Rejuvenating the Blood of Older People With New Stem Cells


Like it or not, the blood of young people and older people is different. Can the blood of an older person be rejuvenated and made young again?

In an article published recently by the scientific journal Blood, a research group at Lund University in Sweden details a series of experiments in which they rejuvenated the blood of mice by reversing, or re-programming, the blood cell-making stem cells.

Stem cell populations throughout the body form and replace cells in the body and help repair organs. Stem cells have the capability to divide an unlimited number of times, and when they divide, one cell remains a stem cell and the other matures into another cell type needed by the body.

Martin Wahlestedt, a doctoral student in stem cell biology at the Faculty of Medicine at Lund University, and principal author of the article explained, “Our ageing process is a consequence of changes in our stem cells over time.” Wahlestedt continued, “Some of the changes are irreversible, for example damage to the stem cells’ DNA, and some could be gradual changes, known as epigenetic changes, that are not necessarily irreversible, even if they are maintained through multiple cell divisions. When the stem cells are re-programmed, as we have done, the epigenetic changes are cancelled.”

Shinya Yamanaka was awarded the Nobel Prize in Medicine last year for this very discovery.

Blood composition changes as we age. For example, blood from a young person contains a certain mix of B- and T-lymphocytes and myeloid cells, but in older people, according to Wahlestedt, “In older people, the number of B- and T-lymphocytes falls, while the number of myeloid cells increases.” Therefore, when an elderly person is affected by leukemia, the cancer usually originates in the myeloid cells, since the elderly have more myeloid cells. Being able to refurbish the blood, as Martin and his colleagues have done in their mouse studies, therefore, presents interesting possibilities for future treatment.

“There is a lot of focus on how stem cells could be used in different treatments, but all that they are routinely used for in clinical work today is bone marrow transplants for diseases where the blood and immune systems have to be regenerated”, said Martin Wahlestedt, continuing:  “A critical factor that gives an indication of whether the procedure is going to work or not is the age of the bone marrow donor. By reversing the development of the stem cells in the bone marrow, it may be possible to avoid negative age-related changes.”

Even if the composition of the blood in old and young mice is remarkably like that in young and elderly people, Martin Wahlestedt stressed that at this stage; the technology is only at the basic research stage and is far from a functioning treatment. The research group is pleased with the results, because they indicate that it may not primarily be damage to DNA that causes blood to age, but rather the reversible epigenetic changes.

Neural Cells Made from Monkey Skin Cells Integrate into Monkey Brains and Form Neurons


Stem cell scientists from the University of Wisconsin at Madison have transplanted neural cells that were made from a monkey’s skin cells into the brain of that same monkey. The transplanted cells formed variety of new brain cells that were entirely normal after six months.

This experiment is a proof-of-principle investigation that shows that personalized medicine in which regenerative treatments are designed for specific individuals is possible. These neural cells were derived from the monkey’s skin cells and were, therefore, no foreign. Therefore, there is no risk of them being rejected by the host immune system.

Su-Chun Zhang, professor of neuroscience at the University of Wisconsin-Madison, said: “When you look at the brain, you cannot tell that it is a graft. Structurally the host brain looks like a normal brain; the graft can only be seen under the fluorescent microscope.”

Marina Emborg, associate professor of medical physics at UW-Madison and one of the lead co-authors of the study, said: “This is the first time I saw, in a nonhuman primate, that the transplanted cells were so well-integrated, with such a minimal reaction. And after six months, to see no scar, that was the best part.”

The skin-derived neural cells were implanted into the monkey brain by means of a state-of-the-art surgical procedure whereby the surgeon was guided by a live MRI. The three rhesus monkeys used in the study at the Wisconsin National Primate Research Center had brain lesions that caused Parkinson’s disease. Up to one million Americans suffer from Parkinson’s disease, and some 60,000 new patients are diagnosed with it each year. Parkinson’s disease results from the death of midbrain neurons that manufacture the neurotransmitter dopamine.

The cells that were transplanted into the brain were derived from induced pluripotent stem cells (iPSCs), which, like embryonic stem cells, can develop into virtually any cell in the adult human body.

Once the iPSC lines were established, Zhang and his colleagues differentiated them into neural progenitor cells (NPCs), which have the ability to form a wide variety of brain-specific cells. Zhang was the first scientist to ever successfully differentiate iPSCs into NPCs, and therefore, this paper utilized his unique expertise.

According to Zhang, “We differentiate the stem cells only into neural cells. It would not work to transplant a cell population contaminated by non-neural cells. By taking cells from the animal and returning them in a new form to the same animal, this is a first step toward personalized medicine. Now we want to more ahead and see if this leads to a real treatment for this awful disease.”

Another positive sign was the absence of any signs of cancer, which is a troubling but potential outcome of stem cell transplants. Zhang jubilantly but guardedly announced that the appearance of the cells is “normal, and we also used antibodies that mark cells that are dividing rapidly, as cancer cells are, and we do not see that. And when you look at what the cells have become, the become neurons with long axons, as we’d expect. The also build oligodendrocytes that are helping build insulating sheaths for neurons, as they should. That means they have matured correctly, and are not cancerous.”

Zhang and his colleagues at the Waisman Center on the UW-Madison campus designed this experiment as a proof of principle investigation, but because they did not transplant enough dopamine-making cells into the brain, the animal’s behavior did not improve. Thus, although this transplant technique is certainly very promising, it is some ways from the clinic.

As noted by Emborg: “Unfortunately, this technique cannot be used to help patients until a number of questions are answered: Can this technique improve the symptoms? Is it safe? Six months is not long enough.” Emborg continued, “And what are the side effects? You may improve some symptoms, but if that leads to something else, then you have not solved the problem.”

Regardless of these shortcomings, this study still represents a genuine breakthrough. “By taking cells from the animal and returning them in a new form to the same animal, this is a first step toward personalized medicine,” said Emborg.

Human Amniotic Fluid Stem Cells Embedded in Beads for Heart Atacks


Human amniotic fluid stem cells (hAFSCs) have been isolated from the “water” that surrounds the baby when it is born. Amniotic fluid is the material is lost when a pregnant woman’s “water breaks.” If the amniotic fluid is retrieved before it ruptures, a specific stem cell population can be isolated from it, and these stem cells grow very well in culture, and can differentiate into a multiple of adult cell types.

hAFSCs

When it comes to the heart, hAFSCs have a bit of a mixed record. One publication from Anthony Atala’s laboratory showed that implantation of hAFSCs into the heart of a laboratory animal after a heart attacked was followed by the formation of bony nodules in the heart tissue (see Chiavegato et al., J Mol Cell Cardiol. 42 (2007) 746-759). However, a follow-up publication, showed that the conditions used in the previous experiments caused the formation of bony nodules in the heart regardless of whether or not hAFSCs were implanted into the heart (Delo DM et al., Cardiovasc Pathol 2011 20(2):e69-78).  Other papers showed that implanted cAFSCs could protect the heart from further deterioration (Bollini S et al., Stem Cells Dev. 2011 20(11):1985-94).  However, a perennial problem is the poor retention of the cells in the heart after injection.  Therefore, one group tried implanting hAFSCs into cellular goo (extracellular matrix). This caused the hAFSCs to stay put in the heart and differentiate into heart muscle cells and blood vessels (Lee WY et al., Biomaterials. 2011 32(24):5558-6).

On the heals of this success comes a paper from Taiwanese researchers who have embedded hAFSCs into polylactic-co-glycolic acid (PLGA) beads and implanted these into the heart of a laboratory animal after a heart attack.  These beads are made of material that is completely biogradable, but the hAFSCs survive and grow well in them.  Also, once they are implanted into the heart, the beads are large enough to prevent them from being displaced.  Once the beads disintegrate inside the heart tissue, the cells are already so deeply implanted into the heart tissue, that they do not become washed out by circulating blood and other fluids.  

Poly lactic-co-glycolic acid
Poly lactic-co-glycolic acid

The implanted hAFSCs differentiated into heart muscle cells and blood vessels.  The blood vessels density in these hearts of the hAFSC implanted animals twice that of the control animals in the area of the infarct and almost three times that of the control outside the area of the infarct.  The scar shrunk in the hAFSC-implanted hearts by ~30%, and the structure of the hAFSC-implanted hearts was much more robust and thick relative to the controls.  Finally, the contraction of the heart muscle was (4 weeks after treatment) twice as strong in the hAFSC-treated hearts compared to the control.  Ejection faction was not measured, and that is a deficiency in this paper, but all the cardiac parameters that were measured were vastly improved in the hAFSC-treated hearts relative to the untreated controls.

This paper shows that the porous PLGA beads are not toxic, deliver cells to the chosen target, and quickly disintegrate without affecting the target tissue, in this case the heart. Clearly hAFSCs have a part to play in the future of regenerative medicine.

Turning Muscle Stem Cells into Brown Fat


Michael Rudnicki’s laboratory at the Ottawa Hospital Research Institute has managed to convert stem cells from skeletal muscle into brown fat. Because brown fat burns calories, studies have shown that trimmer people tend to have more brown fat, Therefore, Rudnicki’s findings are being viewed as a potential treatment for obesity.

According to Rudnicki, “This discovery significantly advances our ability to harness this good fat in the battle against bad fat and all the associated health risks that come with being overweight and obese. Rudnicki is a senior scientist and director for the Regenerative Medicine Program and Sprott Center for Stem Cell Research at the Ottawa Hospital Research Institute.

Obesity is the fifth leading risk death, globally speaking, and an estimated 2.8 million people dying every year from the effects of being overweight or obese, according to the World Health Organization. The Public Health Agency of Canada estimates that 25% of Canadian adults are obese.

in 2007, Rudnicki and his research team demonstrated the existence of a stem cell population in skeletal muscle. In this new publication, Rudnicki and others show that these adult muscle stem cells not only have the ability to produce muscle fibers, but can also make brown fat.

An even more important aspect of this paper (Yin, et al., Cell Metabolism 17(2) 2013: 210), is that it shows how adult muscle stem cells become brown fat. The main switch is a regulatory molecule called microRNA-133 or miR-133. When miR-133 is present, the muscle stem cells produce muscle fibers, but when the intracellular concentration of miR-133 is reduced, the muscle stem cells form brown fat.

Graphic Abstract

Rudnicki’s research staff developed a molecule that could reduce the concentration of miR-133 in cells. This molecule an antisense oligonucleotide or ASO that is complementary to miR-133. When injected into mice, the ASO caused the mice to produce more brown fat and prevented obesity. Additionally, when injected into the hind leg muscle, the metabolism of the mouse increased, and this effect lasted for four months after the ASO injection.

Even though antisense oligonucleotides are being used in clinical trials, such trials with miR-133 ASOs are still years away.

Rudnicki noted that “we are very excited by this breakthrough.” He continued: “While we acknowledge that it’s a first step there are still many questions to be answered, such as: Will it help adults who are already obese to lose weight? How should it be administered? How long do the effects last? Are there any adverse effects we have not yet observed?”

Surely these questions will be addressed in good time, and Rudnicki’s lab is probably working on them as you read this entry.

Taste Stem Cells Identified


Researchers at the Monell Center in Philadelphia, PA have successfully identified the location and markers for taste stem cells on the tongue. These findings will almost certainly allow scientists to grow and manipulate taste cells for clinical and research purposes.

Neurobiologist Robert Margolskee with the Monell Center who was also one of the authors of this study said: “Cancer patients who have taste loss following radiation to the head and neck and elderly individuals with diminished taste function are just two populations who could benefit from the ability to activate adult taste stem cells.”

Taste cells are located in rosette-like clusters known as taste buds in bumpy structures called papillae on the upper surface of the tongue. Two types of taste cells contain chemical receptors that initiate the perception of sweet, bitter, unami salty, and sour taste qualities. A third type of taste cell appears to serve as a support cell for these taste cells.

Gustatory_receptor_cell

A truly remarkable characteristic of these sensory cells is that they regularly regenerate, and all three taste cells undergo frequent turnover. The average lifespan of these cells is 10-16 days, which means that constant regeneration must occur in order for these cells to replace the cells that constantly die.

For decades, scientists who study taste have tried to identify the stem cell population that form these different taste cells. Scientists were also completely uncertain as to the location of these taste cell progenitors. Where they in the taste buds, near the taste buds, or someplace entirely different?

Monell scientists drew upon the strong association between oral taste cells and endocrine cells in the intestine. They reasoned that the cell-surface markers for stem cells in the intestine might also serve as markers for stem cells in the tongue. By using antibodies to a surface protein called Lgr5 (leucine-rich repeat-containing G-protein-coupled receptor 5), the Monrell team observed two strong expression patterns for this marker in the tongue. One signal was underneath taste papillae at the back of the tongue and the second signal was an even weaker signal underneath taste buds in those papillae.

The Monell group hypothesized that the two levels of expression could indicate two different populations of cells that expressed Lgr5 at different levels. The stronger-expressing cells are probably the actual stem cells and those that more weakly express Lgr5 are those progeny of these stem cells that are beginning to differentiate. Therefore, the expression of the stem cell marker in these cells is fading.

Additional work showed that Lgr5-expressing cells were capable of differentiating into any of the three different types of taste cells.

Peihua Jiang. who is also a neurobiologist at the Monell Center, said: “THis is just the tip of the iceberg. Identification of these cells opens up a whole new area for studying taste cell renewal, and contributes to stem cell biology in general.”

In the future, the Monell group plans to program the Lgr5-expressing cells to differentiate into the different taste cell types, and explore how to grow these cells in culture. This will create a renewable source of taste receptor cells for research and perhaps even clinical use.

See Karen Yee, et al., “Lgr5-EGFP Marks Taste Bud Stem/Progenitor Cells in Posterior Tongue.” Stem Cells 2013 DOI: 10.1002/stem.1338.

Stem Cells from Human Adipose Tissue Used to Chase Migrating Cancer Cells


From The Stem Cell Blog – very nice article about fat-based mesenchymal stem cells chasing metastatic cancers. Enjoy.

The Stem Cell Blog

Stemness of primary AMSC lines demonstrated with differentiation along three mesenchymal lineages, Adipocyte (a, d [48], g), Osteocyte (b [48], e, h), and Chondrocyte (c [48], f, i), documented via lineage specific staining with Oil Red O, Alizarin Red, and Collagen II, respectively. (Credit: Pendleton et al. Mesenchymal Stem Cells Derived from Adipose Tissue vs Bone Marrow: In Vitro Comparison of Their Tropism towards Gliomas. PLoS ONE, 2013; 8 (3): e58198 DOI: 10.1371/journal.pone.0058198)
Using Fat to Fight Brain Cancer: Stem Cells from Human Adipose Tissue Used to Chase Migrating Cancer Cells

Mar. 12, 2013 — In laboratory studies, Johns Hopkins researchers say they have found that stem cells from a patient’s own fat may have the potential to deliver new treatments directly into the brain after the surgical removal of a glioblastoma, the most common and aggressive form of brain tumor.


The investigators say so-called mesenchymal stem cells (MSCs) have…

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Transplantable Hematopoietic Stem Cells Made From Induced Pluripotent Stem Cells


Induced pluripotent stem cells (iPSCs) are made from adult cells by genetic manipulation. In short, four different genes, all of which encode DNA-binding proteins that direct gene expression, are introduced into adult cells. The four proteins direct a gene expression program that dedifferentiates a small proportion of the cells to become stem cells that greatly resemble embryonic stem cells.

These iPSCs have the capacity to differentiate into any cell type in the adult body, but there are particular cell types that have proven difficult for iPSCs to make. One of these is the blood cell-making stem cell that normally resides in bone marrow. This stem cells, the hematopoietic stem cell or HSC. Several different types of blood cells have been made from iPSCs, but, again, making HSCs from iPSCs has proven elusive.

A paper from the laboratories of Leslie Silberstein and Daniel Tenen at the Harvard Stem Cell Institute and Harvard Medical School has used a new approach to make HSCs from iPSCs. In this paper, Giovanni Amabile and colleagues injected undifferentiated HSCs into mice whose immune systems were compromised to prevent them from rejecting the implanted cells. The iPSCs formed tumors known as teratomas that contained a wide variety of cells types that included HSCs. Isolation of these HSCs from the teratomas produced pure cultures of HSCs that could be used to reconstitute the immune system of mice.

Isolation of HSCs from teratomas is actually rather easy, since very high-affinity antibodies can bind to the surfaces of HSCs and facilitate their isolation. Once isolated, Amabile and others used them to reconstitute the immune system of imunodeficient mice. This demonstrates that HSCs isolated in this manner are transplantable.

Embryonic stem cells can be converted to HSCs by co-culturing them with OP9 cells, a special mouse bone marrow-derived cell line. If iPSCs were injected into mice with OP9 cells, the number of HSCs they made in culture greatly increased.

OP9 cells
OP9 cells

The cells produced by the HSCs were evaluated for functionality, and the white blood cells made all the right molecules, ate bacteria like they should and also moved like white blood cells. Antibody making cells all made antibodies and T cells responded just as they should and made all the right molecules in response to stimulation. Thus, these HSCs were normal HSCs and produced blood cells that were completely normal from a functional perspective.

This technique could provide a way to make HSCs for human antibody production, drug screening, and, possibly, transplanation. Unfortunately, if these cells have been passed through an animal, there is no way they can be used for human treatments, since they might have picked up animal viruses and animal sugars on their surfaces. If these procedure could be refined to eliminate passing the iPSCs through an animal , then this technique could certainly be used to make transplantable HSCs for the treatment of human diseases of the blood.

See Amabile et al., Blood 121(8):1255-1264.