Biotech Strategy Blog

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Posts from the ‘Parkinson’s Disease’ category

Yumanity logoWe recently wrote about Syros Pharmaceuticals, one of whose founders, Dr Rick Young is based at the Whitehead Institute of MIT in Cambridge MA.

Another biopharma start-up company being spun out from research done at the Whitehead Institute for Biomedical Research is Yumanity Therapeutics.

The company recently launched with Tony Coles as CEO and Ken Rhodes as Chief Scientific Officer. Their focus is on transforming drug discovery for neurodegenerative diseases caused by protein misfolding.

The scientific founder is Dr Susan Lindquist, who spoke with Biotech Strategy Blog about her research and the Yumanity approach to drug development.

The company is committed to “improving human conditions. That’s why we call it Yumanity. The Y is for yeast, but it really is focused on humanity,” said Lindquist.

Dr Linquist started her interview by noting that as we live longer, we are more likely to get neurodegenerative diseases, starkly noting the reality of the lack of progress in drug development in this area:

“There is really, right now, nothing that we can do about them. We just do not understand how to move the needle on these and it’s really becoming an absolute crisis and it is taking a very substantial section of our healthcare budget as it is. As we continue to make better inroads against cancer and HIV and all of the other ills of mankind, it’s just going to get worse, I think. Everybody is beginning to appreciate that there is going to be an economic disaster and that we are going to ruining the next generation in a way that, at this point, is going to be tragic.”

So what is the approach Yumanity is taking, in the hope of succeeding where others have failed?

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Drug development for neurodegenerative brain diseases such as Parkinson’s or dementia, of which Alzheimer’s is the most common form, needs to focus on patients early in the disease, not those where brain damage has already occurred.

Diagnosing and treating patients more effectively earlier will, even if you aren’t able to instigate a cure, offer the ability to modify the disease progression and slow or delay when brain damage occurs.  In the case of Alzheimer’s, once the amyloid plaques (tangles of misshapen proteins) have accumulated in nervous tissue, it has so far been impossible to untangle or remove them.

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In a letter to the science journal Nature, published online on August 21, 2011, scientists from Northwestern University in Chicago report findings that could help develop drugs for patients with Amyotrophic Lateral Sclerosis (ALS), more commonly known as Lou Gehrig’s disease.

ALS is a progressive, fatal, degenerative motor neurone disease, which results in the inability to walk, get out of bed, move arms, hands, swallow or chew. Unlike Alzheimer’s disease, cognitive functions are not usually impaired, making it a particularly nasty disease when faced with awareness of disease progression.

According to Wikipedia, ALS is one of the most common neuromuscular diseases worldwide, with 1 or 2 people in every 100,000 developing ALS each year.

One of the characteristics of ALS and other neurodegenerative disease is the accumulation of protein aggregates or inclusions. Amyloid-ß plaques and intracellular tau neurofibrillary tangles are common in Alzheimer’s disease, for example.

By contrast, in ALS, a hallmark of the disease pathology is the presence of ubiquitin-positive, protein aggregates in spinal motor neurons.

The new research from Northwestern University shows how a mutation in UBQLN2, the gene that encodes ubiquilin 2, may be the cause of ALS in some patients.

The UBQLN2 mutation results in a failure to properly encode the protein, ubiquilin 2, a member of the ubiquitin-like protein family known as ubiquilins. The result is that normal protein degradation through the ubiquilin pathway is impaired, leading to cellular deposits and abnormal protein aggregation.

How did the team at Northwestern discover this insight?

Using DNA sequencing they looked at a five-generation family with 19 affected by ALS and sought to identify the causative gene in the transmission of this disease.  They found that a mutation in UBQLN2, the gene that encodes ubiquilin 2 was the key difference in those family members with or without ALS.

They subsequently tested the hypothesis that UBQLN2 mutations were causative of ALS using clinical data from 40 individuals in 5 families with UBQLN2 mutations. Interestingly in eight patients with the UBQLN2 mutation and ALS, dementia was also present suggesting a possible link between ubquilin 2 inclusions and dementia.

The team explored this correlation by examining brain autopsy samples of 15 cases without UBQLN2 mutations, of which 5 had experienced dementia as well as ALS. They found no ubiquilin 2 pathology in the hippocampus of the 10 ALS patients without dementia, but did find it in the 5 that had experienced both ALS and dementia. They noted:

The correlation of hippocampal ubiquilin 2 pathology to dementia in ALS cases with or without UBQLN2 mutations indicates that ubiquilin 2 is widely involved in ALS-related dementia, even without UBQLN2 mutations.

They also observed that:

We did not observe obvious differences in the distributions of wild-type and mutant ubiquilin2.

The authors concluded:

These data provide robust evidence for an impairment of protein turnover in the pathogenesis of ALS and ALS/dementia, and possibly in other neurodegenerative disorders as well.

These interesting findings by the Northwestern group were reported in Nature, and while promising, must be treated with caution for several reasons:

  1. It is still early-stage preliminary research on a small group of subjects.
  2. The exact function of ubiquilin 2 is not well understood.
  3. Not all ALS patients have the UBQLN2 mutation
  4. If the UBQLN2 mutation is not present in all ALS patients, then this mutation is not the sole means by which ALS develops.
  5. UBQLN2 may not be the only mutation involved in the pathophysiology of ALS.

The data from Northwestern does, however, offer hope that in the future, gene therapy or new treatments could be developed that stop or slow disease progression. Targeting the ubquilin pathway and the UBQLN2 mutation may, for example, prevent the abnormal protein turnover and aggregation that leads to impaired signaling and loss of function seen in ALS.

Further research into pathogenic pathways could lead to new targets for drug development, not only for the treatment of ALS but also dementia, and other neurodegenerative disorders.

ResearchBlogging.orgDeng, H., Chen, W., Hong, S., Boycott, K., Gorrie, G., Siddique, N., Yang, Y., Fecto, F., Shi, Y., Zhai, H., Jiang, H., Hirano, M., Rampersaud, E., Jansen, G., Donkervoort, S., Bigio, E., Brooks, B., Ajroud, K., Sufit, R., Haines, J., Mugnaini, E., Pericak-Vance, M., & Siddique, T. (2011). Mutations in UBQLN2 cause dominant X-linked juvenile and adult-onset ALS and ALS/dementia Nature DOI: 10.1038/nature10353

Story source:  LA Times & Fierce Biotech

It’s a fact of human life that we lose physical and mental function as we get older. In the information age that we currently live in, this translates into a decline in our ability to function and perform the activities of daily living. Can we halt or delay age-related memory loss?

Min Wang and colleagues from Yale University School of Medicine in the August 11 issue of Nature, have published some elegant research that suggests we may be able to, at some point in the future.

It’s important to distinguish the cognitive loss associated with normal ageing from that associated with dementias such as Alzheimer’s disease where major changes to the brain structure and function occur. The Yale researchers accomplished this by using aged monkeys that have a highly developed prefrontal cortex (PFC), the part of the brain associated with working memory. Monkeys, unlike humans, do not develop age-related dementias!

Working memory that allows you to keep things “in mind” e.g. where you put the car keys down, relies on a network of pyramidal neurons in the dorsolateral PFC that excite each other.

The strength of this excitatory network depends on the neurochemical environment e.g. elevated cAMP signaling reduces nerve firing. Wang and colleagues reversed the age-related decline in PFC activity by restoring an optimal neurochemical environment. Through a series of experiments they found that:

The memory-related firing of aged DELAY neurons was partially restored to more youthful levels by inhibiting cAMP signalling, or by blocking HCN or KCNQ channels.

These findings reveal the cellular basis of age-related cognitive decline in dorsolateral PFC, and demonstrate that physiological integrity can be rescued by addressing the molecular needs of PFC circuits.

This research, although preliminary and based on animal models, is promising. It offers the hope that in the future we may be able to reverse or slow-down the age-related memory loss and cognitive defects we would otherwise experience.

Many biotechnology and pharmaceutical companies are focusing on Alzheimer’s disease as a target. What this research suggests is that developing therapies that may delay or slow-down age-related memory decline could also be a valid target for drug development, with a significant market opportunity.

ResearchBlogging.orgWang, M., Gamo, N., Yang, Y., Jin, L., Wang, X., Laubach, M., Mazer, J., Lee, D., & Arnsten, A. (2011). Neuronal basis of age-related working memory decline Nature, 476 (7359), 210-213 DOI: 10.1038/nature10243

Due to the pressure of other commitments, I only had the pleasure of attending the annual meeting of the Association for Research in Vision and Ophthalmology (ARVO) for two days, but one of my key take home messages from the meeting is how we can use the eye as a window into the brain.  This is particularly relevant to Alzheimer’s research.

ARVO researchers at a lunchtime workshop that I attended asked the question of what can we learn from shared disease mechanisms in age-related macular degeneration (AMD), Alzheimer’s Disease (AD) and Glaucoma to devise therapies of the future?

What I learnt in the introduction by Nicholas Bazan from LSU Health Sciences is that both AD and AMD are both multifactorial, genetically complex, progressive, late-onset neurodegenerative conditions.  Common features include:

  1. Age-related neurodegeneration
  2. Amyloid precursor protein mis-processing
  3. Non-resolving inflammatory response
  4. Selective apoptotic cell death

Researchers in the workshop presented early experimental findings.

Catherine Bowes Rickman from Duke presented data that showed anti-amyloid immunotherapy blocks retinal pigment epithelium (RPE) damage and visual function defects in an AMD-like mouse model.  Interesting questions were raised as to whether mouse Aß aggregates differently to human, so is this a good model?

Adriana Di Polo from the University of Montreal discussed Glaucoma and AD: common neurodegenerative pathways and therapeutic targets. It was interesting to note that high rates of visual abnormalities, including glaucoma, have been reported in AD patients, but causality has not been established. Neuronal loss in both glaucoma and alzheimer’s disease occurs via common cell death processes including altered metabolism of Amyloid Precursor Protein (APP) and Aß.

What Di Polo highlighted in her talk was the potential to use therapies effective in one disease to treat the other e.g. galantamine is approved for treatment of mild to moderate AD symptoms.  Because it crosses the retinal-brain barrier and has high bioavailability, she presented results using this in an animal model of glaucoma.

Her conclusion was that “therapeutic modalities that promote neuroprotection in AD may be useful in glaucoma and vice versa.”

The third speaker of this fascinating workshop was Ian Trounce from Melbourne, who challenged the Amyloid theory of AD. His hypothesis was that sAPPα may trigger oxidative stress in mitochondria and be the problem. He discussed the increasing acceptance/overlap in pathologies between Parkinson’s and AD.  He presented data that sAPPα overexpression protects retinal ganglion cells (RGC) from rotenone via PI3K-AKT activation.

Critical feedback on the three presentations was provided by Guy Eakin of the American Health Assistance Foundation (AHAF) and Imre Lengyel from UCL.

As Dr Lengyel succinctly notes in his UCL Institute of Ophthalmology bio:

“It appears that the development of age related macular degeneration (AMD) and Alzheimer’s disease (AD) share similar histopathology, vascular risk factors and genetic predisposition. In addition, the development of AMD appears to use similar or identical steps on the cellular and molecular levels to AD: vascular damage, oxidative stress, inflammation, extracellular protein and peptide degradation or deposition, and the role for lipids and trace elements (especially zinc) in the degenerative process are amongst the many common features. Furthermore, amyloid beta peptides are an integral part of drusen (the hallmark lesion in AMD) and their formation might be similar to plaque formation in AD.”

I applaud ARVO for looking at how the eye can be used as a window into the brain. It raises the intriguing prospect that research on AMD may not only help understand the cause of AD, but that the eye may serve as an experimental model for future new treatments. Collaboration between Opthalmology and Alzheimer’s researchers is something I expect and hope we will see more of.

 

This month is Parkinson’s awareness month.  Following on from my recent interview (that you can read here & here) with Dr Todd Sherer of The Michael J. Fox Foundation for Parkinson’s Research, I was interested to read about progress being made on the road to towards targeted therapies.

The April 2011 issue of Nature Chemical Biology reports the development of a selective inhibitor of leucine-rich repeat kinase 2 (LRRK2), a gene that is mutated in some patients with Parkinson’s disease.

The team of researchers from Dana-Farber Cancer Institute, Harvard Medical School, University of Dundee, Scripps Research Institute and ActivX Biosciences applied a novel, screening strategy focused on selectively inhibiting LRRK2.

The result was the identification of LRRK2-IN-1, a novel analog that inhibits both wild-type and mutant LRRK2 kinase activity. The team confirmed the activity of LRRK2-IN-1 using human lymphoblastoid cells from a Parkinson’s disease patient with the LRRK2 mutation.

Unfortunately, LRRK2-IN-1 was unable to cross the blood-brain barrier, which means that it is not suitable for Parkinson’s disease.  However, this research is progress on the road to LRRK2 inhibition and the development of a targeted therapy in the future.

Moving forwards Parkinsons’ researchers may wish to consider combining new small molecules with nanoparticles that are able to cross the blood-brain barrier; this may be the way to deliver targeted therapies to the brain.

 

ResearchBlogging.orgDeng, X., Dzamko, N., Prescott, A., Davies, P., Liu, Q., Yang, Q., Lee, J., Patricelli, M., Nomanbhoy, T., Alessi, D., & Gray, N. (2011). Characterization of a selective inhibitor of the Parkinson’s disease kinase LRRK2 Nature Chemical Biology, 7 (4), 203-205 DOI: 10.1038/nCHeMBIO.538

Biotech Strategy Blog recently had the privilege to  interview Dr Todd Sherer, Chief Program Officer of the Michael J. Fox Foundation.

In the second part of a two-part interview, Pieter Droppert asks what the future holds for Parkinson’s disease research? You can read the first part of the interview here.

Part 2:  Understanding Parkinson’s disease

Biotech Strategy Blog: Why don’t we know what the cause of Parkinson’s disease is?

Dr Sherer: What we know about the cause of Parkinson’s disease is that, in most cases, it is an interaction between genes and environment that really covers a broad definition. In the last 10 years we have made a lot of advances in knowing the genetics of Parkinson’s disease and there are at least 15 different genes that have now been linked to the cause of Parkinson’s.

There are two big challenges in trying to define the cause of Parkinson’s.

First, there’s probably more than one “cause” of Parkinson’s disease.  For example, we know in certain people if they have a specific genetic mutation, they can get Parkinson’s disease. We also know of cases where people acutely exposed to an environment toxin called MPTP got Parkinson’s disease instantly.  There is probably an array of different triggers that can ultimately lead to Parkinson’s, given that it’s a late onset chronic disease.  So it has been very hard to pinpoint one particular cause.

Second, Parkinson’s disease can have a lot of variability in individuals — some people can have early onset, some later onset.  Some have tremor as the dominant symptom, others posture and walking problems.  It is therefore possible that there could be subsets or subtypes of Parkinson’s disease. That makes it difficult when historically we have looked for a common cause for a broad array of clinical symptoms.

Biotech Strategy Blog: Where do you see the next major breakthrough coming in the next 5 to 10 years?

Dr Sherer: The understanding of the genetics of Parkinson’s will certainly form the building blocks of some future breakthroughs.  Now that we have very tangible therapeutic targets that we know can cause Parkinson’s, it makes a much more rational directed drug development program.  Before those genes were found, a lot of Parkinson’s drug development was focused on oxidative stress, inflammation or mitochondrial dysfunction, all of which contribute to Parkinson’s, but present many different targets.

We have now found a gene called LRKK2, and two to five percent of all Parkinson’s patients get the disease through a mutation in this gene. It is a protein kinase, making it a potentially very druggable target.   There is a lot of interest in these new targets for Parkinson’s that are moving through preclinical research, so I think this knowledge from the genetics is spearheading a new era in Parkinson’s research.

Biotech Strategy Blog: Do you think targeted therapies will have an impact?

Dr Sherer: The hope is that while these new therapies may be targeting genetic causes that are present in a subset of people with the disease, given common mechanisms in the cause of the disease, they may have applicability to all Parkinson’s patients. That remains to be determined, but there is some precedent that may be the case.

Biotech Strategy Blog: What role do you think biomarkers will play in the detection and treatment of Parkinson’s disease?

Dr Sherer: Biomarkers are a real focus area for the Foundation and I think they are a critical piece of the puzzle for a couple of reasons.  Parkinson’s is a difficult disease to diagnose; there is no definitive diagnostic test, so it ends up a clinical diagnosis. Getting a biomarker that could help better confirm the diagnosis would allow people to get the correct treatment earlier in their disease or at least see the correct doctor earlier in their disease.

For all the treatments we have for Parkinson’s, we don’t currently have any that is disease modifying, i.e. one that will slow, delay or reverse the underlying progression of the disease.  While people can be treated for some of the motor symptoms, the disease process continues and there is additional damage to the regions of the brain affected in the disease.  Over time the medicines no longer work because the progression has continued.  We really want a therapy that can alter that progression.

Biomarkers could help speed the development of therapies with potential to alter disease progression, because we would have a way to determine whether the treatments we are testing are actually impacting the disease course. This is something we don’t have a way to do today.  Developing biomarkers that allow us to track the disease and potentially turn back the clock on the disease by identifying people earlier in the process, are both critical pieces.

Biotech Strategy Blog: Given the challenges of getting drugs across the blood/brain barrier, does nanotechnology open up opportunities for the future?

Dr Sherer: The blood/brain barrier is critical for Parkinson’s and other neurological diseases and even within the brain targeting therapies to a particular subset of the region of the brain is also critical.  Any technology that could be used to improve that would be very important.

Biotech Strategy Blog: What take home message would you give to those involved with Parkinson’s research and those suffering from the disease?

Dr Sherer: That’s a tough one. Everyone at the Foundation comes to work every day trying to figure out how can we solve this problem of Parkinson’s disease?  How can we find the right researchers, the right projects that will allow us to move the progress forward to developing new therapies for the disease?

I would encourage researchers to reach out to us and work with us as partners in their research.  We have a lot of knowledge, access to a lot of the experts, research tools that could help accelerate their research, not only from a funding perspective, but also from a collaborative perspective.

For the patients, a similar message that we are working on this problem.  We are dedicated to it and are determined to make improvements in treatment. We want patients to be involved in this process.  The research requires all engaged people and the patients have a lot to contribute.  They live with disease, know what the biggest problems they face are.  They could participate in research to help us answer the questions we have.

It will take all interested parties working together to solve this very difficult disease.

Biotech Strategy Blog: Thank you

Further information on the research the Michael J Fox Foundation is supporting and how you can get involved can be found on the foundation’s website.

Yesterday, I posted the first part of my interview with Dr Todd Sherer, Chief Program Officer at the Michael J Fox Foundation.

Next week, I will be posting the second part of the interview that discusses the significant research the foundation is funding on biomarkers that can help the diagnosis of the disease and monitor its progression.

If you are interested in learning more about the latest developments around Parkinson’s disease biomarkers, then you may wish to consider the April 27, 2011 webinar from the American Association for the Advancement of Science (AAAS) on the “Early Detection of Parkinson’s Disease: The Challenges and Potential of New Biomarkers.”

Moderated by Dr Todd Sherer, the webinar will discuss the only FDA approved biomarker, DaTscan that provides for imaging of dopamine transporters at dopaminergic nerve terminals in the nigrostriatal pathway.  It will also discuss the Parkinson’s Progression Markers Initiative (PPMI) that the foundation is funding.

Today is the deadline to take advantage of the early bird discounts on offer for this webinar.

Biotech Strategy blog recently had the privilege to do a phone interview with Dr Todd Sherer, the Chief Program Officer of the Michael J Fox Foundation.  In this two- part interview, Pieter Droppert asks what the MJFF approach to research funding is and what the future holds for Parkinson’s disease research?

 

Part 1:  Research Funding

Research funding is key to science. Without it there would be no translational medicine that takes basic research and turns it into clinical applications that benefit humans.  One organization that is making a difference and bridging the gap between patients and research is the Michael J Fox Foundation (MJFF).

Biotech Strategy Blog: What does a Chief Program Officer do?

Dr Sherer: My role as Chief Program officer is to lead the research efforts at the Michael J Fox Foundation. My background is as a neuroscientist so I have a PhD in neuroscience, and my lab work was in Parkinson’s disease before I joined the foundation.  At the foundation we have a number of additional scientists, seven in total. They work closely with people with business backgrounds in a collaborative way.  What we are trying to do is apply business principles to scientific research.  So, select the best scientific projects and then design them in a way where there are deliverables, milestones and goal directed research with the ultimate aim to improve treatment for Parkinson’s patients.

Biotech Strategy Blog: MJFF receives 800 grant applications a year, what is your approval process, is it similar to the National Institutes of Health?

Dr Sherer: It is modeled after the NIH process with the one main difference being that our internal scientific staff has a proactive role in making the final funding decisions.  We take the peer review panel to help us evaluate, but the ultimate decision lies with our internal staff.  We do a rapid turn around of those reviews so from receiving an application to funding is usually for us 3 to 4 months total.

Biotech Strategy Blog: What business principles do you use in managing the research that you fund?

Dr Sherer: One of the main things we do with every grant we make is laying out from the beginning: what is actually the goal of that grant. This probably seems logical, but actually a lot of scientific research is very open ended – it is kind of “let me see what I discover”. But we are really trying to define from the beginning: what are we trying to accomplish? Then what we can do is set milestones along the way to that goal to make sure during the course of the project, we are making the progress we need to achieve that goal.

Biotech Strategy Blog: Are grant payments linked to performance?

Dr Sherer: The payments for the grants are all tied to the milestones, and I would say that we are realistic in that we are experienced in how research works.  This is not manufacturing, and we know that you can have the best plan, but it is all based on a hypothesis and things can come up in the course of the research. Our scientific staff here will always work closely with those grantees to make the rational adjustments in the plan based on what we are learning along the way.

Biotech Strategy Blog: In addition to the grant applications that you receive, does the Michael J Fox Foundation initiate its own projects?

Dr Sherer: Yes. We have identified specific priority topics within Parkinson’s disease, whether they be specific therapeutic targets, or something like a biomarker, where we are more proactively working with the research community to develop projects to address critical challenges in those areas.  We also do conduct some research using a virtual research model where the scientists here may outsource some work with contract research organizations.  We have been particularly doing that around research tools so that we can make those tools widely available to our researchers — things like antibodies, plasmids, vectors —  we want to quickly get these made without any licensing or intellectual property restrictions and then make them broadly available to the research community.

Biotech Strategy Blog: Why does MJFF fund research by commercial entities e.g. biotechnology & biopharmaceutical companies?

Dr Sherer: The goal of the foundation, the goal of all the research that we are supporting is to develop new therapies for Parkinson’s disease patients.  We understand that will involve all players in the research space, so it involves academic researchers.  But really to convert those discoveries into therapies for people, we want to proactively engage and interact with the biotech and biopharma community because they are the ones who in the end make the therapies for patients.  About 5 or 6 years ago we decided to more proactively outreach to the biopharma community to determine: if we provided funding, could we induce more companies to work in Parkinson’s disease or accelerate their work in Parkinson’s disease.

Biotech Strategy Blog: What types of biotech & biopharma companies do you fund?

Dr Sherer: There are some companies that have worked in related diseases, like another neurodegenerative disease, and our  funding allows them to apply that technology to Parkinson’s disease.  Another category would be a platform type of company that we have supported, where they could really go to any disease, but the Fox funding allows creates a rationale to choose Parkinson’s.  Then we have funded some companies who are interested in Parkinson’s but for budgetary reasons have made some trade-offs in the design of that study. With additional funding from the foundation they can increase the sample size, hone the end points or what have you, to really make that study more robust.  We have seen a lot more companies working in Parkinson’s as a result of this outreach.

Biotech Strategy Blog: Do you take any rights in any commercial research you fund?

Dr Sherer: In most of our projects we do not have any stipulation like that, particularly in the case where we are funding some preclinical testing. That said, in our largest, multi-million dollar grants, particularly those in late-stage clinical development, we usually have an agreement that there is a return payment after some amount of sales.  That is more the exception than the rule.

Biotech Strategy Blog: Thank you

Part 2 of this interview with Dr. Todd Sherer, Chief Program Officer of the Michael J. Fox Foundation, will provide insight on the current status of research into Parkinson’s disease, and what we can expect the future to hold?

Taxanes are a class of drug that are used in breast, lung and ovarian cancer chemotherapy to disrupt the function of microtubules that are essential to cell division. They include paclitaxel (Taxol®) and docetaxel (Taxotere®).

Paclitaxel is also used to prevent the narrowing (restenosis) that occurs with coronary artery stents that are used to open blocked coronary arteries. Drug coated stents (a.k.a. “drug-eluting stents) reduce scar tissue.

Research published in the February 18, 2011 edition of Science, by Farida Hellal and colleagues has now shown that treatment with paclitaxel reduces the scarring associated with spinal cord injury (SCI) and promotes nerve regeneration.

The paper in Science is well worth reading and takes the reader through a logical thought process as the researchers tested their hypothesis that paclitaxel might stabilize microtubules around the site of SCI.

One of the cellular events that occurs after SCI is the activation of transforming growth factor-ß signaling (TGF-ß).

Increased TGF-ß leads to fibrosis or scarring.  TGF-ß acts on Smad2 to bind to microtubules through kinesin-1.  Hellal and colleagues asked if treatment with paclitaxel would impair Smad-dependent TGF-ß signaling? The answer from their elegant series of experiments is that yes it does.

Not only that, but TGF-ß also regulates the axon growth inhibitor, chondroitin sulfate proteoglycans (CSPGs).  The researchers asked whether pacllitaxel decreased CSPGs after SCI?  They found that cultured meningeal cells and astrocytes treated with 10 nM paclitaxel showed a 35% and 32% decrease of glycosaminoglycan (GAG) levels.

The next logical question is whether the reduction of scar formation by paclitaxel results in any benefits for new nerve formation? The regeneration of dorsal root ganglions (DRG) were evaluated.  In what to me was a finding of great significance, the researchers found (references to figures omitted) that:

“Taxol-treated animals had regenerative fibers growing along the edge of the lesion cavity into the injury site and beyond. The longest axons per animal grew 1199 T 250 mm in the Taxol-treated group versus 176 T 225 mm in the vehicle-treated an- imals (n = 13 animals per group; P = 0.002; two- tailed t-test). The Taxol-treated lesion site thus becomes favorable for regeneration of growth-competent axons.”

The final part of this research asked whether treatment with paclitaxel led to any functional improvement after the test animals received a spinal cord injury? They found that those rats that received paclitaxel after injury, had greater improvement in their locomotor function.   The conclusion being that “Taxol-induced functional recovery correlates with its axon growth–inducing effect.”

The results from any animal study must be viewed with caution, since they don’t necessarily translate to humans.  However, this animal research, if supported by data from human clinical trials, suggests that treatment with taxanes may be of benefit to those with spinal cord injuries.

Given the debilitating effect of any spinal cord injury, this is an important finding.

 

ResearchBlogging.orgHellal, F., Hurtado, A., Ruschel, J., Flynn, K., Laskowski, C., Umlauf, M., Kapitein, L., Strikis, D., Lemmon, V., Bixby, J., Hoogenraad, C., & Bradke, F. (2011). Microtubule Stabilization Reduces Scarring and Causes Axon Regeneration After Spinal Cord Injury Science, 331 (6019), 928-931 DOI: 10.1126/science.1201148

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