Abnormal Blood Stem Cells are the Cause of Leukemia

Cancer is, to a large degree, a disease of stem cells. When stem cells acquire particular mutations, they lose their controls on cell division and begin to divide uncontrollably. Several different studies have established that several types of cancers result from abnormal stem cells. Blood cancers, for example, form when stem cells accrue rare genetic mutations, according a new study. This discovery overturns the traditional view that blood cancers can originate from any blood cell, and it could conceivably help to prevent relapses in leukemia patients.

Stanford University researchers have identified the origins of leukemia. They used so-called “next-generation sequencing” techniques and various other methods to identify rare, pre-cancerous, blood stem cells in six individuals with acute myeloid leukemia. After identifying these pre-cancerous cells, they compared the genetic sequences from the pre-cancerous blood stem cells to the sequences of the same chromosomal regions from the patients’ leukemia-plagued stem cells. This analysis revealed the exact order of rare mutations that blood stem cells accrued in order to become cancerous.

Stanford hematologist Ravi Majeti, co-lead author of the study, commented: “I’m surprised that we identified the clonal hierarchy that led to leukemia in five of the six cases. I didn’t think we’d find that amount of evidence of pre-leukemia stem cells.”

Scientists have suspected for the last few decades that cancer stem cells, and in particular leukemia stem cells, lead to cancer. In 2005, a Stanford pathologist named Irving Weissman added a twist to this idea when he proposed that normal blood stem cells become cancerous stem cells by accumulating rare mutations. Weissman’s hypothesis suggested that leukemia originated in blood stem cells. Weissman’s hypothesis makes sense of a simple fact; blood stem cells live much longer than regular blood cells, which only live up to a few weeks at most. A few weeks is simply not enough time, to acquire the number of rare mutations necessary to become cancerous. Since blood stem cells are capable of self-renewal, they survive in the body throughout the lifetime of an organism. Unfortunately, such a hypothesis, despite its great explanatory power, is very difficult to directly test, and, therefore, has remained controversial.

The best way to test Weissman’s hypothesis is to identify the protein-coding mutations in several acute myeloid leukemias, and then isolate and analyze the rare, pre-cancerous stem cells to determine which, of the leukemia mutations were present in those pre-cancerous stem cells.

In addition to their sequencing approach, this team also used high-throughput flow cytometry to identify markers specific to a patient’s healthy blood cell-making stem cells versus their leukemia stem cells in order to isolate the very rare populations of pre-cancerous stem cells.

These techniques were pioneered by Thomas Snyder, who is a chief scientist at ImmuMetrix and co-lead author of this paper. Snyder worked as a post-doctoral researcher in the laboratory of Stanford bioengineer Stephen Quake when this he collaborated on this study. Together, Quake and Snyder developed those techniques to sort and study the genomes of each individual cell. “It is only when you can look at a single cell and determine its genotype that you can conclusively show the early stages in the evolution of the cancer,” said Snyder.

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.”

A New Muscle Disease Target: Myostatin

A protein found in the muscular system known as myostatin has piqued the interest of muscle researchers who focus on muscular disorders.

Myostatin is a heavily-studied protein and has a function that is common to many different types of animals (cows, sheep, humans, & mice). Myostatin inhibits the growth of muscles so that they do not overgrow and capitalize on the nutrients of the developing embryo or body. Mice that carry mutations in the gene that encodes myostatin have twice the muscle mass of normal mice.  Beef cattle with mutations in the myostatin gene are heavily muscled and highly sought after for restaurants.  Piedmontese and Belgium Blue beef cows example of cattle with mutations in the myostatin gene and are very heavily muscled.  This makes it a potential drug target for people who suffer from degenerative diseases that affect muscles.

Myostatin is also known as growth differentiation factor 8 (GDF-8) and it is secreted by muscle cells and circulates throughout the bloodstream.  It controls the growth of muscles by binding to a receptor on the surface of muscle cells called the “activin type II receptor.”

There is, however, a sizable debate as to which muscles are controlled by myostatin. Fortunately, as new study by Carnagie’s Chen-Ming Fan and Christoph Lepper narrows down the target muscles of myostatin.

Skeletal muscles possess a stem cell population called satellite cells that are activated by muscular injury. After muscle injury, for example, by lifting heavy weights, cause the satellite cells to divide and fuse to existing muscle fibers. Does myostain affect satellite cells or the muscle fibers?

According to work by Fan and Se-Jin Lee, who is a former Carnagie Staff Associate and is currently at the Johns Hopkins University Medical School, muscle growth caused by the inhibition of myostatin is not due to the incorporation of satellite cells into muscle fibers. Their work used genetic and pharmacological means to show this. For example, they knocked our the gene that encodes the receptor for myostatin (Acvr2b) they found that the mice had increased muscle mass that was not due to increased satellite cell activity.  Therefore, their conclusions are rather solid.

Now these results might have implications for the possible use of myostatin as a clinical target. The reason for this is that diseases that cause muscle degeneration tend to produce symptoms later in life because a patient’s satellite cells regenerate the muscle until their populations are eventually depleted. Inhibiting myostatin through pharmacological means could benefit patients over time, since they would tend to spare the satellite cell population by growing muscle without satellite cells.

According to Fan, “More work is needed to determine whether these findings are applicable to various conditions , such as exercise, injury and sarcopenia – degenerative loss of muscle mass associated with aging. However, our findings initially indicate that many different diseases affecting the muscular system could potentially be responsive to drugs that inhibit myostatin and thus promote muscle growth, without regard to the status of the muscle stem cell pool.”

Embryonic Stem Cell Lines Derived from Embryos Frozen for 18 Years

How long do human embryos survive in cryostorage? To be completely honest, no one truly knows. According to the Planer PLC Group, a cryopreservation company, a baby was born from an embryo that had frozen for 16 years at their institution. However, it is possible that embryos might live even longer in cryostorage. Furthermore, one study that examined more than 11,000 cryopreserved human embryos determined that the length of time for which the embryo was frozen had no significant effect on post-thaw survival for in vitro fertilisation (IVF) or oocyte donation cycles, or for embryos frozen at the pronuclear or cleavage stages. This study also showed that the duration of storage did not have any significant effect on clinical pregnancy, miscarriage, implantation, or live birth rate, whether from IVF or oocyte donation cycles (Riggs R, Mayer J, Dowling-Lacey D, Chi TF, Jones E, Oehninger S (November 2008). “Does storage time influence postthaw survival and pregnancy outcome? An analysis of 11,768 cryopreserved human embryos”. Fertil. Steril. 93 (1): 109–15).

However, some embryos do not survive the freezing process. Also, some embryos that are frozen are very low-quality embryos that have an exceedingly low probability of ever making a baby. Since these embryos are of very little value from a reproductive standpoint, they might be of use to stem cell biologists who want to make embryonic stem cells from them. Several studies have shown that low quality embryos are excellent sources of material for embryonic stem cells. For example, Lerou PH, et al., Human embryonic stem cell derivation from poor-quality embryos.Nat Biotechnol. 2008 Feb;26(2):212-4. In this paper Daley’s lab derived embryonic stem cell lines at rates comparable to the rates of embryonic stem cell derivation with high-quality embryos. Another paper by Shetty R and Inamdar MS, “Derivation of human embryonic stem cell lines from poor quality embryos,” in Methods Mol Biol. 2012;873:151-61, Indian researchers derived embryonic stem cell lines from low-quality embryos.

A Chinese laboratory has also used low quality embryos that were discarded by fertility clinics. 166 poor quality embryos gave rise to 4 new embryonic stem cell lines in this paper (see Lui W, et al., J Genet Genomics. 2009 Apr;36(4):229-39). Therefore, this practice is well established.

What is questionable is whether or not the embryo is actually dead. Remember, even though grade III embryos are not desirable because they show lower rates of implantation, they still give rise to live births occasionally. For example, one study showed that grade iV embryos (worse than grade III) gave pregnancy rates of 18.2%. Therefore, these studies are being done with low-grade embryos – not embryos that are clinically dead.

As I have noted before in a previous post, defining death in an embryo is difficult to do, but when there are far more dead cells in the embryo than live ones, the chance of the embryo giving rise to a baby becomes so low as to be impossible. If 60% of the cells in the embryos are dead, then the embryo is usually defined as clinically dead. Such an embryo, if it has not experienced early developmental arrest, can be a reasonable source of embryonic stem cells, according to work from the Daley lab

With this in mid, there is a paper from a research group at Chulalongkorn University and Chilalongkorn Memorial Hospital, Bangkok, Thailand, that shows that embryonic stem cells can be successfully made from embryos that had been frozen for 18 year. This paper shows that even embryos that have been frozen for almost two decades can still yield embryonic stem cells.

Evaluations of these embryonic stem cell lines revealed that they were as pluripotent as similar lines derived from embryos that had only been frozen for a few years.

Jane Taylor, a collaborator in this paper from the MRC Centre for Regenerative Medicine at the University of Edinburgh, Scotland, said, “The importance of this study is that is it identifies an alternative source for generating new embryonic stem lines, using embryos that have been in long-term storage.”

These frozen embryos, if they were not clinically dead, were still human beings. They merely needed to be implanted into a mother’s womb in order to execute their intrinsic developmental program that implants itself into the mother’s womb. By using these embryos to derive embryonic stem cell lines, their lives were ended. All other arguments that try to downgrade the essential status of these embryos because they are too young, too small, in the wrong place or too different from an adult rely upon accidental qualities of the embryo. That is, qualities that are temporary and not integral to the essence of the embryo. Its essence is that of a human being. When it grows larger, it is still a human being and the fact that it executes its intrinsic developmental program to do so merely demonstrates its human essence. The same can be said about it appearance, and age.

Location is an even more problematic criterion by which to disqualify the embryo from the human race.

Therefore, these embryos were destroyed and their human lives, killed. Surely there is a better way to do regenerative science that both respects the value of human life and creates technologies to heal us. Interested? Read the other posts on this blog.

Todd Akins and Pregnancy as a Result of Rape

Republican candidate for U.S. Senator from the state of Missouri, Todd Akin, really stuck his foot in his mouth during an interview on the Jaco Report on Fox. After he stated that abortion should be legal to save the life of the mother, the host asked if it should also be legal in the case of rape.

Akin responded: “People always want to try and make that as one of those things, well, how do you slice this particularly tough sort of ethical question. It seems to me, first of all, that from what I understand from doctors, that’s really rare. If it is a legitimate rape, the female body has ways to try and shut that whole thing down. But let’s assume maybe that didn’t work or something. I think there should be some punishment, but the punishment should be of the rapist and not attacking the child.”

Akin issued an apology but the damage is already done. His statement was poorly worded and garbled. He probably meant to refer to a forcible rape, which is also known as an assault rape as opposed to a date rape. He was probably trying to make this distinction since there have been cases whereby women who become pregnant from consensual intercourse have later claimed rape. His wording failed to properly clarify what he meant.

Even worse was his statement that ” the female body has ways to try and shut that whole thing down.” Again I think he was trying to refer to the physical trauma experienced by a woman when she is raped. Stress and emotional factors can alter a woman’s menstrual cycle. In order to get pregnant, and stay pregnant the body of the woman must produce a complex mix of hormones. This hormone production is under the control of the brain and the part of the brain that controls reproductive hormones (the limbic system) is easily influenced by emotions. An assault rape certainly qualifies as great emotional trauma. Such trauma can radically upset ovulation, fertilization, implantation and even the nurturing of a pregnancy.

Having said all that, women do get pregnant from assault rapes. Approximately 1 in 15 women who are raped will get pregnant from it (see Statistics on Sexual Violence Against Women: A Criminological Study, 1990). Another article by Holmes, Resnick, Kilpatrick, and Best (Rape-related pregnancy: estimates and descriptive characteristics from a national sample of women) from the American Journal of Obstetrics and Gynecology (1996 Aug;175(2):320-4; discussion 324-5), finds that the national rate of rape pregnancies is 5.0% per rape among victims of reproductive age (aged 12 to 45). This rate is higher because some women who are raped are too old or too young to become pregnant from the rape. Nationally, there were an estimated 32,101 rape pregnancies each year. Only 11.7% of rape victims received immediate medical attention after the assault, and 47.1% received no medical attention related to the rape. 32.2% kept the infant, 50% underwent abortion and 5.9% placed the infant for adoption. 11.8% had a spontaneous abortion.

Thus the statistics show that pregnancy as a result of an assault or forcible rape does occur frequently enough so that pro-life politicians, thinkers and workers must take it seriously. The simple fact is that the baby should not pay the price of his or her life for the crimes of the father. That is the crux of the pro-life position. Abortion as a that ends the life of a baby who is the product of a rape still ends the life of a baby who had nothing to do with the crime still kills a baby. Had Akin put it this way, then he would not have stuck his foot in his mouth the way he did.

There are complications with forcing the woman to be a life-support system for a baby she did not wish to conceive, but the fact still remains that a baby’s life hangs in the balance. In the scheme of things, it seems to me that having the woman bear the brunt of the pregnancy is the lesser of two evils and saving the life of the baby is a greater good.  Trying to be cute about it will only get you in trouble and mark you as ignorant and insensitive to women.

Using Junk Biology to Promote “Uselessness” of Men

Wesley Smith over at Secondhand Smoke notes the New York Times op-ed by an actual biology professor, Greg Hampikian, who argues that men are unimportant to the propagation of the human species.

The column says: “Think about your own history. Your life as an egg actually started in your mother’s developing ovary, before she was born; you were wrapped in your mother’s fetal body as it developed within your grandmother.”

He continues: “After the two of you left Grandma’s womb, you enjoyed the protection of your mother’s prepubescent ovary.”

Smith notes the rather obvious truth that neither you nor I were never an egg. Neither were we ever a sperm. Our lives began at the completion of fertilization and at that point, a new person – you – were created. This kind of biological claptrap is being written by someone who should know better, and is used to argue that men are just playthings for women. This is beyond ridiculous; it is asinine.

If that wasn’t bad enough, here comes more: ” Then, sometime between 12 and 50 years after the two of you left your grandmother, you burst forth and were sucked by her fimbriae into the fallopian tube. You glided along the oviduct, surviving happily on the stored nutrients and genetic messages that Mom packed for you. Then, at some point, your father spent a few minutes close by, but then left. A little while later, you encountered some very odd tiny cells that he had shed. They did not merge with you, or give you any cell membranes or nutrients — just an infinitesimally small packet of DNA, less than one-millionth of your mass.”

The sperm gave a packet of DNA, a spindle and the biochemical signals to metabolically activate the embryo and get it dividing. These are all vital contributions to the beginning of human life. Hampikian’s abuse of biology is inexcusable.

See Smith’s post here.

Highly Efficient Method for Converting Blood Stem Cells into Induced Pluripotent Stem Cells Without Viruses

A research group from Johns Hopkins University has designed a protocol that reliably converts stem cells from umbilical cord blood into a primitive stem cell state. From this primitive state, these cells can differentiate into any other type of cell in the body.

This paper was published in the August 8th issue of Public Library of Science (PLoS), and serves as the second publication in an ongoing effort to efficiently and consistently convert umbilical cord blood stem cells and other types of stem cells into stem cells that are usable for use in clinical and research settings in place of human embryonic stem cells, according to Elias Zambidis, M.D., Ph.D., who is an assistant professor of oncology and pediatrics at the Johns Hopkins Institute for Cell Engineering and the Kimmel Cancer Center.

Zambidis said: “Taking a cell from an adult and converting it all the way back to the way it was when that person was a 6-day-old embryo creates a completely new biology toward our understanding of how cells age and what happens when things go wrong, as in cancer development.”

The first paper that is sometimes designated ‘Chapter One‘ of this work was published last spring in PLoS One. In this paper, Zambidis’ group described the successful use of a method that safely transformed several different types of human pluripotent stem cells into heart muscle cells. In the latest experiments, Zambidis and his colleagues describe methods that convert umbilical cord blood stem cells into induced-pluripotent stem cells (iPS), which are adult or fetal cells reprogrammed to an embryonic like state.

According to Zambidis, he and his team developed a “super-efficient, virus-free” method for making iPS cells. This overcomes some troubling difficulties for those scientists who work with iPS cells; namely, the vast inefficiency of making iPS cells from adult cells and the use of mutation-causing viruses to introduce those genes into adult cells required to convert adult cells into iPS cells. Generally, out of hundreds of blood cells, only one or two typically revert into iPS cells. However, with Zambidis’ method, 50-60% of blood cells were engineered into iPS cells.

To circumvent the use of viruses to deliver genes, Zambidis’ team used plasmids, or small circles of DNA that replicate briefly inside cells and then degrade. By using plasmids, the cells receive the genes required to drive adult cells into the iPS state, but because these genes are only required transiently, the plasmids do their job and then go away. Therefore, the production of mutations by viral DNAs that insert themselves into the host cell genome is not a problem with this method from Zambidis’ laboratory.

In order to introduce the genes into the cells, Zambidis’ team used a technique called electroporation. They treated the umbilical cord blood cells with the plasmids and then delivered an electrical pulse to the cells, which made tiny holes in the surface through which the plasmids could slip to the cell interior. Once inside, the plasmids triggered the cells to revert to a more primitive cell state. After genetic engineering, the blood cells were also given an additional new step in which they were stimulated with their natural bone-marrow environment. To do this, the Johns Hopkins team took some of the treated cells in a dish alone, and cultured them together with irradiated bone-marrow cells.

When iPS cells made from umbilical cord blood were compared to iPS cells made from hair cells and from skin cells, they found that the most superior iPS cells came from those made from blood stem cells treated with just four genes and cultured with the bone marrow cells. These cells reverted to a primitive stem cell state within seven to 14 days. Their techniques also successfully converted blood stem cells from adult bone marrow and from circulating blood into iPS cells.

In ongoing studies, Zambidis and colleagues are testing the quality of their newly formed iPS cells. They are also interested in the ability of these iPS cells to differentiate into other cell types, as compared with iPS cells made by other methods. These efficient methods to produce virus-free iPS cells will hopefully speed research to develop stem cell therapies that use nearly all cell types, and may provide a more accurate picture of cell development and biology.