New Antibody Drug Clears Brain of Amyloid Plaques and Delays Onset of Alzheimer’s Disease Symptoms in Small Clinical Trial


An experimental drug called aducanumab seem to be able to remove the toxic proteins that build up and cause the onset of Alzheimer’s disease in the brain, according to findings from a small clinical trial. Because of the small size of this trial, I must stress that these results, though potentially exciting, should also elicit some caution.

The results of this small clinical trial were reported in the journal Nature on August, 31, 2016. In this trial, aducanumab dissolved amyloid-β proteins in patients suffering from early-stage Alzheimer’s disease. This was a Phase I clinical trial, and therefore, was designed mainly to test the safety of aducanumab in human patients. Thus, the final word on whether aducanumab works to mitigate the memory losses and cognitive decline associated with Alzheimer’s disease must be subjected to clinical trials specifically designed to test such things. Two larger phase III trials are presently in progress, and are planned to be completed approximately in 2020 (note: this is an estimate).

The latest study enrolled 165 subjects who were split into different groups; subjects in one group received aducanumab and subjects in the other group were administered a placebo. In the group that received aducanumab infusions, 103 patients were given the drug once a month for up to 54 weeks. These patients experienced a reduction in the amount of tangled amyloid-β in their brains. These clinical recapitulated the results of pre-clinical experiments in laboratory mice that were actually reported in the same paper. Aducanumab seems to clear amyloid-β plaques from the brains of laboratory mice and human patients.

“This drug had a more profound effect in reversing amyloid-plaque burden than we have seen to date,” says psychiatrist Eric Reiman, who serves as executive director of the Banner Alzheimer’s Institute in Phoenix, Arizona. Reiman and his colleagues are in the process of testing other approaches for Alzheimer’s prevention and treatment. “That is a very striking and encouraging finding and a major advance.” Reiman wrote a commentary accompanying the article.

“This is the best news we’ve had in my 25 years of doing Alzheimer’s research, and it brings hope to patients and families affected by the disease,” says neurologist Stephen Salloway of Butler Hospital in Providence, Rhode Island, who is a member of the clinical team that ran the trial.

Patients in those groups that received aducanumab were divided into different subgroups that were given one of four different doses. Those patients who received the highest doses also had the highest reductions in plaques, and a group of 91 patients who had been treated for 54 weeks saw slower cognitive declines than did those who received placebo infusions.

Neuroscientists have had a long-standing and often spirited debate over the significance of the accumulation of amyloid-β in the pathology of Alzheimer’s disease. The memory loss and other symptoms of Alzheimer’s disease almost certainly result from the die-off of neurons in the brain, but do the amyloid-β plaques form as a consequence of this massive neuronal die-off or are they the cause of it? This clinical trial seems to provide good evidence for the “amyloid hypothesis,” since the elimination of amyloid-β protein seems to ameliorate the symptoms of Alzheimer’s disease.

Reiman however, cautions, wisely I think, that this trial is too small to definitively demonstrate that aducanumab actually works. Several other drugs for Alzheimer’s disease have shown promising results in the early-stage of clinical trials only to end in failure, and even in the deaths of patients.

Aducanumab led to abnormalities on brain-imaging scans in less than one-third of the patients. Researchers must closely monitor these anomalies in Alzheimer’s trials, because some participants in previous Alzheimer’s antibody trials have died as a result of brain inflammation. Fortunately, all of the reported imaging abnormalities eventually disappeared in about 4 to 12 weeks, and none of the patients who showed such abnormalities were hospitalized. Curiously, some of the patients who showed imaging anomalies continued to take the drug despite these side effects. Patients who received higher doses of the drug, or who had genetic risk factors for Alzheimer’s, were more likely to develop the brain anomalies.

Biogen, the company that makes aducanumab, has adjusted the drug’s dosage and the monitoring schedule for patients who have an increased genetic risk for Alzheimer’s in its phase 3 trials. According to Reiman, drug makers, like Biogen, must determine if a particular dosage that hits a “sweet spot” that is strong enough to work without causing potentially lethal brain inflammation.

Aducanumab is a bright spot in the field of Alzheimer’s therapeutics after years of failed antibodies and other types of drug trials. The antibody drug solanezumab failed to slow cognitive decline in two large 2013 clinical trials.  However solanezumab may have a second life and is being tested in multiple other trials, one of which includes individuals with mild Alzheimer’s disease. Results from this trial might be reported as early as the end of 2016.

Other therapeutic strategies undergoing clinical trials include strategies that target enzymes called β-secretase 1 that processes amyloid proteins, antibodies that attack the so-called the microtubule-binding tau protein, which is found in high concentrations in the neurofibrillary tangles found in the brains of many Alzheimer’s disease patients.

“The fact that we now have an antibody that gets into the brain sufficiently enough to engage its target and remove plaques is an important development, and we look forward to seeing results from this and other phase 3 trials,” Reiman says.

First Stem Cell Trial for Alzheimer’s Disease Will Enroll Patients Next Year


A research group from the University of Miami Miller School of Medicine will be conducting the first clinical trial that will test the ability of stem cells to treat Alzheimer’s disease.

According the Bernard Baumel, assistant professor of neurology at the Miller School of Medicine and the principal investigator for this phase I clinical trial, said “We believe infusions of these types of stem cells have the potential to be beneficial to individuals with Alzheimer’s disease.” Because this trial is a phase 1 clinical trial, it will test the safety of this treatment strategy.

Baumel and his colleagues plan to test the safety of mesenchymal stem cells (MSCs) as a treatment for Alzheimer’s disease.  In order to acquire high-quality MSCs for this clinical trials, Dr. Baumel is collaborating with his colleague Joshua Hare, Louis Lemberg Professor of Medicine and director of the Miller School’s Interdisciplinary Stem Cell Institute (ISCI).  Dr. Hare is an expert in the use and manipulation of MSCs who has developed a life sciences company called Longeveron that isolates, characterized and stores MSCs for clinical applications.

“Stem cells are very potent anti-inflammatories,” Dr. Baumel said. “Because the amyloid plaques found in the brains of Alzheimer’s disease patients are associated with inflammation, infusions of stem cells may help to improve or stabilize that condition. Those new brain cells may then be able to replace damaged cells in Alzheimer’s patients.”

Previous work in several different laboratories has demonstrated the anti-inflammatory capacities of MSCs (Chen PM, et al J Biomed Sci. 2011; 18:49), but other laboratories have even observed that, under certain conditions, MSCs can differentiate into brain cells (Tsz Kin Ng, et al World J Stem Cells. 2014 Apr 26; 6(2): 111–119). Therefore, MSCs potentially provide a powerful one-two punch for treating Alzheimer’s disease patients.

This clinical trial is called “Allogeneic Human Mesenchymal Stem Cell Infusion Versus Placebo in Patients with Alzheimer’s Disease,” and enrollment for this trial will begin in early 2016 and continue through to 2018. Patients enrolled in the study will have their undergo cognitive function tests before and after the treatment, quality of life assessments and brain volume measurements in order to acquire some knowledge of the potential effectiveness of this cell-based treatment strategy.

Patients with mild Alzheimer’s disease but who are otherwise healthy will be encouraged to enroll in this study.

Cord Blood Cells As a Potential Treatment for Alzheimer’s Disease


Jared Ehrhart from the University of South Florida, who also serves as the Director of Research and Development at Saneron CCEL Therapeutics Inc, and his coworkers have shown that cells from umbilical cord blood can not only improve the health of mice that have an experimental form of Alzheimer’s disease (AD), but these can also be administered intravenously, which is safer and easier than other more invasive procedures.

Laboratory mice can be engineered to harbor mutations that can cause a neurodegenerative disease that greatly resembles human AD. One such mouse is the PSAPP mouse that harbors two mutations that are known to cause an inherited, early-onset form of AD in humans. By placing both mutations in the same mouse, the animal forms the characteristic protein plaques more rapidly and shows significant AD symptoms and brain pathology.

Ehrhart used PSAPP mice to test the ability of human umbilical cord blood to ameliorate the symptoms of AD. He injected one million Human Umbilical Cord Blood Cells (HUCBCs) into the tail veins of PSAPP mice and 2.2 million into the tail veins of Sprague-Dawley rats. Then he harvested their tissues at 24 hours, 7 days, and 30 days after injection. Then Ehrhart and his team used a variety of techniques to detect the presence of the HUCBCs.

Interestingly, the HUCBCs were able to cross the blood-brain barrier and take up residence in the brain. The cells remained in the brain and survived there for up to 30 days and did not promote the growth of any tumors.

Several studies have shown that the administration of HUCBCs to mice with a laboratory form of AD can improve the cognitive abilities of those mice (see Darlington D, et al., Cell Transplant. 2015;24(11):2237-50; Banik A, et al., Behav Brain Res. 2015 Sep 15;291:46-59; Darlington D, et al., Stem Cells Dev. 2013 Feb 1;22(3):412-21). However, in such cases it is essential to establish that the administered cells actually found their way to the site of damage and exerted a regenerative response.

Even though Ehrhart and his troop found that the intravenously administered HUCBCs were widely distributed throughout the bodies of the animals, they persisted in the central nervous system for up to one month after they were injected. In the words of this publication, which appeared in Cell Transplantation, the HUCBCs were “broadly detected in both in the brain and several peripheral organs, including the liver, kidneys, and bone marrow.”. The fact that such a minimally invasive procedure like intravenous injection can effectively introduce these cells into the bodies of the PSAPP mice and still produce a significant therapeutic effect is a significant discovery.

Ehrhart and his colleagues concluded that HUCBCs might provide therapeutic effects by modulating the inflammation that tends to accompany the onset of AD. Furthermore, these cells do not need to be delivered by means of an invasive procedure like intracerebroventricular injection. Furthermore, even though HUCBCs were detected in other organs, their numbers in those places was not excessive and the ability of the HUCBCs to cross the blood-brain barrier suggests that these cells might serve as safe, effective therapeutic agents for AD patients some day.

Gene Therapy for Stroke Applied with Eye Drops


Administering growth factors to the brains of patients with neurodegenerative diseases can prevent neurons from dying and maintain the structure of their brains. For example, a recently published clinical trial by Nagahara and others from the Department of Neuroscience and the University of California, San Diego examined 10 Alzheimer’s disease (AD) patients and showed that these patients responded to Nerve Growth Factor gene therapy. When they compared treated and nontreated sides of the brain in 3 patients who underwent gene transfer, expansion of cholinergic neurons was observed on the NGF-treated side. Both neurons exhibiting the typical pathology of AD and neurons free of such pathology expressed NGF, which indicates that degenerating cells can be infected with therapeutic genes. No adverse pathological effects related to NGF were observed. In the words of this study, “These findings indicate that neurons of the degenerating brain retain the ability to respond to growth factors with axonal sprouting, cell hypertrophy, and activation of functional markers. [Neuronal s]prouting induced by NGF persists for 10 years after gene transfer. Growth factor therapy appears safe over extended periods and merits continued testing as a means of treating neurodegenerative disorders.” See JAMA Neurol. 2015 Oct 1;72(10):1139-47.

Another study that also shows that the brains of AD patients can respond to growth factors comes from a paper by Ferreira and others from the Journal of Alzheimers Disease. These authors hail from the Karolinska Institutet, Stockholm, Sweden, and they implanted encapsulated NGF-delivery systems into the brains of AD patients. Six AD patients received the treatment during twelve months. These patients were classified as responders and non-responders according to their twelve-month change in the Mini-Mental State Examination (MMSE), which is a standard. In order to set a proper standard of MMSE decline and brain atrophy in AD patients, Ferreira and other examined 131 AD patients for longitudinal changes in MMSE and brain atrophy. When these results provided a baseline, the NGF-treated were then compared with these baseline data. Those patients who did not respond to the implanted NGF showed more brain atrophy, and neuronal degeneration as evidenced by higher CSF levels of T-tau and neurofilaments than responding patients. The responders showed better clinical status and less pathological levels of cerebrospinal fluid (CSF) Aβ1-42, and less brain shrinkage and better progression in the clinical variables and CSF biomarkers. In particular, two responders showed less brain shrinkage than what was normally experienced in the baseline data. From these experiments, Ferreira and others concluded that encapsulated biodelivery of NGF might have the potential to become a new treatment strategy for AD.

Now new, even simpler treatment strategy has been developed by a research team funded by the National Institute of Biomedical Imaging and Bioengineering for delivering gene therapy to the brains of AD patients. This team invented an eye drop cocktail that can deliver the gene for a growth factor called granulocyte colony stimulating factor (G-CSF) to the brain. They have tested these eye drops on mice with stroke-like injuries.

When treated with these eye drops, the mice experienced a significant reduction in shrinkage of the brain, neurological defects, and death. Ingeniously, this research group also devised a way to use Magnetic Imaging Systems to monitor how well the gene delivery worked. This one-two punch of an inexpensive and noninvasive delivery system combined with a monitoring technique that is equally noninvasive might have the ability to improve gene therapy studies in laboratory animals. Such a strategy might also be transferable to human patients. Imagine that acute brain injury might be treatable in the near future by emergency medical workers by means of eye drops that carry a therapeutic gene.

The growth factor G-CSF (granulocyte-colony stimulating factor) has more than proven itself in several animal studies. In model systems for stroke, AD, and Parkinson’s disease, G-CSF promotes neuronal survival and decreases inflammation (See McCollum M, et al., Mol Neurobiol. 2010 Jun;41(2-3):410-9; Frank T, et al., Brain. 2012 Jun;135(Pt 6):1914-25; Prakash A, Medhi B, Chopra K. Pharmacol Biochem Behav. 2013 Sep;110:46-57; Theoret JK, et al., Eur J Neurosci. 2015 Oct 16. doi: 10.1111/ejn.13105). Unfortunately, when G-CSF was when tested in a human trial in more than 400 stroke patients, it failed to improve neurological outcomes in stroke patients. Therefore, it is fair to say that the excitement this growth factor once generated is not what is used to be. A caveat with this clinical trial, however, is that G-CSF expression in the brains of these patients might have been rather poor in comparison to the expression achieved in mice. To properly establish the efficacy or lack of efficacy of gene therapies in human patients, scientists MUST convincingly determine that the gene is expressed in the target tissue of test subjects. This has been a perennial problem that has dogged many gene therapy trials.

Philip K. Liu, Ph.D., of the Martinos Center for Biomedical Imaging at Harvard Medical School, and his collaborators, H. Prentice and J. Wu of Florida Atlantic University, developed the novel MRI-based techniques for monitoring G-CSF treatment and the eye drop-based delivery system as well. MRI can efficiently confirm successful administration and expression of G-CSF in the brain after gene therapy delivery. This work was published in the July issue of the journal Gene Therapy.

“This new, rapid, non-invasive administration and evaluation of gene therapy has the potential to be successfully translated to humans,” says Richard Conroy, Ph.D., Director of the NIBIB Division of Applied Science and Technology. “The use of MRI to specifically image and verify gene expression, now gives us a clearer picture of how effective the gene therapy is. The dramatic reduction in brain atrophy in mice, if verified in humans, could lead to highly effective emergency treatments for stroke and other diseases that often cause brain damage such as heart attack.”

Liu’s motivation for this project was to develop a gene delivery method that was simple, and could rapidly and effectively deliver the genes to the brain. A simple gene delivery technique would obviate the need for highly trained staff and expensive, sophisticated equipment. They also sought to successfully demonstrate the efficacy of their technology in laboratory animals so that it could be translated to humans.

To test their system, they deprived mice of blood flow to their brains, and then administered a genetically-engineered adenovirus that had the G-CSF gene inserted into its genome. This particular adenovirus is known to be quite safe in humans and can also efficiently infect brain cells. The adenovirus was also safely and effectively administered through eye drops. The simplicity of the eye drops means that it is easy to give multiple gene therapy treatments. By delivering the G-CSF gene at multiple time points after the induced blockage, Liu and others found that the treated mice showed significant reductions in deaths, brain atrophy, and neurological deficits as measured by behavioral testing of these mice.

MRI examinations also confirmed that G-CSF was expressed in treated mouse brains. Liu and his group used an MRI contrast agent tethered to a segment of DNA that targets the G-CSF gene. This inventive strategy enabled MRI imaging of G-CSF gene expression in mouse brains. The brains of mice treated with the recombinant adenovirus showed significant expression of the G-CSF gene. Control mice treated with the same adenovirus carrying the contrast agent bound to a different piece of DNA produced no MRI signal in the brain.

Control mice that did not receive G-CSF in eye drops, MRI scan identified areas of the brain with reduced metabolic activity and shrinkage as a result of the stroke. Mice treated with the G-CSF gene therapy, however, kept their usual levels of metabolic activity and did not have any evidence of brain atrophy. On average, after a stroke, mouse brain striatum size decreased more than 3-fold, from 15 square millimeters in normal mice to less than 5 square millimeters. But in contrast, G-CSF-treated mice retained an average striatum volume of more than 13 square millimeters, which is close to normal brain volume.

“We are very excited about the potential of this system for eventual use in the clinic,” says Liu, “The eye drop administration allows us to do additional treatments with ease when necessary. The MRI allows us to track gene expression and treatment success over time. The fact that both methods are non-invasive increases the ability to develop, and successfully test gene therapy treatments in humans.”

Liu and his collaborators are now jumping through the multitudes of hoops to take this work to a clinical trial. They are trying to secure FDA approval for the use of the G-CSF gene therapy in human patients. Finally, they also need to invite collaborating with physicians to develop their clinical trial protocol.

Abnormal Lipid Metabolism Suppresses Adult Neural Stem Cell Proliferation in an Animal Model of Alzheimer’s Disease


The brain is deeply dependent on lipid (fatty molecule) metabolism for proper development and function. Could abnormal lipid metabolism affect the brain’s stem cell population? Oh yes.

Karl J.L. Fernandez and his coworkers from the Research Center of the University of Montreal Hospital in Montreal, Canada and other collaborators has shown that neural stem cell populations in the brain can be compromised by abnormal lipid metabolism and that such abnormalities are characteristic of Alzheimer’s disease.

3xTg-AD mice form plaques in their brains that are similar to those in the brains of Alzheimer’s disease patients. Fernandez and his colleagues discovered that 3xTg-AD mice accumulate lipids within ependymal cells, which line the ventricles of the brain and serve as the main support cell of the forebrain Neural Stem Cells (NSCs). Interestingly, brains from Alzheimer’s disease patients, when examined after death also showed the accumulation of lipids within the same cell population.

Fernandes_graphicalabstact

When these lipids were examined further, it was clear that they were oleic acid-enriched fats (oleic acid is found in olive oil). In fact, injecting oleic acid into this area of the brain could recapitulate this pathology. When Fernandez and others inhibited oleic acid synthesis, they were able to fix the stem cell issues in the 3xTg-AD mice.

This fascinating study shows that the pathology in Alzheimer’s disease might be caused by perturbation of fatty acid metabolism in the stem cell niche that suppresses the regenerative functions of NSCs. Preventing accumulation of these fats in the cells surrounding the NSC population can potentially fix the stem cell abnormalities in patients with Alzheimer’s disease.

This study was published in the journal Cell Stem Cell.

Society for Neuroscience Conference 2014 Continued


Let me emphasize that the huge number of posters and talks at the SfN conference made it impossible to attend all of them, so my recollections here are some of the high points that I was able to take in. There is a lot of terrific science going on out there and these conferences are windows into it.

One poster described a feeding study in rats. One group of rats received a diet rich in omega-3 fatty acids, which are found in fish oils and soy. Another group was fed a standard laboratory diet that tends to skim on the omega-3 fatty acids. In the brains of the omega-3-fed rats, the expression off the gene that encodes Brain Derived Neurotropic Factor or BDNF increased significantly.

This is significant because BDNF promotes the survival of nerve cells (neurons) by playing a role in the growth, maturation (differentiation), and maintenance of these cells. In the brain, BDNF protein is active at the connections between nerve cells (synapses), where cell-to-cell communication occurs. The synapses can change and adapt over time in response to experience, a characteristic called synaptic plasticity, and BDNF regulates synaptic plasticity, which is important for learning and memory.

When these researchers examined why the BDNF gene was unregulated in rats fed the omega-3-rich diet, they discovered that the starting point of the gene, which is called the promoter was nice and clear. In the standard diet rats, the promoter of the BDNF gene was chemically modified with methyl (-CH3) groups. In the absence of the methyl groups, the transcription factor CTCF was able to bind and increase the rate of transcription. If the promoter was chemically modified with methyl groups, then a protein called MeCP2 bound to the promoter and prevented expression of BDNF.

This group looked further and discovered that the omega-3-rich diet seemed to influence the expression of BDNF by means of the balance of reduced and oxidized versions of electron carriers in cells, in particular, the ratio of NAD+ to NADH. NAD is a major electron carrier in cells and the ratio of NAD+, the oxidized version of this molecule, to the reduced version of this molecule, NADH, is a measure of the energy charge of the cell and how well-fed the individual is. More importantly, NAD is a substrate for another regulator of gene expression called Sirtuins.

Sirtuins are protein deacetylases, but they are unusual deacetylases since many of them they do not simply hydrolyze acetyl-lysine residues. Instead they couple lysine deacetylation to NAD hydrolysis. This hydrolysis produces O-acetyl-ADP-ribose, which is the deacetylated substrate and nicotinamide, which is an inhibitor of sirtuin activity. The dependence of sirtuins on NAD links their enzymatic activity directly to the energy status of the cell via the cellular NAD:NADH ratio.

The fact that a diet high in omega-3 fatty acids affects the NAD/NADH ratio is significant for Alzheimer’s disease because the sirtuin, SIRT1, deacetylates and coactivates the promoter for the gene that encodes the retinoic acid receptor beta gene, which subsequently upregulates the expression of alpha-secretase (ADAM10). Alpha-secretase is able to suppress beta-amyloid production. ADAM10 activation by SIRT1 also induces the Notch signaling pathway, which is known to repair neuronal damage in the brain. All of this begins with a dietary factor that actually protects the brain from Alzheimer’s disease by profound changes in gene expression.

Another poster from an Italian group used the 5XFAD mouse model of Alzheimer’s disease to test a growth factor called “painless Nerve Growth Factor” on mice with protein plaque formation in their brains. The growth factor was given by placing droplets of the growth factor in the noses of the mice while they were anesthetized. The results were stunning. Normally, 5XFAD mice get plaques quickly in their brains and lots of them. However, the growth factor was able to rescue the onset of behavioral deficits and reduces, although not eliminate, plaque formation. Other brain-specific pathologies found in these mice were reduced, such as astrocytosis. The wandering white cells in the brain known as microglia did a better job of gobbling up protein aggregates and clearing them from the brain, and the markers of inflammation were significantly reduced. I asked the investigator if there were plans to try to move this to clinical trials, and she said that she was unable to do so because of a lack of funding. Maybe someone will collaborate with this dear lady to make it so?

In another poster, the overexpression of an enzyme called heparanase in the brain decreased the burden of protein aggregates in the brains of mice with Alzheimer’s disease. I was not able to get into the details of this poster because of time.

In another poster, a very energetic young man told me about his very interesting work with a Parkinson’s disease model in rodents. If mice are administered a drug called MPTP (short for 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), the dopamine-using neurons in the brain will specifically take up this drug in high concentrations and it will kill them. Therefore, this drug is an excellent model system to study Parkinson’s disease in mice.

Prokineticin-2 is a gene that is expressed in high quantities in the surviving dopamine-using neurons that came from the brains of Parkinson’s disease patients after their deaths. When Prokineticin-2 was overexpressed in cultured dopaminergic neurons, they unregulated a protein called Bcl-2. Bcl-2 is one of the group of proteins can protect cells from dying. Therefore, Prokineticin-2 is a prosurvival protein.

Next, this chap switched from a culture system to a “in a living animal” system or an in vivo system. By using genetically engineered viruses that overexpressed Prokineticin-2 in the brains of mice, he discovered that this viruses did not adversely affect the mice and he did in fact achieve high levels of Prokineticin-2 in the brains of mice with this recombinant viruses. The overexpression did not affect the mice in the least. When he did the same experiment with MPTP-treated mice – oh, just to be clear, he overexpressed Prokineticin-2 first and then administered the MPTP because it takes about 30 days for the viruses to properly upregulate Prokineticin-2 – he saw decreased inflammation in the brain, and increase in Bcl-2 and Pink1 expression in the brain (both of these genes are pro-survival genes), and the behavioral problems of the mice never emerged with the severity of the MPTP mice. When he examined TH – an enzyme that makes the neurotransmitter dopamine, he saw that levels of this enzyme were up too. This means that the dopamine-using neurons were surviving. Is this cool stuff or what?

That’s enough for now. More later.

Fat-Based Stem Cells Support New Brain Cell Growth in Alzheimer’s Disease Mice


Alzheimer’s disease (AD) causes progressive death of brain cells and dementia. The loss of memory, coordination, and eventually motor function is relentless and horrific, and causes extensive suffering, financial pressures and loss. Stem cell treatments have been proposed as a treatment for AD, but such treatments have met resistance because of the complex pathology of AD. Introducing new neurons into the brain will do little good if cells are normally dying. However, some work with laboratory animals has suggested that stem cell treatments can benefit animals with conditions that approximately AD (see Kim S, et al., PLoS One. 2012;7(9):e45757; Bae JS, et al., Curr Alzheimer Res. 2013 Jun;10(5):524-31). However there are few studies that examine the therapeutic effect of mesenchymal stem cells from fat tissue or “adipose-derived stem cells” on mice with AD, and the effect of these cells on the oxidative injury that tends to accompany AD, and if these stem cells stimulate the generation of new neurons in the brains of AD mice.

Now we have evidence that transplantation of mesenchymal stem cells can stimulate for formation of new brain cells in adult rat or mouse models of AD and improve tissue structure and function after a stroke. Dr. Yufang Yan and her team from the School of Life Sciences at Tsinghua University, China transplanted adipose-derived stromal cells (ADSCs) into a part of the brain known as the hippocampus of mice that express the APP/PS1 transgene. Such mice show an AD-like disease, with memory loss and amyloid plaques that form in the brain.

Transplantation of ADSCs in these AD model mice decreased oxidative stress and promoted the growth of new neurons and glial cells in the subgranular and subventricular zones of the hippocampus, and, consequently improved the cognitive impairment in APP/PS1 transgenic AD mice.

These findings were published in Neural Regeneration Research (Vol. 9, No. 8, 2014), and provide theoretical and experimental evidence that ADSCs can be used to treat AD patients.

Genetically Modified As a Potential Treatment of Alzheimer’s Disease


A neurobiology team from UC Irvine (full disclosure, my alma mater) has used genetically engineered neural stem cells to treat mice with a form of Alzheimer’s disease (AD). Such implanted neural stem cells ameliorated some of the symptoms and pathological consequences of this disease in affected mice.

Patients with AD show accumulation of the protein amyloid-beta in their brains. These amyloid-beta clusters form clear plaques in the brain that are also quite toxic to nearby neurons.

Amyloid beta plaques can be cleared with the protein in them is degraded. Fortunately, the enzyme neprilysin can degrade these plaques, but the brains of AD patients show low levels of this enzyme. Neprilysin levels decrease with age and this is probably one of the reasons AD tends to be a disease of the aged.

The UC Irvine group, under the direction of Mathew Blurton-Jones, tried to deliver neprilysin to the brains of afflicted mice and used neural stem cells to do it. The goal of this work was to determine if increased degradation of the amyloid plaques abated the pathological effects of AD.

In this work, two different AD model systems were used. Thy1-APP and 3xTg-AD mice both exhibit many of the pathological effects of AD, and both were used in this study. Neural stem cells were transfected in express 25 times more neprilysin that normal. Then these genetically modified neural stem cells were transplanted into two areas of the brain known to be affected by AD: the hippocampus and the subiculum, which lies just below the hippocampus. Other AD mice were transplanted with neural stem cells that had not been transformed with neprilysin.

Post-mortem examination of both groups of mice even up to three months after transfection of the neural stem cells showed that those mice that received injections of neprilysin-expressing neural stem cells had significant reductions in amyloid-beta plaques within their brains compared to control mice. The neprilysin-expressing cells even seemed to promote the growth of neurons and the establishment of connections between them.

A truly remarkable finding of this work was that numbers of amyloid-beta plaques were also reduced in area of the brain that were some distance from the areas where the stem cells were injected. This suggests that the injected stem cells migrates across the brain, reducing plaque formation as they went.

Future experiments will seek to see if the reduction in amyloid-beta plaques also leads to improvements in cognition. Also, before this protocol can make its transition from animal models of human trials, the UC Irvine group will need to determine if the neprilysin also degrades soluble forms of amyloid-beta.

Every AD mouse model varies as to the types of pathologies observed in the brains of the affected mice. For this reason, this group tested their treatment strategy in two distinct AD mouse models, and in both cases, the neprilysin-expressing neural stem cells reduced the incidence of amyloid beta plaques. This strengthens the conclusion and neprilysin-expressing neural stem cells can indeed degrade amyloid-beta plaques.

More work needs to be done before this work can be used to support a human trial, but this is certainly an encouraging start to something great.

Brain Cell Regeneration Might Improve Alzheimer’s Disease Symptoms


Adi Shruster and Daniel Offen from Tel Aviv University in Israel have shown in a rodent model of Alzheimer’s disease (AD) that stimulating brain cell regeneration can alleviate some of the symptoms of AD.

A particular mouse strain called 3xTgAD serves as a model system for the study of AD. These mice have several genetic modifications that cause the formation of senile plaques in the brain that also lead to behavioral abnormalities and cognitive decline. In short, the Presenilin gene, which plays a definitive role in the onset of AD, has a mutation engineered in it. This particular mutation (M146V) shows a very strong causative link to inherited forms of AD (MA Riudavets, et al., Brain Pathology 2013 23(5): 595–600).

APP+PS1+Notch

 

Additionally, 3xTgAD mice have a synthetic gene inserted in them that overproduces two proteins that also contribute to the onset of AD: amyloid precursor protein (APP) and another protein called tau. The combination of these three genes causes the formation of amyloid plaques and neurofibrillary tangles that are so characteristic of AD, although these plaques are not exactly the same as those observed in human AD patients (see Matthew J. Winton, et al., Journal of Neuroscience 31(21):7691–7699).

Beta_amyloid

Shruster and Offen used these 3XTgAD mice to determine if inducing new brain cells in the brain could improve their condition. Offen overexpressed a gene called Wnt3a in a part of the brain known to play a role in regulating behavior. Wnt3a is known to drive cell proliferation in this part of the brain. After driving Wnt3a expression in the brains of 3XTgAD mice, Offen subjected them to behavioral tests.

Normal mice tend to pause and assess their surroundings when they enter unfamiliar places. However, 3xTgAD mice tend to charge straight in when entering new surroundings. This lack of proper danger assessment in 3xTgAD mice disappeared when Wnt3a was expressed in their brains. Upon post-mortem examination, these mice showed the formation of new nerve cells in their brains. When new brain cell formation was abrogated with X-rays, the behavioral defect was maintained.

Offen commented: “Until 15 years ago, the common belief was that you were born with a finite number of neurons. You would lose them as you age or as a result of injury or disease.”

Human AD patients can lose their sense of space and reality and do very inappropriate things at particular times. Therefore, these mice do recapitulate particular features of the human disease.

Offen and his colleagues think that establishing the growth of new brain cells in human AD patients might alleviate some of the behavioral abnormalities. Furthermore, stem cell treatments might also have a positive role to play in the treatment of AD, although Offen will readily admit that more work must be done.

Using Human Stem Cells to Predict the Efficacy of Alzheimer’s Drugs


Scientists who work in the pharmaceutical industry have seen this time and time again: A candidate drug that works brilliantly in laboratory animals fails to work in human trials. So what’s up with this?

Now a research consortium from the University of Bonn and the biomedical company Life & Brain GmbH has shown that animal models of Alzheimer’s disease fail to recapitulate the results observed with cultured human nerve cells made from stem cells. Thus, they conclude that candidate Alzheimer’s disease drugs should be tested in human nerve cells rather than laboratory animals.

In the brains of patients with Alzheimer’s disease beta-amyloid protein deposits form that are deleterious to nerve cells. Scientists who work for drug companies are trying to find compounds that prevent the formation of these deposits. In laboratory mice that have a form of Alzheimer’s disease, over-the-counter drugs called NSAIDs (non-steroidal anti-inflammatory drugs), which include such population agents as aspirin, Tylenol, Advil, Nuprin and so on prevent the formation of beta-amyloid deposits. However in clinical trials, the NSAIDs royally flopped (see Jaturapatporn DIsaac MGMcCleery JTabet N. Cochrane Database Syst Rev. 2012 Feb 15;2:CD006378).

Professor Oliver Brüstle, the director of the Institute for Reconstructive Neurobiology at the University of Bonn and Chief Executive Officer of Life and Brain GmbH, said, “The reasons for these negative results have remained unclear for a long time.”

Jerome Mertens, a former member of Professor Brüstle’s research, and the lead author on this work, said, “Remarkably, these compounds were never tested directly on the actual target cells – the human neuron.”

The reason for this disparity is not difficult to understand because purified human neurons were very difficult to acquire. However, advances in stem cell biology have largely solved this problem, since patient-specific induced pluripotent stem cells can be grow in large numbers and differentiated into neurons in large numbers.

Using this technology, Brüstle and his collaborators from the University of Leuven in Belgium have made nerve cells from human patients. These cells were then used to test the ability of NSAIDs to prevent the formation of beta-amyloid deposits.

According to Philipp Koch, who led this study, “To predict the efficacy of Alzheimer drugs, such tests have to be performed directly on the affected human nerve cells.”

Nerve cells made from human induced pluripotent stem cells were completely resistant to NSAIDs. These drugs showed no ability to alter the biochemical mechanisms in these cells that eventually lead to the production of beta-amyloid.

Why then did they work in laboratory animals? Koch and his colleagues think that biochemical differences between laboratory mice and human cells allow the drugs to work in one but not in the other. In Koch’s words, “The results are simply not transferable.”

In the future, scientists hope to screen potential Alzheimer’s disease drugs with human cells made from the patient’s own cells.

“The development of a single drug takes an average of ten years,” said Brüstle. “By using patient-specific nerve cells as a test system, investments by pharmaceutical companies and the tedious search for urgently needed Alzheimer’s medications could be greatly streamlined.”

Understanding the Role of a Protein in Familial Alzheimer’s Disease


Lawrence Goldstein, director of the UC San Diego Stem Cell Program and a member of the Departments of Cellular and Molecular Medicine and Neurosciences, has an abiding interest in Alzheimer’s disease (AD).  To that end, he and his colleagues have used genetically engineered human induced pluripotent stem cells to determine the role a particular protein plays in the causation of familial AD.  Apparently, a simple loss-of-function model does not contribute to the inherited form of this disorder.  Goldstein hopes that his findings might be able to better explain the mechanisms behind AD and help drug makers design better drugs to treat this disease.

Familial AD is a subset of the larger group of conditions known as early-onset AD.  The vast majority of cases of AD are “sporadic” and do not have a precise known cause, even though age is a primary risk factor (an estimated 5.2 million Americans have AD).  Familial AD is causes by mutations in particular genes.  One of these genes, PS1, encodes a protein called “presenilin 1,” which acts as a protease (an enzyme that clips other proteins in half).  Presenilin 1 is the catalytic component of a protein complex called “gamma-secretase.”  Presenilin 1 forms a complex with three other proteins (Nicastrin, Aph1, Pen2) to form gamma-secretase, and this enzyme attacks specific proteins that are embedded in the cell membrane and clips them into smaller pieces.

gamma-secretase

By clipping these cell membrane proteins into smaller pieces, gamma-secretase helps the cell transport cellular material from one side of the cell membrane to the other side or form the outside of the cell to the inside.

One of the substrates of gamma-secretase is a protein called amyloid precursor protein (APP).  While the function of APP remains unknown, APP cleavage by the gamma-secretase produces small protein fragments known as amyloid beta.

A consensus among AD researchers is that the accumulation of specific forms of amyloid beta causes the formation of the amyloid plaques that kills off neurons and leads to the onset of AD.  The most abundant product of gamma-secretase cleavage of APP is a protein called “Aβ40.”  This protein is forty amino acids long and does not cause any brain damage.  However, a minority product of APP cleave by the gamma-secretase is “Aβ42,” which is 42 amino acids long and forms the amyloid plaques and neurofibillar tangles that are so characteristic of AD (see Scheuner, D., et al., Nat. Med. 2, 864–870).

According to Goldstein, most of the time, gamma-secretase clips APP without causing any problems, but some 20% of the time, the protein clips APP incorrectly and this results in the plaque-forming forms of amyloid beta.  Goldstein explained: “Our research demonstrates very precisely that mutations in PS1 double the frequency of bad cuts.”

To demonstrate this, Goldstein and his co-workers purchased human induced pluripotent stem cells and differentiated them into neurons.  These neurons contained different alleles (forms) of the PS1 gene, and some of these mutant forms of PS1 contained the types of mutations that cause familial AD.  Once PS1 allele in particular called PS1 ΔE9 increased the ratio of Aβ42 to Aβ40 dose-dependent manner.  Since the PS1 ΔE9 causes familial AD, this research elucidates precisely why it does so.

“We were able to investigate exactly how specific mutations and their frequency change the behavior of neurons.  We took finely engineered cells that we knew and understood and then looked how a single mutation causes changed in the molecular scissors and what happened next.”

Presenilin allele consequences

Goldstein further notes, “In some ways, this is a powerful technical demonstration of the promise of stem cells and genomics research in better understanding and ultimately treating AD.  We were able to identify and assign precise limits on how a mutations works in familial AD.  That’s an important step in advancing the science, in finding drugs and treatments that can slow, maybe reverse, the disease’s devastating effects.”

Why Do Some People Get Alzheimer’s Disease but Others Do Not?


Everyone has a brain that has the tools to develop Alzheimer’s disease. Why therefore do some people develop Alzheimer’s disease (AD) while others do not? An estimated five million Americans have AD – a number projected to triple by 2050– the vast majority of people do not and will not develop the devastating neurological condition. What is the difference between those whole develop AD and those who do not?

Subhojit Roy, associate professor in the Departments of Pathology and Neurosciences at the University of California, San Diego School of Medicine, asked this exact question. In a paper published in the journal Neuron, Roy and colleagues offer an explanation for this question. As it turns out, in most people there is a critical separation between a protein and an enzyme that, when combined, trigger the progressive cell degeneration and death characteristic of AD.

“It’s like physically separating gunpowder and match so that the inevitable explosion is avoided,” says principal investigator Roy, a cell biologist and neuropathologist in the Shiley-Marcos Alzheimer’s Disease Research Center at UC San Diego. “Knowing how the gunpowder and match are separated may give us new insights into possibly stopping the disease.”

Neurologists measure the severity of AD by the loss of functioning neurons. In terms of pathology, there are two tell-tale signs of AD: a) clumps of a protein called beta-amyloid “plaques” that accumulate outside neurons and, b) threads or “tangles” of ‘tau” protein found inside neurons. Most neuroscientists believe AD is caused by the accumulation of aggregates of beta-amyloid protein, which triggers a sequence of events that leads to impaired cell function and death. This so-called “amyloid cascade hypothesis” puts beta-amyloid protein at the center of AD pathology.

Creating beta-amyloid requires the convergence of a protein called amyloid precursor protein (APP) and an enzyme that cleaves APP into smaller toxic fragments called beta-secretase or BACE.

“Both of these proteins are highly expressed in the brain,” says Roy, “and if they were allowed to combine continuously, we would all have AD.”

It sounds inexorable, but it doesn’t always happen. Using cultured hippocampal neurons and tissue from human and mouse brains, Roy and Utpal Das, a postdoctoral fellow in Roy’s lab who was the first author of this paper, and other colleagues, discovered that healthy brain cells largely segregate APP and BACE-1 into distinct compartments as soon as they are manufactured, which ensures that these two proteins do not have much contact with each other.

“Nature seems to have come up with an interesting trick to separate co-conspirators,” says Roy.

What then brings APP and BACE together? Roy and his team found that those conditions that promote greater production of beta-amyloid protein also increase the convergence of APP and BACE. Specifically, an increase in neuronal electrical activity, which is known to increase the production of beta-amyloid, also increased the convergence of APP and BACE. Post-mortem examinations of AD patients have shown that the cellular locations of APP and BACE overlap, which lends credence to the pathophysiological significance of this phenomenon in human disease.

Neurons were cotransfected with APP:GFP and BACE-1:mCherry, neurons were stimulated with glycine or picrotoxin (PTX), and the colocalization of APP and BACE-1 fluorescence was analyzed (see Experimental Procedures for more details). (B) Note that stimulation with glycine greatly increased APP/BACE-1 colocalization in dendrites (overlaid images on right). (C and D) Quantification of APP/BACE-1 colocalization. Note that increases in glycine-induced APP/BACE-1 convergence can
Neurons were cotransfected with APP:GFP and BACE-1:mCherry, neurons were stimulated with glycine or
picrotoxin (PTX), and the colocalization of APP and BACE-1 fluorescence was analyzed (see Experimental Procedures for more details).
(B) Note that stimulation with glycine greatly increased APP/BACE-1 colocalization in dendrites (overlaid images on right).
(C and D) Quantification of APP/BACE-1 colocalization. Note that increases in glycine-induced APP/BACE-1 convergence can

Das says that their findings are fundamentally important because they elucidate some of the earliest molecular events triggering AD and show how a healthy brain naturally avoids them. In clinical terms, they point to a possible new avenue for ultimately treating or even preventing the disease.

“An exciting aspect is that we can perhaps screen for molecules that can physically keep APP and BACE-1 apart,” says Das. “It’s a somewhat unconventional approach.”

Brain Regeneration Promoting Compound to be Tested in Alzheimer’s Clinical Trial


A research team at the University of Southern California (USC) will be initiating a Phase 1 clinical trial to test the effectiveness of their compound “Allo,” which promotes brain cell regeneration, in Alzheimer’s patients.

This new trial is one of four that are investigating new therapeutic targets in Alzheimer’s disease. These trials will also incorporate novel approaches to participant identification and selection.

These trials were reported at the Alzheimer’s Association International Conference in Boston. According to Roberta Brinton of USC, again and Alzheimer’s disease (AD) are characterized by a decline in the ability of the body to self-renew and repair (and this includes the brain). However, the capacity for regeneration is retained, albeit at a decreased level.

Allopregnanolone (3α-hydroxy-5α-pregnan-20-one), or Allo for short, is a neurosteroid that naturally occurs in the brain. Small quantities of it can also be found in the bloodstream. Previous studies have shown that Allo can improve cognitive function in older laboratory animals and in animal models of AD (see Chen S, Wang JM, Irwin RW, Yao J, Liu L, et al. (2011) Allopregnanolone Promotes Regeneration and Reduces β-Amyloid Burden in a Preclinical Model of Alzheimer’s Disease. PLoS ONE 6(8): e2429).

Allopregnanolone
Allopregnanolone

Robert Diaz Brinton, Professor of Pharmacology and Pharmaceutical Sciences, Biomedical Engineering and Neurology at USC, reported the design of her clinical study at the Alzheimer’s Association International Conference. In this trial, participants diagnosed with mild cognitive impairment due to Alzheimer’s disease and mild Alzheimer’s disease will receive doses of Allo, administered once-per-week to establish a safe dose that is well tolerated.

Since Allo is already naturally synthesized in the brain, and reaches high levels during the third trimester of pregnancy, Brinton and her colleagues were able to circumvent the first few stages of safety testing. The secondary goals of this clinical trial include assessing potential short-term effects of Allo dosing on cognition and MRI indicators of AD. Such data will inform a Phase 2 proof of concept trial with MRI-based biomarkers of regeneration efficacy.

“Allopregnanolone is a well-characterized agent with a very promising track record of promoting neural stem cells generation and restoring cognitive function in animal models of Alzheimer’s,” said Brinton. “We consider Allopregnanolone a first class regenerative therapeutic for mild cognitive impairment and Alzheimer’s. Our hope is that, through further research, we will add Allo to the roster of Alzheimer’s treatments.”

One of the critical issues to consider in clinical trials such as this is the ongoing and relentlessly progressive burden of brain death caused AD. It is not sufficient to only generate new neurons and promote the survival of those neurons. It is also necessary to reduce the ongoing burden of the pathology of AD in order for treatments to accrue long-term benefits.

Brinton commented that “we were very encouraged to discover that Allo reduced the burden of Alzheimer’s pathology. Out findings are very exciting as they show that Allo increases the energy capacity of the brain. This is important because the generation of new neurons, new synaptic circuits and synaptic transmission all require substantial energy.”

Making New Neurons When You Need Them


Western societies are aging societies, and the incidence of dementias, Alzheimer’s disease, and other diseases of the aged are on the rise. Treatments for these conditions are largely supportive, but being able to make new neurons to replace the ones that have died is almost certainly where it’s at.

At INSERM and CEA in Marseille, France, researchers have shown that chemicals that block the activity of a growth factor called TGF-beta improves the generation of new neurons in aged mice. These findings have spurred new investigations into compounds that can enable new neuron production in order to mitigate the symptoms of neurodegenerative diseases. Such treatments could also restore the cognitive abilities of those who have suffered neuron loss as a result of radiation therapy or a stroke.

The brain forms new neurons regularly to maintain our cognitive abilities, but aging or radiation therapy to treat tumors can greatly perturb this function. Radiation therapy is the adjunctive therapy of choice for brain tumors in children and adults.

Various studies suggest that the reduction in our cache of neurons contributes to cognitive decline. For example, exposure of mice to 15 Grays of radiation is accompanied by disruption to the olfactory memory and reduction in neuron production. A similar event occurs as a result of aging, but in human patients undergoing radiation treatment, cognitive decline is accelerated and seems to result from the death of neurons.

How then, can we preserve the cache of neurons in our brains? The first step is to determine the factors responsible for the decline is neuron production. In contrast to contemporary theory, neither heavy doses of radiation nor aging causes completely destruction of the neural stem cells that can replenish neurons. Even after doses of radiation and aging, neuron stem cell activity remains highly localized in the subventricular zone (a paired brain structure located in the outer walls of the lateral ventricles), but they do not work properly.

Subventricular Zone
Subventricular Zone

Experiments at the INSERM and CEA strongly suggest that in response to aging and high doses of radiation, the brain makes high levels of a signaling molecule called TGF-beta, and this signaling molecule pushes neural stem cell populations into dormancy. This dormancy also increases the susceptibility of neural stem cells into apoptosis.

Marc-Andre Mouthon, one of the main authors of this research, explained his results in this manner: “Our study concluded that although neurogenesis is reduced in aging and after a high dose of radiation, many stem cells survive for several months, retaining their ‘stem’ characteristics.”

Part two of this project showed that blocking TGFbeta with drugs restored the production of new neurons in aging or irradiated mice.

Thus targeted therapies that block TGFbeta in the brains of older patients or cancer patients who have undergone high dose radiation for a brain tumor might reduce the impact of brain lesions caused by such events in elderly patients who show distinct signs of cognitive decline.

Engineered Neural Stem Cells Restore Cognitive Function


Age-related dementia is a common problem when we age. Neurons in the brain die and neural pathways become corrupted, and we forget things and lose the ability to perform everyday tasks. Can stem cell treatments reverse cognitive decline?

Perhaps they can.  Yun-Bae Kim and Seung U. Kim from the Chungbuk National University College of Veterinary Medicine, in Cheongju, South Korea, and the Division of Neurology at the University of British Columbia Hospital, Vancouver, BC, Canada, have published a couple of papers that use neural stem cells engineered to make the neurotransmitter acetylcholine to treat rodents that have cognitive deficiencies. The results are surprising and hopeful.

Neurotransmitters are small molecules neurons release to talk to each other. Almost a century ago, physicians noticed that patients who took a drug called scopolamine failed to remember certain event after taking the drug. scopolamine is commonly used to treat motion sickness, and if any of you have ever been on board a cruise ship and experienced sea sickness, you were probably prescribed a scopolamine patch. scopolamine works by blocking the neurotransmitter acetylcholine and the fact that scopolamine takers (mind you at much higher concentrations than those used to relieve sea sickness) had memory lapses led neurologists to postulate that acetylcholine plays a role in learning and memory.

scopolamine_molecule

The role of acetylcholine in learning and memory has led to the development of treatments for Alzheimer’s disease patients in the form of drugs that increase the effectiveness of endogenous acetylcholine by decreasing its breakdown. These drugs, donepezil (Aricept) and rivastigmine (Exelon), are inhibitors of an enzyme called acetylcholine esterase. This enzyme degrades acetylcholine, thus effectively raising the internal levels of acetylcholine and increasing its activity. These two drugs improve the memory of patients with age-related dementia or the early stages of Alzheimer’s disease (AD).

Acetylcholine
Acetylcholine

To that end, Yun-Bae Kim and Seung U. Kim and others have engineered neural stem cells to overproduce and enzyme that synthesizes acetylcholine (choline acetyltransferase). The overproduction of this enzyme by these neural stem cells causes them to overproduce acetylcholine. Implantation of these acetylcholine-overproducing neural stem cells into the brains of laboratory animals that show cognitive declines should provide an excellent indication if such an experiment is feasible in human patients.

Donepezil
Donepezil
Rivastigmine
Rivastigmine

In their first experiment, Kim’s research team fed rats a drug that kills off neurons that use acetylcholine. When given to rodents, this drug (ethylcholine mustard aziridinium ion or AF64A) produces memory problems that have some similarities to what is observed in patients with Alzheimer’s disease. Then they transplanted human neural stem cells that made overexpressed acetylcholine into the brains of these memory-challenged rats. Remarkably, the rats with the implanted neural stem cells that overexpressed acetylcholine completely recovered their learning and memory function, and had elevated levels of acetylcholine in their cerebrospinal fluid (CSF). When the brains of these animals were examined in postmortem examinations, they discovered that the human neural stem cells had migrated to various brain regions including cerebral cortex, hippocampus, striatum and septum, and differentiated into neurons and star-like support cells known as astrocytes. This study shows that brain transplantation of human NSCs that over-expressing acetylcholine improved the complex learning and memory problems in rats with a drug-induced type of Alzheimer’s disease.

In their second paper, the Kim research group did a very similar experiment, but they used a different drug to induce learning and memory problems (kainic acid). The drug was injected directly into the part of the brain known to play a role in learning and memory, the hippocampus. This procedure generated animals with profound learning and memory problems.

The engineered human neural stem cells were injected into the ventricles of the brain, and the cells not only found their way into the brain, but they migrated directly to the damaged area of the brain. The neural stem cells differentiated into neurons and astrocytes and restored, to some degree, the learning and memory defects in these animals.

Taken together, these experiments show that engineered neural stem cells can find their way to the damaged areas of the brain and reconstitute those damaged pathways, at least to some degree. Also, these new neural pathways restore at least some learning and memory defects that result from the death of the acetylcholine-using neurons. These experiments are crying out for more work and confirmation by other groups.

See Park D., et al., Cell Transplant. 2012;21(1):365-71 & Park D., et al., Exp Neurol. 2012; 234(2):521-6

Getting Neurons Made From Stem Cells to Show Activity After Transplantation


Stem cells can differentiate into neurons, but can they integrate into the wider neural network and contribute to the function of the central nervous system? The evidence for this is scant. Even though transplanted stem cells can increase the function of the nervous system or decrease or halt the deterioration of the nervous system, there is little direct evidence that neurons made from stem cells can connect and signal to other neurons.

Until now.

The laboratory of clinical neurologist Stuart Lipton at the Sanford-Burnham Medical Research Institute has used embryonic stem cells for this experiment. They differentiated these stem cells into neurons and implanted them into the brains of laboratory rodents. However, transplanting them, they also genetically engineered these neurons so that they would express genes from bacteria that encode fast-acting light-activated ion channels. These ion channels would cause the neurons to activate a nerve impulse if a light was shined on them. This provided a way to artificially activate these neurons to determine if they were connected to other neurons and integrated into the central nervous system and it neural network.

This technique is called “optogenetics,” and it is a relatively new field of molecular biology. By using genes from particular species of bacteria that encode light-activated ion channels, cells that normally do not respond to light can be engineered to respond to particular frequencies of light. The use of optogenetics in stem cells is also novel, but this increasingly powerful technology is capturing the imaginations of more and more scientists every day.

To continue with our story, what happened to the implanted stem cell-derived neurons when they were illuminated? They made nerve impulses, but ion changes were detected in neurons that were located far from the implanted neurons. The only reasonable explanation for these observations is that the implanted neurons are forming proper neural connections with other neurons and any nerve impulses established in the implanted neurons stimulate nerve impulses in connected neurons that then activate neurons in all the neural pathways connected to them.

Lipton said of his work, “We showed for the first time that embryonic stem cells that we’ve programmed to become neurons can integrate into existing brain circuits and fire patterns of electrical activity that are critical for consciousness and neural network activity.”

Even more interestingly, Lipton and his team implanted neurons into a portion of the brain known as the “hippocampus.” This structure helps to consolidate information from short-term memory to long-term memory. It also helps with spatial navigation. Since the rate at which neurons generate or “fire” nerve impulses varies from one region of the brain to another, Lipton wanted to know if his stem cell-derived neurons would fire at the same rate as those native neurons in the hippocampus of the laboratory rodent. The answer was a clear yes. The implanted neurons fired at roughly the same rate as the surrounding, endogenous hippocampal neurons. This suggests that the implanted neurons adapt and ultimately become physiologically like those neurons around them.

hippocampus

Lipton sees great potential for clinical treatments in this work: “Based on these results, we might be able to restore brain activity – and thus restore motor and cognitive function – by transplanting easily manipulated neuronal cells derived from embryonic stem cells.”

Lipton’s optimism is infectious to one extent, but I think we must temper it by realizing that Lipton shined lights on his neurons, and that this is something that we cannot do to the brains of human beings. However, if neurons that respond to other neurons can be made and implanted into the brains of Alzheimer’s disease patients, for example, then this could definitely restore cognitive ability in patients with neurodegenerative diseases.

Human Neurons Derived from Adult Brain Cells


A research group from Mainz, Germany have discovered a protocol that can reprogram a particular type of brain cell from human brains into new neurons.

Within the brain, neurons are the cells responsible for nerve impulses. Learning and memory, personality, volition and responses to stimuli are functions of neurons. When large numbers of neurons die, the patient suffers and their memory leaves them, their personality changes, or worse. Neurodegenerative diseases such as Alzheimer’s disease or Parkinson’s disease cause the death of large numbers of neurons and it is the death of neurons that is responsible for the symptoms of disease like these.

Benedikt Berninger, a faculty member of the Institute of Physiological Chemistry, at the Johannes Gutenberg University Mainz, Germany, and the senior author of this research said, “This works aims at converting cells that are present throughout the brain but themselves are not nerve cells into neurons. The ultimate goal we have in mind is that this may one day enable us to induce such conversion within the brain itself and provide a novel strategy for repairing the injured or diseased brain.”

The cells used by Berninger’s laboratory are known as “pericytes.” Pericytes are found in close association with blood vessels and are important in maintaining the blood-brain-barrier. Pericytes have also been shown to play a role in wound healing in other parts of the body.

Berninger chose pericytes for his research because he wanted to “target these cells and entice them to make nerve cells,” so that he and his research team could “take advantage of this injury response.”

When the converted neurons were subjected to further tests, they produced the normal types of electrical-chemical signals usually found in neurons, and also extended their connections to other neurons. This provided evidence that the converted cells could integrate into neural networks.

In their paper (Karow, et al., Cell Stem Cell 2012 11(4): 471), Berninger’s team write, “While much needs to be learnt (sic) about adapting a direct neuronal reprogramming strategy to meaningful repair in vivo, our data provide strong evidence for the notion that neuronal reprogramming of cells of pericytic origin within the damaged brain may become a viable approach to replace degenerated neurons.”

Fat-Derived Mesenchymal Stem Cells Prevent the Onset of Alzheimer’s Disease in Mice


According to a study by researchers at the RNL Bio Stem Cell Technology Institute and the Seoul National University in Seoul, South Korea, intravenous stem cells infusions can improve the symptoms of Alzheimer’s disease patients and might even prevent Alzheimer’s disease altogether.

Mesenchymal stem cells from human fat tissues (known as adMSCs for adipose-derived mesenchymal stem cells) can be infused into the brains of laboratory animals that have been manipulated so that they acquire a form of Alzheimer’s disease (AD). Then these cells are intravenously infused, the brains of these animals undergo some regeneration.

Researchers injected adMSCs into the tail vein of APPswe Tg2576 mutant mice. These mice express a mutant form of the APP gene that is found in Swedish people who have a very aggressive form of AD. By 11-13 months of age, these mice show a 14-fold increase in the toxic form of amyloid protein called Aß (1-42/43) over normal mice by 2-8 months of age. These elevated Aß levels cause deposition of amyloid deposits in various portions of the brain (the frontal, temporal, and entorhinal cortex (EC), hippocampus, presubiculum, subiculum, and cerebellum, for the interested).

The adMSCs circulated throughout the body and they passed through the blood-brain barrier to home to the site of injury. This is remarkable finding because it was thought that stem cells could not pass through the blood-brain barrier. The researchers labeled their cells with a fluorescent protein and the presence of fluorescence in the brain confirmed that the stem cells do enter the central nervous system.

These APPswe Tg2576 mice had adMSCs infused into them every two weeks from their 3rd month of life until their 10th month. At this time, the mice that had received the stem cell infusions showed greater abilities to remember, learn and did not show AD behavioral symptoms, whereas their control counterparts that received placebo injections had learning and memory disabilities and also showed other AD behavioral symptoms.

When the research teams asked why the infused stem cells improved the neurological characteristics of APPswe Tg2576 mice, they discovered that the stem cell-infused mice had much less inflammation in their brains and also far few inflammation-associated chemicals in their brains. IL-10, for example, is a chemical that protects neurons and quells inflammation in the brain, and IL-10 levels in the brains of stem cell-infused mice were much higher than in the control mice.

Finally, when the brains of these mice were examined at the tissue level, the result was even more astounding; the infused adMSCs prevented the formation of amyloid plaques that are so common in the brains of AD patients. In fact, amyloid protein levels were lower in stem cell-infused mice. It turns out that the adMSCs stimulate the production of a protein called neprilysin, which acts as a pair of amyloid protein scissors. Neprilysin degrades amyloid protein and prevents the formation of the large pools of toxic amyloid pools that kill neurons and tip-off a cascade of dying cells in the brain.

The therapeutic benefits of adMSCs did not stop there. They also induced surviving neurons to divide and differentiate into neurons that aid learning and memory. The chemicals secreted by the adMSCs also stabilized the specialized connections between neurons, known as synapses.

Thus fat-derived MSCs provided preventative and curative functions for AD mice, and hopefully, this pre-clinical research will lead to human clinical trials for AD patients.

StemCells, Inc. Human Neural Stem Cells Restore Memory in Models of Alzheimer’s Disease


StemCells, Inc., a Newark, California-based company has announced preclinical data that demonstrates that its proprietary human neural stem cell line restored memory and enhanced synaptic function in two animal models that are relevant to Alzheimer’s disease (AD). They presented these data at the Alzheimer’s Association International Conference 2012 in Vancouver, Canada.

In this study, neuroscientists from University of California, Irvine transplanted a neural stem cell line called HuCNS-SC, a proprietary stem cell line made by StemCells and is a purified human neural stem cell line, into a specific region of the brain, the hippocampus in laboratory animals. These injections improved the memories of two different types of laboratory animal that act as AD-significant models. The hippocampus is a portion of the brain that is critically important to the control of memory, and unfortunately, it is severely affected by AD. Specifically, hippocampal synaptic density is reduced in AD and these reductions in synaptic connections are highly correlated with memory loss. After injections of HuCNS-SCs, the animals showed increased synaptic density and improved memory after the cells had been transplanted. Importantly, these results did not require reduction in beta amyloid or tau that accumulate in the brains of patients with AD and account for the pathological hallmarks of the disease.

This research study resulted from collaboration between Frank LaFerla, Ph.D., who is the Director of the University of California, Irvine (UCI) Institute for Memory Impairments and Neurological Disorders (UCI MIND), and Chancellor’s Professor, Neurobiology and Behavior in the School of Biological Sciences at UCI, and Matthew Blurton-Jones, Ph.D., Assistant Professor, Neurobiology and Behavior at UCI.

“This is the first time human neural stem cells have been shown to have a significant effect on memory,” said Dr. LaFerla. “While AD is a diffuse disorder, the data suggest that transplanting these cells into the hippocampus might well benefit patients with Alzheimer’s. We believe the outcomes in these two animal models provide strong rationale to study this approach in the clinic and we wish to thank the California Institute of Regenerative Medicine for the support it has given this promising research.”

Stephen Huhn, M.D., FACS, FAAP, Vice President and Head of the CNS Program at StemCells Inc, added, “While reducing beta amyloid and tau burden is a major focus in AD research, our data is intriguing because we obtained improved memory without a reduction in either of these pathologies. AD is a complex and challenging disorder. The field would benefit from the pursuit of a diverse range of treatment approaches and our neural stem cells now appear to offer a unique and viable contribution in the battle against this devastating disease.”