Lipid Nanoparticles - How do they work - Structure of LNPs - LNPs in mRNA vaccine Pfizer/Moderna

In this video, Dr. Aizaz from Medicovisual describes how Lipid Nanoparticles work and what is their structure.
Previously we have already discussed how mRNA vaccines work. The idea is to transport the mRNA of the spike protein of coronavirus into the cell. The cell will then create spike proteins and will train the immune system to recognize the Sars-CoV-2 from its spike protein.
The problem here is that a naked RNA cannot enter into the cell. And of course, without entry into the cell, the mRNA vaccine will never work. Furthermore, the RNA particles present outside the cell will be quickly degraded by the RNAses present in the extracellular environment.
To solve this problem, Lipid nanoparticles were created. These are incredibly small particles, measured at a nanoscale. [From your secondary school knowledge, you must be knowing that 1 nm = 10-9m]. These tiny lipid nanoparticles are made up of fat/lipids. They can keep the RNA safe from the RNAses and can faithfully transport the RNA inside the cell, into its cytosol.
But the question is why does mRNA, which is a type of RNA by the way, cannot, by itself, cross the cell membrane and enter into the cell? Why does it need external help from either a viral vector or a lipid nanoparticle?
The reason is that RNA [and DNA too] is negatively charged, because of the presence of negatively charged Phosphate ions attached with each of its structural subunits; nucleotides. So, it is the Phosphate ions that impart a net negative charge to the RNA and DNA.
Charged or ionic substances have a hard time crossing the cell membrane made up of lipid bilayer.
When surrounded by the lipid nanoparticle, RNA can cross the lipid-bilayered cell membrane as it becomes a lipophilic substance.
You can imagine it from a simple analogy. Let us suppose you want to a restricted area where only Police is allowed to go. Of course, you will be denied entry at the gate. [Think of the gate as the cell membrane].
You still want to go to that restricted area. You call your friend who is a police officer. You sit in his police van and then easily pass through the security checkpoint.
The same is happening here. Foreign RNA is not allowed to go inside, so it enters into this police van or LNP to cross the cell membrane.
After understanding why there is a need for a lipid nanoparticle. Let us now discuss what is it made up of and then will understand how it works.
Structure and components of LNPs
As discussed earlier, RNA is negatively charged. You must be aware of the fact that opposite charges attract. So, cationic lipids [positively charged ions] will attract and thus bind with the negatively charged [Anionic] RNA.

Cationic lipids contain an amine group head that has a positive charge on it. Along with that, it has legs made up of fatty acid chains, that are non-polar or non-ionic.
When such cationic lipids come across the RNA, they will obviously orient their charged [cationic] amine head towards the RNA and will orient the legs outward.
Permanently cationic [having a permanent positive charge] lipids are toxic and can disrupt the integrity of cell membrane [1]
To mitigate this problem, ionizable cationic lipids are used. These lipids are either neutral or slightly charged [cationic] at physiological pH. But in the lab, they create the vaccine at an acidic pH.[2] On acidic pH, the Proton or H+ ion quickly attaches with the amine head of the lipid causing it to acquire a positive charge. Due to this positive charge, it embraces and encapsulates the negatively charged RNA.

At physiological pH, as these ionizeable cationic lipids will become neutral, they may cease to embrace the RNA. So this particle is further surrounded by one or more additional layers of phospholipids. Thus RNA will still remain packed and protected inside the core of lipid nanoparticle.
They are mostly non-cationic structural lipids with some cationic lipids too embedded in between them, here and there.

Then there are some lipids, conjugated with a special molecule called PEG [Polyethylene glycol], that too are embedded into this outer layer. The outer layer of PEG prevents the aggregation or fusion of LNP particles with each other due to its steric hindrance [3]
Polyethylene glycol offers a steric hindrance and prevents the immediate take-up of these lipid nanoparticles by immune cells followed by their destruction. [3] Thus, it slows down the clearance of these LNPs quickly from the body.
PEGylation is reversible in such a way that LNPs gradually undergo de-PEGylation. PEG is gradually removed and the de-PEGylated LNP is then picked up by the cells gradually.
Cholesterol is also present interspersed in the spaces between the nanoparticles. It maintains the integrity and imparts the structure stability to LNP. Cholesterol, and structural phospholipids, forming the outer layer of LNP, are also called helper lipids

[rutujadhaware]

Can you please give me reference of journal Or something from which u got this information

[imtiazbashir]

Only video on internet to explain this topic clearly.
Thank you 😊😊

[wasimabbasi]

Good explanation. I had no idea of LNP and was just trying to understand how RNA gets encapsulated and the chemistry behind it. Thanks

[Littleprinceleon]

Many antivax stuff gets millions of views, but for some reasons the algorithm didn't favour this minilecture despite it being almost optimal in its content and style.. Sad things happen. Wish you good luck

[sanajaniece]

You're great at what you do. Thank you so much for this!

[LBPBlackHills]

I just discovered your channel, and I am irked that I hadn't found it sooner! Your videos are fantastic!

[capricioushorse]

Thank you for this very clear and easy to follow explanation. The visuals were very helpful, too.

[anwarulhaq]

Very clearly explaned lecture.Easily understandable by medical and related personals

[alexogrady]

Data is now showing that the lipids travel throughout the body in the days following the injection. Then they accumulate in such areas as the spleen and bone marrow. What is the explanation for this, will these lipids eventually break down or is this cause for concern?

[kelbell]

I’m trying to get answers to these questions:

do lipid nanoparticles themselves enter the nucleus and potentially cause harm to dna without being destroyed by the cells first?

How long do lipid nanoparticles take to be destroyed by cell and how do they take to leave the body?

[thisworldofwonders]

Excellent video, very informative! Thank you!

[j.v.n]

I have been trying to work out if the LNPs are specific or non specific too, thank you for your research.

[acluster]

This is fantastic!! Thank you for your clear explanation.

[sktgenerous]

Really it was Great explanation sir, thank you so much for this vedio, stay blessed sir

[pavanwalvekar]

Hi Dr Aizaz. It is a great video with lot of clarity. I am currently working on a article with this topic and I have a query. Do these lipid nanoparticles release the encapsulated mRNA in a sustained manner or mRNA are released rapidly once they enter the cell? In other words, are the LNPs long-acting systems or short-acting? Thank you.

[carom]

Thanks Dr. Azaiz for the illustration! Very helpful. Were you able to get an update from the vaccine manufacturers in regards to the use of non-specific or ligand-specific LNPs? I’d imagine there would have to be some kind of specificity, otherwise these particles would be everywhere. Pls provide an update if u have one. Thanks!

[sandrabertelli]

Thank you for your explanation. Your videos are perfect!

[theklskyclinic]

Did Pfizer get back to you if it was specific or nonspecific

[jo-nathan.thomas]

I love the analogy of using the cop car to drive the RNA behind the enclosed area.

However, I need to be more clear about who’s or what is driving or controlling that lipid nanoparticle?

[GhostFromTheFuture]

If the used LNP would be targeted, it would have components on its surface that would facilitate entry. There is no such component mentioned in any files from the FDA or the EMA as being part of the formulation. Ergo, unless proven otherwise, we can say those LNPs are untargeted.