Many point to the success of various delivery methods like engineered viruses or nanopolymer complexes as the techniques of the future. While these techniques have their advantages, it is clear that for a drug delivery vehicle to be truly useful it must:
- be easy to build and store
- be non-toxic
- be ethical
- be able to be repeated as therapeutic
- have exquisite selectivity and efficient delivery
These attributes are hard to find in a single model. Let’s take a look at few current or recent trends in smart drug delivery research.
Engineered viruses can deliver genes with great efficiency and selectivity but are relatively hard to make, have much higher toxicity, are ethically questionable, and are time limited by the immune system. While being non-toxic and easy to make, nanopolymers are much more effective at delivering smart drugs to the cytoplasm rather than the nucleus of cells. This delivery limitation greatly impacts what can be accomplished in clinics.
Liposome models are thought to be outdated today since all but one clinical trial with this vehicle type have failed over the past 3 decades. However, liposomes have continued to be widely studied. Dan Peer of the University of Tel Aviv, Israel, has shown that encapsulating liposomes with hyaluronic acid (sugar polymers) leads to liposomes which can be easily loaded and stored. However, an encapsulating layer reduces delivery efficiency. Others have used membrane fusion peptides to catalyze the mixing of the liposome with the cell membrane. This fusion interaction requires that the two membranes come in physical contact. Since encapsulating liposomes from the outside does not allow physical contact of the two membranes, membrane fusion is incompatible with encapsulation.
With our technology, we build our liposomes with a rigid, stabilizing internal scaffold structure. This internal structure gives the same storage and loading stability to the liposome without encapsulation. This allows the exterior of the liposome to interact with other membranes. Since the outside of our liposome design is free, we can use membrane fusion catalysis to deliver all of our vehicle contents into the cell.