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Stem cell therapy
This document discusses stem cell therapy and the properties and types of stem cells. It outlines the history of key stem cell discoveries from the 1950s to present. Stem cells can be embryonic, adult, hematopoietic, or other types. Clinical trials are exploring using stem cells to treat conditions like macular degeneration, multiple sclerosis, spinal cord injuries, diabetes, and more. Challenges include developing cell types that can properly integrate and replacing lost or damaged tissues.
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Stem cell therapy
- 1. Stem cell therapy Moderator Dr. Mohd. Tariq Salman Resident Dr. Karun Kumar (JR-II)
- 3. Properties of stemcells •If the cell is able to form all cell types of the embryo & adult (Fertilized egg cell) Totipotent stem cell •Stem cell able to differentiate into all 3 germ layers Pluripotent stem cell (Embryonic stem cell)
- 7. •Multipotent stem cell Differentiate to form cells of some but not all 3 germ layers (Bone, cartilage, connective tissue) •Unipotent stem cell Able to form just one other cell type (Spermatogonia)
- 10. Types of stemcells 1. Embryonic stem cells Stem cells harvested from a blastocyst (pluripotent) 2. Adult (Somatic) stem cells Stem cells harvested from tissues in an adult body (multipotent)
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- 15. On the roadto stem cell therapy •Interest in human embryonic stem cells Shortage of donor organs •First-in-man studies aimed at reversing macular degeneration have already taken place in London, and around 25 patients have been included in the first phase 1 studies (safety and feasibility) worldwide.
- 16. Stem cell timeline YearDiscovery 1956 First successful bone marrow transplant 1981 Embryonic stem cells are isolated from mouse blastocysts (Martin Evans, UK) 1988 Haemopoietic stem cells from adult mice are purified and characterized 1997 Dolly the sheep (Ian Wilmut, Edinburgh) 1998 First human embryonic stem cells are isolated 2001 Mouse embryonic stem cells are created by nuclear transfer 2002 Pancreatic stem cells derived from mouse embryonic stem cells cure diabetes in mice
- 17. Year Discovery 2004 Typeof nerve cell lost in Parkinson’s disease is produced from human embryonic stem cells 2005 Human embryonic stem cells were shown to differentiate into active functioning nerve cells when placed in mouse brains 2005 Pancreatic cells were derived from adult stem cells 2006 Embryonic stem cells were derived from the morula of a mouse 2006 Embryonic stem cells were first grown without animal products in the culture 2010 Person with spinal injury first to receive medical treatment derived from human embryonic stem cells 2012 Human embryonic stem cells show promise in treating blindness 2013 Human embryonic stem cells produced from fetal cells using therapeutic cloning
- 18. Year Discovery 2014 CharlesVacanti (Harvard Medical School) and Haruko Obokata (Riken Center for Developmental Biology) announced that any cell can potentially be rewound to a pre-embryonic state using a simple 30 minute technique 2014 Teams led by Dieter Egli of the New York Stem Cell Foundation and Young Gie Chung from CHA University in Seoul, South Korea, independently produce human embryonic stem cells from adult cells, using therapeutic cloning. Egli's team use skin cells from a woman with diabetes and demonstrate that the resulting stem cells can be turned into insulin- producing beta cells. In theory, the cells could be used to replace those lost to the disease.
- 19. STAP Stimulustriggered acquisition of pluripotency
- 20. Mouse embryo madewith reprogrammed cells
- 21. Stem cell researchfraud (2014)
- 22. Battle against baldness(CNBC 29th January, 2015)
- 23. Battle against multiplesclerosis (29/1/15) Dr. Mark Freedman of the Ottawa Hospital Research Institute is leading research to determine if a type of stem cell can help alleviate the symptoms of multiple sclerosis
- 24. Professor Anthony Hollander,a cartilage tissue engineer, who cultured stem cells from Claudia Castillo to build a new windpipe (trachea) in year 2008 Claudia Castillo, who received a transplanted windpipe that was engineered from her own stem cells
- 25. Dr. De Lucawith Claudio
- 26. Type 1 Diabetes •Abnormalactivation of the immune system Destruction of the insulin- producing beta cells •Beta cells from pluripotent stem cells or adult progenitors in the pancreas Source of cells for treatment of diabetes
- 27. Spinal cord injury •Oligodendrocytecells that produce myelin can be generated from stem cells; if these are injected into the site of the crush injury they could repair the myelin layer locally, and thus restore function and cure the paralysis
- 28. Demyelinating diseases •Fetal tissuecan also be a source of myelinating cells and, although also controversial, various trials are ongoing
- 29. Making the blindsee •Problem with corneal transplants •Few human donors to meet clinical need •Unsuitable in destruction of limbus •Alternative Cultivation of limbal cells
- 30. Macular degeneration Retinitispigmentosa
- 31. Eye an idealorgan for stem cell transplant 1. Immune-privileged site •Transplanted cells that are not HLA matched are not rejected •Immunosuppressive medication is not required 2. Eye is a “ closed” unit (any stem cells injected would find it difficult to misbehave and escape to other parts of the body) 3. We have two eyes, it may be possible to treat one eye without the risk of losing vision altogether
- 32. •Human embryonic andpluripotent stem cells can easily differentiate into retinal pigment epithelial cells, the cells that need replacing Cells are cultured & surgically inserted into the retina ↓ Pick up signals from light & transmit images to the brain
- 33. Deafness •Inner ear haircells can be generated from pluripotent stem cells, both from mice and humans •When the stem cell derived inner ear hair cells from mice are transplanted to the ears of mice in which deafness was induced by the same chemotherapy reagents as used to treat cancer, their hearing was restored
- 35. Best stem cellfor transplantation •Acute & life-threatening disease (MI) Allogenic & derived from 1. Living (bone marrow) 2. Deceased (Insulin producing beta cells) •Chronic disease Autologous stem cell transplantation
- 36. Bone marrow transplantationby stem cell mobilization Stem cells are collected from blood after giving certain growth factors (e.g. GM-CSF) to the patients ↓ These growth factors temporarily recruit stem cells from the bone marrow into the blood which are stored till needed ↓ The patient is treated with cytostatic drugs (chemotherapy) or undergoes irradiation ↓
- 37. The blood stemcells can subsequently be returned to the blood of the patient at any chosen time point through a simple intravenous infusion into the blood stream ↓ They will find their own way back “home” to the bone marrow, where they will settle and start producing new blood cells, at no risk of rejection since they are the patient’s own cells
- 38. Where to transplantstem cells 1. Myocardial infarction New cardiac cells have to be transplanted directly into the heart muscle 2. Kidney disease Replacing kidney cells with stem cell derivatives will need the transplanted cells to exert their function within the kidney itself
- 39. 3.Diabetes Anyreplacement beta cells, from stem cells or pancreas progenitors could be transplanted at another site in the body and not in pancreas. (The portal vein of the liver, to which the cells can be delivered simply under local anesthetic is being used as a transplantation site for beta cells from donors)
- 40. 4. Parkinson’s disease Challenge because the distance to which neuritis grow cannot be predicted. Dopaminergic nerve cells in the brain exert their effect through the neuritis (at a site distant from where the cell body “sits” in the brain) •In mice and rats the neurites from these neurons can easily grow out over that distance, but in the much larger human brain, this can be several centimeters and is very difficult.
- 41. Cell types availablefor stem cell transplantation 1. First isolated from large intestine of mice •These cells self organize into “organoids” or “miniguts” •Use To treat intestinal conditions in which the intestinal epithelial layer is damaged (ulcers)
- 42. 2. Hematopoietic stemcells obtained from umbilical cord blood Enable reconstitution of the blood cell population of a patient after destructive chemotherapy •2 or more matched cord blood samples are required for one adult patient
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- 44. The future :Cerebral organoids
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- 47. Transplantation of stem cells: Where we stand ? •Most commonly used experimental animals Mice because 1. There are many different strains of mice with mutations in their DNA that are similar to those causing human disease 2. Easy to handle 3. Inexpensive to keep
- 48. Stem cells candifferentiate in vitro to cells that resemble oligodendrocytes
- 49. Clinical trials withoutpatients ? (Organs-on-chips)
- 51. Vision of thefuture Cancer metastasis on a chip
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- 53. Applications of organs ona chip 1. Drug toxicity screening (Heart and liver most susceptible organs) 2. Human disease models (Development of novel drugs to treat the illness) 3. Investigate routes for optimal drug uptake in the body (Eg. To measure the rate of transport through the intestinal wall after oral intake)
- 54. 4. By capturingthe genetic variation in the normal and sick human population, these models are expected to increase the speed and reduce costs of drug development. 5. Safe and effective drug development tuned to the specific genetic profile of the patient (Personalized medicine)
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Editor's Notes
- #2 Forty years after Neil Armstrong first stepped on the moon, we’re on the brink of another giant leap for mankind — only this time the new frontier is under a microscope instead of beyond the clouds. Through out history, man kind has looked for the fountain of youth ; the elixir for eternal life, keeping us forever young in body and mind. In the discovery of stem cells, has the modern biomedical scientist finally succeeded where wizards and alchemists failed? Let’s find out. The Nobel Prize in Physiology or Medicine 2012 jointly to Sir John B. Gurdon and Sir Shinya Yamanaka for the discovery that mature cells can be reprogrammed to become pluripotent. John B. Gurdon discovered in 1962 that the specialisation of cells is reversible. In a classic experiment, he replaced the immature cell nucleus in an egg cell of a frog with the nucleus from a mature intestinal cell. This modified egg cell developed into a normal tadpole. The DNA of the mature cell still had all the information needed to develop all cells in the frog.Shinya Yamanaka discovered more than 40 years later, in 2006, how intact mature cells in mice could be reprogrammed to become immature stem cells. Surprisingly, by introducing only a few genes, he could reprogram mature cells to become pluripotent stem cells, i.e. immature cells that are able to develop into all types of cells in the body.
- #4 In the adult body in vivo there are no totipotent or pluripotent stem cells. This does not mean that the artificial conditions of culture cannot convert (“reprogram”) some adult cells into stem cells with pluripotent properties. These multi potent or uni potent stem cells are also known as progenitor cells. Progenitor cells can divide, but this capacity is generally considered more limited than that of pluripotent stem cells. Progenitor cells are predestined to differentiate only into the cell types that are needed for the proper function in their own specific organ or tissue and they are thought to be important for turnover and repair of the organ.
- #9 Mesenchymal stem cells, or MSCs, are multipotent stromal cells that can differentiate into a variety of cell types,[1] including: osteoblasts (bone cells),[2] chondrocytes (cartilage cells),[3] and adipocytes (fat cells). This phenomenon has been documented in specific cells and tissues in living animals and their counterparts growing in tissue culture. Mesenchyme Tissue: Connective tissue from all three germ layers in the embryo. This tissue can become cells that make up connective tissue, cartilage, adipose tissue, the lymphatic system, and bone in the adult body.
- #10 Mesenchyme is embryonic connective tissue that is derived from the mesoderm and that differentiates into hematopoietic and connective tissue, whereas MSCs do not differentiate into hematopoietic cells
- #11 Adult stem cells (or Somatic Stem Cell): Stem cells that are harvested from tissues in an adult body. These cells are usually multipotent, meaning they can differentiate into cells from some, but not all, of the three germ layers. They are thought to act to repair and regenerate the tissue in which they are found in, but usually they can differentiate into cells of completely different tissue types. Umbilical cord blood contains multipotent and pluripotent stem cells. There are three known accessible sources of autologous adult stem cells in humans:Bone marrow, which requires extraction by harvesting, that is, drilling into bone (typically the femur or iliac crest). Adipose tissue (lipid cells), which requires extraction by liposuction. Blood, which requires extraction through apheresis, wherein blood is drawn from the donor (similar to a blood donation), and passed through a machine that extracts the stem cells and returns other portions of the blood to the donor.
- #12 All blood cells are divided into three lineages.[5] Erythroid cells are the oxygen carrying red blood cells. Both reticulocytes and erythrocytes are functional and are released into the blood. In fact, a reticulocyte count estimates the rate of erythropoiesis. Lymphocytes are the cornerstone of the adaptive immune system. They are derived from common lymphoid progenitors. The lymphoid lineage is primarily composed of T-cells and B-cells (types of white blood cells). This is lymphopoiesis. Myelocytes, which include granulocytes, megakaryocytes and macrophages and are derived from common myeloid progenitors, are involved in such diverse roles as innate immunity, adaptive immunity, and blood clotting. This is myelopoiesis.
- #14 In general, there are three different ways by which stem cells can divide. At the top, stem cells (yellow) divide into two new stem cells that are identical. This is called symmetric cell division. The stem cells can also divide in such a way that one cell remains a stem cell and the other differentiates to give rise to a specialized cell (blue) that is not a stem cell. This is called asymmetric cell division. The lower part of the illustration shows stem cells dividing into one new stem cell and one specialized cell. In this way, the pool of stem cells remains unchanged. Finally, both daughter cells can differentiate. The stem cell pool is then lost. Haematopoietic stem cells (HSCs) reside in the medulla of the bone (bone marrow) and have the unique ability to give rise to all of the different mature blood cell types and tissues. HSCs are self-renewing cells: when they proliferate, at least some of their daughter cells remain as HSCs, so the pool of stem cells does not become depleted.This phenomenon is called asymmetric division
- #16 It is still too soon to ask patients whether they can see better, because too few cell were used for injection (the potential risks of teratoma had to be minimized), but once these trial s are compl ete, it may then be possib le to te st for effective ness and then ask the pat ients “Can you see?”
- #20 Now, Vacanti, along with Haruko Obokata at the Riken Center for Developmental Biology in Kobe, Japan, and colleagues have discovered a different way to rewind adult cells – without touching the DNA. The method is striking for its simplicity: all you need to do is place the cells in a stressful situation, such as an acidic environment. The idea that this might work comes from a phenomenon seen in the plant kingdom, whereby drastic environmental stress can change an ordinary cell into an immature one from which a whole new plant can arise. For example, the presence of a specific hormone has been shown to transform a single adult carrot cell into a new plant. Some adult cells in reptiles and birds are also known to have the ability to do this. To investigate whether the process could occur in mammals, Obokata and colleagues used mice that were bred to carry a gene that glows green in the presence of Oct-4, a protein that is only found in pluripotent cells. The team took a blood sample from the spleen of these mice when they were one week old, isolated white blood cells called lymphocytes, and exposed them to various strong but fleeting physical and chemical stresses. One batch of cells was exposed to a "sub-lethal" acidic environment, with a pH of 5.7, for 30 minutes. The team then tried to grow the cells in the lab. Not much happened at first – some cells died, and the rest still looked like white blood cells. But on day 2, a number of cells began to glow green, meaning they were producing Oct-4. By day 7, two-thirds of the surviving cells showed this pluripotent marker, together with other genetic markers of pluripotency – many of which are also seen in embryonic stem cells. In contrast, iPS cells can take four weeks to reach this stage. The team call their new cells "stimulus-triggered acquisition of pluripotency", or STAP cells. To make sure they really were pluripotent, the team injected the STAP cells from the spleen into an early-stage mouse embryo, or blastocyst. These are typically five or six days old with about eight cells already formed inside. The STAP cells seemed to integrate themselves into the structure, and the embryo went on to form the three "germ layers" that eventually give rise to all cell types in the body. The embryos developed into pups that incorporated STAP cells into every tissue in their body. These pups subsequently gave birth to offspring that also contained STAP cells – showing that the cells incorporated themselves into the animal's sperm or eggs, and were inherited.
- #22 Haruko Obokata (小保方 晴子 Obokata Haruko?, born 1983) is a Japanese former stem-cell biologist and the former Research Unit Leader of the Laboratory for Cellular Reprogramming at RIKEN Center for Developmental Biology.[3][4] She claimed she had developed a radical and remarkably easy way to make cells, called Stimulus-Triggered Acquisition of Pluripotency (STAP) cells, that can grow into any tissue in the body.[5] However, the Riken research institute started an investigation into claims of irregularities in images of her several articles including the paper associated with the discovery of STAP cells[6] in response to the allegations made on blogs and social networking sites.[7][8] The "STAP cells scandal" has become one of the most well-known potential frauds in science
- #23 Typical hair replacement surgery requires doctors to take hair follicles from one part of the head or body and transplant them onto a bald or thinning area. This works if you have enough healthy follicles you aren't already using.In contrast, a group of researchers has found a way to regrow a type of cell crucial for the development of healthy follicles, making it possible to grow new hair without having to sacrifice tissue from another part of the body.By genetically modifying adult human skin cells, scientists at the University of Pennsylvania and the New Jersey Institute of Technology were able to make a kind of stem cell—called an epithelial stem cell—that is one of the building blocks for functioning hair follicles. When the scientists planted their epithelial cells onto mice, the stem cells transformed into cells for both human skin and hair follicles. The cells even produced structurally recognizable hair shafts."This is the first time anyone has made scalable amounts of epithelial stem cells that are capable of generating the epithelial component of hair follicles," lead researcher Xiowei Xu said in a press release published along with the study. Since they can also regenerate skin cells, the stem cells could also be used for applications such as healing wounds or burns.
- #24 Two Canadian research centres are gearing up for a clinical trial to determine if a type of stem cell can help alleviate the symptoms of multiple sclerosis. Researchers at the Ottawa Hospital and Winnipeg’s Health Sciences Centre will each recruit 20 MS patients for the trial that will test whether mesenchymal stem cells can help repair damage caused by the disease. MS is thought to be an autoimmune disease that creates inflammation that damages the protective covering of the nerves, leading to physical and cognitive impairment. Mesenchymal stem cells found in bone marrow, fat, skin tissue and umbilical cord blood have the ability to modify the immune system and reduce inflammation. Half the patients in the study will be randomly selected to receive their own stem cells soon after extraction and expansion in the lab; the other half will get a mock solution, followed by their previously frozen stem cells 24 weeks later. Lead researcher Dr. Mark Freedman of the Ottawa Hospital Research Institute says the stem cell therapy has shown preliminary effectiveness in clinical trials involving some other diseases.Freedman and Ottawa Hospital colleague Dr. Harry Atkins pioneered a different kind of stem cell therapy for MS that uses hematopoietic stem cells to replace a patient’s defective immune system with a new one that no longer attacks the brain and spinal cord. “Our experience with hematopoietic stem cell transplantation has been very encouraging, but this therapy has serious risks and it is only appropriate for a very small percentage of people with aggressive early MS,” said Freedman.“On the other hand, we really don’t know what the effect of mesenchymal stem cell therapy will be in people with MS,” he said. “It involves a different treatment approach that does not require the use of chemotherapy and therefore has fewer risks compared with hematopoietic stem cell transplantation. “Mesenchymal stem cell therapy, if successful, might offer a future treatment option for a larger group of patients.” The researchers were awarded a $4.2-million grant to conduct the study from the Multiple Sclerosis Society of Canada and the Multiple Sclerosis Scientific Research Foundation.
- #25 A 7 cm tracheal segment came from a 51-year-old transplant donor who had died of cerebral haemorrhage. Trachea was decellularized over a six-week period so that no donor cells remained. Stem cells were obtained from the recipient’s own bone marrow, grown into a large population and matured into cartilage cells (chondrocytes). The donor trachea was then seeded with chondrocytes on the outside, using a novel bioreactor developed at the Politecnico di Milano, Italy, which incubates the cells and allows them to migrate into the tissue under conditions ideal for each individual cell type. To replicate the lining of the trachea, epithelial cells were seeded onto the inside of the trachea using the same bioreactor. Four days after seeding, the graft was used to replace the patient’s left main bronchus. The operation was performed in June 2008 at the Hospital Clinic, Barcelona, by Professor Paolo Macchiarini of the University of Barcelona. These remarkable results show that it is possible to produce a tissue-engineered airway with mechanical properties that permit normal breathing and that is free from the risks of rejection seen with conventional transplanted organs. The patient did not develop antibodies to her graft, despite not taking any immunosuppressive drugs. Lung function tests performed two months after the operation were all at the better end of the normal range for a young woman. After one month, a biopsy elicited local bleeding, indicating that the blood vessels had already grown back successfully. In addition, studies in Sweden have shown that it is actually possible to engineer the trachea itself without requiring a donor trachea at all.
- #26 He is also investigating the use of epithelial stem cell mediated gene therapy for junctional epidermolysis bullosa, a serious genetic skin disease. Claudio, who is 42 years old, is one of his patients with this debilitating skin complaint, which is caused by a mutation in a gene called laminin 5. This gene codes for a protein important for sticking layers of the skin together. If it does not function properly, then the skin peels off in large, chronic blisters. Claudio has suffered all of his life from huge open wounds over the whole of his body. Although it is possible to make new skin from a patient’s own epithelial skin stem cells, in Claudio’s case this would not help, since he has a genetic defect and any new skin made from his own cells would have the same problem as Claudio’s own skin.Dr. De Luca has attempted to solve this by combining the epithelial skin stem cells with gene therapy. He has introduced a good copy of the laminin 5 gene into the defective skin stem cells and used these to make new skin by tissue engineering techniques, growing the cells on a carrier material. These sheets of genetically repaired skin have been transplanted to both of Claudio’s upper legs and have attached well, giving him a large area of reconstructed skin. He has no pain and no open wounds in these grafts, which have remained stable for several years, without any sign of tumor formation or other negative side effects. Two technologies, gene therapy and stem cell technology, have been successfully combined in one treatment.
- #29 Demyelinating diseases can be divided in those affecting the central nervous system and those presents in the peripheral nervous system, presenting different demyelination conditions. The disorders affecting the CNS include: Multiple sclerosis, together with Devic's disease and other disorders with immune system involvement called inflammatory demyelinating diseases. CNS Neuropathies like those produced by Vitamin B12 deficiency Central pontine myelinolysis Myelopathies like Tabes dorsalis (syphilitic Myelopathy) leukoencephalopathies like Progressive multifocal leukoencephalopathy Leukodystrophies These disorders are normally associated also with the conditions Optic neuritis and Transverse myelitis, which are inflammatory conditions, because inflammation and demyelination are frequently associated. Demyelinating diseases of the peripheral nervous system include: Guillain-Barré syndrome and its chronic counterpart, chronic inflammatory demyelinating polyneuropathy Anti-MAG peripheral neuropathy Charcot-Marie-Tooth Disease Copper deficiency associated conditions (peripheral neuropathy, myelopathy, and rarely optic neuropathy Progressive inflammatory neuropathy
- #30 Dr. Graziella Pellegrini from the University of Modena and Reggio Emilia in Italy is one of the small group of scientists who have managed to culture limbal stem cells in the laboratory. These cells can be collected from the “good eye” or from the damaged eye if a small area of the limbus has been spared in some cases of bilateral injuries. Once sufficient numbers of cells have been grown in the laboratory, the damaged cornea can be removed under anesthetic and the cultured limbal cells placed around the iris of the damaged eye on a scaffold material where they will start to regenerate the different layers that make up the cornea. Within months, the cornea can be completely reconstituted and the clear covering of the eye restored.
- #31 In contrast with macular degeneration, retinitis pigmentosa causes narrowing of peripheral vision until the visual field is eliminated. For advanced RP patients, objects are seen as if through a keyhole. Two images simulate the vision of an RP patient. Macular degeneration (age related blindness) is caused by degeneration of the retina resulting in vision loss in the macula at the center of the visual field. As this simulated photographic representation shows, macular degeneration makes it difficult to focus on central objects and recognize faces. However, the condition leaves peripheral vision intact
- #35 A major cause of why acquired hearing loss is permanent in mammals lies in the incapacity of the sensory epithelia of the inner ear to replace damaged mechanoreceptor cells, or hair cells. Sensory hair cells are mechanoreceptors that turn fluid movements generated by sound into electrochemical signals interpretable by the brain. Degeneration and death of hair cells is the cause of hearing loss in >80% of individuals with progressive deafness The location of sensory hair cells in the inner ear. Pluripotent stem cells can be induced to form sensory hair cells. The California Institute of Regenerative Medicine (CIRM) is one organization supporting research into their use curing some kinds of deafness.
- #36 Allogenic Foreign to the own body; in the case of an allogenic transplantation, the transplanted tissues or cells are genetically different from the recipient. Autologous In the case of autologous transplantation, the transplanted tissues or cells are derived from the recipient.
- #37 However allogenic transplantation of blood stem cells, where a carefully selected donor provides the patient with cells, is also possible. For this, as with organ transplantation, it is of the utmost importance to have a good immunological HLA match between donor and patient to avoid either rejection of the transplant by the patient, or a graft-versus-host reaction where the transplanted cells attack the tissues of the patient. If possible, autologous transplantation is preferred, but this can only be done if sufficient healthy bone marrow can be obtained from the patient before the chemotherapy treatment, or a technique to free the bone marrow of residual tumor cells can be used. granulocyte-macrophage-colony stimulating factor
- #39 The site in the body to which stem cells should be delive red depends on which dise ase they are bein g used to treat. Some cell typ es will only function within the co ntext of the org an in which they belo ng, while others func tion just as wel l at sites enti rely separate from those in which they wo uld norm ally be found.
- #42 An organoid is a three-dimensional organ-bud grown in a laboratory that specializes in regenerative medicine. The technique for growing organoids has rapidly improved since the early 2010s, and it was named by The Scientist as one of the biggest scientific advancements of 2013
- #44 Entire intestinal crypts can be formed from single stem cells located at the bottom of intestinal crypts. (a) shows the top of a villus. (b) shows villi at different time points, with the descendants of stem cells appearing in blue. (c) shows a similar picture, but here the descendants of single stem cells each have a different color. It is clear that “ribbons” of one color run from bottom to top of a crypt and, therefore, all the cells within the ribbon must be the descendant of a single stem cell, forming all the different cell types of the cryptvillus structure.
- #45 In this cross section of a brain organoid, neurons can be seen in green and neural progenitor cells in red. Human stem cells can, however, form many of the cell types in the human brain and may offer a solution. Recently, researchers succeeded in generating organized brain tissue they called cerebral organoids from human-induced pluripotent stem cells (Figure B10.3.1). In these in vitro cultured cerebral organoids, different regions of the brain, such as cerebral cortex, choroid plexus, and ventral forebrain could be identified. Specific differentiation steps induced by neural growth factors, followed by three-dimensional culture in spinning bioreactors, were sufficient to produce parts of the human brain. The cerebral organoids displayed a remarkable three-dimensional self-organizing capacity (similar to that described for intestinal organoids) and were strikingly similar in morphological organization and molecular characterization to human brains. Moreover, identical differentiation and culture procedures using induced pluripotent stem cells from patients suffering from microcephaly, a disorder leading to a severe reduction in the size of the brain associated with mental retardation, resulted in cerebral organoids much smaller than their normal counterparts. Most likely this was a result of premature neural differentiation of radial glial stem cells, which caused a depletion of the progenitor cell population and impaired expansion of brain tissue. Under these culture conditions, cerebral organoids reached a maximal diameter of 4 mm. For more complex and bigger organoids, it would be crucial to incorporate other cell types or cellular structures, such as a vascular network for the delivery of oxygen and nutrients, to avoid necrosis of cells in the central regions of the organoids
- #46 Cord blood is collected from the umbilical cord vein attached to the placenta after the umbilical cord has been detached from the newborn.[2] Cord blood is collected because it contains stem cells, including hematopoietic cells, which can be used to treat hematopoietic and genetic disorders. One unit of cord blood generally lacks stem cells in a quantity sufficient to treat an adult patient. The placenta is a much better source of stem cells since it contains up to ten times more than cord blood.[3] Some placental blood may be returned to the neonatal circulation if the umbilical cord is not prematurely clamped.[4] According to Eileen K. Hutton, PhD, and Eman S. Hassan, MBBch, cord clamping should be delayed a minimum of two minutes to prevent anemia over the first three months of life and enriching iron stores and ferritin levels for as long as 6 months. The median size of cord blood collections in family banks is 60mL or 2 ounces. That small volume of liquid corresponds to 470 million Total Nucleated Cells (TNC) or 1.8 million cells that test positive for the stem cell marker CD34. Thus, most healthy full-term babies have over a million blood-forming stem cells in their umbilical cord blood. By comparison, most public cord blood banks will only keep collections that are much bigger than average, and throw out the donations that are below a threshold of a billion TNC, corresponding to a blood volume of about 90-100 mL or 3 ounces.
- #47 Clamping and cutting the cord After you've delivered your baby, whether vaginally or by c-section, the cord is clamped and then cut in the usual way – either by your partner or your medical provider. You can delay cord clamping, as long as the delay is brief – no more than a minute or two. (If cord clamping is delayed too long, the blood in the cord will clot. And once the blood clots, it's of no benefit to anyone – it doesn't go to your baby and can't be collected for storage.) Extracting the cord blood Your medical provider then inserts a needle into the umbilical vein on the part of the cord that's still attached to the placenta. The needle doesn't go anywhere near your baby. The blood drains into a collection bag. Typically, 1 to 5 ounces are collected. The entire process takes less than 10 minutes. Off to the bank! The blood is shipped to a cord blood bank, where it's tested, processed, and cryopreserved (preserved by controlled freezing) for long-term storage if deemed acceptable according to quality standards. Some family cord blood banks now offer to collect a segment of the umbilical cord in addition to the cord blood. Umbilical cord tissue contains stem cells that are different from cord blood stem cells, and researchers are studying their possible use. leukemia, aplastic anemia, thalassemia, Hodgkin's disease, and non-Hodgkin's lymphoma. (Cord blood stem cells have also been used to treat sickle cell anemia, but that procedure is not yet on the FDA-approved list.)Cord blood transplants are also used to treat rare metabolic disorders that would otherwise be fatal for infants (Krabbe disease and Sanfilippo syndrome, for example).
- #48 Most commonly used experimental animals are mi ce, becau se there are man y diffe rent strains of mice with mutations in their DN A that are similar to thos e causing human diseas e (Figure 7.8). They are also fairly easy to handle and are relatively inexpensive to keep. Sufficient experience is available with respect to humane treatment of the animals, even when they do have particular diseases. In fact, some diseases in mice have very mild symptoms compared to, say, humans or even larger animals such as dogs. This type of research in animals is called preclinical research. Many stem cell therapies in development are already at this stage, which shows promise with respect to future clinical application. In this section we provide examples of the status of some of these preclinical studies, the outcome of which essentially determines the chance of real clinical applications.
- #49 To da te, most preclini cal resea rch with human pluripo tent stem cells has been perform ed in mice. In ad dition, rats and pigs have also been used, with the advant age that these large r animal s more closely reflect human phy siology . On e of the most interes ting typ es of preclin ical experi ments has been the transplan tation of differen tiated stem cells to rats that were paraly zed and unable to walk becau se of an experi menta lly induced spinal cord lesio n. Un der anesth esia, the nerves of the spin al co rd were eithe r compl etely sever ed or crushed (Figure 7.9). After injection of embryonic stem cells that had been differentiated in the laboratory to oligodendrocytes, the rats regained much of the ability to walk. Spectacular as films of these animals are to see, extrapolation to humans can only be made to a limited extent in terms of effectiveness. This is because in these rodents the spinal cord not only contains nerve extensions, as in humans, but also complete nerve cells. This suggests that electrical signaling from the brain with associated movement of the legs in these animals is organized differently than in humans, implying that the therapeutic requirements for restoring nerves are also likely to be different.
- #50 The term was coine d to descri be a cell cu lture-base d model system in wh ich cells of differen t kinds are placed on smal l structure s (ch ips), usually made of synth etic polymer s, that had been “patterne d” into groov es, channel s, or spira ls usin g the sa me kind of technology used for making electr ical chips. The se chip and cell combinations can mi mic (or model) the sm allest func tional subun it of an organ or tissue. Using org ans-on-c hips , it is bec oming possibl e to mimic many organs and tissue s in the human body but in a mini aturized format outside the body. Depend ing on the cell types used and the format of the patte rning on the chip, the alveoli of a lung, smal l numb ers of synchronou sly contr acting heart cells, or even mini kidne y and live rlike stru ctures can be created. By add ing bacteria, immune ce lls, dru gs, or even cells from disease d tissue to the chips , it may even be possibl e to model human diseas e state s, not only reducing the use of experi menta l animals for research , but also pro viding bet ter ways of looki ng for cures for human ailm ents. Many of the electronic devices we use today contain one or more “chips” or tiny printed circuits. The microfabrication process necessary to make these electronic chips takes place in a specialized clean room facility. Clean rooms have extremely low dust and particle levels in the air because of specialized filter systems.
- #51 Example of a microfluidic chip manufactured from polymer material. Cells can be cultured in microincubation chambers on the chip, which are connected to each other by tiny channels and kept at body temperature. Liquids can be pumped through the cell culture chambers, and processes or changes taking place in the cells can be measured over time. This can be done in several different ways, but here is an example in which the chip containing cells is monitored under a microscope. The microscope can be seen at the top of the picture.
- #52 cancer metastasis on a chip. Invasion of tumor cells from the primary tumor into surrounding matrix and subsequently into channels that represent the blood circulation. Once the cells have escaped into the circulatory system, they can “seed” into a new tissue or organ site and are said to become metastatic. This process can be mimicked on these chips, enabling development of drugs to prevent growth of metastatic tumors. A cross-section of the chip shows a metastatic seeding site compartment and the connection with the primary tumor site through microfluidic channels simulating the blood circulation. Additional channels can be designed for flowing through certain immune cells that are thought to play complex and yet not fully explained roles in both prevention and promotion of the metastatic process. PDMS Polydimethylsiloxane
- #53 Developed at Wyss Institute (Harvard University) by Professor Don Ingber 2 sterile fluidic compartments separated by a porous flexible membrane Can be mechanically stretched at various strains and frequencies by applying cyclic suction to the hollow side of the chambers in this flexible device A schematic representation of a “lung-on-a-chip” as developed by the Wyss Institute. A flexible membrane (middle) is covered on the top with lung epithelial cells (green) and on the bottom with endothelial cells that are present in blood vessels. By allowing air (blue arrow) and (synthetic) blood (red arrow) to flow through the chambers, lung function can be examined. The chamber on either side of the device can be inflated and deflated to mimic the stretching of lungs. Bacteria and immune cells can also be added to mimic infection and certain proteins to mimic asthma.
- #54 New era of personalized medicine is rapidly ushering
- #56 Fluorophores will emit light of a certain wavelength, which can be seen by the eye as having a specific color after illumination with light of another wavelength. Dyes in many commonly used highlighter pens contain fluorophores. These become visible under ultraviolet light and we see them as fluorescent.