| Health / Health News |
Nanoparticles used to transport anti-cancer agent to cells
Research indicates metal-organic frameworks (MOFs) could present a viable platform for delivering a potent anti-cancer agent, known as siRNA, to cells.
Small interfering ribonucleic acid (siRNA), has the potential to inhibit overexpressed cancer-causing genes, and has become an increasing focus for scientists on the hunt for new cancer treatments.
Researchers used computational simulations to find a MOF with the perfect pore size to carry an siRNA molecule, and that would breakdown once inside a cell, releasing the siRNA to its target.
Some cancers can occur when specific genes inside cells cause over-production of particular proteins. One way to tackle this is to block the gene expression pathway, limiting the production of these proteins.
SiRNA molecules can do just that – binding to specific gene messenger molecules and destroying them before they can tell the cell to produce a particular protein. This process is known as ‘gene knockdown’.
Scientists have begun to focus more on siRNAs as potential cancer therapies in the last decade, as they offer a versatile solution to disease treatment – all you need to know is the sequence of the gene you want to inhibit and you can make the corresponding siRNA that will break it down.
Instead of designing, synthesising and testing new drugs – an incredibly costly and lengthy process – you can make a few simple changes to the siRNA molecule and treat an entirely different disease.
One of the problems with using siRNAs to treat disease is that the molecules are very unstable and are often broken down by the cell’s natural defence mechanisms before they can reach their targets. SiRNA molecules can be modified to make them more stable, but this compromises their ability to knock down the target genes. It’s also difficult to get the molecules into cells – they need to be transported by another vehicle acting as a delivery agent.
The Cambridge researchers have used a special nanoparticle to protect and deliver siRNA to cells, where they show its ability to inhibit a specific target gene.
Fairen-Jimenez from the Cambridge Department of Chemical Engineering and Biotechnology leads research into advanced materials, with a particular focus on MOFs: self-assembling 3D compounds made of metallic and organic building blocks connected together.
There are thousands of different types of MOFs that researchers can make – there are currently more than 84,000 MOF structures in the Cambridge Structural Database with 1000 new structures published each month – and their properties can be tuned for specific purposes.
By changing different components of the MOF structure, researchers can create MOFs with different pore sizes, stabilities and toxicities, enabling them to design structures that can carry molecules such as siRNAs into cells without harmful side effects.
“With traditional cancer therapy if you’re designing new drugs to treat the system, these can have different behaviours, geometries, sizes, and so you’d need a MOF that is optimal for each of these individual drugs,” says Fairen-Jimenez. “But for siRNA, once you develop one MOF that is useful, you can in principle use this for a range of different siRNA sequences, treating different diseases.”
“We used a MOF that could encapsulate the siRNA and when it's encapsulated you offer more protection. The MOF we chose is made of a zirconium based metal node and we've done a lot of studies that show zirconium is quite inert and it doesn't cause any toxicity issues.”
Using a biodegradable MOF for siRNA delivery is important to avoid unwanted build-up of the structures once they’ve done their job. The MOF that Teplensky and team selected breaks down into harmless components that are easily recycled by the cell without harmful side effects.
The large pore size also means the team can load a significant amount of siRNA into a single MOF molecule, keeping the dosage needed to knock down the genes very low. (University of Cambridge)
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