How wrapping drugs in spider silk helps craft a better cancer vaccine
Strong and light, spider silk is one of the most impressive materials in the natural world. Both the real thing and synthetic versions have been used to improve everything from clothing to car seats, cooling electronics to preserving produce, making sweet music or helping people hear it, and even patching up severed nerves. Now, scientists in Germany and Switzerland have found a new use for spider silk – wrapping up cancer drugs to protect them until they can reach their tumorous targets.
One of the most promising paths to combat cancer is immunotherapy, where drugs train the body's immune system to hunt down and kill the cancer cells. To do so, certain peptides need to be delivered to the lymph nodes, where they can stimulate the T lymphocytes (or T-cells) into action. The problem is, these peptides are too fragile if injected alone, degrading long before they'll reach the goal.
"To develop immunotherapeutic drugs effective against cancer, it is essential to generate a significant response of T lymphocytes," says Carole Bourquin, director of the new study. "As the current vaccines have only limited action on T-cells, it is crucial to develop other vaccination procedures to overcome this issue."
And that's where the spider silk comes in. While other researchers have used silicon nanoparticles as carriers for drugs, researchers at AMSilk and the Universities of Geneva, Freiburg, Munich and Bayreuth have now wrapped the vital peptides in spider silk. In particular, the team used synthetic sider silk biopolymers, which are lightweight, non-toxic and can resist damage from light and heat.
"We recreated this special silk in the lab to insert a peptide with vaccine properties," says Thomas Scheibel, an author of the study. "The resulting protein chains are then salted out to form injectable microparticles."
In tests, the team found that the silk transport capsules successfully protected the peptides as they made their way to the lymph nodes, leading to a boosted immune response from the T-cells. The silk particles were also able to withstand heat of up to 100° C (212° F) for several hours at a time.
"Our study has proved the validity of our technique," says Bourquin. "We have demonstrated the effectiveness of a new vaccination strategy that is extremely stable, easy to manufacture and easily customizable."
The researchers say this technique could eventually be used to carry other types of drugs too. In its current form it can at least extend to other peptide payloads, but the team says further work with need to be done to test whether larger antigens can be packed inside. On the plus side, the silk microparticles should also protect the drug outside the body, meaning vaccines might not need to be kept cool during transportation and storage.
The research was published in the journal Biomaterials.
Source: University of Geneva
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