Bourquin, a specialist in antitumor immunotherapies at the faculties of medicine and science of the UNIGE said, “To develop immunotherapeutic drugs effective against cancer, it is essential to generate a significant response of T lymphocytes. As the current vaccines have only limited action on T-cells, it is crucial to develop other vaccination procedures to overcome this issue.”

In order to develop this microcapsule, scientists utilized synthetic spider silk biopolymers. The resulting protein chains are then salted out to form injectable microparticles.

When ingesting the capsule, Silk microparticles inside it deliver the peptide to the center of the lymph node cells, thereby considerably increasing T lymphocyte immune responses. Moreover, these particles are highly resistant to heat- can withstand over 100°C for several hours without damage.

Professor Carole Bourquin, a specialist in antitumor immunotherapies at the faculties of medicine and science of the UNIGE said, “Our study has proved the validity of our technique. We have demonstrated the effectiveness of a new vaccination strategy that is extremely stable, easy to manufacture and easily customizable.”

In theory, this process would make it possible to develop vaccines that do not require adjuvants and cold chains. An undeniable advantage, especially in developing countries where one of the great difficulties is the preservation of vaccines. One of the limitations of this process, however, is the size of the microparticles: while the concept is in principle applicable to any peptide, which is all small enough to be incorporated into silk proteins, further research is needed to see if it is also possible to incorporate the larger antigens used in standard vaccines, especially against viral diseases.

Scheibel said, “More and more, scientists are trying to imitate nature in what it does best. This approach even has a name: bioinspiration, which is exactly what we have done here.”

This research is published in Biomaterials.