[Sciences/Pharmacokinetics] Do nano-particles of the Pfizer COVID-19 vaccine cross the blood-brain barrier and infect your brain with mRNA (or will fritz your gonads)?

1. Introduction
[EDIT: Updated the article on 07/05/2021 to reflect some updates on my analysis]

I have recently seen some claims I considered moot resurfacing on social media: first that COVID-19 vaccines render women infertile; second that mRNA vaccines cross the blood-brain barrier and therefore lead to neurological diseases.
These claims have been rebutted by various science communicators including Edward from Deplatform Disease and myself on Skeptical Raptor few months ago, as the Pfizer and Moderna vaccines were rolling out in the US.

Thing is, with anti-vaxxers, claims are never completely dead and keep rising up like some zombies straight out of a Walking Dead episode.

This time, it seems to be materialized through this screenshot, that appear to spread virally on social media over the weekend, especially in various iterations of that screenshot, with a yellow highlight in a table with the following tissue: “ovaries” and total lipid concentrations as only information.

Screenshot depicting estimated aminolipid contents in rats following injection of the Pfizer COVID-19 nanoparticle formulation (source: Facebook).

2. What is the screenshot coming from?

As always, getting back to the source of a document is essential to put this information back into the context. This screenshot appeared to be coming from a leaked document (if I have to judge on the “Pfizer – Confidential” footers) that I was able to find the source. Unfortunately the document is in Japanese but I can speculate this document likely came from an application packet submitted to the Japanese equivalent of the FDA to seek authorization of sale of the vaccine on the Japanese market. 3. What is the document about?
It seems the document provides us with some pharmacokinetics data on the mRNA vaccine done in rats (Wistar Han strain, both males and females) to assess the pharmacokinetics of the nanoparticles inside these rodents to assess the pharmacokinetics of both the lipid nanoparticles and the mRNA (using the luciferase as reporter of mRNA transcription, I will explain it later).
For the majority of the experiments, we have the following situation been used (according to Table 1):

Nanoparticles were used using two aminolipids (ALC-0315 and ALC-1059) at concentrations of 15.3 and 1.96mg/kg respectively. mRNA was encapsulated in these nanoparticles at 1mg/kg (to give you an idea, the actual dose of mRNA in a Pfizer shot is 30ug or 0.03mg from patients ranging of 12 years and older)

Table 1 provides us with some pertinent PK parameters including the half-life (time to eliminate 50% of a drug), the AUC (to compare the relative bioavailability, distribution and calculate the clearance of a drug) and finally the Kanji translated by Google Translate (sorry but that poor Gaijin is illiterate to Japanese despite decades of anime) as “Distribution ratio to the liver“, with 60% of ALC-0315 found in the liver, 20% of ALC-0159 respectively. The number of animals also appear to be N=3/group (male, female as groups).

We have therefore extensive data on the aminolipids metabolism and the metabolites obtained both in vivo (plasma samples mostly), in vitro (using liver microsomes homogenates, a classic in PK/PD studies); distribution of LNPs in tissues and organs using a non-metabolized radio-tracer ([3H]-08-A01-C0 which I quote the document “[3H]-08-A01-C0 = An aqueous dispersion of LNPs, including ALC-0315, ALC-0159,distearoylphosphatidylcholine, cholesterol, mRNA encoding luciferase and trace amounts of radiolabeled [Cholesteryl-1,2-3H(N)]-Cholesteryl Hexadecyl Ether, a non-exchangeable, non-metabolizable lipid marker used to monitor the disposition of the LNPs“, which was given at a dose of 50ug in animals) and finally bio-luminescence assays in which it consisted of injecting 2ug of RNA encapsulated in the LNP formulation in the hind-limbs of rats (we can assume these were adult rats, therefore a weight of 200-250g is not unheard of), followed by live imaging of the animals to track the luciferase activity (following injection of coelenterazine, the conversion of this substrate by luciferase results in bio-luminescence at close proximity which can be detected through a special camera, as Figure 2).

4. What the data is telling us?

The first thing I would tell is that the person behind the yellow highlight not only have absolutely no idea of what to look for in Table 3 but also went into a cherry-picking expedition to use numbers in scaring people with numbers. That person is providing us with amount of the radiolabeled tracer detected in the tissue (e.g. ug/g tissue), with the approximation of total lipids amount in tissue. This assumes that the nanoparticles made it through the tissue complete, but we cannot exclude that we are maybe measuring only the 08-A01-C0 compound accumulation.
In practice, we usually focus our attention on the percentage of injected dose (% ID) when it comes to appreciate the distribution and the delivery of a drug into an organ/tissue. In some fields, like the BBB, such value is usually not sufficient, and we further correct these values to sort the amount that diffused across the blood-brain barrier (BBB) against the amount that is retained in the cerebral vasculature by the time of euthanasia.
Therefore, we have to put our attention on the right-half of the table. I have plotted these values into a plotting software (Graphpad Prism 9) to have a graphical representation.

What we can see is that the LNPs reach a Cmax value of 52.9% of the ID by 1 hour following IM injection and see a biphasic phase of distribution and elimination (which I suspect the drug would follow a 2-model compartment). Liver is the organ with the highest uptake (we know that 60% of the LNPs are uptaken by the liver) with a Cmax of about 18% of the injected dose by 8 hours. This is expected as liver has a formidable blood flow compared to other organ (Q=1500mL/min). Spleen (very important lymphoid organs) comes in as a good second with a Cmax~1%ID by 8 hours. Kidneys in the other hand sees a much lower uptake despite being an organ with a decent blood flow (GFR=~120mL/min) with a Cmax`0.2%ID, suggesting these LNPs maybe eliminated mostly via hepatic clearance route (including metabolism).

[EDIT: I have performed an area-under-the curve analysis, just for the fun of it. We are lacking data, so we will use for informational purpose. The use of the AUC trapezoidal method can allow to guesstimate how much of that radiotracer accumulated in the tissue/organs over the 48 hours period.
If we look at the AUC values of these from 0 to 48 hours, about 57% of the injected dose is found in the liver, 3% in the spleen, 0.25% in the kidneys, 0.17-0.18% in the gonads and finally 0.04% of the injected dose is found in the brain). ]

What about ovaries? Well we are in the same ballpark than kidneys and indeed nothing really much about (0.1%ID after 48 hours). Interestingly, the author hyper focused on female gonads and occulted to show that male gonads (testes) were getting the same %ID (0.07%). I don’t think it was an accident from the author, just a sign of a deliberate attempt to manipulate the narrative by spinning the numbers.
And last, brain, my favorite organ. The amount entering the brain is maybe the lowest of our organ of interest as we measured a meager 0.02% ID there. Keep in mind, we have to be careful on this number as we may have an overestimation here. In the field, when you do brain perfusion and you are about to collect your last plasma timepoint before sacrificing the animal, you have to be sure to perform a “flushing” of your cerebral blood vessels with PBS, to remove any residual blood volume that can contain your drug. Unless you can correct for the vascular volume (which is not as simple), you have to perform this procedure as we did in a paper I collaborated on. Failure to do so can can lead to overestimation of your brain uptake. Until I have evidence of such flushing occurred, we can hypothesize that the investigators sacrificed their animals at the time points, extracted and weighted all organs and proceeded with the radioactive counts. Therefore, that 0.02% ID should be considered as a grand maximum, likely overestimating the real concentration.

Taken together, we can see that aside of the liver and spleen, the uptake of the radiolabeled tracer (and by extension nanoparticles) remains very low in gonads and in the brain, with amounts of 0.1% and 0.01% respectively at 48 hours.

The second set of data we have to look at is the bio-luminescence data (see Page 5). The lab injected 1ug of mRNA in each hind leg, totaling 2ug mRNA in each rat. Considering an average weight of 200g per rat, we can approximate a dose of 10ug/kg for the luciferase assay. As a control (to remove the background noise), control animals were injected with saline buffer. The average bio-luminescence signals were given, and I personally added 10% of this average as an estimated standard deviation to have an error margin, which a value commonly accepted in biological sciences (10% variation around average is considered pretty good data variability).
[Added: The bio-luminescence is also set to a mininum of 10E6 AU, which is important for the rest of the analysis.]

We can see that the luciferase activity at the injection site (which we can refer as our reference tissue) is significantly high within hours of injection (2 hours being the first reported timepoint) and decreases over time. [Added: What is important to note is how does the %ID actually compares to the bioluminescence. The common sense would be the more of the lipids are biodistributing in the tissue, the more mRNA (and therefore luciferease activity) we should detect, no? Well it is more complicated than this. Let’s plot the %ID in the tissue versus the bio-luminescence.

As you can see, an increase of lipid tracer in the tissue does not correlate with an increase in mRNA activity (as seen by Luc activity). It can be meaning two different things:
* The accumulation of the radiotracer present in the LNPs does accumulate in the tissue because of its non-metabolization and therefore may overestimate the half-life of the LNPs.
* Lets assume the LNPs found a way in the tissues, does not mean they made it safely with their cargo. They may accumulate as residues, or may come as empty shells with little or no mRNA left.]

We can assume that the luciferase expression at the injection site last for up to 10 days before being no different of background noise (we also have to be careful to not extrapolate as-is for the spike S protein, as the mRNA and protein kinetics of luciferase enzyme may greatly differ from the recombinant spike protein). However, the risk of off-target effect and having the mRNA expressed outside the injection site seems to be quite dim. Luciferase activity in the liver (which apparently uptake 60% of the injected dose) is down to background level by 48 hours post-injection. [Added: If we look at the profile, we can guess there is some metabolism in the liver that makes the clearance of LNPs and/or mRNA faster than the muscle tissue. From the data of the muscle bio-luminescence, we can see the decay of the bio-luminescence follows a first-order kinetics and puts with a half-life of ~0.75 days].
Ovaries luciferase activity was basically in the range of the saline group (and would be barely detected over noise, if we refer to the expected min. The penetration of the dye emission wavelength should be enough to be caught by the camera, even through solid tissue. If we don’t see any luminescence, it is likely because it is below or same intensity than background in saline) and brain luciferase activity in the brain was basically noise from the beginning to start (remember we have no access on the standard deviation but the numbers being that close from saline suggest we are scrapping background noise).
In conclusion, the risk of having the mRNA expression outside the injection is very unlikely and meaningless when it comes to biological activity.

5. The perils of dismissing the dose and the allometric scale in assessing the risk
So, we have evidence that the LNPs are pretty safe by barely accumulating in gonads and in the brain, that the mRNA activity is mostly not being found to have off-target, but what about the dose and how does it correlate to clinical situation?
This is where important concept of doses and allometric scale have to be introduced.
First, the dose used for the PK study. It was 1mg/kg of mRNA given in rats. As a comparison, the regular dose of the Pfizer vaccine is 30 ug (0.03mg) given to any patient of 12 years and older.  An average 12-years old girl would be 40 kgs per the CDC chart (rounded up to the lower value and for the ease of calculation). This would indicate a dose of 0.00075mg/kg. That’s already a difference of 1333-fold between what we gave to these rats and what we gave to humans, but there is more!
We also have to account to the allometric factor, because rats are not small human. [EDIT: For adjusting to the allometric scale, we will use this calculator ]. The allometric scale tells us that 1mg/kg dose in rats results in a human-equivalent dose (HED) of 68mg/kg if your patient is a 70-kgs adult; 45mg/kg if you are a 40-kgs teenager (~12 year old girl falling in the 50th percentile of the CDC growth chart).

Therefore, we have to multiply it by 45 (40-kgs patient) or 68 (70-kgs), which means if we want to transpose the PK findings as done in the rats, we would need to inject about 60’000 doses of the Pfizer vaccine in ONE girl (91’000 doses if you are a 70-kgs adult). That’s about half one-fourth of all doses distributed to Amarillo until now given to only ONE person [EDIT: One 12-year old teenage girl that is in the 50th percentile], ALL AT ONCE! You see where we going? The very extreme implausibility of the claims that COVID19 vaccines affect ovaries and the brain.
To finish it up, we can also look at the actual mRNA and luciferase.
We know that 8microg/kg was sufficient to see some liver activity, but no activity in gonads and brain. How does it translate to humans? First, lets apply the allometric scale (68x). We would need 544microg/kg for the HED, and translated to a 12-years old girl that would be 21760microg of mRNA delivered, which is about 725 doses of Pfizer given in ONE person at once! You can see that since we cannot detect notable activity if I give 725 doses at once, chance are I will not detect any activity when given a single dose or even two doses of Pfizer.

6. Concluding remarks

In conclusion, we can take the following messages:
– This is a document leaked on the PK of nanoparticles as found in the Pfizer vaccine, showing animal studies have been done before or during the clinical trials and we have the documentation.
– It helps clarify an ambiguous statement made by Pfizer in their summary submitted to the European Medicine Agency a couple of weeks ago about the distribution of the mRNA vaccine.
– The studies were done in a very conservative fashion at doses exceptionally high and impossible to reach in humans
– At such doses, it was shown that aside from the liver and spleen, the distribution of LNPs was minimal in gonads and the brain.
– The amount of mRNA required to be present in the tissue to appreciate an off-target effect is ridiculously low and impossible to achieve in real life and was transient in the liver.
– When accounting for the clinical dose and the allometric scale, this study shows that the Pfizer vaccine is very safe with a very low incidence of the off-target effect. To achieve the same result in humans, it would take a ridiculously high amount and a sheer incompetent healthcare practice to have the probability of having any issues of off-target effect occur in humans.

[Sciences/BBB] T Lymphocytes and Cytotoxic Astrocyte Blebs Correlate across Autism Brains (DiStasio et al., Ann Neurol 2019)

I  have been recently approached on social media to discuss about the recent study published by Anderson and colleagues in Annals of Neurology (https://onlinelibrary.wiley.com/doi/abs/10.1002/ana.25610), in which the authors reported the presence of residing CD8 cytotoxic T-cells in the perivascular space of brain samples from ASD patients. I wrote about it, and gave my first impressions about reading the study. After such discussion, I realized that I have an interesting review that worth being shared here on my blog.
Here is the summary of my review of this paper as I wrote it on social media. I made some corrections (mostly spelling and grammar), as well as some changes in the writing style (I wrote these comments on the spur of the moment, as I went through the paper). Also due to copyrights, I will not show any figures and tables from the study.

About the authors: The first author is Dr. Marcello DiStasio (MD/PhD) and the senior author is Dr. Matthew P. Anderson, MD/PhD. He is a clinical faculty of Harvard Medical School and member of the Department of Neurology and Pathology a Beth Israel Deaconess Medical Center, with an affiliation with Boston Children’s Hospital Intellectual and Developmental Disabilities Research Center.  So we have some high profile and experts in neurodevelopment disabilities.

About the journal: The journal is published under Wiley, and is the official journal of the American Neurological Association and the Child Neurological Society. It has an impact factor of 9.49 and is in the top quartiles of neurology and neurosciences journal. Therefore, we have a study published in a very good journal that is relevant to the topic.

About the study design: The study is mostly observational and relies mostly on histological methods (tissue sections followed by staining using chemical dyes and/or antibodies targeting specific proteins). Tissue samples are freshly isolated from postmortem patients (which is a big plus compared to formalin-fixed samples, and opens up the ability to perform protein and RNA analysis if the samples are immediately treated for extraction). The sample size is pretty decent (N=25-30) with a large age spectrum and various types of ASD represented. First interesting to note, 50% of the ASD brain (N=25, not bad) have a history of seizures. Less than 30% of control brains (N=30) have history of seizures. Important thing to consider as a comorbidities and evenutally as a cofounding factor.

About the results: This is my summary of the different figures. By copyright concerns I am not showing the actual figures, but you can overlap my comments to the figures as I have separated them into sections.
Figure 1: Me being cranky, I wanted to see control brain pictures, but not avail. Also with immuno pictures, you have to be super-precautious because there is a high risk of cherry-picking a brain slice, and claim it is representative of all brain. Nevertheless lets discuss it here. On the left panel, we have an H&E staining. Pretty much a vanilla staining. Now, if you want to show a certain protein, you can do it with the right antibody and staining (DAB/peroxidase stain). It appears as the dark brown color. We can see a strong GFAP staining around the vasculature (hollow structure). Astrocytes usually line up blood vessels by forming end-feet process. S100B and ALDH1L1 are pretty standard proteins for astrocytes. However seeing GFAP expression in human astrocytes means these cells are stressed out and are reactive. This is what the quantitative bar graph is telling us. We can also see some CD8 in this perivascular space. These are the cytotoxic T-cells. I wonder what they are doing there, as they can cross the BBB only during brain injury, as microglial cells will äctivate” these endothelial cells and allow white blood cells to adhere on their surface and cross the BBB into a complicated tango dance.
Figure 2: Here there is an attempt of some matrix correlation. GFAP versus CD8 cells. And we can see there is some (expected) correlation between these two (see linear regression and R2) with ASD brains have higher rates of both compared to controls. Interestingly we see similar pattern between ASD that are genetic versus the idiopathic.
Figure 3: digs in more about the immune cells and some correlations (although the scatter of the ASD brains is less convincing here). Overall it seems we have a higher number of lymphocytes in the ASD brain compared to control, both in the white matter (WM, this is where our cables go through) and grey matter (GM, this is where our processing units are) and lepomeningeal (LM, this is our brain surface protective skin, basically the meninges, pours the CSF into the veinous blood). What seems interesting is that at young age we have lymphocytes sitting in our perivascular space, doing nothing(?) and decrease as we age (thats interesting for the non-neuroimmunologist that I am). However, these number at best slightly increase in ASD brain as we age (and I guess not convincingly enough, otherwise the authors would have reported the R2 value), or at least remain the same. With the exception of the medulla (brain stem) most blood vessels show a higher number in ASD brains versus control brains. Interestingly, cortical blood vessels being the predominant population harboring such feature. Very few NK cells to be honest on the panel.
Figure 4: Again this one makes me cringe a bit as a reviewer, because the author do not show the controls data. Yeah, I am pissed. Anyway. Again, perivascular space. Again immune cells highly present (CD3+), CD8 lymphocytes being the predominant type of T cells, in contrast not many CD4 lymphocytes (usually the T helpers, but my immunology is outdated for 20 years at least). Granzyme staining denotes the presence of natural killer (NK) cells. CD20 is a marker for B cells. What is interesting is mostly not much B-cells in either ASD and control brains, the graph more like a refried version of what we already know (higher number of immune cells and CD8 cells).
Figure 5:  is a bit of a useless graph, I don’t see anything that brings us more information than before.
Figure 6: It shows us a Masson trichrome staining. It is a chemical (histological) staining aimed to make collagen fibers visible under a certain color compared to other tissues. Collagens exist in different forms (based on their alpha-fibrils) but the one you expect to see around the vasculature is Collagen Type IV (COL4A1). This one forms a basement membrane (BM) that is like a net around blood vessels. Think about standing on a trampoline. Thats it. Collagen IV forms the net that supports the BBB. Normally, you would expect the BM to be thinned out, this is the case after stroke as cells secrete protein-degrading enzymes (like matrix metalloproteinases MMP2 and MMP9) that will break it down into pieces. But here it is thickened and hhad a bigger thickness than normally. Why so? What does not mean? I dont know. The only time I have seen such things was in transgenic mice overexpression erythropoietin (EPO). These mice had a such high hematocrit that would make blood be like Aunt Jemima corn syrup. If I remember, my former PhD adviser had a collaboration with an electron microscopist and observed similar thickening. Why this is happening is a good question that is likely the next study.
Figure 7: See Figure 5 comment.
Overall thoughts, limitations and outlook: Overall, it is very interesting study, that has some methodological limitations to be noted. First, we are missing any information about the BBB integrity in general, as I wish the authors would have shown some immunofluorescence to compare changes in tight junction (TJ) proteins expression (claudin-5, occludin) in blood vessels and assess differences in TJ strands. The second problem is the lack of information about microglia activation (that would be done by Iba1 staining. The authors noted they performed it, observed a higher expression in ASD brain but decided not to show the data) and more importantly the status of endothelial cell activation (using ICAM1, VCAM1 staining). Are these residing CD8 T cells freshly migrated or just being duck sitting for a while? Is the inflammation status in the brain (and the BBB) ON or OFF at the time of autopsy? What about pro-inflammatory cytokines levels between ASD and control patients? As usual, studies like that opens much more questions that it answers. The second problem is that the study by itself fairly descriptive and observational. It would be interesting how this would compare to clinical findings done in patients. Do we see flares on the MRI indicating of the BBB opening? How does that data compares to patients with MS?
I would also be very careful on making any claim about a “leaky” or “down-regulated” BBB at this point. There is no data about the barrier integrity (TJ complexes integrity) or assessment of the barrier function (for example an MRI scan with gadolinium as contrasting agent) to support the claim. I have seen this claim floating around in non peer-reviewed articles (including in The Scientist), as a BBB expert I would not jump into that conclusion quickly until I see real data on that
This is the type of interesting study, because it opens 100 questions that incentivize to further look down the road. I hope that the authors were able to prepare RNA and protein samples for transcriptome analysis (RNAseq) and proteome analysis (2D-electrophoresis coupled with MALDI) that could help us learn more.

 

 

[Sciences/BBB] X-linked adrenoleukodystrophy and blood-brain barrier: latest insights from preclinical and clinical studies

Two studies came out of interests in the last few weeks about the dysfunction of the blood-brain barrier in X-linked adrenoleukodystrophy (ALD): an in vitro study from Azarin and colleagues (I know Dr. Azarin as we collaborated on several publications together) using patient derived stem cells to model the blood-brain barrier in a dish (https://www.ncbi.nlm.nih.gov/pubmed/29615068) and a brief communication from clinical data showing an improved blood-brain barrier function (by MRI) in ALD patients treated with stem cells (https://www.ncbi.nlm.nih.gov/pubmed/30635285).

Before I go into details, I think it is important to discuss about ALD. ALD is a X-linked genetic disease (it affects mostly boys, as they carry only one copy of the X chromosome) affecting one in 18’000 patients and with a grim prognosis. It usually onset between 4-10 years old children, resulting in their rapid neurological deterioration and eventual death within 2-5 years. As of today, there is no treatment.

ALD pathophysiology is mainly occurring as a demyelinating disease. Myelin is a complex fatty acid acting as an insulant around nerves axons, by ensheathing such axons very similarly as a plastic insulant around copper wires in electrical wires.  In ALD patients, there is an abnormal processing of very long chains fatty acid (VLFCA), resulting in its buildup in the serum and in the brain white matter, resulting in abnormal immune response in the brain and neuroinflammation. About 50% of ALD patients will display a childhood cerebral ALD (ccALD), as displaying the clinical features mentioned. Because it is primarily a disease affecting neurons, a lot of research have been focusing on neurons and ignored non-neuronal cells.

These two studies add to the list of neurological diseases associated with ALD. First, the study by Azarin and colleagues (University of Minnesota-Twin Cities) show that brain endothelial cells (BMECs) differentiated from induced pluripotent stem cells (iPSCs) derived from ALD patients have a deficit phenotype compared to controls, have poorer barrier tightness and maturation. Moreover, they show that such BMECs have lipid inclusions (a cellular feature of lysosomal storage disorders) and express genes involved in inflammation at higher levels than controls. Interestingly, they also identified a polymer (PEO-PPO) can alleviate the dysfunction and partially restore the barrier function. It was interesting to see this study finally out, as I have seen the poster of it at the recent Gordon Research Conference.

Second, the study by Lund and colleagues (University of Minnesota-Twin Cities too) noted an improvement of the BBB (using MRI imaging and gadolinium as contrasting agent) in patients that received an hematopoietic stem cell transplant (bone-marrow transplant) as seen by a reduction in Gd leak by day 30 and improvement of patients outcomes. At this point, there is no clear evidence of how it works (the author speculate that some monocytes from the donor may migrate in the brain and attenuate the neuroinflammation) and if there are an overall improvement of the patient function.

Still, these two articles are interesting as it bring an insight of the contribution of the BBB in the ALD pathophysiology and further demonstrate the importance of the BBB as a contributing factor in several neurological diseases.

[Sciences/Junk Sciences] Zeolites, blood-brain barrier and “Autism Detox” scam.

Recently, it came to my attention of another scam popped up on social media. This scam came in form of the “Autism Detox” page on Facebook coming with the following description:

“Zeolite”, “blood-brain barrier”, ‘detoxify toxins and heavy metals” and “cellular level”.
Incredible how much amount of BS claims can be packed in such a small vaporizer. Not only this was enough BS, the owner of this page went the extra mile and claims it is an “autism detox” as well.
I call this an utter amount of BS and since I am a scientist, I will explain why it is an utter amount of BS.

1. What are zeolites?
Zeolites are crystalline structure made of aluminum, silicium and oxygen. These crystals are formed by the aggregation of 4 oxygen atoms around aluminum Al3+ and Silicium Si4+ (notice how Avers that yells “shark” on aluminum in vaccines are fine absorbing aluminum from zeolites).
These frameworks of AlO4 and SiO4 can form 3-D geometrical structures harboring charges and possibly acting as a caging structure as shown below (Moshoeshoe et al., Am J Mat Sci 2017):

As you can see different structures exist. Now, which zeolites are used in the product described in this “detox”? According to the vendor website (https://www.coseva.com/toxin-removal/advanced-trs/), clinoptilolite (CLI) (amongst water and a proprietary formula). According to Mosheoshoe and colleagues, CLI harbors the following chemical composition ((Na,K)6(Si30Al6O72) •20H2O)) and harbor the following crystalline structure:

Notably, CLI also display one of the lowest cation exchange capacity (CEC) of 2-2.6 mEq/gram. In summary, CLI is a small zeolite crystalline structure with limited cation exchange (against Ca2+, K+ and Na+). First, it shows that these compounds have a molecular weight exceeding the size recommended for small molecules (~832 Da>500 Da), a ring size bigger than the tight junction pore (5.6 Angstroms>4 Angstroms) and an non-negligeable amount of molecular charges. All these features make CLI very unlikely to cross the blood-brain barrier and no studies have provided a direct experimental evidence that CLI crosses the BBB.

2. Does zeolites even cross the GI tract?

Good question! The only paper that I found discussing about zeolites is a paper from Cefali and colleagues (Cefali et al., Pharm Res 1995). Unfortunately I cannot access the paper but the abstract provides two important parameters: Cmax and AUC. In particularly, it also provides the value of aluminum hydroxide (yep, that stuff found in vaccines).
Cmax is indicative of the maximal concentration reached upon administration via extravascular route (IM, PO or SC). The AUC is representative of the total amount that reached the circulation from the time of administration until the time the drug becomes undetectable in blood. From the abstract we have the following information “The mean plasma silicon AUC values (+/- S.D.) were 9.5 +/- 4.5 [Note: Zeolite A], 7.7 +/- 1.6, 8.8 +/- 3.0, 6.1 +/- 1.9 mg.hr/L [Note: Aluminum Hydroxide] and the mean plasma silicon Cmax values (+/- S.D.) were 1.07 +/- 1.06 [Note: Zeolite A], 0.67 +/- 0.27, 0.75 +/- 0.31, 0.44 +/- 0.17 mg/L [Note: Aluminum Hydroxide] for Zeolite A, sodium aluminosilicate, magnesium trisilicate, and aluminum hydroxide respectively. Although mean silicon AUC and Cmax values were elevated when compared to baseline after administration of the silicon containing compounds, only the AUC from Zeolite A reached statistical significance (p = 0.041). The mean plasma silicon Tmax values (+/- S.D.) were 7.9 +/- 6.4, 5.8 +/- 4.6, 6.9 +/- 6.3 and 8.5 +/- 3.4 hrs for Zeolite A, sodium aluminosilicate, magnesium trisilicate and aluminum Hydroxide respectively.”. Since we have a Cmax and AUC value for Zeolite A and aluminum hydroxide very similar, we can assume that both compounds may likely show similar bioavailability. Considering the bioavailability of Al is very low (0.3%), it is very likely that zeolite and CLI may not show a higher value that this one. Thus, out of 100g ingested of zeolite, maybe less than 0.3g will likely reach the bloodstream. In conclusion the amount of zeolite capable to cross the GI is very small and considering the volume of a TRS “Detox” (28mL), the amount of zeolite capable to cross the GI tract after swallowing a whole bottle of it is likely to be ZERO.

3. What about the rest of the claims?
As far we have seen:
1) CLI absorption at the GI tract is likely close to ZERO, even if you sip a whole bottle at once (see 2).
2) CLI cannot cross the BBB because of the physicochemical constrains (see 1). The only paper listed in Pubmed is a letter written to a journal with no scientific evidence or experimental data backing up the claim (https://www.ncbi.nlm.nih.gov/pubmed/23224491).
3) The claim of detox is utterly BS: there are two organs that do it for you. The liver and the kidneys. Thats it.
4) Heavy metal detox mostly occurs via renal (kidney) filtration. Even if zeolites can trap ions like Na+ or K+, I still have to find a paper that shows me it can trap heavy metals (Cd2+, Pb2+, Hg2+…..). CLI has been shown to only trap three ions (Ca2+, Na+ and K+) with the poorest ability.
5) Claiming that autism be cured is not fallacious but criminal. Until now, there is no cure for autism. There is no evidence that chelating ions cure autism (chelation therapies have even been proven to be dangerous and responsible for the death of at least one boy). There is also no published mechanism of action demonstrating how a treatment can reverse a condition mostly identified as genetic.

 

[Neurosciences/BBB] Brain Endothelial Erythrophagocytosis and Hemoglobin Transmigration Across Brain Endothelium: Implications for Pathogenesis of Cerebral Microbleeds (Chang et al., Frontiers Cell Neurosci 2018)

I usually don’t post BBB papers on my blog because most of the time they address concepts or answers questions that are not relevant for the public in general, but I thought this one was an interesting paper to share. This is an original article published by Rudy Chang and colleagues in Frontiers in Cellular Neuroscience las month. It is open-access, that allows everyone to access to it. Another interesting feature is the disclosure of the reviewers that help improve the peer-review process and transparency.
Why I found this paper interesting? Its because it propose a novel mechanism of cerebral microbleeds, without affecting the tight junction complexes. In the field, when we consider brain bleeds, we consider a loss of the barrier function and a massive brain leakage. Such phenomenon occurs when you have an hemorrhagic stroke due to an aneurysm, or due to a arterioveinous malformation resulting in an unstable blood vessel. The presence of blood in the brain parenchyma is harmful for two reasons:
1) You are injecting a volume inside a closed space (cranium) that will lead to an increased mechanical pressure (intracerebral pressure) and ultimately brain damage by tissue crunching.
2) Red blood cells (RBCs) may be damaged (hemolysis) and release their content into the extracellular space. Heme is toxic at high concentration (through mechanisms that yet to be identified) and can further damage neurons via generations of free radicals and other damage-inducing signaling pathways.
In this article, they demonstrate that you may achieve a similar outcome than brain bleeds without having a leaky BBB. In particular, this study demonstrate the ability of damaged RBCs to cross the BBB via transcytosis (via an engulfment inside the BBB and the exit to the other side). For this study, they used bEND.3 cells (an immortalized mouse brain endothelial cells) and compared mouse RBC that were considered healthy or induced damage via tert-butylhydroperoxide (t-BHP). t-BHP induces oxidative stress (via the release of radical oxygen species such as hydroxyl radicals), in this case leading to the exposure of a particular phospholipid named “phosphatidylserine” (PS) from the inside to the outside of the cell surface membrane.
In this study, they demonstrated that oxidative stress mattered in RBC cell adhesion to b.End3 cells. Treatment of b.End3 cells with t-BHP or LPS (a bacterial membrane lipid, commonly used to induce an inflammation state at the BBB) failed to yield similar results. in addition to demonstrating the ability of RBC to adhere on b.End3 cell surface (the first step needed for cellular transcytosis), they also demonstrated the ability to have these cells to engulf and get trapped into these cells. This process appeared slow and it took about 18-24h to see a significant number of RBCs inside the cells. Finally, they show that such RBCs were capable to migrate through the b.End3 monolayers and popped out in the other side. Similar outcome was observed in vivo, but to a certain extent.
It is a very interesting study, because it can maybe explain some aspect of diseases associated with RBCs such as cerebral malaria (we can imagine that Plasmodium may use RBCs as a Trojan horse to cross the BBB). However, I also have some criticism of the study. First, it uses the b.End3 that has fairly poor barrier function (TEER<100Ohms.cm2), much less than the tightness expected in vivo (>2000Ohms.cm2). The second issue is inherent to working with non-human cells. Do we have the same outcome when it comes to the human BBB and human RBCs? Maybe this phenomenon is exclusive to rodents and may have limited impact in humans. Finally, and as seen with the in vivo data, RBCs maybe able to cross the BBB but they maybe likely get retained by 1) the basement membrane supporting brain endothelial cells and 2) rest in a limbo state in the perivascular space (a virtual space between the basement membrane and an external protein mesh called “glia limitans” wrapped around cerebral blood vessels). We have some hints as RBCs appear juxtaposed near the vasculature, as stuck by a mesh surrounding the vessels. I don’t think that RBCs can cleave such mesh because I assume they don’t have the molecular machetes (matrix metalloproteinases) to cut their way through. Yet, I think it is a very interesting paper, that work to be investigated with a human BBB model, using a more robust model.

[Sciences/BBB] Acute Necrotizing Encephalitis (of childhood), a blood-brain barrier perspective.

This is a blog post following a request by a page follower on my Facebook account to provide an “layman” perspective on acute necrotizing encephalitis (ANE), also referred as acute necrotizing encephalitis of childhood (ANEC). This is a very short and surely incomplete summary but it should be a great starter to give the current perspective of this condition through the lens of the blood-brain barrier.

It is a condition that was firstly discovered by Mizuguchi and colleagues in 1995 firstly described in infants and toddlers (http://jnnp.bmj.com/content/jnnp/58/5/555.full.pdf). It was firstly described in patients from Asian origin (Japan). It was initially described to occur during the winter period, in particular with region that had experienced an influenza A outbreak. The main clinical feature of the disease marked by the presence in the magnetic resonance imaging (MRI) of increased water content inside the brain, mostly associated with edema (brain swelling). This increased water content can only be explained by the opening of the blood-brain barrier.

Water diffusion between the blood and the brain is tightly regulated by the blood-brain barrier (BBB). The BBB provides two kinds of barrier: a physical barrier (by the presence of tight junctions) and a chemical barrier (by the presence of solute carriers and drug efflux pumps). The case of water as a molecule (H2O) is very interesting. Water is a very small molecule (the molecular weight is 18g/mol or also 18 Daltons) but also a very polarized molecule. Hydrogens and the oxygen atoms forming H2O are not completely neutral, hydrogen carries a tiny positive-charge and oxygen carries two tiny-negative charges (we refer in chemistry as electronegative charges). Think about having a tiny magnet. In the opposite, cell membranes are made of phospholipids. As their name say, they are lipids by definition or what we commonly call them as “fatty acids”. Lipids have a distinct composition, they are mostly formed by carbons and hydrogens. Carbon is not much a magnet atom, it neither likes to carry positive charges nor negative charges. This is why lipids are commonly referred as apolar molecules. Now, polar and apolar molecules behave like water and oil mixed together: they simply do not mix and will sequestrate themselves, usually forming a oil droplet surrounded by water. Water entrance inside the brain is believed to occur mostly via paracellular route, as depicted in the picture below (source: http://www.nature.com/nrn/journal/v7/n1/full/nrn1824.html?foxtrotcallback=true).

Tight junctions are very tights, letting water fall through the cracks only in a tiny amount. Imagine having a very good rooftop that only let water fall through one drop every hour. The problem with the opening of the BBB following various factor is the massive entrance of water. Think about having a hole in your rooftop and facing a tropical storm shower outside: you are facing now a massive and unregulated entrance of water inside the brain, leading to a brain swelling.
In peripheral tissue, edema (swelling) formation can naturally expand, resulting in a swollen tissue. The problem with the brain is its anatomical structure: it is encased inside a rigid shell (skull) that has no exit route for the penetrating water. This results in an increased pressure inside the brain (we usually referring as increase in intracranial pressure or ICP). This increased pressure induce a mechanical stress, crushing brain cells via mechanical stress and ultimately neuronal cell death. Such swelling appears to occur in specific brain regions, with a primary lesion site in the gray matter (neurons), with persistent deposition of hemosiderin and white matter (axon fibers) cysts during and after the recovery phase. Until now, we don’t exactly know what cause such disease, but appears as following a viral infection including flu (influenza A and B, swine flu (H1N1), parainfluenza virus), varicella, measles, rubella and various herpesviruses (HHV-6, HHV-7) (https://www.hindawi.com/journals/mi/2015/792578/#B1), although the presence of such viral agents (detection by polymerase chain reaction) in spinal tap as well as post-mortem signs of brain inflammation remains anecdotal.

Interestingly, it seems that patients suffering from ANE undergo a very severe immune response commonly referred as “cytokine storm”, as several studies noted an increase in inflammatory markers (in particular interleukin-1beta, interleukin-6 and tumor necrosis factor-alpha (TNF-alpha) making this phenomenon the most prevalent hypothesis.

Immune cells communicate to each other via a common language called “cytokines”. Cytokines are like a “RED ALERT” system, they signal some breach in security or incoming danger.
Brain microvascular endothelial cells (BMECs) lining the blood side of the BBB can also understand the “cytokine” language and understand such signal as “RED ALERT – OPEN THE BBB SIGNAL” as depicted in the picture below (source: https://www.researchgate.net/profile/Nicolas_Weiss/):

Now where are these cytokines coming from and how they are triggered? It is a very good question. This is where the viral infection comes in. I will not details much about the immune response to viruses, but you can ask @TheMadVirologist for any questions related to viruses. For this I will use a figure that resume the immune response to viruses (source: https://www.researchgate.net/profile/Francoise_Stoll-Keller/).

Upon infection, infected cells will display viral particles on the cell surface and will also secrete a protein called “interferon-gamma”. This is a sort of cellular “SOS Danger” to the immune system. Natural killer cells, dendritic cells and macrophages may start the early response, also known as “innate immunity” to contain the viral infection. In addition, free circulating viruses can be spotted by B cells through their array of surface antibodies and trigger what we refer to as “acquired immunity”. Viral infection will trigger an immune response and we can think that maybe an overactive immune system may exaggerate the danger resulting into the “cytokine storm”. Another hypothesis is that such cytokine storm maybe triggered by natural killer (NK) cells.

This hypothesis is further supported by the presence of a higher count of natural killer leukocytes in ANE patients during the recovery phase. Natural killer (NK) cells are immune cells normally targeting cancer cells and cells infected by viruses.  This “cytokine storm” maybe the causative agent of the blood-brain barrier disruption (BBB) by different mechanisms (source: http://stroke.ahajournals.org/content/strokeaha/42/11/3323/).

but appears to occurs via an matrix-metalloproteinase (MMPs) dependent pathway. Under the stimulation of such cytokines, brain endothelial cells and astrocytes may increase the production and releases of MMPs locally. These MMPs act as little scissors that can chop the extracellular matrix supporting brain endothelial cells and astrocytes end-feet processes. In addition, these MMPs can also chop tight junction proteins that are involved in tight junction (TJ) complexes. These TJs are very important as they provide the barrier limiting the diffusion of water and solutes between the blood and the brain.

In addition to the cytokine storm hypothesis, it seems that other factors maybe involved in the pathophysiology of the disease. Until now, Ran binding protein 2 (RANBP2) (http://www.cell.com/ajhg/fulltext/S0002-9297(08)00630-7). RANBP2 is a protein involved in the nuclear pore complex, yet the relevance of this mutation at the blood-brain barrier remains unknown. In neurons, it is associated with cellular structures different from the cell nucleus, in particular it is associated with mitochondria (power house of cells) and microtubules.

Another protein of interest associated is EphB2, a receptor for ephrins (https://www.ncbi.nlm.nih.gov/pubmed/?term=ephb2+blood-brain+barrier). Ephrins play an important role in brain wiring during development (axon guidance) but also play a role in the formation of the vascular tree.

The function of EphB2 and ephrins at the blood-brain barrier remains unclear. However, a recent study identified the expression of EphB2 at the cell surface of endothelial cells including primary human non-BBB (HUVECs) and BBB (HBMECs) endothelial cells. Furthermore, a case report from a patient suffering from systemic lupus erythromatous (SLE), an autoimmune disorder, presenting the case of ANE showed the presence of antibodies in the serum capable to bind selectively to EphB2.

Yet, at this point we don’t know if this antibody binding is enough to trigger the BBB disruption or it requires the recruitment of immune cells to trigger such disruption.

 

 

 

 

 

 

 

 

 

[BBB/Junk Sciences] Polysorbate 80 and the BBB or how to put anti-vaxxers into a blowing cognitive dissonance

Here we go again, anti-vaxxers keeping on moving the goalpost to fit their belief instead to change to adjust it to the facts. First it was mercury, then it was formaldehyde, then aluminum, today the “ingredient du jour” is polysorbate 80 and tomorrow they will blame it to PBS saline solution.

The latest fad as I have seen is to blame polysorbate 80 as a source of “vaccine-injury” with the bold claim that it breaks down the blood-brain barrier (BBB). Lets put the fact straight and debunk this one for all. But what is even better is the “what if” counter-argument. What if polysorbate 80 was indeed a good ingredient? I will come to that later.

Polysorbate (aka Tween 80) is a amphiphile compound   as you can see the molecular structure below (source Wikipedia):

You can see the structure made of a lipophilic (loves fat) tail and a series of hydrophilic  (loves water) tails, loaded with oxygen and hydroxyl groups. This is a typical structure of a detergent: one side will mix well with water, the other will mix very well with fat and oils. The result? You can form microspheres that can dissolve well in water and dissolve fat into water. This is how a detergent works, it helps to breakdown fats into small spheres and dissolve them in the drain water.
Polysorbate 80, due to this property, is very good to dissolve drugs and medicines that under normal condition would barely dissolve into biological fluids. This is why we have it in vaccines, but we also have it in medicines. Thats the job of biopharmaceutics: finding formulations to dissolve drugs into the body and allow them to reach a concentration high enough to display their therapeutic activity.

The use of polysorbate 80 in drug delivery of anti-cancerous drug is probably the first and foremost main driving factor on investigating its effect on the BBB. Brain tumors (primary and metastatic alike) are up until now one of the most dreaded and deadliest form of cancer. For instance, the average expected lifespan upon diagnosis of a grade IV glioma (aka glioblastoma multiforme) is grim: 18-months, with less than 5% survival after 5 years. The major issue is being able to deliver drugs and chemotherapy across the BBB. As reported by Pr. William Partridge (UCLA) the BBB remains the bottleneck in drug development for the treating neurological disorders (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC539316/?fref=gc&dti=873247819461536)

The first report of the investigation of polysorbate 80 on the BBB is probably by Spiegelman and colleagues in 1984 (http://thejns.org/doi/pdf/10.3171/jns.1984.61.4.0674), investigating the effect of the solvent used in etoposide solution for treating cancer. According to their  result, they noted a statistical difference in the BBB permeability  (using Evans Blue and 99mTc as tracers) following the injection of 1.125ml/kg. According to their paper, 5mL solution contained 400mg of polysorbate 80 or a concentration of 80mg/mL. Based on this, we can assume that the BBB effect was observed for a dose of 90mg/kg. Thats a very huge dose.
If we go back to the manure anti-vaxxers say, the amount injected via vaccines is enough to cause a barrier opening. According to John Hopkins University Institute of Vaccine Safety (http://www.vaccinesafety.edu/components-DTaP.htm), the expected concentration of polysorbate is lesser or equal to 100mcg or micrograms. Thats 0.1mg per dose. If we assume such dose is injected to a newborn (average weight ~3 kgs), then the amount injected is about 0.033mg/kg. Thats 2700 times less than what has been reported to induce a BBB disruption. Also you have to factor the bioavailability of polysorbate (that is 100% upon IV route) making this number a very optimistic number.
Now, the interesting twist about polsyorbate 80 is its use to enhance some drug carriers and its widely used for finding novel formulation to enhance the delivery of anti-cancerous drugs across the BBB. You can find a list of publications on Pubmed about that aspect (https://www.ncbi.nlm.nih.gov/pubmed/?term=polysorbate+80+blood-brain+barrier). What if polysorbate 80 not only will not injure your brain, but actually may help deliver drugs to help your brain fight disease?

 

Keep in mind that polysorbate 80 is good at dissolving lipid in water solutions but it is not good to let charged molecules accross the BBB, just in case someone comes with the claims that it conjugates with aluminum. Thats some high-school chemistry level.

 

 

[Neurosciences/BBB] 8th GLUT1 Deficiency Conference – Summary

Today wrapped the second and last day of the 8th GLUT1 Deficiency conference that was held in Nashville, TN this year. It was my second time I am attending this conference and honored to be a guest speaker this year.

 

The whole conference took place at the Inn at Opryland, part of the Gaylord Resort at Opryland. It is a fairly impressive complex with shuttle to the Opry Mills outlet shopping center and, the Gaylord Resort & Convention Center (in which the AACP is also holding a meeting starting today but I am just attending one day meeting there).

According to the organizers, we had about 220 attendees, with 68 families present. What I liked this year was the blending between parents, healthcare providers and scientists. In the previous conference, the first day was family and healthcare providers and the second day was the professional day. This allowed a unique interactions, questions & answers and discussion.

 

It was also a very good time for updating my knowledge on the disease. Not much on the basic science, but more on the current treatment and dietary intervention with various experts of the field including Pr. Jorg Klepper (University of Essen, Germany); Pr. Juan Pascual (UT Southwestern, Dallas, TX); Pr. Eric Kossoff (John Hopkins University, Baltimore, MD) and other scientific experts.

My learning from the conference is that the disease in an evolutive disorder. We learn more about the disease as we learn from the patients growing in. As the patient grows, he or she displays different symptoms: “funny eyes movements” during infancy, presence of absence seizures during toddler times and learning attention and deficit during early school age, presence of movement disorders in both during childhood and adulthood and migraines, hemiplegia and “writers hand fatigue” syndrome. This seems to be linked by an impaired glucose uptake in the cerebral cortex and the thalamus.  It also seems that there is at some point in the disease the presence of a sexual dimorphism, as female patients seems to experience in their teenage years a “paroxysmal dystonia” that seems triggered by moderate and vigorous exercise. So, the GLUT1DS is not a static disorder. It is a disorder evolving over time with its clinical manifestations evolving as well.
The second thing I learned is the variety of “ketogenic diets”. There is not one single “keto diet” but several variants with different dosages and variety, including a Modified Atkins Diet.

It seems there is not a “one size fits all” but rather different types of diets that also seems to vary with age.

The younger age appears to need the following of a strict keto diet and as the patients age, some softening and flexibility can be introduced. It seems the critical time for the keto diet is infancy and childhood. The earlier the child is introduced, the better. There are also several companies providing cookbooks, supplements like keto powders or kets-friendly products aimed for patients.

In terms of diagnosis, some interesting news came from a French biotech startup that can measure GLUT1 levels in RBC within 24 hours using a proprietary cell assay (that looks like an antibody assay) using a flow cytometry-based approach.
Another interesting result is the outcome of the ketogenic diet for GLUT1DS patients. For the vast majority of GLUT1DS patients (95% of patients), the keno diet significantly decrease the number of seizures by at least 50%. In contrast, other types of epilepsies combined only show a 50% of patients showing a responsive outcome to keto diet. Still, 5% of GLUT1DS do not respond to keto diet and there is a fraction of patients that show a normal glucose CSF levels and/or GLUT1 expression. We certainly have a lot of patients that undergo undiagnosed or misdiagnosed for years as “drug-refractory epilepsies”. But it seems that some patients maybe falsely diagnosed as GLUT1DS. Hopefully, with the decrease in price for DNA testing (it seems 23andMe can detect some GLUT1 SNPs) may help to broaden the diagnosis and identification of patients.
Some interesting topics presented at the conference was some possible drug adverse effects reported in G1D heterozygous mice in particular to diazepam and phenobarbital but also other drugs. Some parents noted the anecdotical adverse reactions following certain treatment. However, the absence of studies directly investigating such drug adverse effects in G1D patients most of the time go under the radar, with the health practitioner attributing it to the disease condition rather than some particular drug adverse effects. Having from screening tools can greatly help.
Another interesting presentation is the study of G1D heterozygous mice. These mice seems to display a lower brain vascular density compared to wild-type. This is not surprising considering the recent work of Pr. Peter Carmeliet (Universidaed Leuwen, Belgium) on endothelial cell metabolism. According to Pr. Carmeliet, brain endothelial cells highly depend on glycolysis to function despite being in presence of plenty amount of oxygen levels.
There have been also discussion of trying to setup a comprehensive guide for parents for a consensus on GLUT1DS diagnosis and management that can help them as a source for documentation during their visit with their doctors. There is also a discussion of improving the community outreach to professionals and politicians to improve the funding and the recognition of GLUT1DS as a condition, discussing about supporting open-access options for certain papers allowing parents a free-access to these new studies and also finding ways to support GLUT1DS awareness and management among minority populations and in other geographic areas (especially South America).
The person missing at this meeting by his presence was certainly Pr. Daryl DeVivo (Columbia University, New York, NY). Little patients left him some very kind words and their name on a paper board. I found it was a very cute gesture and remembered us that his absence was felt.

The interesting silver lining comes from Europe, as they have set now a sister association that held their first European GLUT1 meeting last fall and plan to hold it in London in 2018 and in Paris in 2020.
For me, I am looking forward to attend the 2019 meeting in Washington DC and hopefully bring on some more breaking news from my lab there.

 

 

 

[Stem Cells/BBB] Modeling Psychomotor Retardation using iPSCs from MCT8-Deficient Patients Indicates a Prominent Role for the Blood-Brain Barrier

Vatine et al. show that human iPSC-based modeling can pinpoint the origin of a neuronal disorder in the brain as a defect in transport of thyroid hormone across the blood-brain barrier, rather than in the neurons themselves.

Source: Modeling Psychomotor Retardation using iPSCs from MCT8-Deficient Patients Indicates a Prominent Role for the Blood-Brain Barrier

[Stem Cells/BBB] Huntington’s Disease iPSC-Derived Brain Microvascular Endothelial Cells Reveal WNT-Mediated Angiogenic and Blood-Brain Barrier Deficits

Lim et al. show that HD iPSCs-derived brain microvascular endothelial cells have impaired angiogenic and barrier properties. Transcriptomic analysis provides mechanistic insights into pathways that underlie dysfunction, and WNT inhibition prevents angiogenic deficits. This system also suggests strategies to reduce disease burden and assess BBB penetration of drugs for HD.

Source: Huntington’s Disease iPSC-Derived Brain Microvascular Endothelial Cells Reveal WNT-Mediated Angiogenic and Blood-Brain Barrier Deficits