Josh Brahm runs the Life Report podcast and is one of the nicest guys on the planet. Josh invited me to his podcast at the end of last year to talk about my book and stem cell research in general. The editing of that exchange has become available.
Martin Knight and his colleagues from the Queen Mary’s School of Engineering and Materials Science and the Institute of Bioengineering in London, UK have shown that growing adult stem cells on micro-grooved surfaces disrupts a particular biochemical pathway that specified the length of a cellular structure called the “primary cilium.” Disruption of the primary cilium ultimately controls the subsequent behavior of these stem cells.
Primary cilia are about one thousand times narrower than a human hair. They are found in most cells and even though they were thought to be irrelevant at one time, this is clearly not the case.
The primary cilium acts as a sensory structure that responds to mechanical and chemical stimuli in the environment, and then communicates that external signal to the interior of the cell. Most of the basic research on this structure was done using a single-celled alga called Chlamydomonas.
Martin Knight and his team, however, are certain that primary cilia in adult stem cells play a definite role in controlling cell differentiation. Knight said, “Our research shows that they [primary cilia] play a key role in stem cell differentiation. We found it’s possible to control stem cell specialization by manipulating primary cilia elongation, and that this occurs when stem cells are grown on these special grooved surfaces.”
When mesenchymal stromal cells were grown on grooved surfaces, the tension inside the cells was altered, and this remodeled the cytoskeleton of the cells. Cytoskeleton refers to a rigid group of protein inside of cells that act as “rebar.” for the cell. If you have ever worked with concrete, you will know that structural use of concrete requires the use of reinforcing metal bars to prevent the concrete from crumbling under the force of its own weight. In the same way, cytoskeletal proteins reinforce the cell, give it shape, help it move, and help it resist shear forces. Remodeling of the cytoskeleton can greatly change the behavior of the cell.
The primary cilium is important for stem cell differentiation. Growing mesenchymal stromal cells on micro-grooved surfaces disrupts the primary cilium and prevents stem cell differentiation. This simple culture technique can help maintain stem cells in an undifferentiated state until they have expanded enough for therapeutic purposes.
Once again we that there are ways to milk adult stem cells for all they are worth. Destroying embryos is simply not necessary to save the lives of patients.
Stem cell scientists from the laboratory of Ophir Klein at UC San Francisco have discovered a new role for a protein called Bmi1 that might give clues as to how to get adult stem cells to regenerate organs.
Ophir Klein, the director of the Craniofacial and Mesenchymal Biology Program and chairman of the Division of Craniofacial Anomalies at UC San Francisco, said “Scientists have known that Bmi1 is a central control switch within the adult stem cells of many tissues, including the brain, blood, lung and mammary gland. Bmi1 also is a cancer-causing gene that becomes reactivated in cancer cells.”
All stem cells are somewhat immature in comparison to their adult counterparts. Stem cells also have the capacity to divide almost indefinitely and generate specialized cells. Bmi1 acts as a molecular switch that, if pushed in one direction, drives stem cells to proliferate and grow, but if pushed in the opposite direction, keeps cell proliferation in check. Research from Klein’s lab now suggests that Bmi1 might prevent the progeny of stem cells from differentiating into the wrong cell types in the wrong location.
This new discovery suggests that manipulation of Bmi1 and other regulatory molecules might be some of the steps included in laboratory recipes to turn specialized cell development on and off to create new cell-based treatments for tissue lost to injury, disease, or aging.
Also, the dual role of Bmi1 in pathological settings might be intriguing. Cancers are, in many cases, driven by adult stem cells that behave abnormally. If these stem cells could be differentiated, then their growth would slow. Possibly, inactivating Bmi1 in tumor stem cells might be one strategy.
In these experiments, Klein and his colleagues examined those adult stem cells found in the large incisors of mice. Unlike humans, these teeth grow continuously and are, therefore, an attractive model for stem cell research. Klein explained, “There is a large population of stem cells, and the way the daughter cells of the stem cells are produced is easy to track – it’s if they are on a conveyor belt.” Early in life, human beings possess a stem cell population that similarly drive tooth development, but they become inactive after the adult teeth are fully formed during early childhood.
In the current study, postdoctoral research fellows Brian Biehs and Jimmy Hu showed that at the base of the growing mouse incisor there is a stem cell population that actively expresses Bmi1. In these cells, Bmi1 suppressed a set of genes called Hox genes. When activated, the Hox genes trigger the development of specific cell types and body structures.
In the mouse incisor, Bmi1 keeps these stem cells in their stem cell state and prevent them from differentiating prematurely or inappropriately. “This new knowledge is useful in a fundamental way for understanding how cell differentiating is controlled and may help us manipulate stem cells to get them to do what we want to do,” said Klein.
As they state in the abstract of their paper: “As Hox gene upregulation has also been reported in other systems when Bmi1 is inactivated our findings point to a general mechanism whereby BMI1-mediated repression of Hox genes is required for the maintenance of adult stem cells and for prevention of inappropriate differentiation.”
Thus this finding from the Klein lab may provide a vital clue for the manipulation of adult stem cells and, perhaps, cancer cells.
During liposuction patients lose a fat cells, fat-based mesenchymal stem cells, and now, according to new results from UCLA scientists, stress-enduring stem cells.
This new stem cell population has been called a Multi-lineage Stress-Enduring Adipose Tissue or Muse-AT stem cells. UCLA scientists found Muse-AT stem cells by accident when a particular machine in the laboratory malfunctioned, killing all the cells found in cells from human liposuction, with the exception on the Muse-AT stem cells.
Gregorio Chazenbalk from the UCLA Department of Obstetrics and Gynecology and his research team discovered, after further tests on Muse-AT stem cells, that they not only survive stress, but might be activated by it.
The removal of Muse-AT stem cells from the human body by means of liposuction revealed cells that express several embryonic stem cell-specific proteins (SSEA3, TR-1-60, Oct3/4, Nanog and Sox2). Furthermore, Muse-AT stem cells were able to differentiate into muscle, bone, fat, heart muscle, liver, and neuronal cells. Finally, when Chazenbalk and his group examined the properties of Muse-AT stem cells, they discovered that these stem cells could repair and regenerate tissues when transplanted back into the body after having been exposed to cellular stress.
“This population of cells lies dormant in the fat tissue until it is subjected to very harsh conditions. These cells can survive in conditions in which usually cancer cells can survive. Upon further investigation and clinical trials, these cells could prove a revolutionary treatment option for numerous diseases, including heart disease, stroke and for tissue damage and neural regeneration,” said Chazenbalk.
Purifying and isolating Muse-AT stem cells does not require the use of a cell sorter or other specialized, high-tech machinery. Muse-AT stem cell can grow in liquid suspension, where they grow as small spheres or as adherent cells that pile on top of each other to form aggregates, which is rather similar to embryonic stem cells and the embryoid bodies that they form.
We have been able to isolate these cells using a simple and efficient method that takes about six hours from the time the fat tissue is harvested,” said Chazenbalk. “This research offers a new and exciting source of fat stem cells with pluripotent characteristics, as well as a new method for quickly isolating them. These cells also appear to be more primitive than the average fat stem cells, making them potentially superior sources for regenerative medicine.”
Embryonic stem cells and induced pluripotent stem cells are the two main sources of pluripotent stem cells. However, both of these stem cells have an uncontrolled capacity for differentiation and proliferation, which leads to the formation of undesirable teratomas, which are benign tumors that can become teratocarcinomas, which are malignant tumors. According to Chazenbalk, little progress has been made in resolving this defect (I think he overstates this).
Muse-AT stem cells were discovered by a research group at Tokohu University in Japan and were isolated from skin and bone marrow rather than fat (see Tsuchiyama K, et al., J Invest Dermatol. 2013 Apr 5. doi: 10.1038/jid.2013.172). The Japanese group showed that Muse-AT stem cells do not form tumors in laboratory animals. The UCLA group was also unable to get Muse-AT stem cells to form tumors in laboratory animals, but more work is necessary to firmly establish that these neither form tumors nor enhance the formation of other tumors already present in the body.
Chazenbalk also thought that Muse-AT stem cells could provide an excellent model system for studying the effects of cellular stress and how cancer cells survive and withstand high levels of cellular stress.
Chazenbalk is understandable excited about his work, but other stem cells scientists remain skeptical that this stem cells population has the plasticity reported or that these cells are as easily isolated as Chazenbalk says. For a more skeptical take on this paper, see here.
Type 1 diabetics must inject themselves with insulin on a daily basis in order to survive. Without these shots, they would die.
In most cases, type 1 diabetics have diabetes because their immune systems have attacked their insulin-producing cells and have destroyed them. However, a recent study at the University of Missouri has revealed that the immune system-dependent damage to the pancreas in type 1 diabetics goes beyond direct damage to the insulin-producing cells in the pancreas, The immune response also destroys blood vessels that feed tissues within the pancreas. This finding could provide the impetus for a cure that includes a combination of drugs and stem cells.
Habib Zaghouani and his research team at the University of Missouri School of Medicine discovered that “type 1 diabetes destroys not only insulin-producing cells but also blood vessels that support them,” explained Zaghouani. “When we realized how important the blood vessels were to insulin production, we developed a cure that combines a drug we created with adult stem cells from bone marrow. The drug stop the immune system attack, and the stem cells generate new blood vessels that help insulin-producing cells to multiply and thrive.”
Type 1 diabetes or juvenile diabetes, can lead to numerous complications, including cardiovascular disease, kidney damage, nerve damage, osteoporosis and blindness. The immune response that leads to type 1 diabetes attacks the pancreas, and in particular, the cell clusters known as the islet of Langerhans or pancreatic islets. Pancreatic islets contain several hormone-secreting cells types, but the one cell type in particular attacked by the immune system in type 1 diabetics are the insulin-secreting beta cells.
Destruction of the beta cells greatly decreases the body’s capability to make insulin, and without sufficient quantities of insulin, the body’s capability to take up, utilize and store sugar decelerates drastically, leading to mobilization of fats stores, the production of acid, wasting of several organs, excessive water loss, constant hunger, thirst, urination, acidosis (acidification of the blood), and eventually coma and death if left untreated.
The immune system not only destroys the beta cells, it also causes collateral damage to small blood vessels (capillaries) that carry blood to and from the pancreatic islets. This blood vessel damage led Zaghouani to examine ways to head this off at the pass and heal the resultant damage.
In previous studies, Zaghouani and others developed a drug against type 1 diabetes called Ig-GAD2. Treatment with this drug stops the immune system from attacking beta cells, but, unfortunately too few beta cells survived the onslaught from the immune system to reverse the disease. In his newest study, Zaghouani and his colleagues treated non-obese diabetic (NOD) with Ig-GAD2 and then injected bone marrow-based stem cells into the pancreas in the hope that these stem cells would differentiate into insulin-secreting beta cells.
“The combination of Ig-GAD2 and bone marrow [stem] cells did result in production of new beta cells, but not in the way we expected,” explained Zaghouani. “We thought the bone marrow [stem] cells would evolve directly into beta cells. Instead, the bone marrow cells led to growth of new blood vessels, and it was the new blood vessels that facilitated reproduction of the new beta cells. In other words, we discovered that to cure type 1 diabetes, we need to repair the blood vessels that allow the subject’s beta cells to grow and distribute insulin throughout the body.”
Zaghouani would lie to acquire a patent for his promising treatment and hopes to translate his preclinical research discovery from mice to larger animals and then to humans. In the meantime, his research continues to be funded by the National Institutes of Health and the University of Missouri.
To repair cartilage, surgeons typically take a piece of cartilage from another part of the injured joint and patch the damaged area, this procedure depends on damaging otherwise healthy cartilage. Also, such autotransplantation procedures are little protection against age-dependent cartilage degeneration.
There must be a better way. Bioengineers want to discover more innovative ways to grow cartilage from patient’s own stem cells. A new study from the University of Pennsylvania might make such a wish come true.
This research, comes from the laboratories of Associate professors Jason Burdick and Robert Mauck.
“The broad picture is trying to develop new therapies to replace cartilage tissue, starting with focal defects – things like sports injuries – and then hopefully moving toward surface replacement for cartilage degradation that comes with aging. Here, we’re trying to figure the right environment for adult stem cells to produce the best cartilage,” said Burdick.
Why use stem cells to make cartilage? Mauck explained, “As we age, the health and vitality of cartilage cells declines so the efficacy of any repair with adult chondrocytes is actually quite low. Stem cells, which retain this vital capacity, are therefore ideal.”
Burdick and his colleagues have long studied mesenchymal stem cells (MSCs), a type of adult stem cell found in bone marrow and many other tissues as well that can differentiate into bone, cartilage and fat. Burdick’s laboratory has been investigating the microenvironmental signals that direct MSCs to differentiate into chondrocytes (cartilage-making cells).
A recent paper from Burdick’s group investigated the right conditions for inducing fat cell or bone cell differentiation of MSCs while encapsulated in hydrogels, which are polymer networks that simulate some of the environmental conditions as which stem cells naturally grow (see Guvendiren M, Burdick JA. Curr Opin Biotechnol. 2013 Mar 29. pii: S0958-1669(13)00066-9. doi: 10.1016/j.copbio.2013.03.009). The first step in growing new cartilage is initiating cartilage production or chondrogenesis. To do this, you must convince the MSCs to differentiate into chondrocytes, the cells that make cartilage. Chondrocytes secrete the spongy matrix of collagen and acidic sugars that cushion joints. One challenge in promoting MSC differentiation into chondrocytes is that chondrocyte density in adult tissue is rather low. However, cartilage production requires that the chondrocytes be in rather close proximity.
Burdick explained: “In typical hydrogels used in cartilage tissue engineering, we’re spacing cells apart so they’re losing that initial signal and interaction. That’s when we started thinking about cadherins, which are molecules that these cells used to interact with each other, particularly at the point they first become chondrocytes.”
In order to simulate this microenvironment, Burdick and his collaborators and colleagues used a peptide sequence that mimics these cadherin interactions and bound them to the hydrogels that were then used to encapsulate the MSCs.
According to Mauck, “While the direct link between cadherins and chondrogenesis is not completely understood, what’s known is that if you enhance these interactions early during tissue formation, you can make more cartilage, and, if you block them, you get very poor cartilage formation. What this gel does is trick the cells into think it’s got friends nearby.”
See L Bian, et al., PNAS 2013; DOI:10.1073/pnas.1214100110.
A laboratory at the University of North Carolina at Chapel Hill has, for the first time, isolated adult stem cells from human intestinal tissue. This achievement should provide a much-needed resource for stem cells researchers to examine the nuances of stem cell biology. Also, these new stem cells should provide stem cell researchers a new tool to treat inflammatory bowel diseases or to mitigate the side effects of chemotherapy and radiation, which often damage the gut.
Scott T. Magness, assistant professor in the departments of physiology at UNC, Chapel Hill, said, “Not having these cells to study has been a significant roadblock to research. Until now, we have not had the technology to isolate and study these stem cells – now we have the tools to start solving many of these problems.”
The study represents a leap forward for a field that for many years has had to resort to conducting experiments with mouse stem cells. While significant progress has been made using mouse models, differences in stem cell biology between mice and humans have kept researchers from investigating new therapeutics for human afflictions.
Adam Grace, a graduate student in Magness’ lab, and one of the first authors of this publication, noted, “While the information we get from mice is good foundational mechanistic data to explain how this tissue works, there are some opportunities that we might not be able to pursue until we do similar experiments with human tissue”
This study from the Magness laboratory was the first in the United States to isolate and grow single intestinal stem cells from mice. Therefore, Magness and his colleagues already had experience with the isolation and manipulation of intestinal stem cells. In their quest to isolate human intestinal stem cells, Magness and his colleagues also procured human small intestinal tissue for their experiments that had been discarded after gastric bypass surgery at UNC.
To develop their technique, Magness and others simply tried to recapitulate the technique they had developed in used to isolate mouse intestines to isolate stem cells from human intestinal stem cells. They used cell surface molecules found on in the membranes of mouse intestinal stem cells. These proteins, CD24 and CD44, were also found on the surfaces of human intestinal stem cells. Therefore, the antibodies that had been used to isolate mouse intestinal stem cells worked quite well to isolate human intestinal stem cells. Magness and his co-workers attached fluorescent tags to the stem cells and then isolated by means of fluorescence-activated cell sorting.
This technique worked so well, that Magness and his colleagues were able to not only isolated human intestinal stem cells, but also distinct types of intestinal stem cells. These two types of intestinal stem cells are either active stem cells or quiescent stem cells that are held in reserve. This is a fascinating finding, since the reserve cells can replenish the stem cell population after radiation, chemotherapy, or injury.
“Now that we have been able to do this, the next step is to carefully characterize these populations to assess their potential, said Magness. He continued: “Can we expand these cells outside the body to potentially provide a cell source for therapy? Can we use these for tissue regeneration? Or to take it to the extreme, can we genetically modify these cells to cure inborn disorders or inflammatory bowel disease? Those are some questions that we are going to explore in the future.”
Certainly more papers are forthcoming on this fascinating and important topic.
Materials researchers at the University of Southampton, UK, have invented a new plastic that directs pluripotent stem cells to attach and differentiate into bone. This technology could lead to new therapies for people who suffer osteoporosis and osteoarthritis and need hip replacements.
Dr. Emmajayne Kingham has collaborated with University of Glasgow researchers to develop special plastics, grow embryonic stem cells on them, and assess the behavior of the cells on the plastic material. Normally, stem cells require chemicals in order to direct their differentiation. However, in this experiment, the only directing the cells was the microscopic topography of the plastic surface.
This plastic material, polycarbonate, is a very versatile material and is found in substances as hard an inflexible and bullet-proof glass to compact discs. This material is also rather inexpensive and because it can direct the differentiation of embryonic stem cells into bone tissue cells, it can make bone from pluripotent stem cells quite cheaply.
Professor Richard Oreffo, the leader of the Southampton research team said: “To generate bone cells for regenerative medicine and further medical research remains a significant challenge. However, we have found that by harnessing surface technologies that allow the generation and ultimately scale up of human embryonic stem cells to skeletal cells, we can aid the tissue engineering process. This is very exciting.”
Oreffo continued: “Our research may offer a whole new approach to skeletal regenerative medicine. The use of nontopographical patterns could enable new cell culture designs, new device designs, and could herald the development of new bone repair therapies as well as further human stem cell research.”
These data expand on previous work in which the Southampton research group teamed up with another research group from the University of Glasgow to show that plastic surfaces with embossed patterns encouraged the growth and spread of adult stem cells while preventing the stem cells from differentiating. Such a process uses inexpensive polycarbonate plastics that are inexpensive and relatively easy top manufacture.
“Our previous collaborative research showed exciting new ways to control mesenchymal stem cell – stem cells from bone marrow of adults – growth and differentiation on nanoscale patterns,: said Nikolaj Gadegaard from the University of Glasgow.
He continued, “This new Southampton discovery shows a totally different cell source, embryonic, also respond in a similar manner and this really starts to open this new field of discovery up. With more research impetus, it gives us the hope that we can go on to target a wider variety of degenerative conditions than we originally aspired to. This result is of fundamental significance.”
Scientists at Queen’s University Belfast hope to design a new approach for treating the eyesight of diabetic patients by using adult stem cells.
Millions of diabetics every year are at risk for losing their eyesight due to diabetic retinopathy. When high blood sugar causes blood vessels in the eye to leak or become blocked, failed blood flow damages the retina and lead to vision impairment. If left untreated, diabetic retinopathy can lead to blindness.
The Queen’s University Belfast group have initiated the REDDSTAR study, which stands for Repair of Diabetic Damage by Stromal Cell Administration, and this study involves researchers from the Queen’s Center for Vision and Vascular Science in the School of Medicine, Dentistry and Biomedical Sciences. REDDSTAR begins with the isolation of stem cells from patients and expanding them in the laboratory. Then these patient-specific cells are delivered to the patient from whom they were originally drawn in order to repair the blood vessels in the eye. This blood vessel repair is especially useful in patients with diabetic retinopathy.
Presently, diabetic retinopathy is treated with laser ablation of new blood vessels that grow in response to damage. These new blood vessels become so dense that they obscure vision. However, presently, there are no treatments to control the progression of diabetic complications.
Alan Stitt, the director of the Centre for Vision and Vascular Science at Queen’s and lead scientist for the REDDSTAR study, said, “The Queen’s component of the REDDSTAR study involves investigating the potential of a unique stem cell population to promote repair of damaged blood vessels in the retina during diabetes.” Professor Stitt continued: “The impact could be profound for patients, because regeneration of damaged retina could prevent progression of diabetic retinopathy and reduce the risk of vision loss.”
“Treatments for diabetic retinopathy are not always satisfactory. They focus on end-stages and fail to address the root causes of the condition. A novel, alternative therapeutic approach is to harness adult stem cells to promote regeneration of the damaged retinal blood vessels and thereby prevent and/or reverse retinopathy.”
Stitt said the new research project is one of several regenerative medicine approaches ongoing at his research center. Their approach is to isolate a rather well-defined population of stem cells and then deliver those stem cells to sites in the body that have been ravaged by diabetes. In particular patients, these strategies have produced remarkable benefits from stem cell-mediated repair of their blood vessels. Treatments such as this one are simply the first step in the quest to develop exciting, effective and new therapies in an area of medicine where such therapies are desperately needed.
In the REDDSTAR study, stem cells from bone marrow are used and these stem cells are provided by Orbsen Therapuetics, which is a spin-off from the Science Foundation Ireland-funded Regenerative Medicine Institute (REMEDI) at NUI Galway.
This project will design protocols for growing these bone marrow-derived stem cells and they will be tested in several preclinical models of diabetes and diabetic complications at research centers in Belfast, Galway, Munich, Berlin, and Porto before human clinical trails take place in Denmark.
Queen’s Centre for Vision and Vascular Science is a key focus of the University’s ambitious 140-million pound “together we can go Beyond” fundraising campaign. This campaign is due to expand the Vision Science program further when the University’s new 32-million pound Wellcome-Wolfson Centre for Experimental Medicine opens in 2015. Along with vision, two new programs in Diabetes and Genomics will also be established in the new Center. These Center should stimulate further investment and global collaborations between biotech and health companies in Ireland.
BRCA1 is a gene that plays a huge role in breast cancer. Particular mutations in BRCA1 predispose women increased risks of breast cancer cervical, uterine, pancreatic, and colon cancer and men to increased risks of pancreatic cancer, testicular cancer, and early-onset prostate cancer.
BRCA1 encodes a protein that helps repair damage to chromosomes. When this protein product does not function properly, cells cannot properly repair acquired chromosomal damage, and they die or become transformed into cancer cells.
What does this have to do with stem cells? A study led by Cédric Blanpain from the Université libre de Bruxelles showed that BRCA1 is critical for the maintenance of hair follicle stem cells.
Peggy Sotiropoulou and her colleagues in Blanpain’s laboratory showed that when BRCA1 is deleted, hair follicle cells how very high levels of DNA damage and cell death. This accumulated DNA damaged drives the follicle stem cells to divide furiously until they burn themselves out. This is in contrast to the other stem cell populations in the skin, particularly those in the sebaceous glands and epidermis, which are maintained and seem unaffected by deletion of BRCA1.
Sotiropoulou said of these results: “We were very surprised to see that distinct types of cells residing within the same tissue may exhibit such profoundly different responses to the deletion of the same crucial gene for DNA repair.”
This work provides some of the first clues about how DNA repair mechanisms in different types of adult stem cells are employed at different stages of stem cells activation. Blanpain and his group is determining if other stem cells in the body are also affected by the loss of BRCA1. These results might elucidate why mutations in BRCA1 causes cancer in the breast and ovaries, but not in other tissues.
Researchers from the extremely prolific Salk Institute laboratory of Juan Carlos Izpisua Belmonte have designed a new method for generating stem cells from mature, adult cells that has the potential to boost laboratory production of stem cells. This technique could overcome an important barrier to regenerative medical therapies that would replace damaged or unhealthy tissues.
This new stem cell production technique allows for the unlimited production of stem cells and stem cell derivatives and also considerably reduces the time it takes to produce these cells; instead of taking two months, Juan Carlos’ lab can make them in two weeks.
Ignacio Sancho-Martinez, one of the first authors of this paper, said, “One of the barriers that needs to be overcome before stem cell therapies can be widely adopted is the difficulty of producing enough cells quickly enough for acute clinical application.”
Sancho-Martinez and his colleagues in the Belmonte laboratory published this new method in the journal Nature Methods.
Stem cells are important for regenerative medicine because of their pluripotency. Pluripotency refers to the ability of a stem cell to differentiate into any cell in the adult human body. Pluripotent stem cells for research and clinical uses are derived from one of two sources; embryos or from adult cells that have been reprogrammed to be pluripotent.
Pluripotent stem cells from embryos – embryonic stem cells (ESCs) – have the disadvantage of being rejected by the immune system when they are placed in the body of a patient. Therefore, scientists have attempted to develop clinical therapies with pluripotent stem cells made by reprogramming adult cells – induced pluripotent stem cells or iPSCs. Because these cells are made from the patient’s own cells, they should possess the same set of surface proteins as the patient. Therefore the patient’s immune should not recognize them as foreign.
Unfortunately, there are drawbacks to iPSCs. The method by which iPSCs are made from adult cells is rather inefficient and is also time-consuming and labor-intensive. Furthermore, once the iPSCs are made, they must be differentiated into the desired cell type. Differentiation is rarely 100% efficient and if the differentiated cells cannot be effectively isolated from the incompletely differentiated cells, they can cause tumors upon implantation.
To circumvent these problems, scientists have tried to reprogram cells to something other than a pluripotent state. Reprogramming adult cells into a “multipotent” state rather than a pluripotent state is potentially easier, faster, and does not carry the risk of tumor formation. Unlike pluripotent cells, which can become any adult cell type, multipotent cells can only differentiate into a small subset of the possible adult cells. The reprogramming of adult cells into multipotent progenitor cells is called “direct lineage conversion.”
While direct lineage conversion works rather well, it is a one-for-one conversion; one skin cell is converted into one muscle cell, and so on. This makes the technique inherently unproductive, since regenerative medical strategies will require large quantities of cells. Thus, Izpisua Belmonte’s laboratory examined ways to increase the output from direct lineage conversion.
Leo Kurian, a Salk Institute post-doctoral researcher, and one of the first co-authors on this paper, explained it this way: “Beyond the obvious issue of safety, the biggest consideration when thinking about stem cells for clinical use is productivity.”
To this end, this Salk Institute team invented a new technique that they called “indirect lineage conversion,” or ILC. During ILC, somatic cells are pushed back to an earlier stage of development that is suitable for the specification of multipotent progenitor cells. Because these multipotent progenitor cells have the capacity to divide, they can be expanded to greater numbers.
ILC has the potential to produce multiple lineages once adult cells are transferred to the a special environment designed by Belmonte’s lab. Most importantly, ILC saves time and also reduces the risk of tumor formation, since the adult cells are reprogrammed to become particular lineage progenitors rather than iPSCs. In the words of Sancho-Martinez, “We don’t push then to zero, we just push them back a bit.”
See Leo Kurian, et al., “Conversion of human fibroblasts to angioblast-like progenitor cells.” Nature Methods 2012; DOI:10.1038/nmeth.2255.
Stem cell scientists from Dublin, Ireland have exploited the electrical properties of a material that is widely used in nanotechnology to grow cells that can more efficiently regenerate the heart.
In Ireland, heart disease is the leading cause of death. Heart attacks damage the heart muscle, and the adult heart has very little ability to heal itself. Presently, there are no approved methods for repairing damaged heart muscle.
New work from a research team at the Regenerative Medicine Institute (REMEDI) at the National University of Ireland, in collaboration with Trinity College Dublin brought together the skill of materials scientists, biologists and physicians.
Cell-based therapies for heart disease have been the subject of intense research over the last ten years, and there have certainly been some very hopeful clinical trials in the last few years. This new approach, led by Drs. Valerie Barron and Mary Murphy at the REMEDI, capitalized on an observation of carbon nanotubes. Carbon nanotubes are reactive to electrical stimulation. These nanotubes were then used to modify the activity of mesenchymal stem cells from bone marrow.
According to Dr. Barrow, “The electrical properties of the nanomaterial triggered a response in the mesenchymal (adult) stem cells, which we sourced from human bone marrow. In effect, they became electrified, which made them morph into more cardiac-like cells.” She continued: “This is a totally new approach and provides a ready-source of tailored cells, which have the potential to be used as a new therapy. Excitingly, this symbiotic strategy lays the foundation for other clinically challenging areas such as in the brain and the spinal cord.”
Mesenchymal stem cells have a deep history as a source of cells for treating heart attack patients. Mesenchymal stem cells (MSCs) have the capacity to improve the heart if implanted after a heart attack, but the mechanism by which they do this is multifaceted and somewhat mysterious. The therapeutic capacity of MSCs is improved if they are pre-conditioned or genetically modified to survive better in the hostile environment of the heart after a heart attack. However, MSCs have only a very limited ability to differentiate into heart muscle cells, and this is one of the largest limitations MSCs as therapeutic agents for heart attacks.
This new work suggests that MSCs can be shifted into a more heart muscle-like state by means of electrical stimulation. Nanotube-mediated stimulation seems to be even more effective for such a shift, and this work might be the beginning of a new strategy to augment the therapeutic capacities of MSCs for treating heart attacks.
Adipose tissue, otherwise known as fat, contains a stem cell population. This stem cell population consists of mesenchymal stem cells (MSCs). MSCs have the ability to form cartilage, bone, fat, or smooth muscle rather readily, but the efficiency with which different MSC populations forms these cells types differs dramatically.
To that end, MSCs can be used to form blood vessels, since they form endothelial cells (the cell types that line the inside of blood vessels). The beauty of this capacity is that millions of patients with cardiovascular disease need small-diameter vessel grafts for those procedures that require the rerouting of blood around blocked arteries.
Blood vessels grown in the laboratory from fat-derived MSCs can help solve this problem, since they are made from living tissue and not artificial materials. Blood vessels made from artificial materials (for example, Rayon), tend to promote the formation of blood clots.
The lead author of this work is Matthias Nollert, who is associate professor at the University of Oklahoma School of Chemical, Biological and Materials Engineering in Norman, Oklahoma. His commented on this work: “Current small-diameter vessel grafts carry an inherent risk of clotting, being rejected or otherwise failing to function normally. Our engineered blood vessels have good mechanical properties and we believe they will contract normally when exposed to hormones. They also appear to prevent the accumulation of blood platelets – a component in blood that causes arteries to narrow.
For this study, adult stem cells derived from fat were differentiated into smooth muscle cells in the laboratory and they seeded onto a very thin layer of collagen (a protein found in tendons, ligaments, basement membranes, and many other places). Once the stem cells multiplied, they were rolled into tubes that matched the diameter of small blood vessels. Then after growing in culture for three-four weeks, they formed usable blood vessels.
This technique has the potential to become an “off-the-shelf” technique to make replacement vessels for vascular surgery, according the Nollert. Nollert and his group hope to have a working prototype to test in laboratory animals within the next six months.
Transplantation of adult stem cells into the heart after a heart attack has shown remarkable promise as a treatment for heart patients. The implanted stem cells improve heart function, reinforce heart structure, improve blood circulation in the heart, and reduce the size of the heart scar. Such treatments. however, are hampered by the lack of persistence of implanted stem cells. Only a vast minority of the implanted stem cells survive in the inhospitable environment of the infarcted heart, and the massive cell die-off limits the efficacy of stem cell transplants in the heart.
Fortunately, there are ways to allay this problem. Genetically engineering stem cells to express proteins known to enhance cell survival is one way to ensure that implanted cells survive when implanted. However, getting FDA approval for a clinical trial with genetically-engineered cells will prove to be immensely difficult. A more promising approach is to pretreat the cells with various growth factors, growth conditions or drugs to precondition them to survive in the heart. To that end, scientists at the Davis Heart and Lung Research Institute at Ohio State University have used a commonly prescribed heart drug called “carvedilol” to enhance the survive of bone marrow mesenchymal stem cells in the heart.
Faternat Hassan and his colleagues in the laboratory of Mahmood Khan treated mesenchytmal stem cells (MSCs) from rats with carvedilol and a related drug called “atenolol.” These drugs are members of a drug category called “beta-blockers.”
Beta-blockers are given to lower blood pressure, or to protect the heart after a heart attack from undergoing further deterioration. They bind to the receptors for epinephrine and norepinephrine and block them, which slows the heart down and reduces blood pressure. After a heart attack, however, Beth Haebecker at Oregon Health and Science University has shown that the sympathetic nerves to the heart make very large amounts pf norepinephrine and this is responsible for the remodeling and eventual deterioration of the heart. Beta-blockers can prevent this norepinephrine-based deterioration of the heart.
Over ten years ago, Yue et al. (1992) and Feuerstein (1998) showed that carvedilol has the ability to quench the deleterious effects of damaging molecules. Therefore, carvedilol might protect stem cells from dying in the heart after transplantation.
To begin, Khan’s group cultured MSCs with carvedilol and atenolol for one hour and then subjected the cells to chemical stress by treating them with hydrogen peroxide. The carvedilol-treated cells survived the hydrogen peroxide treatment much better than either the atenolol-treated MSCs or the negative controls that were not pretreated with anything.
For their next experiment, they divided into five groups of six animals each. The first group was operated on but were not give heart attacks. The second group was given heart attacks and no further treatments. The third group was given carvedilol (5 mg/kg body weight) after the heart attack. The fourth group, was MSC treatments, and the fifth group received MSC transplantations plus carvedilol at the previously mentioned dosages. The results showed that the MSC + carvedilol group fared substantially better than all the rest (except for the sham operated group). The heart structure and heart physiology were far superior in the MSC + carvedilol group.
Finally, Khan’ group made a remarkable discovery. Carvedilol prevented the heart from undergoing extensive cell death and decreased the formation of scar tissue. When combined with MSCs, carvedilol’s effect on cell death was amplified. Further investigation demonstrated that carvedilol prevented activation of a protein called “caspase-3.”
Caspases are proteins that degrade other proteins, but they are activated when the cell is damaged beyond all reasonable expectations of repair and the only fitting response for the cell is to die. This process of programmed cell death is called “apoptosis.” The induction of apoptosis is, as you might guess, very tightly controlled, and one of the main regulators of the initiation of apoptosis are the caspases. Caspases exist as inactive enzymes in the cell, but they are activated if the cells is exposed to drugs,conditions, or chemicals that induce cell death. There are three caspases that activate the rest of them and they are caspase 3, 8, & 9, and of these, caspases 3 and 9 are the most important.
Carvedilol treatment caused a significant down-regulation of caspase-3 in heart muscle cells after a heart attack. Furthermore, it prevented the expression of caspase-3 in implanted MSCs, thus increasing MSC survival. Additionally, genes that are known to improve cell survival were also activated in heart muscle cells after carvedilol and MSC treatment.
Thus carvedilol did double duty. It helped the ailing heart, but it also helped the heart help itself by preventing the untimely death of transplanted MSCs. This allowed the MSCs to work their healing processes for a much longer time. The final result was that the carvedilol + MSC-implanted rats showed hearts that were in much better shape than the those in the other groups with the exception of the sham-operated group.
This also suggests that carvedilol should be used with transplanted MSCs in the next clinical trial that utilizes transplanted MSCs.
Wesley Smith has an interesting post about the ability of fat-based stem cells to differentiate into bone-making cells that make good bone. Apparently, human clinical trials are in the works. An Israeli biotechnology company used a bioreactor to grow the cells, and then seeded the stem cells into a three-dimensional scaffold. This scaffold directed the bone-making cells to form bone that resembled living human bone. These bones have been implanted into living animals and seem to be ready for human clinical trials.
Nevertheless, Smith uses these reports to reminisce back to Amendment 2 in the state of Missouri in 2006, when scientists testified before the state legislature than adult stem cells were “unipotent,” which means that they are only able to form one kind of adult cell type. This was a lie in 2006 and is even more a lie in 2012. This goes to show that scientists are funded by public money and it is not beneath them to shade the facts to get more public money. We should always view what scientist say with some degree of skepticism and criticism. Bowing to them as “experts” is an insult to the scientific method, which does not recognize authority, only the quality of evidence. Check out Smith’s blog entry here and the 2006 one here.
Adult stem cells that have been transplantation into a sick patient are often faced with harsh conditions that lead to their untimely death before they can help the patient. Several different strategies have been applied to stem cells to “toughen them up” so that they can resist these conditions. Treating them with particular growth factors have proven effective in some experiments, as has oxygen or glucose deprivation. A recent paper in the journal ANTIOXIDANTS & REDOX SIGNALING by Gang Lu, Muhammad Ashraf, and Khawaja Husnain Haider from the Department of Pathology at the University of Cincinnati, Ohio has shown that treatment of stem cells with insulin-like growth factor-1 (IGF-1) and glucose and oxygen deprivation activate a biochemical pathway that seems to be common to many different types of stem cells that help cell resist ischemic (oxygen-poor) conditions.
This paper examined bone marrow stem cells. When the bone marrow stem cells were deprived of oxygen and glucose for 12 hours, they discovered that a well-known signaling molecule called ERK1/2 was activated. ERK1/2 stands for “extracellular signal-related kinases-1/2. These molecules are “kinases,” which simply means that they are enzymes that attach phosphate groups to other proteins. These phosphate groups change the 3-D structure of proteins can induce them to change they function. ERK1/2 are activated whenever the cell binds particular types of growth factors. Growth factor-binding sets a series of steps in motion that leads to the activation of ERK1/2. ERK1/2 phosphorylates its target, which sets a phosphorylation cascade into motion, and this changes the behavior of the cell.
There are ways to inhibit ERK1/2 activation, and when the University of Ohio team did just that (with a drug called PD98059), the bone marrow stem cells did not activate ERK1/2 when derived of oxygen and glucose and the cells died. This shows that activation of ERK1/2 occurs as a result of oxygen and glucose deprivation, and the activation of ERK1/2 is required for the cells to survive the harsh conditions.
Next, they discovered that ERK1/2 is also activated by treating the cells with IGF-1. Since IGF-1 treatment also helps stem cells adapt to harsh conditions, it is possible that these two treatments use the same internal mechanism to help stem cells adapt to harsh conditions.
What is a downstream target of ERK1/2 that throws the switch that allows cells to adapt the harsh conditions? The researchers received two clues when they discovered that drugs that prevent the release of calcium ion stores into the cell interior also prevent cells from adapting to harsh conditions. This tipped them off that a target of calcium-ion signaling was probably the downstream target of ERK1/2. That target is protein kinase C (PKC).
To shore up their hypothesis, they treated stem cells with a chemical that is known to activate PKC (phorbol esters). These chemicals completely acclimatized the cells to harsh conditions and when the bone marrow stem cells were grown after they had been engineered with a permanently active form of PKC, the stem cells did not require any preconditioning in order to resist harsh conditions.
These data are remarkable and since calcium signaling is a pathway that we know a great deal about and there are lots of chemicals available to manipulate it, it should be possible to precondition a whole host of stem cells to resist harsh conditions before they are ever used. These types of treatments should improve adult stem cell treatments for a variety of conditions.
Brazilian and American scientists have made induced pluripotent stem cells (iPSCs) from stem cells found in teeth. These adult stem cells are immature enough so that forming iPSCs from that is relatively easy.
Human immature dental pulp stem cells (IDPSCs) are found in dental pulp. Dental pulp is the soft living tissue inside a tooth, and it houses various stem cell populations. These stem cells express a whole cluster of genes normally found in very young and immature cells. Therefore, IDPSCs are “primal” cells that are very young and undifferentiated.
According to Dr. Patricia C.B. Bealtrao-Braga of the National Institute of Science and Technology in Stem and Cell Therapy in Ribeirao Preto, Brazil, human IDPSCs are easily isolated from adult or baby teeth during routine dental visits. IDPSCs are not viewed as foreign by the immune system and can be used in the absence of any drugs that suppress the immune system. They have very valuable cell therapy applications, including the reconstruction of large cranial defects.
Another research project in the Republic of Korea, at the college of Veterinary Medicine, Gyeongsang National University, Republic of Korea have examined a stem cell population from third molars called human dental papilla stem cells (DpaSCs). DpaSCs can form dentin and dental pulp, but they also have biological features that are similar to those of bone marrow-derived mesenchymal stem cells (MSCs).
MSCs have been very heavily studied. While these stem cells have remarkable therapeutic capabilities, they have the disadvantage of only being able to grow in culture or a short period of time. After growing in culture for about a week, MSCs tend to go to sleep and not grow anymore.
DPaSCs, however, have a remarkable capacity to grow in culture. Data from work done in the laboratory of Gyu-Jin Ryo has shown they can grow for a longer period of time than MSCs in culture without going to sleep. Therefore, they not only can form a greater number of progeny, but they can also, potentially, form larger tissues and structures.
Based on their increased culture capabilities, DPaSCs can provide a source of stem cells for tooth regeneration and repair and, possibly, a source of cells for a wide variety of regenerative medical applications.
The gas hydrogen sulfide smells like rotten eggs, and it is also poisonous in high quantities. It is produced throughout the body, and the exact role of it is unknown. However, scientists from the Nippon Dental University in the laboratory of Ken Yaegaki have shown that small quantities of this gas can induce particular adult stem cells to differentiate into liver cells.
Human teeth contain several stem cell populations, and one of these, the dental pulp stem cells, can make liver cells with remarkable efficiency. Dental pulp is composed of connective tissue and cells and dental pulp stem cells can be obtained from teeth after extraction.
Human tooth pulp stem cells contain a subpopulation that possesses a particular cell surface molecule called “CD117,” which is also known as the mast/stem cell growth factor receptor. Those cells with this surface protein were isolated from the rest of the stem cells. They then grew these stem cells in culture, and transferred them to a culture medium that contained a basic nutrient medium (Dulbecco’s modified Eagle’s medium for those who might be interested) and added to that medium, insulin, an iron-binding protein called transferrin, and two growth factors (embryotrophic factor and hepatocyte growth factor) for five days. Then they transferred the cells to another medium that was similar to the previous medium, but also had a cytokine called “oncostatin” and a steroid drug called dexamethasone for 15 days. The atmosphere for these cells included either 5% carbon dioxide, and no or a small amount of hydrogen sulfide (0.05 ng ml−1).
After growing cells under these conditions, those cells that had been grown in the presence of hydrogen sulfide were more liver-like when it came to their biochemistry. Liver cells store large amounts of sugar in the form of glycogen, produce a waste product called urea as a result of a pathway called the urea cycle, and make a large cadre of enzymes and proteins that are specific to the liver. In almost every case, the cells grown in the presence of hydrogen sulfide made more liver-specific proteins than those grown without hydrogen sulfide. The production of urea and glycogen were also increased, and glycogen storage was about five times greater in the hydrogen sulfide-treated group than in the control. especially glycogen which was approximately five times greater compared to the control (p < 0.01). As a result of these experiments, the research group concluded that physiological concentrations of hydrogen sulfide increase the ability of human tooth pulp stem cells to undergo differentiation into liver cells.
Yaegaki commented, “Until now, nobody has produced the protocol to regenerate such a large number of hepatic (liver) cells for human transplantations. Compared to the traditional method of using fetal bovine serum to produce the cells, our method is productive and, most importantly, safe.” Yaegaki continued: “Moreover, these facts suggest that patients undergoing transplantation with the hepatic cells may have no possibility of developing teratomas or cancers, as can be the case when using bone marrow stem cells.”
Clearly, dental stem cells are from a tissue that is normally thrown out. This new life for exfoliated teeth might provide a new role for these tooth-bound stem cells, and might also provide a new way to treat those with devastating liver diseases. For example, systemic lupus erythematosis can decimate the patient’s liver, and without a transplant, the patient might die. Adaptation of this protocol might drive other adult stem cell populations to produce liver cells for therapeutic purposes. The potential is certainly great.
A whole gaggle of stem cells treatments for heart attack patients have been completed. Some patients are definitely helped, but others are not. Some clinical trials have shown a definitively positive effect from stem cell infusions in combination with standard care. Other trials, however, have failed to show any positive benefits to combining stem cell infusions with standard care. What do these clinical trials as a whole tell us?
This question is the realm of “meta-analyses.” While several clinical trials that have given stem cell treatments on heart attack patients have been subjected to meta-analyses, more stem cell trials have been completed, and further analyses are necessary. Meta-analyses take data from separately published studies that were conducted at different times and places and combine these data into a giant database that is subjected to rigorous statistical analysis. One organization that excels at meta-analyses, and has a solid reputation in the field is the Cochrane Library. The Cochrane Library has just completed a systematic meta-analysis of the data generated in 33 different clinical trials that used adult stem cells to treat the hearts of heart attack patients. The Cochrane Library’s analysis revealed that heart function definitely improves after stem cell treatments. However, these same analyses showed that the data are limited by the predominance of small trials and larger clinical trials are necessary to more rigorously demonstrate if the benefit of stem cell treatments in the heart actually means that the treated patients will benefit from a longer and healthier life.
Heart attacks are caused by blocked coronary arteries that prevent life-giving oxygen from flowing to heart muscle. This lack of oxygen causes the demanding heart muscle cells to die, and this cell death damages the heart and leads to the production of a scar that does not contract or conduct electrical impulses. Clinical trials have used adult stem cells from the patient’s own bone marrow to repair and reduce this damage. Although, unfortunately, this treatment regime is only available in facilities that have close links to medical research facilities.
The Cochrane Library authors (David M Clifford and colleagues), cobbled together data from as many clinical trials that used bone marrow stem cells to treat heart attack patients as they could find. In 2008, Cochrane reviewed 13 clinical trials to address this very question. However, since that time, 20 more clinical trials have been completed, and this year, 33 clinical trials that treated 1,765 patients were analyzed. Since the earlier trials continued patient follow-up, there are new data points from many older clinical trials that were also included. These data provide a more precise indication of the effects of stem cell therapy several years after completion of stem cell treatment.
In the analyzed trials, all 1,765 patients had already undergone angioplasty, which is a conventional treatment for heart attack patients. Angioplasty uses an inflatable balloon that is fed into the coronary artery by means of a fine catheter. This catheter is inserted into a large vein and guided by imaging methods to the blocked coronary arteries. Once in place, the balloon is slowly inflated to push the obstructing material to the sides of the artery. This opens up the blocked artery and allows the flow of blood to the heart muscle. To keep the blood vessel open, sometimes a stent is inserted into the blocked vessel. If angioplasty is combined with bone marrow stem cell treatments, the Cochrane reviews finds that such treatments can produce moderate long-term improvement in heart function that is sustained for up to five years. Unfortunately, there was not enough data to reach firm conclusions about increases in survival rates.
Senior author of this review, Enca Martin-Rendon, from the Stem Cell Research laboratory at the John Radcliffe Hospital in Oxford, UK, said, “This new treatment may lead to moderate improvement in heart function over standard treatments. Stem cell therapy may also reduce the number of patients who later die or suffer from heart failure, but currently there is a lack of statistically significant evidence based on the small number of patients treated so far.”
Will such treatments become part of the treatment for a heart attack? At this point it is difficult to say with any certainty. It is simply too early to establish guidelines for standard practice, since several labs have used differing transplantation and cell isolation and storage methods. According to the Cochrane Review, further work is required to properly standardize the procedure. For instance, there is little agreement on the dosage of cells for the heart, even though several studies have shown a dose-specific effect. Secondly, a standardized protocol for when after the heart attack treatment should be given, and what methods most accurately measure heart function must be constructed before such a procedure is universally offered to patients. Martin-Rendon noted, “The studies were hard to compare because they used so many different methods. Larger trials with standardized treatment procedures would help us to know whether this treatment is really effective.
A larger trial is already in the works, since the task force of the European Society of Cardiology for Stem Cells and Cardiac Repair received a recent, sizable grant from the European Union Seventh Framework Programme for Research and Innovation (EU FP7-BAMI) to initiate such a large trials. The Principal Investigator for this trial (called BAMI) who is also a co-author of this review, Anthony Mathur, said, ”The BAMI trial will be the largest stem cell therapy trial in patients who have suffered heart attacks and will test whether this treatment prolongs the life of these patients.”