Big pharma backs pollen-based drug delivery

Three major multinational pharmaceutical companies are currently carrying out clinical trials using the pollen-based delivery system, to assess its viability for use with their drug pipeline. Details regarding the identity of the commercial partners could not be disclosed.

The drug delivery system is based on the fact that some plant pollens and spores are able to cross the wall of the human gut, where they are then destroyed within the blood stream. Using pollen-based vehicles to transport drugs would harness this mechanism, so as the pollen is destroyed, the active ingredient encapsulated within is released.

This opens up the potential to deliver some drugs orally that are traditionally delivered by injection, or protect an active ingredient so that it can be delivered directly to the lower gut.

The encapsulation technique used means that very high loading is possible, sometimes even more than weight for weight, and more than one type of drug can be attached to a single vehicle if required.

The researchers used sporopollenin, which makes up the majority of the outer layer of pollen grains, filling the empty shell with nanomaterials to be delivered into the blood stream. The sporopollenin microcapsules acted as micro-reactors, as the researchers added starting materials which then underwent a chemical reaction to form the desired active ingredient within the pollen-based shell.

The University of Hull-based team have shown that it possible to produce drug-loaded sporopollenin in such quantities as to make it commercially viable, and perhaps therefore an attractive prospect for pharma companies looking for alternative delivery methods for injectable drugs.

The research team developed methods by which a wide range of chemical entities can be attached to or encapsulated within the empty coating of the spores, including peptides, nucleotides and metals. The team even suggest that targeted drug delivery could be achieved by incorporating metals within the pollen-based shell, and then applying an external magnetic field.

The spores themselves come from the common club moss, Lycopodium clavatum​, and the sporopollenin coating has key properties that made it suitable for this alternative form of drug delivery. For example, being very resistant to highly acidic or alkaline conditions, but unable to persist in the bloodstream, means that some drugs which had previously been rejected as they were unable to reach the blood may now become viable.

A spin-out company from the university, Sporomex, has exclusive rights to the encapsulation technology and has filed several patents worldwide. The company signed a contract with the first undisclosed pharmaceutical company last year, and is also conducting its own clinical trials with sporopollenin encapsulated treatments.