[Solutions spotlight] Special delivery: Lipid nanoparticles usher in new treatments

Oct. 4, 2021

RNA-based vaccines have played a starring role in the ongoing COVID-19 pandemic and there is great potential for RNA to be applied to further indications. But nucleic acids are highly negatively charged and fragile and the right delivery systems are needed to protect RNA from degradation. One technology — lipid nanoparticles — has proven to enable the drug delivery of RNA-based therapeutics. Karen Langhauser  and MilliporeSigma’s Dr. Estelle Beguin discuss lipid nanoparticles and the role they will play in the success of emerging therapies and vaccines.


Karen Langhauser: For decades before the pandemic, scientists dreamed about the seemingly endless therapeutic potential of RNA. The powerful technology has the ability to direct cells in the body to make specific proteins needed to prevent or fight diseases. But in science turning promise into reality is never easy. For RNA to live up to its hype, it had to be able to get inside the target cells. Fortunately, and in this case unfortunately, the human immune system won't let just anything stroll across the protective membranes of cells. And given that nucleic acids are highly negatively charged and very fragile, they would be destroyed before reaching their targets in the body.

Without the right delivery system to protect it from degradation, RNA would not be effective. This was one of the reasons why not everyone was convinced that RNA-based vaccines would be the answer to slowing the COVID pandemic. Yet here we are. Currently, it is estimated that 43% of the world population has received at least one COVID vaccine dose. And two of the most widely used and most protective vaccines in the world are in fact mRNA-based. So how did scientists pull it off? They used the technology called lipid nanoparticles to usher fragile RNA molecules into cells. Because of this, many are calling these tiny lipid spears the unsung heroes of the pandemic.

I am Karen Langhauser and you're listening to a special Solution Spotlight edition of Off Script, Pharma Manufacturing's podcast that goes beyond the pages of our magazine to discuss the issues that matter most to the industry. To get a better understanding of lipid nanoparticles, I'm joined today by Dr. Estelle Beguin who is the Strategic Marketing Manager for Synthetic Lipids at MilliporeSigma.

Estelle, thank you so much for joining me today.

Dr. Estelle Beguin: Thanks. Thanks for the intro.

Karen: I want to start today with a topic we've all heard a lot about in the past year and a half, RNA-based COVID treatments and vaccines. While they've proven extremely effective in the fight against COVID, RNA-based therapeutics are not without challenges, especially in terms of formulation and delivery. Can you walk us through the importance of drug delivery for RNA?

Dr. Beguin: Yes, definitely. So really, RNA-based therapeutics and vaccines have definitely been in the spotlight recently with the development of COVID-19 vaccines during this pandemic but actually if you look at the first lipid-based gene therapy that was encapsulating a cyanate this was approved in 2018. And so really the field has been gearing up now for years to harness really the powerful nature of nucleic acid to treat and prevent diseases.

Now, if we kind of look at the different cases, in the case of DNA therapies for example, a gene of interest can be delivered which can then be used to purposely cause a sustained expression of a desired protein. Then if we look at RNA systems, these have different scenarios. So, for example, we have large messenger RNA. So, for example, mRNA that can be used to only cause a transient expression of certain proteins and this is applicable, for example, in the case of protein replacement therapy or COVID-19 vaccines, and then once this mRNA is degraded, and the protein expression then stops.

And the mRNA does not then integrate into the genome and this really kind of provides tighter control over when the treatment starts and stops. So, there's a little bit of a safety aspect to that. Then if we look at short RNA strands, so for example, small interferon RNA, short activating RNA, these can be used to silence or activate the expression of certain genes. And this is particularly relevant in the diseases that are caused by the overproduction or the insufficient production of a specific protein. So, that's interesting as well.

And overall, nucleic acids are extremely versatile in the way they can be used really to modulate gene expression or protein production. But these are fragile systems, and so if they were to be administered as is, they would degrade and be cleared out prior to reaching really the cells where they need to get to in order to take action. And so, this is when lipid-based formulations are then crucial to really promote their stability but also enable their efficient delivery into the cells.

Karen: Yeah, so to expand on that, what makes this lipid-based delivery an attractive system for RNA therapeutics?

Dr. Beguin: Yeah. So, to continue I guess on this topic. So, RNA, being highly negatively charged and very fragile system, as I mentioned, they need to be protected to ensure that they can reach the target cells and be released into the cytoplasm of the cells in their active form. While there are other delivery systems that are also studied for this purpose, for example, viral vectors or polymer-based systems, lipid nanoparticles really stood out as a promising option. And really LNPs, so lipid nanoparticles demonstrated an efficient stabilization of RNA and delivery into the cytoplasm of the cells but they also provided kind of this flexibility in the formulation and the manufacturing of the final drug product.

For example, they can be customized to have specific encapsulation, release or targeting properties. Additionally, some of these lipids have immunostimulant properties and can therefore act to also promote the efficacy of the drug product.

Karen: So, the performance of RNA-based drugs is dependent on a few factors, one of which is the composition of the drug delivery vehicle. Why does this matter so much?

Dr. Beguin: So, the composition of LNPs has a significant impact on the overall performance of the RNA-based drug product because the formulation affects the encapsulation efficiency of the RNA is by distribution and how well it is released into the cell. For instance, the formulation would need to be optimized if a new RNA encapsulated. Additionally, since the RNA is encapsulated within lipids, these lipids are then in direct interaction with the biological environment from the onset of administration and therefore this is why their composition also dictates to which specific tissues or cells the RNA is going to be delivered.

Karen: It's my understanding that when lipid nanoparticles are used as a delivery vehicle, they're usually composed of four different lipids. Can you talk about the important roles of each of these lipids?

Dr. Beguin: Yeah, certainly. So, for LNPs, for example, most formulation will include four different types of lipids. So, I'll just go one by one really. So, you have kind of ones that we will label as neutral lipids. That's for example synthetic cholesterol that would be used in the formulation and this is a component that would be used to improve the structural stability of the particle by providing rigidity, and so the little cholesterol compound would then go in between the tails of the lipids and provide that rigidity to the particle.

The second would then be cationic lipids, and cationic lipids are crucial really for the formulation of LNPs when they're encapsulating nucleic acid because the cationic lipids, through electrostatic interaction, can enable the encapsulation of the, for example, mRNA. And so, this is a crucial part of the formulation to enable that efficient encapsulation.

Then we also have PEGylated lipids and those are generally used for enabling the stability of the particle, preventing aggregation, preventing clearance. And so, they're also a component as far as the formulation.

And then the last one is phospholipids. That's a helper lipid that will also work at providing stability to the particle by providing, I guess, also rigidity to the system. And for an example of helper lipid would then be the SPC.

Karen: That's interesting. So, another important factor is the quality and consistency of the lipids used in these formulations. Why is this so vital and what can be done to ensure this high lipid quality?

Dr. Beguin: Yeah, so lipidized source and quality are definitely essential factors to be considered when designing a lipid-based formulation because these have a direct impact on the impurity profile, on the properties of the final drug product. For instance, they might impact particle characteristics such as structure, stability and release properties. And also, to ensure the reproducibility of the formulation and results. It is essential really for these lipids to be synthesized of high purity raw materials themselves with consistent quality because then these characteristics could be carried over to the lipids and then to the final drug products manufactured with those.

So of course, when considering the need for a consistent and high purity excipients, chemically synthesized lipids have significant advantage over natural lipids because these are made from the single type of lipids of known quality while naturally occurring lipids would and can be composed of a mixture of lipids and might present then also some batch-to-batch variability.

To ensure really the high purity of chemically synthesized lipids with consistent quality and good handling properties, the purity of the starting material needs to be very tightly controlled and optimization actually of the manufacturing process and purification methods are often also required. It is definitely important to control any impurities that are within the lipids as these can alter, really, and change the characteristics of the final formulation, like the stability and the RNA release profile, for example.

Karen: During the pandemic with many RNA therapeutics and vaccines being developed, the industry urgently needed a large supply of these high-quality lipids. How did MilliporeSigma rise to the challenge here?

Dr. Beguin: Yeah, so within our SAFC portfolio we have over 24 years of experience in the GNP manufacturing of lipids and really an established center of excellence that makes us a trusted supplier for this material. We also have extensive experience with the successful execution of the large number of projects ongoing with different clients. In addition, our SAFC portfolio has a dedicated contract manufacturing capabilities and a global network of facilities and experts to efficiently really enable the scale-up of processes as needed by our customers.

All these facilities are frequently inspected by a regulatory agency, so the FDA, DEA and other health agencies as well as customers and therefore we have the appropriate network really and expertise within MilliporeSigma to support pharma companies developing vaccines against COVID-19 right as pandemic started really. So, this is a capability that we already had and that we used exactly at that time.

We were already actually already working with mRNA companies before the pandemic and the progress made in this field during this time just encouraged us to further support the growth and development of RNA-based therapeutics and vaccines. The recent acquisition actually on our side of AmpTec further expands our presence within the mRNA field and this also reflects on our faith in the technology.

Really another point on our lipids team is also highly experienced, with over 85 years of combined experience working in this field. We have a deep know-how to develop solutions for even the most challenging customer projects that comes to us. An example. We were able to meet the challenge of producing very large quantities of lipids for BioNTech's COVID-19 vaccines and our goal really is to provide the best support possible to our customers, both our existing customers and other companies now advancing in the field of mRNA therapeutics and vaccines and the science that's coming with them.

Karen: Excellent. So yeah. It sounds like MilliporeSigma played a very important role here. Looking towards the future, what role will lipid-based RNA therapeutics play?

Dr. Beguin: That's a great question. So, before COVID-19, there were already many activities actually ongoing in the development of RNA therapeutics. It is however certain that the emergency approval of mRNA-based COVID-19 vaccines with their successful clinical results, this has fast-forwarded the development of other mRNA therapeutics in really an incredible way.

There's a lot of potential for this technology to also be applied to other indications outside of COVID-19. For instance, against other infectious diseases or for cancer vaccines. And we have seen ourselves a rapid increase in the number of clinical investigation and clinical trials using RNA and DNA to support. As more clinical successes are reported and published using this technology and as we prove that medicine can be designed to act at the genetic level, there is going to be a paradigm shift in the way diseases are addressed. And so, lipid-based RNA therapeutics definitely have a very exciting future ahead.

Karen: That certainly sounds very promising. Thank you so much, Estelle for joining us today. We appreciate your input.

Dr. Beguin: Thank you for having me.

Karen: Thank you. You've been listening to a Special Solution Spotlight episode of Off Script. Thanks so much for joining us. Stay safe and stay informed.

For more, tune into Off Script: A Pharma Manufacturing Podcast.

About the Author

Off Script: | Off Script: A Pharma Manufacturing Podcast