The Biodistribution of the Lipids, Part 1

In which I rant

If I hear, “the LNPs go everywhere in the body” again I am going to scream. So do drugs. So does sugars in your blood, cholesterol etc etc. This statement does not give us any information specific to these LNPs or accurately describes its biodistribution in order to help determine which organs are more affected than others. It leaves the shoulder, well so does EVERY IM medication, unless it is a depot product.

Pharmacokinetics, what is that?

Typically we say pharmacokinetics is what the body does to drugs etc and pharmacology what drugs do to the body. I’ve had 3 years of pharmacokinetic studies, most docs or scientists much less, so theirs is often a superficial understanding.

Pharmacokinetics is essentially the study of the

• ABSORPTION,

• DISTRIBUTION,

• METABOLISM and

• EXCRETION of drugs

Pharmacokinetics also studies associated toxicity because it is not limited to healthy people but includes variations in bioavailability, physiologic or pathologic conditions, disease-related dose adjustment, and drug interactions. We do this, because pharmacokinetics allow customization of drug dosage regimes to enhance outcomes and decrease toxicities for individuals.

Schematic of pharmacokinetics and absorption, distribution, metabolism, and excretion concept (A), and same schematic highlighting interplay between free and bound drug (to plasma proteins), and pathway from site of administration to site of action (B).

As you can see, it is extremely difficult to describe the mRNA vaccines in this manner because they are actually 3 “drugs” and because you cannot measure them in plasma, a necessity for pharmacokinetic assessment and modelling. (LNPs are in the plasma for like 6hrs then disappear never to be measured again…because they go into tissues and intracellularly and that is very hard to measure). In effect, I propose you can modify the traditional ADME to:

• ABSORPTION

• BIODISTRIBUTION

• TRANSFECTION

• GENE TRANSLATION

• EXOSOME FORMATION AND ELIMINATION

One enterprising pharmacokinetic specialist tried to describe the pharmacokinetics of the genetic vaccines and concluded you simply could not. He did come up with 11 different compartments (anything over 4 in traditional drugs and your smoking something..) and noted as a pro-drug there is the pharmacological phase and then the immunological phase.

He did note that the clinical outcome of these genetic vaccines is the sum of the variability of both these phases, pharmacological (11 variables and counting) and immunological (how many more variables?).

This implies that the variance coefficient of the summed response probability distributions has a larger value than the variance of each underlying distribution. In other words, due to the multi-phased mode of action of genetic vaccines, their clinical outcome has more variability than that of traditional vaccines.

Ya think? Then add the variability of the manufacturing process etc. So the variability in response is very very large just based on statistical probabilities. This variability in metabolism is usually sufficient to scuttle a drug or vaccine because of its unpredictability and lack of a dose response. But not here, of course. And I ask, can this variability be fixed? Or will I get an answer as I did previously “it is a vaccine, single dose, variability in dosing and response is less of an issue because you are just looking for a sufficient antibody response.”

Absorption

As far as us pharmacists are concerned there is no practical difference, all IM injections end up in the blood stream, it’s just slower. There is no specific kinetic or toxicological reason why vaccines cannot be given IV, but it is easy to administer an IM injection vs IV. In fact, IV administration of BCG vaccine was much more efficacious than the traditional intradermal administration.

Here is a typical curve of concentration over time of IV bolus, IM or oral administration. Most IM is absorbed into plasma in under an hour.

Moderna’s draining lymph nodes

Moderna, in its Science Day 2022 presentation, provided data to support “it stays in the arm” premise. Here, they present data using an SM102 (their proprietary ionizable lipid) biodistribution from mRNA-1647, which is a previously failed CMV vaccine containing 6 different mRNAs given IM to mice. You tell me how comparable that is to the current vaccine. However, this study does provide some useful information. Although, there is NO distribution to spleen, liver or other organs, the muscle itself does not get transfected and those draining lymph nodes are very much affected.

So what did we learn

1. muscle did not get transfected with mRNA and did not produce protein

2. after 3 days, mRNA and protein are not detected at the injection site

3. those poor draining lymph nodes are very much affected and Moderna does not state how long mRNA and protein are detected in the draining lymph nodes, nor the consequences to the lymph nodes or the rest of the lymphatic system

The bio corona of the LNPs

This is something NO ONE talks about and is absolutely crucial. The LNPs are 50% regular cholesterol and about the size of a cholymicron (a triglyceride rich lipoprotein). When an LNP is injected IV, the PEG component sloughs off and is replaced by ApoE, a cholesterol particle as well as other molecules. This is clearly explained in this review article by Pieter Cullis and colleagues.

The LNPs interact FIRST with biological fluids depending on the administration site; interstitial fluid and lymph when given IM, to blood plasma when given IV. These biomolecules include electrolytes, lipids and most importantly proteins. These include apolipoproteins such as ApoE, immunoglobulins, coagulation factors and many others.

This forms the biocorona which is defined as:

Biomolecular corona: The sum of all electrolytes, proteins, and lipids, which are adsorbed by the surface of nanomaterials, including LNPs when they make contact with a biological environment. These biomolecules for a corona that associates almost irreversibly with the surface defining its biological identity.

Biological identity: The physiochemical properties such as size, shape, charge, aggregation state of LNPs together with their coronas. The biologcal idenity depens on the composition of the surrounding biological environment and determines the subsequent nano-bio interactions.

The biocorona defines the biodistribution of the LNPs and makes it a completely different entity than the LNPs that came out of the vial. It now has a biological identity. I cannot emphasize that enough. They are now biological entities. Not just synthetic fats as the LNPs are now covered and hidden and assumed to be human biological particles by the body.

Different PEG lipids can determine if it is shed fast from the LNPs (as in the product Onpattro which is almost all trafficked to the liver) or a slower PEG shedding like those for the mRNA vaccines. BTW, if you really want to know about the biodistribution of LNPs start by researching Onpattro which is an siRNA\LNP particle targeting the liver.

See Recent advances in LNPs for delivery of mRNA

Are there undesired effects from changes in size, chemistry, charge and other changes from the biocorona relating to toxicity and biodistribution. Obese vs lean. Old vs young. High cholesterol vs very low cholesterol levels. There is still a lot to learn about the LNPs and its biocorona.

Biodistribution

The Japanese biodistribution data does not inform us of the true nature of the Pfizer or Moderna vaccine

The biodistribution study of the Pfizer vaccine is well known and is best illustrated below comparing total lipid concentration by organ over time given IM in rats. Note that the data only goes to 48 hours and levels in liver, spleen, adrenals, ovaries and bone marrow are still rising. But what exactly are we measuring in this study?

In this study all you are measuring is the biodistribution of the cholesterol component of the LNPs which do not contain the vaccine mRNA but contain luciferase instead. As we discussed above, an LNP+luciferase particle may be completely different from an LNP+vaccine mRNA particle due to the packing of the mRNA in the LNPs, the biomolecular corona formed and other known and unknown variables.

At each time point 3 rats were sacrificed. and tissue samples were taken. Then the radioactivity of the tissues, urine, feces and blood were analyzed. That is how we get these values. But we dont know if these are intact LNPs or just the cholesterol or dissolved LNPs, we dont know how much mRNA was released in the cells, and we dont know if the spike protein was made or not. Plus were all important tissues sampled? A direct correlation between the cholesterol distribution of the LNPs and actual spike protein production cannot be assumed. The study can be read in full at: Full data on biodistribution study by Pfizer

So how and what is required for determining the biodistribution of LNP gene therapies? There are actually 3 “drugs” to measure

1. the intact LNPs

2. the mRNA

3. the expressed protein

and also the individual lipids forming the LNPs

In addition, we should know how each element is metabolized and how each element is eliminated or recycled by the body.

We will continue this in Part 2 where I will rant even more.

Yes, I deactivated my twitter account for 30 days for mostly personal reasons. I will be back though.

Please comment and share and ask what questions on biodistribution that you would like answers for and I will do my best in Part 2.

Thank you for reading

Pray the rosary.