New Neuron Formation Required for Maintenance of Olfactory Nerves in Mice


For many years, scientists and neurologists were convinced that neurons in the brain only formed during early development, and after that it was simply impossible for new neurons to be formed.  More recent work, however, has shown this to be largely untrue, since several regions of the brain possess resident stem cell populations that can divide to replenished damaged neurons and even augment learning and memory.  The capacity of neural stem cell populations to regenerate the central nervous system is a continuing field of intense research, and scientists at the National Institutes of Health (NIH) have reported one region of the central nervous system that can form new brain cells; the mouse olfactory system, which processes smells.  This work appeared in the October 8 issue of the Journal of Neuroscience.

“This is a surprising new role for brain stem cells and changes the way we view them,” said Leonardo Belluscio, Ph.D., a scientist at NIH’s National Institute of Neurological Disorders and Stroke (NINDS) and lead author of the study.

The olfactory bulb is at the front of the brain (shown as “A” in he picture below), and is rather small in humans, but somewhat larger in other animals.  This structure receives information directly from the nose about volatile odors.  Neurons in the olfactory bulb sort through this smelly information and relay neural signals to the rest of the brain.  This is the point at which we become aware of the smells in our surroundings.  The loss of the sense of smell is sometimes an early symptom in a variety of neurological disorders, including Alzheimer’s and Parkinson’s diseases.

Olfactory lobes in brain

 

Neurogenesis is the process by which neuroprogenitor cells are produced in the subventricular zone deep in the brain.  After birth, these cells migrate to the olfactory bulb, which becomes the final location of these cells.  Once they arrive at the olfactory bulb. the neuroprogenitor cells divide, differentiate, and form connections with existing cells to become integrated into the neural circuitry in the olfactory bulb and elsewhere.

Dr. Belluscio studies the olfactory system, and for this study, he collaborated with Heather Cameron, Ph.D., a neurogenesis researcher at the NIH’s National Institute of Mental Health.  The goal of this study was to better understand how the continuous addition of new neurons affects the neural organization of the olfactory bulb.  They used two different types of genetically engineered laboratory mice that had specifically genes knocked out.  Consequently, these mice lacked the specific stem cell populations that generate the new neurons during adulthood, without affecting the other olfactory bulb cells.  Previously, this remarkable level of specificity had not been achieved.

Belluscio and his coworkers had previously shown that plugging the nostrils of the animals so that they are not subject to olfactory stimulation causes the axonal extensions of the olfactory neurons to dramatically spread out and lose the precise network of connections with other cells that are normally observed under normal conditions.  They also showed that this widespread disrupted circuitry could re-organize itself and restore its original precision once the sensory deprivation was reversed.  Therefore, Belluscio and his team temporarily plugged a nostril in their lab animals to block olfactory sensory information from entering the brain.  However, if laboratory animals that do not produce new neuroprogenitors are subjected to this type of manipulation, once the nose is unblocked, new neurons are prevented from forming and entering the olfactory bulb, and, therefore, the neural circuits remain in disarray. “We found that without the introduction of the new neurons, the system could not recover from its disrupted state,” said Dr. Belluscio.

Further examination showed that elimination of the formation of adult-born neurons in mice that did not experience sensory deprivation also caused the organization of the olfactory bulb organization began to degenerate, eventually resembling the pattern observed in animals prevented from receiving sensory information from the nose.  Belluscio and his team also noticed that the extent of stem cell loss was directly proportional to the degree of disorganization in the olfactory bulb.

According to Belluscio, circuits of the adult brain are thought to be rather stable and that introducing new neurons alters the existing circuitry, causing it to re-organize. “However, in this case, the circuitry appears to be inherently unstable requiring a constant supply of new neurons not only to recover its organization following disruption but also to maintain or stabilize its mature structure. It’s actually quite amazing that despite the continuous replacement of cells within this olfactory bulb circuit, under normal circumstances its organization does not change,” he said.

Dr. Belluscio and his colleagues think that these new neurons in the olfactory bulb are important for the maintenance of activity-dependent changes in the brain, which help animals adapt to a constantly varying environment.

“It’s very exciting to find that new neurons affect the precise connections between neurons in the olfactory bulb. Because new neurons throughout the brain share many features, it seems likely that neurogenesis in other regions, such as the hippocampus, which is involved in memory, also produce similar changes in connectivity,” said Dr. Cameron.

The underlying basis of the connection between neurological disease and changes in the olfactory system is also unknown but may come from a better understanding of how the sense of smell works. “This is an exciting area of science,” said Dr. Belluscio, “I believe the olfactory system is very sensitive to changes in neural activity and given its connection to other brain regions, it could lend insight into the relationship between olfactory loss and many brain disorders.”

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New Standard of Care for Umbilical Cord Blood Transplants


New research led by John Wagner, Jr., M.D., director of the Pediatric Blood and Marrow Transplantation program at the University of Minnesota and a researcher in the Masonic Cancer Center, University of Minnesota, has established a new standard of care for children who suffer from acute myeloid leukemia (AML).

In a recent paper in the New England Journal of Medicine, Wagner and his coworkers compared clinical outcomes in children who suffered from acute leukemia and myelodysplastic syndrome who received transplants of either one unit or two units of partially matched cord blood. This large study was conducted at multiple sites across the United States, between December 2006 and February 2012. Coordinating the study was the Blood and Marrow Transplant Clinical Trials Network (BMT CTN) in collaboration with the Pediatric Blood and Marrow Transplant Consortium and the Children’s Oncology Group.

Umbilical cord blood provides a wonderfully rich source of blood-forming stem cells, and has been demonstrated to benefit many diseases of the blood or bone marrow, as in the case of leukemia and myelodysplasia, or bone marrow failure syndromes, hemoglobinopathies, inherited immune deficiencies and certain metabolic diseases. For leukemia patients cord blood offers several advantages since there is no need for strict tissue-type matching (human leukocyte antigen or HLA matching) or for a prolonged search for a suitable donor.

Wagner and others discovered that the survival rates of children who received either one or two units of umbilical cord blood were about the same, but, overall, their recorded survival rates were better than those reported in prior published reports. These higher survival rates, therefore, represent a new standard of care for pediatric patients, for whom there is often an adequate single cord blood unit, and for adults for usually require double units, since a single unit with an adequate number of blood-forming stem cells simply may not exist at time.

“Based on promising early studies using two cord blood units in adults for whom one unit is often not sufficient, we designed this study in order to determine if the higher number of blood forming stem cells in two cord blood units might improve survival,” explained Wagner. “What we found, however, was that both treatment arms performed very well with similar rates of white blood cell recovery and survival.”

Children with blood cancers who receive transfusions of umbilical cord blood show quantifiable clinical benefits even though the blood may not match their own tissue types. The reason stems from the immaturity of cord blood stem cells and their ability to suppress rejection from the immune system. This is an important aspect of umbilical cord blood transplants, since patients who cannot find a matched unrelated donor also benefit from cord blood transplants. However, cord collection from the placenta after birth often results in a limited number of blood-forming stem cells, which decreases the potential benefits of cord blood. The “double UCB approach” was pioneered at the University of Minnesota as a strategy to overcome this inherent limitation in the use of umbilical cord blood.

Despite the similarities in survival rates between children who received one unit or two units of cord blood, some differences were noted. Children transplanted with a single cord unit had faster recovery rates for platelets and lower risks of Graft Versus Host Disease; a condition in which the transplanted donor blood immune cells attack the patient’s body, which causes several complications.

“This is helpful news for physicians considering the best treatment options for their patients,” said Joanne Kurtzberg, M.D., chief scientific officer of the Robertson Clinical and Translational Cell Therapy Program, director of the Pediatric Blood and Marrow Transplant Program, co-director of the Stem Cell Laboratory and director of the Carolinas Cord Blood Bank at Duke University Medical Center. “We found children who have a cord blood unit with an adequate number of cells do not benefit from receiving two units. This reduces the cost of a cord blood transplant for the majority of pediatric patients needing the procedure. However, for larger children without an adequately dosed single cord blood unit, using two units will provide access to a potentially life-saving transplant.”

“The involvement of multiple research partners was instrumental to the success of the study completion,” added Dennis Confer, M.D., chief medical officer for the National Marrow Donor Program® (NMDP)/Be The Match® and associate scientific director for CIBMTR. “This trial is a testament to the importance of the BMT CTN and the collaboration of partners like the Children’s Oncology Group.”

Mary Horowitz, M.D., M.S., chief scientific director of CIBMTR and professor of medicine at the Medical College of Wisconsin, concurred. “Because of this tremendous collaboration, we were able to expand the scale of this research to multiple transplant centers across the United States and Canada. And the results will undoubtedly improve clinical practice, and most importantly, patient outcomes.”

Interestingly, in this study, patients who received cord blood with significant HLA mismatches showed no detrimental effects on their outcomes. Future studies will examine a closer look at how the HLA match within the cord blood unit impacts outcomes for patients, particularly those within minority populations.

Small Human Stomach Organoids Made From Induced Pluripotent Stem Cells


A new study published in the international journal Nature describes, for the first time, the use of human pluripotent stem cells to create a three-dimensional stomach-like mini-organ. This is the beginning of what might become an unprecedented tool for examining the genesis of diseases such as stomach cancer to diabetes.

Jim Wells and his colleagues at Cincinnati Children’s Hospital Medical Center used human pluripotent stem cells, which are made from mature human cells through a combination of genetic engineering and cell culture techniques, to grow a their miniature stomachs. Wells’ group then used their mini-stomachs also known as gastric organoids, in collaboration with scientists from University of Cincinnati College of Medicine, to study the infection of stomach tissue by the bacterium Helicobacter pylori, which causes peptic ulcer disease and stomach cancer.

According to Wells, a scientist in the divisions of Developmental Biology and Endocrinology at Cincinnati Children’s, this is the first time anyone has succeeded in making three-dimensional human gastric organoids (hGOs). This achievement may present new opportunities for drug discovery, modeling early stages of stomach cancer and studying some of the factors that give rise to obesity related diabetes. This work also represents the first time researchers have produced three-dimensional human embryonic foregut, which is a good starting point for generating other foregut organ tissues such as the lungs and pancreas. “Until this study, no one had generated gastric cells from human pluripotent stem cells (hPSCs),” Wells said. “In addition, we discovered how to promote formation of three-dimensional gastric tissue with complex architecture and cellular composition.”

a, Schematic representation of a typical antral gland showing normal cell types and associated molecular markers. b–g, Immunofluorescent staining demonstrated that day-34 hGOs consisted of normal cell types found in the antrum, but not the fundus. The hGO epithelium contained surface mucous cells that express MUC5AC (b, left), similar to the P12 mouse antrum (b, right), but not ATP4B-expressing parietal cells (c, left) that characterize the fundus (c, right). SOX9+ cells were found at the base of the hGO epithelium (d, left), similar to the progenitor cells found in the P12 antrum (d, right). Furthermore, hGOs contained MUC6+ antral gland cells (e) and LGR5-expressing cells (yellow arrow) (f). Boxed regions in b–f are shown as high magnification images below (b, c, d) or to the right (e, f) of the original. g, Day-34 hGOs also contained endocrine cells (SYP) that expressed the gastric hormones GAST, SST, GHRL and serotonin (5-HT). Scale bars, 100 μm (original images in b–f) and 20 μm (magnified images in b–f and g). Marker expression data are representative from a minimum of 10 independent experiments, except LGR5-eGFP data, which is a representative example from two separate experiments. DAPI, 4′,6-diamidine-2-phenylindole.
a, Schematic representation of a typical antral gland showing normal cell types and associated molecular markers. b–g, Immunofluorescent staining demonstrated that day-34 hGOs consisted of normal cell types found in the antrum, but not the fundus. The hGO epithelium contained surface mucous cells that express MUC5AC (b, left), similar to the P12 mouse antrum (b, right), but not ATP4B-expressing parietal cells (c, left) that characterize the fundus (c, right). SOX9+ cells were found at the base of the hGO epithelium (d, left), similar to the progenitor cells found in the P12 antrum (d, right). Furthermore, hGOs contained MUC6+ antral gland cells (e) and LGR5-expressing cells (yellow arrow) (f). Boxed regions in b–f are shown as high magnification images below (b, c, d) or to the right (e, f) of the original. g, Day-34 hGOs also contained endocrine cells (SYP) that expressed the gastric hormones GAST, SST, GHRL and serotonin (5-HT). Scale bars, 100 μm (original images in b–f) and 20 μm (magnified images in b–f and g). Marker expression data are representative from a minimum of 10 independent experiments, except LGR5-eGFP data, which is a representative example from two separate experiments. DAPI, 4′,6-diamidine-2-phenylindole.

Wells’ gastric organoids are a significant advance in gastroenterological research because distinct differences in development and architecture of the adult stomach limit the reliability of mouse models for studying human stomach development and disease.

As a research tool, human gastric organoids may help clarify other unknown features of the stomach, such as identifying those biochemical processes in the gut that allow gastric-bypass patients to become diabetes-free soon after surgery before losing significant weight. Medical conditions such as obesity-fueled diabetes and the metabolic syndrome are of great interest to public health workers, given the explosion of global cases in the last few decades. A major challenge to addressing these and other medical conditions that involve the stomach has been a relative lack of reliable laboratory model systems to accurately recapitulate human biology.

The key to growing human gastric organoids was to identify the developmental steps involved in normal stomach formation. Manipulation of these processes in a cell culture system drove human pluripotent stem cells to form immature stomach tissue. In culture and over the course of a month, these steps resulted in the formation of 3D human gastric organoids that were around 3mm (1/10th of an inch) in diameter. Wells and his colleagues also used this approach to identify steps that go awry when the stomach does not form correctly.

In collaboration with his colleagues, Kyle McCracken, an MD/PhD graduate student in Wells’ laboratory, and Yana Zavros, PhD, a researcher at UC’s Department of Molecular and Cellular Physiology, Wells showed that his gastric organoids were rapidly infected by H. pylori bacteria. Within 24 hours of inoculation, the bacteria had triggered significant biochemical changes to the organ, and the human gastric organoids faithfully mimicked the early stages of H. pylori-induced gastric disease. McCracken also noticed activation of a cancer gene called c-Met, which is one of the first stages in the induction of stomach cancer, an important long-term sequel to peptic ulcer disease. McCracken was also surprised by the rapid spread of infection in the tissues of his human gastric organoids.

a, Day-34 hGOs contained a zone of MKI67+ proliferative cells similar to the embryonic (E18.5) and postnatal (P12) mouse antrum. b, Using hGOs to model human-specific disease processes of H. pylori infection. Pathogenic (G27) and attenuated (ΔCagA) bacteria were microinjected into the lumen of hGOs and after 24 h, bacteria (both G27 and ΔCagA strains) were tightly associated with the apical surface of the hGO epithelium. c, Immunoprecipitation (IP) for the oncogene c-Met demonstrates that H. pylori induced a robust activation (tyrosine phosphorylation (pTyr)) of c-Met, and this is a CagA-dependent process. Furthermore, CagA immunoprecipitated with c-Met, suggesting that these proteins interact in hGO epithelial cells. Phosphorylated c-Met (phos. c-MET) and CagA control lysates were not immunoprecipitated but used to confirm molecular masses. The molecular mass markers are indicated (130 and 170 kilodaltons (kDa)) and shown in Extended Data Fig. 9c. IB, immunoblotting. d, Within 24 h, H. pylori infection caused a CagA-dependent twofold increase in the number of proliferating cells in the hGO epithelium, measured by 5-ethynyl-2′-deoxyuridine (EdU) incorporation. *P < 0.05; two-tailed Student’s t-test; n = 3 biological replicates per condition, data representative of 4 independent experiments. Scale bars, 100 μm (a) and 20 μm (b). Error bars represent s.e.m.
a, Day-34 hGOs contained a zone of MKI67+ proliferative cells similar to the embryonic (E18.5) and postnatal (P12) mouse antrum. b, Using hGOs to model human-specific disease processes of H. pylori infection. Pathogenic (G27) and attenuated (ΔCagA) bacteria were microinjected into the lumen of hGOs and after 24 h, bacteria (both G27 and ΔCagA strains) were tightly associated with the apical surface of the hGO epithelium. c, Immunoprecipitation (IP) for the oncogene c-Met demonstrates that H. pylori induced a robust activation (tyrosine phosphorylation (pTyr)) of c-Met, and this is a CagA-dependent process. Furthermore, CagA immunoprecipitated with c-Met, suggesting that these proteins interact in hGO epithelial cells. Phosphorylated c-Met (phos. c-MET) and CagA control lysates were not immunoprecipitated but used to confirm molecular masses. The molecular mass markers are indicated (130 and 170 kilodaltons (kDa)) and shown in Extended Data Fig. 9c. IB, immunoblotting. d, Within 24 h, H. pylori infection caused a CagA-dependent twofold increase in the number of proliferating cells in the hGO epithelium, measured by 5-ethynyl-2′-deoxyuridine (EdU) incorporation. *P < 0.05; two-tailed Student’s t-test; n = 3 biological replicates per condition, data representative of 4 independent experiments. Scale bars, 100 μm (a) and 20 μm (b). Error bars represent s.e.m.

There is a relative dearth of literature on how the human stomach developments, which was a significant impediment to Wells’ research. Wells and his coworkers had to use a combination of published works and studies from his own lab, to answer a number of basic developmental questions about how the stomach forms. Over the course of two years, by experimenting with different factors to drive the formation of the stomach, Wells and his colleagues came upon a protocol that resulted in the formation of 3D human gastric tissues in culture.

a, Schematic representation of the in vitro culture system used to direct the differentiation of pluripotent stem cells into three-dimensional gastric organoids. b, Defining molecular domains of the posterior foregut in E10.5 mouse embryos with Sox2, Pdx1 and Cdx2; Sox2/Pdx1, antrum (a); Sox2, fundus (f); Pdx1, dorsal and ventral pancreas (dp and vp); Pdx1/Cdx2, duodenum (d). c, Posterior foregut spheroids exposed for three days to retinoic acid (2 μM) exhibited >100-fold induction of PDX1 compared to control spheroids, measured by qPCR at day 9. *P < 0.05; two-tailed Student’s t-test; n = 3 biological replicates per condition, data representative of 4 independent experiments. d, Time course qPCR analysis of antral differentiation (according to protocol detailed in Fig. 2a) demonstrated sequential activation of SOX2 at day 6 (posterior foregut (FG) endoderm), followed by induction of PDX1 at day 9 (presumptive antrum). Day-9 antral spheroids had a 500-fold increase in SOX2 and a 10,000-fold increase in PDX1 relative to day-3 definitive endoderm (DE). *P < 0.05; two-tailed Student’s t-test; n = 3 biological replicates per time point, data representative of 2 independent experiments. The pancreatic marker PTF1A was not significantly increased. e, Stereomicrographs showing morphological changes during growth of gastric organoids. By 4 weeks, the epithelium of hGOs exhibited a complex folded and glandular architecture (arrows). D, day. f, Comparison of mouse stomach at E18.5 and day-34 hGOs. Pdx1 was highly expressed in the mouse antrum but excluded from the fundus. Human gastric organoids expressed PDX1 throughout the epithelium and exhibited morphology similar to the late gestational mouse antrum (arrows). Scale bars, 100 μm (b and f) and 250 µm (e). Error bars represent s.d.
a, Schematic representation of the in vitro culture system used to direct the differentiation of pluripotent stem cells into three-dimensional gastric organoids. b, Defining molecular domains of the posterior foregut in E10.5 mouse embryos with Sox2, Pdx1 and Cdx2; Sox2/Pdx1, antrum (a); Sox2, fundus (f); Pdx1, dorsal and ventral pancreas (dp and vp); Pdx1/Cdx2, duodenum (d). c, Posterior foregut spheroids exposed for three days to retinoic acid (2 μM) exhibited >100-fold induction of PDX1 compared to control spheroids, measured by qPCR at day 9. *P < 0.05; two-tailed Student’s t-test; n = 3 biological replicates per condition, data representative of 4 independent experiments. d, Time course qPCR analysis of antral differentiation (according to protocol detailed in Fig. 2a) demonstrated sequential activation of SOX2 at day 6 (posterior foregut (FG) endoderm), followed by induction of PDX1 at day 9 (presumptive antrum). Day-9 antral spheroids had a 500-fold increase in SOX2 and a 10,000-fold increase in PDX1 relative to day-3 definitive endoderm (DE). *P < 0.05; two-tailed Student’s t-test; n = 3 biological replicates per time point, data representative of 2 independent experiments. The pancreatic marker PTF1A was not significantly increased. e, Stereomicrographs showing morphological changes during growth of gastric organoids. By 4 weeks, the epithelium of hGOs exhibited a complex folded and glandular architecture (arrows). D, day. f, Comparison of mouse stomach at E18.5 and day-34 hGOs. Pdx1 was highly expressed in the mouse antrum but excluded from the fundus. Human gastric organoids expressed PDX1 throughout the epithelium and exhibited morphology similar to the late gestational mouse antrum (arrows). Scale bars, 100 μm (b and f) and 250 µm (e). Error bars represent s.d.

Wells emphasized importance of basic research for the eventual success of this project, adding, “This milestone would not have been possible if it hadn’t been for previous studies from many other basic researchers on understanding embryonic organ development.”

While this does represent a terrific stride toward better model systems for gastric research and pathology, these gastric organoids are very immature and lack several of the cell types found in mature stomach tissue. For example, these organoids lack chief cells, which secrete the stomach enzyme pepsin (in an inactive form called pepsinogen), and parietal cells, which produce stomach acid. This is significant because chronic inflammation of the stomach can cause loss of parietal cells, which decreases chief cell differentiation and induce chief cells to transdifferentiate back into neck cells. This leads to overproduction of mucus cells. This mucus cell metaplasia is known as spasmolytic polypeptide expressing metaplasia (SPEM) that seems to be a precancerous condition for the stomach. Also if parietal cells are lost, mature chief cells do not form. This seems to imply that parietal cells secrete factors that lead to differentiation of chief cells, so if lost. These gastric organoids also do not make ECL cells or enterochromaffin-like cells, which secrete histamine, one of the most important regulators of stomach acid production. A prolonged stimulation of these ECL cells causes increased numbers of them. This is especially important in gastrinomas, which are tumors in which there is an excessive secretion of the stomach hormone gastrin, one of the key factors contributing to Zollinger-Ellison syndrome.  The hallmark of this disease is ulceration of the stomach and upper small intestine (duodenum) as a result of excessive and unregulated secretion of gastric acid.  Most commonly, hypergastrinemia is the result of these gastrin-secreting tumors or gastrinomas that develop in the pancreas or duodenum.  Thus, in only this short discussion, we have noted several diseases of the stomach that cannot be modeled with this particular system because these stomach-specific cells are not present.

Therefore, while this is a fantastic model system for stomach development and H. pylori infection, more work remains in order to make a stomach model that more accurately models the adult stomach.

“In Body” Muscle Regeneration


Researchers at Wake Forest Baptist Medical Center’s Institute for Regenerative Medicine have hit upon a new strategy for tissue healing: mobilizing the body’s stem cells to the site of injury. Thus harnessing the body’s natural healing powers might make “in body” regeneration of muscle tissue is a possibility.

Sang Jin Lee, assistant professor of Medicine at Wake Forest, and his colleagues implanted small bits of biomaterial scaffolds into the legs of rats and mice. When they embedded these scaffolds with proteins that mobilize muscle stem cells (like insulin-like growth factor-1 or IGF-1), the stem cells migrated from the muscles to the bioscaffolds and formed muscle tissue.

“Working to leverage the body’s own regenerative properties, we designed a muscle-specific scaffolding system that can actively participate in functional tissue regeneration,” said Lee. “This is a proof-of-concept study that we hope can one day be applied to human patients.”

If patients have large sections of muscle removed because of infections, tumors or accidents, muscle grafts from other parts of the body are typically used to restore at least some of the missing muscle. Several laboratories are trying the grow muscle in the laboratory from muscle biopsies that can be then transplanted back into the patient. Growing muscle on scaffolds fashioned from biomaterials have also proven successful.

Lee’s technique overcomes some of the short-comings of these aforementioned procedures. As Lee put it, “Our aim was to bypass the challenges of both of these techniques and to demonstrate the mobilization of muscle cells to a target-specific site for muscle regeneration.”

Most tissues in our bodies contain a resident stem cell population that serves to regenerate the tissue as needed. Lee and his colleagues wanted to determine if these resident stem cells could be coaxed to move from the tissue or origin, muscle in this case, and embeds themselves in an implanted scaffold.

In their first experiments, Lee and his team implanted scaffolds into the leg muscles of rats. After retrieving them several weeks later, it was clear that the muscle stem cell population (muscle satellite cells) not only migrated into the scaffold, but other stem cell populations had also taken up residence in the scaffolds. These scaffolds were also contained an interspersed network of blood vessels only 4 weeks aster transplantation.

In their next experiments, Lee and others laced the scaffolds with different cocktails of proteins to boost the stem cell recruitment properties of the implanted scaffolds. The protein that showed the most robust stem cell recruitment ability was IGF-1. In fact, IGF-1-laced scaffolds had four times the number of cells as plain scaffolds and increased formation of muscle fibers.

“The protein [IGF-1] effectively promoted cell recruitment and accelerated muscle regeneration,” said Lee.

For their next project, Lee would like to test the ability of his scaffolds to promote muscle regeneration in larger laboratory animals.

Pretreatment of Mesenchymal Stem Cells with Melatonin Improves Their Healing Properties in Animals with Strokes


The transplantation of mesenchymal stem cells or MSCs as they as affectionately known, does indeed benefit patients who have had a stroke. Unfortunately, the benefits of MSC transplantation if is limited by inability of these cells to survive after they are implanted into a low-oxygen environment. When a person suffers from a stroke, a blood vessel that feeds the brain has been blocked, and this blockage results in the death of particular cells in the brain. The affected areas of the brain, however, have been deprived of oxygen, and the transplantation of new cells into these areas can result in the prompt death of the implanted cells.

Fortunately, previous studies have revealed that pretreatment of the implanted cells with the hormone melatonin can increase the survival of MSCs that were implanted into kidneys that suffered oxygen deprivation. Therefore, could melatonin pretreatment also improve MSC survival in the case of strokes?

A new study by Guo-Yuan Yang and his colleagues at the Med-X Research Institute in Shanghai, China has examined the effects of melatonin pretreatment on the survival of MSCs that were implanted into the brains of laboratory animals that suffered a stroke.

In a nutshell, Yang and his colleagues showed that melatonin pretreatment greatly increased survival of cultured MSCs when these cells were subjected to low-oxygen conditions. Then when they went whole hog and transplanted their melatonin-pretreated MSCs into the brains of animals that had suffered a stroke, they once again observed that these cells survived at a substantially higher rate than their untreated counterparts. Melatonin-pretreated MSCs also further reduced bleeds into the brain (infarction) and improved the behavioral outcomes of the laboratory animals.

When Yang’s group examined the molecules secreted by the melatonin-treated MSCs, they discovered that the melatonin-pretreated MSCs made a lot more blood-vessel-promoting proteins (such as vascular endothelial growth factor or VEGF), and nerve cell-promoting molecules. Not surprisingly, the rats implanted with melatonin-pretreated MSCs shows significantly more new blood vessels formed, new neurons formed, and better looking brains in general.

Melatonin treatment increased the levels of two signaling molecules, p-ERK1/2, in MSCs. These particular signaling molecules are linked to higher survival rates. When Yang and his crew blocked melatonin signaling by treating cells with as drug called luzindole, these positive effects were reversed and when another drug called U0126, which prevents ERK from becoming phosphorylated was also applied to the cells, it completely reversed the protective effects of melatonin.

These results show that melatonin improves MSC survival and function. Furthermore, melatonin does this by activating the ERK1/2 signaling pathway. Therefore, mesenchymal cells pretreated by melatonin may represent a viable approach to enhance the beneficial effects of stem cell therapy for strokes, and maybe other conditions too? Well shall see. Stay tuned…..

Toxic stem cells to fight tumors


A Harvard team has developed special stem cells that secrete toxins that kill cancer cells, and cause no harm to healthy ones.

“Now, we have toxin-resistant stem cells that can make and release cancer-killing drugs,” Khalid Shah, a co-author of the study and the director of the Molecular Neurotherapy and Imaging Lab at Massachusetts General Hospital and Harvard Medical School, said in an official statement.

According to Shah, experiments in mice have proven very successful.

During the tests, the main part of the brain tumor was surgically removed, followed by the application of stem cells that were placed at the site of the tumor embedded in a biodegradable gel to kill the remaining cancerous cells.

Once within the cancer cell, the toxin disrupts its ability to synthesize proteins, killing it in a matter of days.

“After doing all of the molecular analysis and imaging to track the inhibition of protein synthesis within brain tumors, we do see the toxins kill the cancer cells,” he declared.

Shah said that the toxins that kill cancer have been used to treat a few types of blood cancers. However, these toxins were not effective dealing with solid tumors because these cancers are not as accessible and the toxins in the stem cells don’t have enough time to kill the cancer, since they only have a short half-life.

However, the new modified stem cells developed by Shah’s team change this limitation. “Now, we have toxin-resistant stem cells that can make and release cancer-killing drugs,” he said.

The study, published in the journal Stem Cells, possibly represents a breakthrough in cancer research, since it kills cancer cells while keeping remaining, healthy cells intact.

Scientists have applied for approval from the FDA to start the clinical trials of the method.

Experts praised the study as “the future” of cancer research.

“This is a clever study, which signals the beginning of the next wave of therapies. It shows you can attack solid tumors by putting minipharmacies inside the patient which deliver the toxic payload direct to the tumor,” Chris Mason, a professor of regenerative medicine at University College London, who was not participating in the study, told the BBC.

Human articular cartilage defects can be treated with nasal septum cells


A report from collaborating research teams from the University and the University Hospital of Basel specifies that cells isolated from the nasal septum cartilage can adapt to the environment the knee and repair articular cartilage defects. The ability of nasal cartilage cells to self-renew and adapt to the joint environment is associated with the expression of genes know as HOX genes. This research was published in the journal Science Translational Medicine in combination with reports of the first patients treated with their own nasal cartilage.

Lesions in articular or joint-specific cartilage is a degenerative that tends to occur in older people or younger athletes who engage in impact-heavy sports. Sometimes people who have experienced accidents can also suffer from cartilage lesions. Cartilage lesions present several challenges for orthopedic surgeons to repair. These surgeries are often complicated, and the recovery times are also long. However, Prof. Ivan Martin, professor of tissue engineering, and Prof. Marcel Jakob, Head of Traumatology, from the Department of Biomedicine at the University and the University Hospital of Basel have presented a new treatment option for cartilage lesions that includes the use of nasal cartilage cells to replace cartilage cells in joints.

When grown in cell culture, cartilage cells extracted from the nasal septum (also known as nasal chondrocytes) have a remarkable ability to generate new cartilage tissue after their growth in culture. In an ongoing clinical study, the Basal research group have taken small biopsies (6 millimeters in diameter) from the nasal septa of seven of 25 patients below the age of 55 years. After isolating the cartilage cells from these cartilage samples, they cultured these cells and expanded them and applied them to a three-dimensional scaffold in order to engineer a cartilage graft with a specific size (30 x 40 millimeters).

Martin and his colleagues used these very cartilage grafts to treat the cartilage lesions in human patients. After removing the damaged cartilage tissue from the knee of several patients, their knees were treated with the engineered, tailored tissue from their noses.

Two previous experiments demonstrated the potential efficacy of this procedure. First, a previous clinical study conducted in cooperation with plastic surgeons and the Basel group used the same method to successfully reconstruct nasal wings affected by tumors.

Secondly, a preclinical study with goats whose knees were implanted with nasal cartilage cells showed that these cells were not only compatible with the knee-joint, but also successfully reconstituted the joint cartilage. Lead author of this study, Karoliina Pelttari, and her colleagues were quite surprised that the implanted nasal cartilage cells, which originate from a completely different set of embryonic cell types than the knee-joint were compatible. Nasal septum cells develop from neuroectodermal cells, which also form the nervous system and their self-renewal capacity is attributed to their lack of expression of some homeobox (HOX) genes. However, these same HOX genes are expressed in articular cartilage cells that are formed by mesodermal cells in the embryo.

“The findings from the basic research and the preclinical studies on the properties of nasal cartilage cells and the resulting engineered transplants have opened up the possibility to investigate an innovative clinical treatment of cartilage damage,” says Prof. Ivan Martin about the results. Several studies have confirmed that human nasal cells maintain their capacity to grow and form new cartilage despite the age of the patient. This means that older people could also benefit from this new method, as could patients with large articular cartilage defects.

The primary target of the ongoing clinical study at the University Hospital of Basel is to confirm the safety, efficacy and feasibility of nasal cartilage grafts transplanted into joints, the clinical effectiveness of this procedure, from the data presently in hand, is highly promising.