Stem Cell Therapies for Myelin Disorders May Undergo Clinical Trials Soon


The highly-regarded journal Science has published a review article by University of Rochester Medical Center scientists Steve Goldman, M.D., Ph.D., Maiken Nedergaard, Ph.D., and Martha Windrem, Ph.D. that argues that stem cell researchers are very close to human application of stem cell therapies for a class of neurological diseases known as myelin disorders. Myelin disorders consist of a lengthy list of rather nasty diseases:

1) multiple sclerosis, which is a disease that affects the brain and spinal cord and damages the myelin sheath that surrounds and protects nerve cells. This damage slows down or blocks messages between the brain and body, which leads to the symptoms of MS, which include visual disturbances, muscle weakness, trouble with coordination and balance, sensations such as numbness, prickling, or “pins and needles,” and thinking and memory problems.

2) white matter stroke, a lack of blood flow to white matter, which is quite severe, since blood flow to the white matter far less than that of gray matter.

3) cerebral palsy, a group of disorders that involve the brain and nervous system functions, that include movement, learning, hearing, seeing, and thinking. There are several different types of cerebral palsy, including spastic, dyskinetic, ataxic, hypotonic, and mixed. Cerebral palsy is caused by injuries or abnormalities of the brain. Most of these problems occur as the baby grows in the womb, but they can happen at any time during the first 2 years of life, while the baby’s brain is still developing. In some people with cerebral palsy, parts of the brain are injured due to low levels of oxygen (hypoxia) in the area. It is not known why this occurs. Premature infants have a slightly higher risk of developing cerebral palsy. Cerebral palsy may also occur during early infancy as a result of several conditions, including: bleeding in the brain, brain infections, head injuries, infections in the mother during pregnancy, severe jaundice.

4) certain dementias, and

5) rare but fatal childhood disorders called pediatric leukodystrophies. Leukodystrophies are a varied group of diseases that primarily affect the white matter of the central nervous system (CNS). These diseases include both primary myelin disorders, axonal/neuronal degeneration and inflammatory disorders. There are two types of leukodystrophies: dysmyelinating diseases, which usually results from inherited defects in an enzyme pathway or organelle function that causes abnormal formation, destruction, or turnover of myelin, and demyelinating disorders that result in abnormal destruction of normal myelin and/or axons.

According to Goldman, “Stem cell biology has progressed in many ways over the last decade, and many potential opportunities for clinical translation have arisen. In particular, for diseases of the central nervous system, which have proven difficult to treat because of the brain’s great cellular complexity, we postulated that the simplest cell types might provide us the best opportunities for cell therapy.”

Myelin disorders share a common pathological factor and that is a cell that makes myelin, called an “oligodendrocyte.”  Oligodendrocytes arise from a cell found in the central nervous system called “glial progenitor cells (GPCs).  GPCs give rise to oligodendrocytes and “sister cells” called “astrocytes.”  Both cells serve rather critical functions in the central nervous system.

Astrocytes

Oligodendrocytes produce myelin, a fatty substance that insulates the fibrous connections between nerve cells that are responsible for transmitting signals throughout the body. When myelin-producing cells are lost or damaged in conditions such as multiple sclerosis and spinal cord injury, signals traveling between nerves are weakened or even lost.

Oligodendrocyte

Astrocytes are the unsung heroes of the central nervous system.  They were largely neglected for some time, but are now coming into their own as one of the main glial (support cells) in the brain.  Astrocytes secrete a cocktail of growth factors that keep neurons and oligodendrocytes healthy and help them properly signal to other cells.

Because they give rise to cells that are so central to the function of so many other brain cells, GPCs and their offspring represent a promising target for stem cell therapies.  An added bonus of using GPCs is that (unlike other cells in the central nervous system) they are rather homogeneous and are also don;t mind being manipulated and cultured.  Consequently, they are easy to transplant.  In fact, several animal studies have established that transplanted oligodendrocytes will disperse and repair or “remyelinate” damaged nerves.
“Glial cell dysfunction accounts for a broad spectrum of diseases, some of which – like the white matter degeneration of aging – are far more prevalent than we previously realized,” said Goldman. “Yet glial progenitor cells are relatively easy to work with, especially since we don’t have to worry about re-establishing precise point-to-point connections as we must with neurons. This gives us hope that we may begin to treat diseases of glia by direct transplantation of competent progenitor cells.”

Several key technological advances have made these recent advances in neural stem cell protocols possible.  First of all, superior imaging technologies with more advanced MRI scanners that provide sharper and more magnified images can provide more precise information about the specific damage in the central nervous system that result from myelin disorders.  Additionally, once cells are transplanted, these new scanning techniques allow scientists to more precisely trace their implanted cells and determine what those cells are doing.

Another important advance are the major obstacles that have recently been overcome in recent work.  First, there have been significant advances in the manipulation and handling of GPCs and their progeny.  Goldman’s lab  has pioneered the techniques for GPC manipulation.  He and his colleagues have determined the precise steps used in the induction of GPC differentiation into either oligodendrocytes or astrocytes.  Goldman’s lab has produced GPCs by reprogramming skin cells and he has also identified specific cell surface molecules that act as markers for GPCs.  The identification of markers is a huge advance because it allows him and his co-workers to isolate the differentiated cells away from those that might potentially cause tumors.

The Nedergaard lab has done a tremendous amount of work to understand the structure of the neural networks of the brain and their functional contributions to the brain as a whole.  Together, these two labs have developed models of normal human neural activity and brain disease that are based on laboratory animals that have been transplanted with human GPCs.  This enables the human neural cells to operated within a living brain instead of a culture dish.  Such experimental has already opened several new strategies for modeling and potentially treating human glial diseases.

The authors contend that these advances have accelerated research to the point where human clinical trials for myelin disorders will probably occur soon.  As an example, patients with multiple sclerosis would benefit from the invention of a new generation of stabilizing anti-inflammatory drugs, since multiple sclerosis results from thsensitizatione  of the immune system to the myelin sheath.  However, such drugs always have nasty side-effects.  If you do not believe me, just examine this short list of side effects for one of these drugs.  Instead MS patients would definitely benefit from a progenitor-based cell therapy that could repair the now permanent and untreatable damage to the central nervous system that results from this disease.  Also several childhood diseases of white matter are also excellent candidates for cell-based treatments.
“We have developed a tremendous amount of information about these cells and how to produce them,” said Goldman. “We understand the different cell populations, their genetic profiles, and how they behave in culture and in a variety of animal models. We also have better understanding of the disease target environments than ever before, and have the radiographic technologies to follow how patients do after transplantation. Moving into clinical trials for myelin disorders is really just a question of resources at this point.”

Induced Pluripotent Stem Cells Lead Neuroscientists to the Cause of Neuron Loss in Parkinson’s Disease


Salk Institute scientists have made induced pluripotent stem cells (iPSCs) from patients with early-onset Parkinson’s disease (PD) in order to study precisely what goes wrong in the brains of PD patients. Their findings may lead to new ways to diagnose and even treat PD.

At the Salk Institute for Biological Studies in La Jolla, CA, Juan Carlos Izpisua Belmonte and his colleagues have examined the effects of mutations in a gene that encodes the leucine-rich repeat kinase 2 (LRRK2) protein on cultured neurons. LRRK2 mutations are responsible for approximately 2% of all inherited and sporadic cases of PD in North American Caucasian populations and up to 20% of all PD cases in Ashkenazi Jewish patients and approximately 40% of all PD cases in patients of North African Berber Arab ancestry. Therefore, the LRRK2 gene product plays a central role in PD pathology.

When iPSCs derived from PD patients who carry LRRK2 mutations, they were differentiated into neurons that were cultured in the laboratory. Cultured neurons from PD patients show profound disruption of the nuclear membrane and this undoes all nuclear architecture, which leads to cell death.

According to Dr. Izpisua Belmonte, “This discovery helps explain how PD, which had traditionally been associated with loss of neurons that produce dopamine and subsequent motor impairment, could lead to locomotor dysfunction and other common non-motor manifestations, such as depression and anxiety. Similarly, current clinical trials explore the possibility of neural stem cell transplantations to compensate for dopamine deficits. Our work provides the platform for similar trials by using patient-specific corrected cells. It identifies degeneration of the nucleus as a previously unknown player in PD.”

Izpisua Belmonte and his colleagues were also able to confirm that these disruptions of the nuclear membrane also occur in brain tissue from deceased PD patients. While it is still unclear if these disruptions to the nuclear membrane are the result of PD or are a cause of PD, Izpisua Belmonte’s lab used gene replacement techniques that were initially developed and perfected in work with mouse ESCs to fix the mutation in the PD patient-derived iPSCs. When they fixed the mutation, the disruptions to the nuclear membrane failed to form. Belmonte thinks that this could open the door for drug treatments of PD patients, although he did speculate as to how a pharmacological agent might mitigate abnormal nuclear architecture.

These results underscore the power of using iPSCs to model genetic diseases. As Belmonte noted, “We can model disease using these cells in ways that are not possible using traditional research methods, such as established cell lines, primary cultures and animal models.”

Another finding that nicely comports with data from clinical observations of PD patients is the tendency for patients to become progressively worse as they age. Likewise, in their cultured neurons differentiated from that were iPSCs derived from PD patients, Belmonte and his group observed progressively greater deformities in the nuclear membranes of the cells as they aged.

“This means that, over time, the LRRK2 mutation affects the nucleus of neural stem cells, hampering [sic] both their survival and their ability to produce neurons. It is the first time to our knowledge that human neural stem cells have been shown to be affected during Parkinson’s pathology due to aberrant LRRK2. Before development of these reprogramming technologies, studies on human neural stem cells were elusive because they needed to be isolated directly from the brain,” said Belmonte.

Belmonte further opined that dysfunctional neural stem cell populations that are afflicted with LRRK2 mutations might also contribute to other health issues associated with this particular form of PD, which includes depression, anxiety, and the inability to smell.

Modeling diseases with iPSCs also has an added bonus, since this model system can effectively recapitulate the effects of aging. Since unique dysfunctions result from aging, there are very few ways to model such events. However, using cultured cells made from iPSCs can bypass this problem, since the age-related pathologies will typically show up in culture.

Protein Induction of Pluripotent Stem Cells Made More Efficient


Clinicians and stem cells scientists have been hopeful but also quite cautious about the use of induced pluripotent stem cells iPSCs in human treatments. One of the primary concerns in the use of viral vectors that insert themselves into the genome of the cells they infect. Such insertions can create activating mutations or insertional inactivation mutations that can transform cells into tumors.

However, scientists at Stanford University School of Medicine have designed a safer way to make iPSCs that is also very efficient. This method is an extension of a protocol that has already been tried; treating the cells with recombinant proteins that can pass through the cell membrane and transform the cells into iPSCs without the use of viruses. Unfortunately, this protocol has proven to be rather inefficient relative to methods that use genetically engineered viruses.

The Stanford researchers discovered that viruses were not simply burrowing into cells to deposit genes. According to John Cooke, MD, PhD, professor of medicine and associate director of the Stanford Cardiovascular Institute and senior author of this work: “It had been thought that the virus served simply as a Trojan horse to deliver the genes into the cell. Now we know that the virus causes the cell to loosen its chromatin and make the DNA available for the changes necessary for it to revert to the pluripotent state.”

The derivation of iPSCs does not require the destruction of embryos. and therefore, offer an ethical alternative to embryonic stem cells (ESCs). Instead of using embryos, iPSCs are made from adult cells that have been genetically engineered to overexpress four different genes (Oct4, Sox2, Klf4 and c-Myc). These four genes are heavily expressed in ESCs and by transiently overexpressing them in adult cells, the adult cells revert to an ESC-like state.

The derivation of iPSCs from adult cells was discovered by Shinya Yamanaka and his colleagues, and Yamanaka won the Nobel Prize for this achievement.

The research of Cooke and his colleagues, however, provides an important clue as to how this reversion to the embryonic state occurs. Cooke noted, “We found that when a cell is exposed to a pathogen, it changes to adapt or defend itself against a challenge. Part of this innate immunity includes increasing access to its DNA, which is normally tightly packaged. This allows the cell to reach into its genetic toolbox and take out what it needs to survive.”

It is this loosening of the structure of DNA in adult cells that allows the pluripotency-inducing proteins to modify the expression pattern of the cell and transform it into an ESC-like cell.

This type of response to viral infections that causes the DNA of cells to loosen up has been termed “transflammation” by Cooke and his team. They think that this finding could easily simplify and increase the efficiency of iPSC derivation.

Cooke’s laboratory initially tried to increase the efficiency of cell-permeable proteins that can reprogram adult cells into iPSCs. These proteins can bind to their target sequences on DNA and can also enter the nucleus when they pass into the cell. Why were these proteins so inefficient when compared to viral-based techniques?

To answer this question, Cooke’s lab examined the gene expression patterns of cells treated with iPSC-inducing viruses or iPSC-transforming proteins. They discovered that the gene expression patterns differed extensively. This led Cooke to hypothesize the virus itself was causing some sort of change in the adult cells that was necessary for iPSC derivation.

To test this hypothesis, they repeated the experiment with recombinant proteins but also concomitantly treated the cells with an unrelated virus. This dramatically increased the rates of pluripotency transformation. The increased rate of transformation was also linked to a signaling pathway called the toll-like receptor-3 (TLR-3) pathway.

Toll-like receptors (TLRs) have been established to play an essential role in the activation of innate immunity by recognizing specific molecular patterns normally found on microbial components. Each TLR recognizes a different set of microbial-specific molecules, and TLR-3 binds to double-stranded RNA molecules. Therefore, these cells activate those pathways that are normally turned when they are infected by viruses.

According to Cooke, “These proteins are non-integrating, and so we don’t have to worry about any viral-induced damage to the host genome.” Cooke also pointed out that cell-permeable proteins can allow the researchers to exert greater amounts of control over the reprogramming process. This, essentially could speed the use of iPSCs in human therapies. Cooke continued: “Now that we understand that the cell assumes greater plasticity when challenged by a pathogen, we can theoretically use this information to further manipulate the cells to induce direct reprogramming.”

Therefore, to sum up, the elimination of TLR3 reduces the efficiency and yield of human iPSC generation, but if TLR3 is activated, it enhances human iPSC generation by cell permeant peptides. Also, TLR3 activation enables changes to the structure of DNA (epigenetic changes), and these changes promote an open chromatin state that makes iPSC generation much more efficient.

Human Neural Stem Cell Line From StemCells Inc. Makes Myelin in Shiverer Mice


Physicians and research scientists at the Oregon Health Science University in Portland, Oregon have used banked neural stem cells to make myelin in mice that have a severe disease that prevents the synthesis and deposition of myelin around nerves. This proof-of-concept experiment shows that such a treatment strategy is feasible for human patients.

In previous posts on this blog site, I have discussed the importance of the myelin sheath that surrounds and insulates certain nerves. I will not reiterate those points here, but simply refer you to those older posts.

In humans, myelin loss is not noticed until the patient begins to show symptoms.  Myelin disorders are quite disabling and even fatal in some cases.  Such disorders include cerebral palsy in children born prematurely, multiple sclerosis, and others.

Myelin loss has also been found to play an important role in age-related senility.  Researchers at the Oregon Health and Science University Doernbecher Children’s Hospital used very advance Magnetic Resonance Imaging to study myelin (white matter) in the brains of adults of all stages.  They discovered that widespread changes in the white matter, and damage to the myelin of the brain were highly correlated with progressive senility (See Black SA, et al., “White matter lesions defined by diffusion tensor imaging in older adults.” Annals of Neurology, 2011 Volume 70, Issue 3, pages 465–476).

Stephen Back and his colleagues at OHSU examined the ability of human stem cells to make myelin and heal the sick animals.  To test this possibility, Back used a mouse called the “Shiverer immunodeficient” mouse, that develops progressive neurological damage because of its inability to make myelin.  Remember that small regions of demyelination that cover particular segments or even patches of nerves are followed by repair, regeneration, and complete recovery of neural function.  However, extensive demyelination or myelin loss is typically followed by degeneration of the axon (the extension of the neuron that conducts nerve impulses to other neurons) and also the neuron cell body.  Neuron death and axonal death are often irreversible.

The use of the Shiverer mouse presented some unique challenges.  Most neural stem cell experiments utilize newborn rather than adult mice.  Back explained:  “Typically, new-born mice have been studied by other investigators because stem cells survive very well in the newborn brain.  We, in fact, found that the stem cells preferentially matured into myelin-forming cells as opposed to other types of brain cells in both newborn mice and older mice.  The brain-derived stem cells appeared to be picking up on cues in the white matter that instructed the cells to become myelin-forming cells.”

Back collaborated with StemCells Inc., to make use of their proprietary neural stem cell line.  His initial experiments showed that implanting these neural stem cells made myelin sheaths in presymptomatic newborn animals.  However, these experiments did not indicate whether or not these stem cells would survive after transplantation into older animals that were already showing symptoms and declining in health.  Black, therefore, wanted to perform a much more difficult experiment by transplanting the neural stem cells into very sick adult animals that showed the horrific symptoms of demyelination.

MRI studies confirmed that implanted neural stem cells did in fact make new myelin within weeks after transplantation.  However, the detection of something such as myelin in mice usually requires the use of dyes of some other agent that fills the thing you want to detect in order to see it.  Many of these Shiverer animals are so sick that they cannot survive MRI experiments.  Therefore OHSU used a very sophisticated piece of equipment to solve this problem:  ultra-high field MRI scanners that could detect myelin without the use of dyes.

Back further explained:  “This is an important advance because it provides proof of principle that MRI can be used to track the transplants as myelin is being made.  We actually confirmed that the MRI signal in the white matter was coming from human myelin made by the stem cells.”

This study is in combination with a clinical study at the University of California, San Francisco that examines the use of this same neural stem cell to myelinate the nerves of children with severe demyelination diseases.  Back’s group provides the crucial pre-clinical work that serves as the foundation for this clinical study.

Back noted:  “These findings provide us with much greater confidence that going forward, a wide variety of myelin disorder might be candidate for therapy.  Of course, each condition varies in terms of severity, how fast it progresses and the degree of brain injury it causes.  This must all be taken into consideration as neurologists and stem cell biologist [sic] work to make further advances for these challenging brain disorders.”

Neural Stem Cell Found in Skeletal Muscle


Scientists at the Wake Forest School of Medicine have more fully characterized a stem cell that was isolated from muscle, but does not differentiate into muscle. Instead, this stem cells expresses several genes normally found in cells that inhabit the nervous system. These cells might serve as a source of material for the treatment of neurodegenerative diseases.

Osvaldo Delbono, professor of internal medicine at Wake Forest University and the senior author of this study said this: “Reversing brain degeneration and trauma lesions will depend on cell therapy, but we can’t harvest neural stem cells from the brain or spinal cord without harming the donor.”

Delbono continued, “Skeletal muscle tissue, which makes up 50% of the body, is easily accessible and biopsies of muscle are relatively harmless to the donor, so we think it may be an alternative source of neural-like cells that potentially could be used to treat brain or spinal cord injury, neurodegenerative disorders, brain tumors and other diseases, although more studies are needed.”

In 2011, Delbono and his colleagues isolated a stem cell from skeletal muscle that expressed several genes that you usually find in very young nervous tissue (the early neural marker Tuj1, light and heavy neurofilament for those who are interested). These cells did not express genes normally expressed in other tissues, such as smooth muscle or blood vessels.

Upon further characterization, the muscle-derived stem cells were able to respond to the neurotransmitter glutamate. This strongly intimates that these stem cells express the types of ion channels normally found in neurons. Also, these neural-like stem cells from muscle were clearly not derived from muscle satellite cells (another muscle stem cell population that produces skeletal muscle in response to muscle injury). Instead this stem cell is  interspersed in between muscle fibers. These cells were also able to proliferate and survive in culture (see Birbrair, et al., PLoS ONE 6(2): e16816. doi:10.1371/journal.pone.0016816).

In this new publication, Delbono’s group isolated muscle-specific neural stem cells from non-human primates and aging mice and injected them into the brain. The injected cells not only survived in the brain, but also migrated the those areas of the brain where neural stem cells are located.

The next issue they addressed was whether or not these stem cells will induce tumors upon injection. Neither stem cells from non-human primates nor those from aged mice produced tumors upon injection into the brain or when injected under the skin.

Alexander Birbrair, a postdoctoral student in Debono’s laboratory and the first author in this paper said, “Right now, patients with glioblastomas or other brain tumors have a very poor outcomes and relatively few treatment options.” Birbrair continued: “Because our cells survived and migrated in the brain, we may be able to use them as drug-delivery vehicles in the future, not only for brain tumors but also for other central nervous system diseases.”

Delbono’s team is also investigating whether these neural-like cells also have the capability to differentiate into functional neurons in the central nervous system.

See Alexander Birbrair, et al., Skeletal muscle neural progenitor cells exhibit properties of NG2-glia. http://dx.doi.org/10.1016/j.yexcr.2012.09.008,

One Embryo – Three Parents?


The web is alive with reports that scientists at the Oregon Health & Science University have managed to make embryos that contained genetic material from two mothers and one father. There has been a certain amount of “creepiness” applied to this experiment, but there are various reasons why this experiment was done. I will fully admit that there is a degree of creepiness to this experiment and the destruction of these embryos is also deplorable. However, this is a strategy to cure some genuinely nasty genetic diseases. Therefore, the research is not for nothing.

Deoxyribonucleic acid or DNA is the molecule all living organisms use to store genetic information, with the exception of some RNA viruses, but there is a debate as to whether or not viruses are actually alive. DNA is housed within the nucleus and is organized into linear molecules of DNA known as chromosomes.

However, there is another compartment in human cells that also houses DNA. The power-generation structure of the cell is called the mitochondrion. Mitochondria are enclosed by two membranes; and inner and outer mitochondrial membrane. There is also an internal network of membranes called cristae. Embedded in the membranes of the cristae are the components of the electron transport chain that are used for energy production.

Directly inside the mitochondrion is a soluble region known as the mitochondrial matrix. Soluble enzymes are found in the matrix as are metabolites and other small molecules. Another large molecule found in the mitochondrial matrix is the mitochondrial genome, which consists of multiple copies of small, circular molecule of DNA.

The mitochondrial genome encodes several genes necessary for the energy production machinery of the mitochondrion. The vast majority of the energy production machinery components are encoded by the nuclear genome, but the small number of mitochondrial components encoded by the mitochondrial genome are crucial for energy production.

Replication of the mitochondrial DNA is accomplished by a DNA replication system that is specific to the mitochondrion.  Unfortunately, this DNA replication system is less accurate than that used in the nucleus.  Therefore, mutations in mitochondrial DNA are relatively common.  Loss of function mutations in mitochondrial genes can compromise the ability of the mitochondrion to make chemical energy, and such mutations have dire consequences for several different organ systems.

The list of genetic diseases causes by mutations in mitochondrial DNA is long.  Here is a short list:

1.  Kearns-Sayre Syndrome – weakness or paralysis of the eye muscles, impaired eye movement and  drooping eyelids, loss of vision, abnormalities of the electrical signals that control the heartbeat, coordination and balance problems, abnormally high levels of protein in the fluid that surrounds and protects the brain and spinal cord, muscle weakness in their limbs, deafness, kidney problems, or a deterioration of cognitive functions (dementia). Affected individuals often have short stature and suffer from diabetes mellitus.

2.  Leber hereditary optic neuropathy – first sign is blurring and clouding of vision, and over time, vision worsens with a severe loss of sharpness and color vision.

3.  Leigh Syndrome – first signs are seen in infancy and are usually vomiting, diarrhea, and difficulty swallowing, eating problem, an inability to grow and gain weight at the expected rate, severe muscle and movement problems, weak muscle tone, involuntary muscle contractions, and problems with movement and balance, loss of sensation and weakness in the limbs.

4. MELAS – mitochondrial encephalomyopathy lactic acidosis, stroke-like episodes – signs and symptoms appear in childhood and may include muscle weakness and pain, recurrent headaches, loss of appetite, vomiting, and seizures. Stroke-like episodes beginning before age 40, and often involve temporary muscle weakness on one side of the body, altered consciousness, vision abnormalities, seizures, and severe headaches resembling migraines.  Strokes can progressively damage the brain, leading to vision loss, problems with movement, and a loss of intellectual function.

5.  MERRF – myoclonus epilepsy and ragged-red fibers – characterized by muscle twitches (myoclonus), weakness (myopathy), and progressive stiffness (spasticity).

6.  MILS – maternally inherited Leigh syndrome – a progressive brain disorder that usually appears in infancy or early childhood.  Affected children may experience vomiting, seizures, delayed development, muscle weakness, and problems with movement. Heart disease, kidney problems, and difficulty breathing can also occur in people with this disorder.

7.  Pearson Syndrome – a fatal disorder of infants with anemia and exocrine pancreatic insufficiency.  It is now known to be a rare, multisystemic, mitochondrial genetic disease, with anemia (low red blood cell count), neutropenia (low white blood cell count), and thrombocytopenia (low platelet count), as well as variable liver, kidney, and endocrine failure. Death usually occurs early in life.

8.  Progressive external ophthalmoplegia – Weakness of the eye muscles, drooping eyelids (ptosis), weakness or paralysis of the muscles that move the eye.  Affected individuals may also have general weakness of the skeletal muscles particularly in the neck, arms, or legs that may be especially noticeable during exercise.

9.  NARP – neuropathy, ataxia, retinitis pigmentosa – Beginning in childhood or early adulthood, numbness, tingling, or pain in the arms and legs; muscle weakness; and problems with balance and coordination; also vision loss learning disabilities, developmental delay, seizures, dementia, hearing loss, and cardiac conduction defects.

None of these diseases sounds terribly pleasant, and there are no known cures or effective treatments for them.

The severity of these diseases depends upon the proportion of the mitochondria that possess the mutated version of the mitochondrial genes.  Typically, mitochondria contain multiple copies of their genomes, and mutant versions of these genomes are mixed with normal copies.  When mitochondria divide, the copies of the genomes are randomly distributed between the two daughter mitochondria.  Therefore, some mitochondria will have mainly copies of the mutant version of the genome while others will have mainly copies of the normal version of the genome.  This condition is called heteroplasmy, and how widely these mutant versions are distributed throughout the body determines the severity of the mitochondrial genetic disease.

Mitochondria are inherited from the mother.  This is due to the fact that the egg, which is supplied by the mother, contains a large quantity of mitochondria, whereas the sperm that fertilizes the egg, only has relatively a few mitochondria.  Therefore, mitochondrial genetic diseases will only be transmitted through the mother, and if a mother is known to have a mitochondrial genetic disease, she will pass that disease onto her children, regardless of the health of the father.

This is the main reason for the technology tested in this paper: Masahito Tachibana, et al., Towards germline gene therapy of inherited mitochondrial diseases, Nature (2012) doi:10.1038/nature11647.  In this paper, scientists from the Division of Reproductive & Developmental Sciences at the Oregon National Primate Research Center in Oregon Health & Science University, used a technique that extracts the nuclear genome from the egg and transplants it into the egg of a donor, after which the egg is fertilized with normal sperm.  This technique would bypass the mitochondrial mutations in the mother’s eggs and replace that genome with a new genome that does not carry such a mutation.

The technique used in this paper is called “spindle transfer.”  This technique takes an oocyte donated by a woman who carries and suffers from a mitochondrial genetic disease and isolates and transplants the chromosomes (nuclear genetic material) from the patient’s unfertilized oocyte into the cytoplasm of another donated, enucleated egg, that contains healthy mtDNA as well as other organelles, RNA and proteins.  Such a child born a result of this spindle transfer procedure will be the genetic child of the patient but will carry healthy mitochondrial genes from the egg of the donor. Prior studies in a monkey model showed not only the feasibility of the spindle transfer (ST) procedure but also that ST is highly effective and completely compatible with normal fertilization and birth of healthy offspring (see Tachibana, M. et al. Mitochondrial gene replacement in primate offspring and embryonic stem cells. Nature 461, 367–372 (2009)).  This strategy might have an important future as a therapy to avoid transmission of serious mitochondrial diseases.

In this paper, seven volunteers (aged 21–32 years) donated a total of 106 mature eggs, and 65 eggs were used for the ST procedure and 33 served as non-manipulated controls.  Of the 64 ST eggs, 60 of them survived intracytoplasmic sperm injection (ICSI; 94%) and 44 formed showed the early signs of successful fertilization (73%).  These results were comparable to those found in the non-manipulated eggs; 32 oocytes survived ICSI (97%) and 24 (75%) formed pronuclei .  However, when these embryos were further observed, 48% (21/44) of the ST eggs were normal, but 87% of the non-manipulated embryos were normal.  Therefore, these manipulations can decrease the efficiency of fertilization.

If fertilization occurs normally, the ST embryos seem to be able to form blastocysts as well as the normal controls.  Blastocyst formation rate in the normally fertilized ST group (13/21, 62%) was statistically similar to controls (16/21, 76%).  Embryonic stem cell derivation rates were higher in the normal embryos (56%)  than in the ST group embryos (32%).

This paper uses an ingenious technique to potentially help women with a genetic disease.  That should give us some hope.  However, what I find reprehensible in this paper is the destruction of all these embryos.  These were young human lives that were snuffed out for the sake of convenience.

Wesley Smith at the Human Exceptionalism Blog has a different take on this technique.  Here are his words:  “Also note, that preventing illness is just the key that opens the door to many of these Brave New World technologies. Eventually–given the way things go these days–if the procedure ever becomes doable, it will go quickly from the “medical” to the “consumerist,” e.g., facilitating lifestyle choices and personal preferences.  That’s what happened with IVF, after all, which is no longer restricted to treating the infertile. Indeed, if we ever normalize polyamory, one could see the technique as a way for three partners to have biologially related children.”

Smith has a good point.  However, given the devastating nature of these mitochondrial genetic diseases, it seems to me that using this technique to prevent such horrific diseases from being passed on is a good thing.  However, we should certainly not let this technique be a license into another foray into experimental lifestyles.  Could we use this technique for medical purposes only?  Smith seems to think that the answer to this question is “No.”  I am certainly sympathetic to his caution, but I am also unwilling, at this point, to prevent mothers with these diseases from using this technology to have healthy babies that do not die at a young age.  If there is another way to purge such diseases from the mother’s eggs, then I am all ears, but for now this seems to be the best and only way.

Preliminary Results of Stem Cell Treatment for Stroke Show No Major Side Effects


A collaborative effort between physicians and scientists at the University of Texas Health Science Center in Houston and other centers, has spawned a clinical trial to test a stem cell treatment for stroke patients.

The lead researcher, Sean Savitz, professor of neurology and the director of the stroke program at UT, presented the first results from 10 stroke patients who were treated with stem cells at the World Stroke Congress in Brasilia, Brazil. This clinical trial is the only randomized, double-blind, placebo-controlled intra-arterial clinical trial in the world for ischemic stroke. The goal of this trial is to test the safety and efficacy of a therapy developed by a company called Aldagen Inc. (a wholly-owned subsidiary of Cytomedix Inc.) that uses a patient’s own bone marrow stem cells to treat stroke patients.

In this clinical trial, after a patient has suffered a stroke, the bone marrow stem cells are administered between 13-19 days after the stroke. This therapy, which is known as ALD-401, uses a technology developed and owned by Aldagen to isolate cells from bone marrow that express very high levels of a particular enzyme. This enzyme marks the cells that express it as stem cells. Pre-clinical studies with these isolated cells in mice showed that mice that had suffered from a stroke showed enhanced recovery when given intra-arterial infusions of these stem cells.

All patients infused with these stem cells will be monitored for 12 months after the infusion. The patient’s mental and physical functions will be closely watched, and any side effects from the infusions will be noted and treated.

According the Dr. Savitz, “We have been approved by the Data Safety Monitoring Board (DSMB) to move the study into the next phase, which will allow us to expand the number of sites in order to complete enrollment.”

Since the 10 people treated in this study have not shown any adverse side effects, Savitz wants to eventually enroll 100 patients. According to the submitted protocol for this study, the initial study only placed 10 patients at risk for this untested treatment. Therefore, before more patients could be enrolled in the clinical trial, the Food and Drug Administration had to review the safety data on the first ten patients before more could be enrolled. The FDA has approved the move to the next phase of this clinical trial.

In pre-clinical trials, some of which were conducted at the UTHealth Medical School, bone marrow stem cells promoted the repair of the brain after an ischemic stroke. Savitz and his colleagues induced stroked in rats and measured the amount of oxygen that flowed into the brain by means of Magnetic Resonance Imaging or continuous laser Doppler flowmetry. In rats that made been given injections of bone marrow-derived stem cells, the oxygen flow to the brain was significantly better than in rats that had suffered a stroke but had not been given the stem cell treatments. Savitz’s group also showed that a molecule that dilates blood vessels called nitric oxide was necessary to keep the vessels open and to allow entry of the stem cells into the brain so that they could repair the damage. When Savitz and his group prevented nitric oxide synthesis with an inhibitor called L-NAME, the infused stem cells were unable to enter the brain and fix it, and oxygen flow to the brain tanked. It was the strength of these pre-clinical studies that convinced the FDA to approve this present human clinical trial that tests this same procedure in human patients.

Ischemic strokes result from blood clots in the tiny vessels in the brain, which starves portions of the brain for oxygen, thus killing off brain cells. Stroke is the leading cause of disability in the United States and the fourth most common cause of death, according the statistics provided by the Centers for Disease Control and Prevention in Atlanta, Georgia.