Categories
Neurosciences Stroke Uncategorized

[Neurosciences/Stroke] Summary of #ISC20 meeting attendance

A couple of days ago, I attended the second full-day of the American Heart Association International Stroke Conference (#ISC20) that held in Los Angeles, CA from February 19th until February 21st.
Considering this is a meeting mostly driven towards clinical science  (physicians, nurses….), it was a very good year for basic sciences as I had a pretty well loaded schedule of scientific sessions.
My goal is not to provide a detailed description of the findings but really try to keep this summary succint and easy to understand for the layman language. Here are some of the highlights that caught my attention:
* We knew that age is an important predictor of stroke severity and recovery outcome. What we did not knew about is one of these parameters involved is inflammation. A study presented data suggesting that the infusion of young plasma in aged mice undergoing stroke fared better than infusion of old plasma , in terms of infarct size and outcomes. A probable mechanism of action seems to involve a shift of balance in the microglia population (pro-inflammatory vs. anti-inflammatory microglia) and seems to involve exosomes (30-40nm sizes)  diffusion from plasma into the brain.
* Further work on the gut-brain axis and stroke, especially this one on the effect of ischemic stroke on the gut. What is interesting is that an ischemic stroke may have a ripple effect on the gut lining in mice, as it can significantly alter the colon integrity. What was interesting is the sex dimorphism observed, as young female were showing an intact GI lining compared to other group, aligning with the well-established finding that young females fared better than other groups in terms of stroke severity and outcome. Two possible gene candidates identified: MUC4 and CD44, as well as mucin-related genes. Changes in intraepithelial cells (IECs) seems a key factor in such changes.
* Microglia is an important type of immune cells, resident cells inside the brain in resting state. However following injury (DAMPs) or infection (PAMPs), these microglial cells can become activated and trigger the first steps of neuroinflammation. In particular, aging seems to increase the microglial cells population secreting TNF-alpha (a well-known pro-inflammatory factor) suggesting that microglia activation maybe inherently bad for stroke severity and outcome. Therefore, blocking or targeting microglial cell population (by depleting them) would be considered beneficial no? Well turns out maybe not. A study targeted microglia by depleting these cells in both young and old animals using PLX-5622 for 21 days. Interestingly, such treatment resulted in worsened stroke outcome, as the infarct size noted in MCAO group was bigger versus the vehicle group. What was also interesting was such animals showed an increased numbers of monocytes and neutrophils, and an increase in reactive astrocytes in aged animals. There was also changes in the gut microbiota as two genus (Verrucombroia and Akkermansia) were increased in this group, as well as a decrease in Iba1+ gut macrophages.
* Ischemic brain has an effect on the macrophage transcriptome. A study looked at macrophage gene expression profile between circulating monocytes/macrophages in the periphery versus macrophages that migrated into the ischemic injury site. More than 3000 genes were identified as differentially expressed, with an important clustering of genes associated with the peroxisome proliferator-activated receptors (PPARs) including PPAR-delta and PPAR-gamma.
*  MicroRNAs (mIR) play an important role in ischemic stroke injury. In particular a study showed that inhibition of mIR-15a and mIR-16-1 following MCAO (for up to 21 days) resulted in an increased post-stroke angiogenesis (using conditional KO animals). Treatment with AZD0530 resulted in a worsening outcome. A possible mechanism of action may occur via Src-dependent mechanism, that still need some brush-up (is Src activation or inhibition needed?).
* This year, the Thomas Willis award and lecture went to Pr. Maiken Nedergaard (University of Rochester) on the contribution of the glymphatic system. I have to say this is still a very controversial topic that remains highly contested within the BBB field (especially from those interested in fluids movements inside and outside the brain). I have been following as a bystander so I just really keep it on what I have seen presented (and not coming with a knowledge of her papers). According to Pr. Nedergaard, it is a “highly polarized” pumping system, pumping the CSF down to the arterial system, pumped by the glia endfeet processes and clearing in the venous system. According to her, meninges and dura have lymphatic vessels. Amongst things exchanged are ions, lactates and she was also able to observe movements of microspheres up to 1 micron size (aggregates moved to same speed than single ones).
The CSF tracer diffusion was much more present when animals were in sleeping state or under anesthesia, all into the cortex. Similar observations were done in patients as well. The flow is fast and occurs from central to periphery. The CSF accounts about 10% of the brain. According to her findings, tracer was flowing in despite reduced blood flow, all along the cerebral arteries and increase observed mainly in the ipsilateral side.
She also reported a decrease in the volume of CSF after stroke, suggesting that the CSF maybe the source of acute edema. Interestingly, she reported an increase of intracellular calcium influx (known to occur during the ischemic depolarization) preceding the CSF flux, and would still occur later after stroke as the  post-stroke vasoconstrictions would drive such CSF flux.
The rest of the day was marked by some other sessions, meeting old collaborators and friends in the stroke field (an opportunity to meet beyond the emails)  and by the visit of some posters.
Overall, it was a good stroke conference this year, and hopefully next year would allow me to spend more time (it is always tenuous to attend it as it falls right in my busiest semester). Next year? It will take place in the (very) mildly hypoxic mile-high city (Denver, CO), allowing me to drive (or maybe just an hour fly away whichever will be the cheapest option). See you in ISC2021 in Denver!

 

 

Categories
Neurosciences Sciences Stroke Uncategorized

[Sciences] Restoration of brain circulation and cellular functions hours post-mortem (Vrselja et al., Nature 2019)

You may have heard about that groundbreaking story last on “pig brains being revived” sounding almost like a scenario of a zombie movie. Let’s say science journalism love to use superlatives and sensationalistic headlines to grab few more clicks and views.
As usual, my skepticism was to first look at the paper and see how the claims hold on. The publication behind that “pig zombie paper” is the study from Vrselja and colleagues published in Nature last week and available here: https://www.nature.com/articles/s41586-019-1099-1
So what is about this story? First it is published in Nature, a top-tier peer-review journal. Second it is a huge paper, coming from Yale University. The paper was initially submitted on February 22, 2018 and got accepted March 1st. You can say a bit more than a year and that suggest that this paper likely went at least two rounds of review and probably more than three peer-reviews (three were named as well as other anonymous). One of the peer-reviewer was Pr. Constantino Iadeccola (Cornell University, NY), a “rock star” in the field of cerebral blood flow (which nicely match for the paper).
Overall, it is a very good paper with some reservations on the greater impact that I will explain later.
To understand the paper, you need to understand first that as until now we consider the brain highly dependent on continuous cerebral perfusion with blood flow to survive. The brain is highly dependent on oxygen and glucose (at least 20% of our daily uptake is taken by this tissue that only represent less than 2% of the human body weight).
We assume that if you stop flowing the brain with blood (e.g. cardiac arrest), you will die within minutes from massive and irreversible brain damage. The whole idea of this paper was: “what if we could maintain a blood flow for 24 hours, can we maintain some neurological function?”. In particular, the authors have developed a kind of artificial blood, cell-free, called BEx. It contains a hemoglobin carrier called Hemopure(R), glucose/pyruvate, as well as a cocktail of neuroprotective agents, antibiotics and some echogenic agents (to measure blood flow). The caveat is that as a control the authors used a simple saline solution without glucose and pyruvate (see supplementary tables below). Considering the importance of glucose for the brain tissue, and the absence of glycogen storage in that tissue, I would argue that this is a non-negligible flaw in the experimental design, giving a serious advantage to the BEx and maybe even overestimating the BEx activity.
Screen Shot 2019-04-17 at 2.06.26 PM

Nethertheless, let’s continue the discussion. Pig brains were not obtained from pigs euthanized for the sole purpose of the experiments, but rather obtained as waste from the slaughterhouse. Thats ethically much more acceptable, even 3R-friendly (as it valorize animal tissues considered as waste) and much more easy for obtaining an IACUC approval. About 300 post-mortem brains were used, I guess mostly for the development and optimization of the technique. The sample size (N) appears to be 32 pigs/group, which is very good for statistical power of analysis.
The surgical procedure (to connect these brain to the system) was about 10 minutes of warm anoxia, which would probably represent a severe cardiac arrest in which CPR is not performed immediately. They exposed these brain to either 1 hour or 10 hours post-mortem interval (PMI) without flow, with control perfusate or with BEx. Note that the perfusion to occur happened about 3 hours since the initial brain flush, the surgical preparation appears indeed tidious, but reproduce a pulsate blood flow similar to what would happen in animals. They also cooled down the brain to 25ºC, which is known that cooler temperature improve the chance of reducing brain damage (the common sense is that drowning in an hypothermic environment (frozen lake) increase your chance of resuscitation compared to drawing in a normothermic environment (swimming pool). The experiment lasted 10 hours for all groups, except the 1 hour PMI group.
The first results shown demonstrated the presence of a functional flow inside the brain tissue, and some vascular reactivity, using nimodipine infusion (a Ca channel blocker commonly used to reduce blood flow) and showing changes in blood flows. In other words, there is a proof of principle that it works.
The second result looked at changes in cerebral edema as a crude estimation of the blood-brain barrier (BBB) function. The control perfusate showed an increased water content, which is not surprising as some of our in-house data (and other studies) suggesting that the BBB function has a greater dependence to glucose than to oxygen when it comes to maintaining the barrier integrity. Since the CP is glucose-free, that is not surprising. The BEx group of course fare better (same level than 1 hour PMI group) but wonder how it would have fared if the CP contained the same amount of glucose and pyruvate. My personal thought is why did not the authors performed a gadolinium imaging of these two brains? They provide some T1 scans, which are nice but confirming changes in the BBB leakiness using gadolinium as contrasting agent would have been better.
Figure 3 show us a series of tissue staining of these brain, in particular from the hippocampal region. As expected, the Nissl staining worsened in the PMI, the presence of CP partially improved the situation and the BEx was similar to the 1 hour PMI and has the lowest cell death (as imaged by active caspase-3). When you look between CP and BEx, the difference is not that dramatic and makes me wonder that if we had the right CP formulation (with same glucose/lactate content), we would unlikely have a difference between CP and BEx, suggesting that perfusion with a saline solution oxygenated and with the correct amount of glucose can do as well than a more complex one.
Figure 4 show that the perfusion with BEx help to maintain astrocytes and microglial cells alive and functional (as measured by the secretion of pro-inflammatory cytokines following treatment with LPS).
Figure 5 show that there are some functional neurons present in BEx, capable to show electrophysiological activity. Small activity (not enough to be detected by EEG) but measurable by patch-clamp analysis.
Overall, it is a nice paper, considering it got published in Nature. There are some interesting stuff, but there are also some questionable limitations and caveats that I would have pointed as a reviewer and expected reviewers from Nature to have pointed it before letting it accepted. It shows that no matter what, never blindly trust a paper even if published in Nature.
The idea is very interesting and can help us better understand the post-mortem brain. It also raises the importance of CPR or any procedure aimed to keep a steady flow in the brain after injury or cardiac arrest and maybe worth considering it.

Categories
Junk Sciences Neurosciences Stroke Uncategorized

[Stroke/Junk Sciences] Does a needle can save you from a stroke injury? No! No! No!

Some of you have seen this video going around, claiming you can save someone suffering from stroke injury using a needle. The idea behind this video, according to HealthyChoices365, is that a Chinese “professor” claimed this will save the person’s life following a stroke.
This is kind of the thing that, as a basic scientist in the field, boils me for the last few days. First, it is plain quackery. The needle prick has nothing to do with the stroke event: it is distal from the site to have an effect. Second, using this technique on a patient has a direct impact on the patient’s stroke outcome and recovery. Let me explain why this is bullshit and should be called for what it is: A gazillion pile of bullshit that has much more weight that all the coal West Virginia has and had since the geological formation of that region (no pun intended, W. Va has one of the highest number of stroke per capita in the US, since it is Xmas season the lump of coal is simply appropriate).
In brief, stroke is the 5th cause of death in the US (3rd amongst women) and a leading cause of disability. We have two types of stroke: ischemic (85%) and hemorrhagic (15%) with the later accounting for 40% of stroke-related deaths. We estimate that about one US citizen will experience a stroke event every 5 minutes.

1. Stroke 101: Back to basics
In the ischemic stroke, we have a clot (usually formed at the carotid artery bifurcation) that is formed due to the presence of atherosclerotic plaques. These plaques can become unstable and crumble over time. These crumbles are made of clot that navigate through the carotid artery that irrigate the brain. Such clot will act as a plug or a cap, once it reaches a vessel with a diameter smaller than the clot, it will occlude it and block the blood flow.
This create what we call an ischemic situation. In such ischemic situation, the brain is deprived of both oxygen (20% of all oxygen is wired to the brain) and nutrient (in particular, glucose. The brain accounts for about 25% of the total glucose level utilization in the whole body). Neurons are the most sensible brain cells to stroke injury. They cannot adapt to hypoxia (lack of oxygen). Few minutes of hypoxia is enough to cause severe and irreversible brain damage. We estimate about 1 million neurons die every minutes that a stroke is left untreated.
Furthermore, neurons are post-mitotic cells. They cannot divide anymore. When a neuron is gone, it is gone, as well as its neuronal circuitry. You see, each minute matters because what is lost is lost.
Stroke signs can be resumed by the “FAST” acronym: Face droop, Arm weakness, Speech issues, Time to call 911. By the time you are showing signs, it has been already a couple of hours your brain has been starving off glucose and oxygen. It is important that once you have the signs to call 911 and asked the paramedics to direct you to the closest stroke center.
The most important thing to happen in stroke diagnosis is to determine which type of stroke the patient is undergoing: ischemic or hemorrhagic? These two are very different and confusing one with another can have a deadly effect. You don’t want to give a clot-buster to someone with hemorrhagic stroke because it will make the bleeding worse. You don’t want to give a clotting agent to a patient with ischemic stroke because you will increase the risk to develop a second stroke.
The current procedure is the use of endovascular intervention: the neurosurgeon insert a catheter in the femoral artery and using an angiography method to see blood vessels “live on screen” reach the site of stroke injury to either remove the clot or to put a stent in place to stop the bleeding process. From discussing with a physician, this takes about 10-15 minutes once the patient is in the OR.

2. Why this video is BS and should be called BS:
Now, lets see why I call this video BS.
First, the idea of finger prick to treat stroke is BS. We are trying to act on the stroke from a remote site. The thing is, the clotting process occurs in a very local fashion. So trying to act on a stroke with pricking a finger with a needle is mostly useless.
Second, as I said, it is important to know which type of stroke we are treating. You cannot identify which type of stroke is involved just by the clinical signs. You need imaging (CT scan or MRI) to be able to distinguish ischemic stroke from hemorrhagic stroke.
Third, this useless procedure is a formidable waste of time on the patient. As we said, each minute lost is a precious minute lost that will condition the outcome and the recovery. How long should we waste before calling 911 because we noted no improvement: 15 minutes? 30 minutes? 60 minutes? By the time the patient realized this intervention is bogus, his/her chance to survive and recover from the stroke injury are almost close to zero.

To conclude, let me finish this post with a call: PLEASE! PLEASE! PLEASE! Whenever you or a loved one is showing the FAST signs, CALL 9-1-1!!!! Know your nearest hospital with a certified Stroke Center and have the paramedics bring you there. THERE IS NO THERAPY FOR STROKE! OUR BEST BETS ARE PREVENTION (80% of stroke events can be prevented) AND INTERVENTION (by keeping the “door-to-bed” to a minimum).

Categories
Blood-Brain Barrier Sciences Stroke

[Sciences/BBB] Endothelial TLR4 and the microbiome drive cerebral cavernous malformations (Tang et al., Nature 2017)

You may have heard about this study that showed how your gut bacteria were responsible for stroke. Of course headline news always love to stretch scientific findings as much as I use to stretch my Stretch Armstrong when I was a kid. However, the paper cited was indeed published in Nature and can be found here:
https://www.nature.com/nature/journal/vaop/ncurrent/full/nature22075.html

It is a very interesting paper to read, because a lot of it sounds like a serendipity and lucky strikes. This paper investigated changes in two mouse models of cerebral cavernoma (Ccms). Ccms are a particular type of hemorrhagic stroke because they are mostly genetics (there are three Ccm genes described, in this study they focused on Krit1 and Ccm2) and most of the time go unnoticed. Mutations in those genes result in some alterations in brain microvessels, making some tiny anatomical abnormalities resulting in a higher susceptibility in some of these micro vessels to spontaneously burst and bleed.

The authors of this study have been developing Cre/Lox mice colonies for Ccm2 and Krit1 to better understand the pathology of this disease. The advantage of Cre/Lox is you can knockout a gene in a specific place at a specific time, just by injecting or providing a molecule (usually tamoxifen) that will induce it.

They have been breeding mice that were deficient in Ccm2 or Krit1 and were as expected developing brain micro bleeds (usually around their first two weeks of postnatal age). Following some changes in the animal facility, they observed that a small fraction of their mice colonies suddenly became resistant to cerebral micro bleeds: they still carried the mutations but they fail to develop these microbleeds. Therefore some non-genetic factors were influencing this resistance pattern.
Things became even more interesting as they found that among some of these resistant mice, some developed again the microbleeds within a same littler. The only difference between those developing the microbleeds and those which did not were apparently related to the intraperitoneal (i.p.) injection of tamoxifen. Have the authors provided the tamoxifen through the drinking water, that would have ended the story here.
The authors indeed found that those who reversed their phenotype from resistant to susceptible developed a bacterial infection at the site of the i.p. injection suggesting that such micro bleed was driven by some bacterial factor. They showed that similar results were obtained if they injected LPS (a common Gram-negative antigen) to these mice.

They identified two receptors known to play a role in cellular response to pathogens (we refer such signaling pathways as Pathogen Associated Molecular Patterns or PAMPs): TLR4 (toll-like receptor 4) and CD14 (TLR4 co-receptor). By knocking down these receptors in their Ccm-resistant animals, they were capable to block such bacteria-induced response. The possible interactions of Gram-negative bacteria with these two receptors at the blood-brain barrier maybe enough to trigger the cerebral micro bleeds.

What is also interesting is that mutations in these two genes (some single nucleotide polymorphism or SNP) in patients known to have an history of Ccm also resulted in a higher probability to have brain microbleeds.

I will not spoil the rest of the story but it confirms the presence of a brain-gut axis in Ccm, suggesting the possible effect of the gut microbiota as a risk factor to increased microbleeds in Ccm patients. Let it be clear, these bacteria WILL NOT induce Ccm in normal invididuals. It increase the risk of bleeds in patients already at risk of Ccm.

Another limitation is that in vitro data to confirm the presence of TLR4/CD14 at the BBB and fails to explain how these receptors are triggered by the gut microbiota. The authors suggested a bacteremia (circulating bacteria from gut to the brain via bloodstream) but I remain skeptical about it.

Nevertheless it is a very good paper that worth being read.

 

Categories
Blood-Brain Barrier Neurosciences Sciences Stroke

[Neurosciences/BBB/Stroke] Breaking The Wall: Brain pericytes impairs the BBB integrity following ischemic stroke injury. 

Interesting study, reminds me one of my earlier study. Brain pericytes are a particular cell type with a disputed origin (some think they come from neural crest, some think they come from mesoderm and some think they are mesenchymal stem-cell like cells) that play an important role in the brain and retinal vascular integrity.
Pericytes play an important function by stabilizing vessels and tightening the blood-brain barrier and the blood-retina barrier. Loss of pericytes have been associated with disruption of the retinal barrier in diabetic retinopathy whereas it was associated with leaky vessels and impaired amyloid beta clearance.
Interestingly, pericytes have been also associated with an impaired barrier recovery following stroke injury acceding to this study by Shih and colleagues (http://www.jneurosci.org/…/2016/11/14/JNEUROSCI.2891-16.2016). The mechanism of action is something known as it involves matrix metalloproteinases (MMPs). MMPs are enzymes that cleaves matrix proteins into fragments as well as tight junction proteins. The increase in MMP activity following ischemic stroke injury was known but until now it was mostly associated with astrocytes and endothelial cells. In my previous work, I have demonstrated that pericytes were deleterious to the barrier function following hypoxic stress.

Source: Rogue Cells Leave the BBB Defenseless During Stroke Trending | Labroots | Virtual Events, Webinars and Videos

Categories
Blood-Brain Barrier Neurosciences Stroke Uncategorized

[Stroke/BBB] Hyperfibrinolysis increases blood brain barrier permeability by a plasmin and bradykinin-dependent mechanism

This is an article sharing from Oscar, a follower of this page in which he has co-authored (see link to the study below). It is a peer-reviewed article recently published in Blood (a fairly good and robust journal, the official journal of the American Society of Hematology) that focused on the effect of the overexpression of tissue plasminogen activator (tPA) on the BBB integrity.
tPA is the drug of choice for ischemic stroke (80% of total stroke), as it acts as a clot buster (it basically breaks down any clots blocking small brain vessels into pieces). tPA is also until now the only FDA-approved drug. However, tPA has severe downsides. First it has a very limited time-window efficacy that places it uses only for stroke events that have initiated less than 5 hours. Usually this time period is often passed, between the onset of the stroke outcome (the FAST signs), the arrival of 911 and drive to the appropriate stroke center and the differential diagnosis between ischemic and hemorrhagic stroke. After that time-window, tPA becomes pretty useless.
The second issue with tPA is that although it may help reperfuse the ischemic brain tissue and save the neurons inside it during the first hours, it is accompanied by a risk of hemorrhagic transformation within the first 72 hours after stroke by increasing the risk of brain bleeding. Hemorrhagic stroke is even more noxious than ischemic stroke as we have several issues to deal with: a massive entrance of water and ions resulting in brain swelling but foremost the release of hemoglobin (due to the rupture of red blood cells) inside the brain. The heme inside such hemoglobin is a very reactive and aggressive chemical. It is normally inactivated as it transformed into bilirubin and excreted via the bile. But when you have an important release of heme, you have an accumulation of bilirubin (responsible of the jaundice) that has still a toxicity. Therefore, it is important to find a protection mechanism against tPA-induced hemorrhagic stroke injury.
This paper elegantly describe the effect of overexpression of tPA in mice and what does it means in terms of increased plasmin production and its mechanism on action at the BBB. It suggest that plasmin production induced by tPA induces the production of bradykinin (BK), which in turn induces the BBB disruption. Such hypothesis is further supported by the presence of some data obtained from human patients following tPA administration after ischemic stroke injury, in which the authors have measured an elevation of BK levels.
I would say the only drawback of this paper is the absence of in vitro data that directly demonstrate the direct impact of BK on the BBB function and the mechanism by which BK impact the BBB integrity (tight junctions remodeling? destruction of tight junctions by matrix metalloproteinases?).

If you are interested to learn more about this study, you can find the full-text below (behind paywall): http://www.bloodjournal.org/content/early/2016/08/16/blood-2016-03-705384

Categories
Neurosciences Pharmacology Stroke

[Stroke] Surviving stroke injury with a little help of my friends: Astrocytes provides neurons with mitochondria following stroke injury

A very nice study published by Eng Lo (Mass General Hospital), a whiz kid in the field of stroke research. It really brings in a new paradigm in terms of our understanding of stroke injury and stroke repair.
We know that astrocytes play a crucial role in helping the brain recover from stroke injury and try to rescue neurons by secreting growth factors.
But we have been failing to find methods to deliver growth factors in a non-invasive way because producing growth factors by biological engineering is very expensive but also you can only deliver them by directly injecting them in the brain with limited spread.
This very nice piece of work published in Nature and reported by Science (if Science reports on a paper published in a concurrent journal, you bet it should be that good) tells you it is surely a very elegant piece of work here. The paper indeed show that astrocytes seem to go the extra-mile and even provide mitochondria to neurons to help them cope with stroke injury.

Source: Transfer of mitochondria from astrocytes to neurons after stroke : Nature : Nature Research

Categories
Junk Sciences Neurosciences Stem Cells Stroke

[Stroke] When a Stroke Patient Gets Worse after Stem Cell Infusions A… : Neurology Today

One of biggest danger facing the stem cell field is the proliferation of “stem cell clinics” inside and outside the United States promising miracle cures for any neurological diseases. The problem with this “stem cell tourism” is not only the huge financial investment into a medical procedure that has yet to filter through scientific rigor and clinical efficacy (at this time, we are still at the stage to assess if these procedures are safe), it is also the risk of developping post-operative complications with “worst case scenarios” happening often, in particular growth of tumor. This is what happened to a stroke patient that not only did not see his stroke injury recovered but now has to fight off the grow of a tumor inside his brain.

Neurology Today discuss the case of this patient, with the intervention of different experts explaining the current state of stem cell clinical trials and the danger of stem cell tourism.

Source: When a Stroke Patient Gets Worse after Stem Cell Infusions A… : Neurology Today

Categories
Neurosciences Sciences Stem Cells Stroke Uncategorized

[Neurosciences/Stroke/Stem Cells] A cautionary tale in selling overhyped stroke stem cell therapy

Waking up this morning with a “stunning” finding about the recent publication of a study by Stanford researchers that noted the improved outcome in stroke patients following injection of stem cells have been positively headlined in the fairly serious “Washington Post” journal.
As a neuroscientist and stroke researcher, this sounds like a very good news because there are not much good news when we discuss stroke clinical trials that show something better than placebos. But also me and others like Pr. Paul Knoepfler as he rightly wrote in his blog post to not fail into overhyping and overselling a pilot study and by the way promising the moon to patients and come back to them with a disappointing news.

I thought it would be a great idea to discuss a bit more about this paper, its observations and  outcomes and current limitations.

1. What is the study that was has been cited in the Washington Post and how does it stand in terms of scientific publication?

According to the Washington Post, this study has been published in Stroke journal and authored  by Gary Steinberg, MD-PhD (Stanford University) listed as leading author. Based on the information, we are likely referring to the following article. I have attached a screenshot of the abstract page from the journal website:
Stroke
First thing, is to classify the authorship ranking. Dr. Gary Steinberg is what we refer as the primary author, usually the person that has performed most of the experiments and analyzed the data. On the other hand, we have Dr. Neil E. Schwartz as a senior author. It is usually the one that has the first thought process, planned the experimental design, wrote and finalized the manuscript and usually the one that have put the money on the table (the funding awardee) to run this study. Here, I would argue that we have a difference in what we consider as the lead author of the paper. I would consider Dr.Schwartz as the lead author due to the ranking, but thats some science bickering.
The paper got published in Stroke, that is the flagship journal of the American Stroke Association (a subdivision of the American Heart Association). Being published in a society journal is a good step but in case not enough to justify the overhyping. Why? Impact factor. Impact factor matters. Stroke, according to the American Heart Association, has an impact factor of 5.76. Thats good but a clinical paper can get better rating. For instance, Circulation (the highest-ranked AHA journal) is listed with an IF~15, whereas Nature Medicine (a mastodon for high-impact translational studies) has an IF of 27.
The paper is surely good, but does it qualify for the “stunning” adjective? Certainly not and the overselling of it is not justified by the publication metric.
Also note the title, this is a Phase I, IIa. So it means it is very a early stage of the clinical trial. Phase I in the first stage of clinical trial in which we test the safety of a novel treatment, Phase IIa is to try if there is any efficacy in a very small subset of patients (less than 50). Again, at this stage, it is a dangerous step to oversell something that yet to show efficacy with hundreds of patients.

2. What does the paper says?
The paper is behind paywall so I cannot publish any figures and text. The paper got one round of revision, as it was received in February 9, revised in April 1 and accepted in April 26. If we consider a 4-6 weeks turnover between the time you submit your draft and the editor respond to you with reviewer comments, we can speculate that the revision was minimal and quickly addressed by the author.
This study rely on using mesenchymal stem cells (MSCs) in a small cohortof patient. The study uses a particular type of MSC, the SB623 bone marrow MSC cell line.
MSCs are a particular type of stem cells. They have the least pluripotency because they have already been engaged inside a differentiation (to make it simple, they are programmed to give rise to blood cells such as white blood cells, red blood cells or platelets) and therefore have little opportunity to be re-wired to form neurons or cardiac cells. However, because they are already into a certain differentiation stage, these cells are considered as the safest for implantation. Other stem cells (such as embryonic or induced pluripotent stem cells) are nefariously known to wreck havoc if injected as undifferentiated (they cause what we call teratomas), safety of differentiated precursor cells (such as neural precursor cells) remains to be addressed. Thats also alleviate the issue encountered with previous stem cell therapy based studies that consisted as injecting a mixture of bone-marrow stem cells without knowing exactly which sub-population is carrying the protective effect. Interestingly, these MSCs carry a plasmid allowing the overexertion of a protein called Notch-1 intracellular domain (ICD). Notch-1 ICD is a fragment of the full Notch-1, that is cleaved by certain enzymes. Such ICD can therefore act as a messenger inside the cell and exert some biological activity.
The study used three doses of cells and were directly injected around the site of infarct (peri-infarct area). In stroke injury, we have the core or infarct area that is considered as the ground zero. We consider it as the necrotic area or the wasteland zone. Everything inside is dead and highly hostile for repopulation. However, the peri-infarct surrounding this zone is battling for days and weeks, torn between signals telling neurons to survive the injury from signals telling neurons to die. This fine balance is one target for therapies as we consider finding factors that can title neurons in favor of survival can help them recover and minimize the loss done by the stroke injury.
What is interesting is that these MSCs have been shown to only survive for one month. Thats a good point for the safety issue.  In this cohort of patients (18 in total), very few side effects were noted suggesting a fairly safe method for up to 12 months. However, one caveat of this study is the lack of proper control or placebo.

3. Why this study has been overhyped and oversold by the WaPo?

All patients improved over the 12 months period compared to their initial timepoint (the day after stroke injury). Furthermore, all three doses have been pooled together, so we cannot tell if there is a better recovery with a higher number of cells. This is a serious concern that has to be mentioned: we cannot tell if these patient recovered by their own or due to the treatment.
If we had a placebo group, we could have been able to compare and contrast the gain due to the stem cell treatment. We also cannot see how each individual and each group have been recovering. It would be interesting to see how age and sex (male/female) played a role in the recovery.
This is the sin of mainstream news media: they have again sinned in overselling a study that is interesting but still lacking solid evidence to sell that case. The study and approach is interesting but the version sold in the news is a  far-stretched version of where the study actual said. Selling it as “stunning” is not only wrong and inappropriate, it is also a dangerous move that will serve some for-profit stem cell clinics to make profits on patients that have been experiencing stroke and despairingly looking for a “miracle cure”.

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Neurosciences Sciences Stroke Uncategorized

[Sciences] International Stroke Conference 2016 – Day 2 & 3

As I am writing this post, the #ISC16 is slowly concluding. This is my third ISC (2011 and 2014) and I was glad to see high quality basic science build up over the years.
It was so instructive and intense in terms of science that shut my brain off by the end of the day.
The basic science was very interesting, with a presentation by Dr. James Faber (University of of North Carolina – Chapel Hill) that explored the strain differences between mice in terms of brain vascular collateral branching. The brain is mostly perfused by two main arteries: the anterior cerebral artery (ACA) and the middle cerebral artery (MCA). These are big pipes that branches out into smaller pipes to provide collateral branches, very similar to what you would expect from having faucet water pipes, all being fed by a main water pipe from the city water utility. Dr. Faber nicely described how two different mouse strains (the C57/Bl6 and Balb/c) have opposite collateral densities: one has a lot, the other has almost not. Why it matters? It matters because it can tell us how much the brain tissue is perfused and how well it can sustain ischemia. If you have an auxiliary supply, you are at better odds to cope and recover than if you are lacking it.
Dr. Faber indeed found that one single gene was dictating why these two mice stains show major differences and such differences in branching was only present in the brain but absent in the retina.
Another interesting study was published by Dr. Franklin West (University of Georgia) that have been using pigs as a model for stroke injury and even generating porcine induced pluripotent stem cells (piPSCs) to differentiate into neural stem cells. I found it was a very exciting and interesting aspect as it can help assess the relevance of iPSC-derived model of the BBB by allowing us to directly compare and benchmark iPSC-derived porcine BMECs versus primary porcine BMECs (that can be readily obtainable from pig brains harvested from slaughterhouses).
Aside from scientific presentation, there was also some exhibition mostly focused to clinicians but one key aspect was the development of stroke mobile units as displayed below:

Yep, a CT scan on wheel, specially designed for stroke emergency. As we have mentioned, time matters during stroke injury. However an  important bottleneck in the door-to-operating table is the diagnostic between ischemic and hemorrhagic stroke. On the former, you want to dissolve a clot. On the latter, you want to induce a clot to stop the hemorrhage. This can only be done by doing a CT scan. Thats takes time and by the time you arrive at the hospital and being headed to the radiology, precious minutes have been vanished.
I found that was some impressive advances in technology to have a CT scan on wheel allowing the specialized paramedics to make the diagnosis on the way to the hospital and have the patient directed straight into the operating room. In the evening, we had our poster session and it was an interesting moment to be the senior author, shadowing my student describing the poster:


One sad moment as we were un mounting the poster was to see the poster graveyard were orphaned poster are left abandoned by their owners, like pets on the roadside during holidays. Unfortunately, no poster shelters for these poor folks. I always consider that posters should be brought back to the lab to display your lab achievement and only die due to aging (outdated data).

As the conference ending up, there are some special lecture. The Willis Award was given this year to Dr. Ulrich Dinargl (Center for Stroke Research, Berlin), also co-editor of the Journal of Cerebral Blood Flow & Metabolism. Dr. Dinargl nicely advocated for preclinical models of stroke, as we learn from failures and from negative experiences. The recent move of several journals, including JCBFM, to have a “negative results” section is a welcome move than can save valuable time and money to other research groups and avoid others to engage into scientific dead-ends.

Auld Lang Syne, as the curtain drops, we are already eyeing on next year……with a much closer venue. Glad to see the next ISC being held in Houston, Texas.