Anders Björklund (born 11 July 1945) is a Swedish neuroscientist and pioneer in the study of cell- and gene-based reparative and neuroprotective mechanisms in the brain. He has spent his academic career at Lund University in Sweden, as professor since 1983 and as senior professor at the Wallenberg Neuroscience Center since his formal retirement in 2012.
64-1741: (Redirected from Bjorklund ) Björklund or Bjørklund or Bjorklund is a surname of Swedish and Norwegian origin. Notable people with the surname include: Björklund [ edit ] Anders Björklund (born 1945), Swedish neuroscientist Elina Björklund (born 1970), Finnish business executive Eva Björklund (born 1942), Swedish Left Party politician Gustafva Björklund (1794–1862), Swedish cook book author Heléne Björklund (born 1972), Swedish social democratic politician Henrik Björklund (born 1990), Swedish ice hockey player Irina Björklund (born 1973), Finnish actress Jan Björklund (born 1962), Swedish politician Joachim Björklund (born 1971), Swedish professional footballer Kristoffer Björklund (born 1978), Swedish football player Leni Björklund (born 1944), Swedish Social Democratic politician Mirjam Björklund (born 1998), Swedish tennis player Rolf Björklund (born 1937), Finnish sprint canoer Timothy Björklund , American director of animated film and television Bjørklund [ edit ] Kjetil Bjørklund (born 1967), Norwegian politician Terje Bjørklund (born 1945), Norwegian composer and jazz musician Thor Bjørklund (1889–1975), Norwegian inventor Bjorklund [ edit ] Angie Bjorklund (born 1989), American basketball player Arnold L. Bjorklund (1918–1979) United States Army soldier during World War II Blake Bjorklund (born 1985), American stock car racer Bob Bjorklund (1918–1994), American football player David F. Bjorklund (born 1949), American professor of psychology Gary C. Bjorklund , American physicist and president of
128-478: A teratoma . Ethical considerations regarding the use of unborn human tissue are another reason for the lack of approved treatments using embryonic stem cells. Many nations currently have moratoria or limitations on either human ES cell research or the production of new human ES cell lines. Mesenchymal stem cells (MSC) or mesenchymal stromal cells, also known as medicinal signaling cells are known to be multipotent, which can be found in adult tissues, for example, in
192-423: A distinctive set of cell surface markers. However, in vitro culture conditions can alter the behavior of cells, making it unclear whether the cells shall behave in a similar manner in vivo . There is considerable debate as to whether some proposed adult cell populations are truly stem cells. Embryonic stem cells (ESCs) are the cells of the inner cell mass of a blastocyst , formed prior to implantation in
256-734: A functional G1 phase. hESCs show that the activities of Cyclin E/Cdk2 and Cyclin A/Cdk2 complexes are cell cycle-dependent and the Rb checkpoint in G1 is functional. ESCs are also characterized by G1 checkpoint non-functionality, even though the G1 checkpoint is crucial for maintaining genomic stability. In response to DNA damage , ESCs do not stop in G1 to repair DNA damages but instead, depend on S and G2/M checkpoints or undergo apoptosis. The absence of G1 checkpoint in ESCs allows for
320-466: A method to convert mature body cells back into stem cells. These were termed induced pluripotent stem cells (iPSCs). The term stem cell was coined by Theodor Boveri and Valentin Haecker in late 19th century. Pioneering works in theory of blood stem cell were conducted in the beginning of 20th century by Artur Pappenheim , Alexander Maximow , Franz Ernst Christian Neumann . The key properties of
384-864: A recently discovered pluripotent stem cell type found in multiple adult tissues, including adipose, dermal fibroblasts, and bone marrow. While rare, muse cells are identifiable by their expression of SSEA-3 , a marker for undifferentiated stem cells, and general mesenchymal stem cells markers such as CD90, CD105 . When subjected to single cell suspension culture, the cells will generate clusters that are similar to embryoid bodies in morphology as well as gene expression, including canonical pluripotency markers Oct4 , Sox2 , and Nanog . Adult stem cell treatments have been successfully used for many years to treat leukemia and related bone/blood cancers through bone marrow transplants. Adult stem cells are also used in veterinary medicine to treat tendon and ligament injuries in horses. The use of adult stem cells in research and therapy
448-466: A research student in the laboratory of Bengt Falck, the co-inventor of the Falck-Hillarp histofluorescence method for the visualization of monoamine-containing neurons in the brain, and defended his doctoral thesis at Lund University, Sweden, in 1969. He was trained as a neuroanatomist and during his early postdoctoral years he carried out a series of detailed studies of the organization and projections of
512-451: A reservoir group of progenitor cells . These cells transition to a neurogenic state and start to divide asymmetrically to produce a large diversity of many different neuron types, each with unique gene expression, morphological, and functional characteristics. The process of generating neurons from radial glial cells is called neurogenesis . The radial glial cell, has a distinctive bipolar morphology with highly elongated processes spanning
576-426: A series of open-label clinical trials in patients with Parkinson's disease. These trials, led by hid former student Olle Lindvall, provided proof-of-principle that immature dopamine neurons can survive and mature in the striatum in advanced Parkinson patients, and restore dopamine neurotransmission in the area of the striatum re-innervated by the grafted neurons. Although the clinical outcome has been highly variable,
640-585: A somatic cell cycle, oscillatory activity of Cyclin-Cdk complexes is observed in sequential action, which controls crucial regulators of the cell cycle to induce unidirectional transitions between phases: Cyclin D and Cdk4/6 are active in the G1 phase, while Cyclin E and Cdk2 are active during the late G1 phase and S phase; and Cyclin A and Cdk2 are active in the S phase and G2, while Cyclin B and Cdk1 are active in G2 and M phase. However, in mESCs, this typically ordered and oscillatory activity of Cyclin-Cdk complexes
704-479: A somatic cell-like cell cycle, and induces expression of differentiation markers. In human ESCs (hESCs), the duration of G1 is dramatically shortened. This has been attributed to high mRNA levels of G1-related Cyclin D2 and Cdk4 genes and low levels of cell cycle regulatory proteins that inhibit cell cycle progression at G1, such as p21 , p27 , and p57 . Furthermore, regulators of Cdk4 and Cdk6 activity, such as members of
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#1732855499001768-423: A specific cell type. They do not contribute to the extraembryonic membranes or to the placenta . During embryonic development the cells of the inner cell mass continuously divide and become more specialized. For example, a portion of the ectoderm in the dorsal part of the embryo specializes as ' neurectoderm ', which will become the future central nervous system (CNS). Later in development, neurulation causes
832-440: A stem cell population is maintained (does not shrink in size): 1. Asymmetric cell division : a stem cell divides into one mother cell, which is identical to the original stem cell, and another daughter cell, which is differentiated. When a stem cell self-renews, it divides and disrupts the undifferentiated state. This self-renewal demands control of cell cycle as well as upkeep of multipotency or pluripotency, which all depends on
896-525: A stem cell were first defined by Ernest McCulloch and James Till at the University of Toronto and the Ontario Cancer Institute in the early 1960s. They discovered the blood-forming stem cell, the hematopoietic stem cell (HSC), through their pioneering work in mice. McCulloch and Till began a series of experiments in which bone marrow cells were injected into irradiated mice. They observed lumps in
960-553: A theoretically potential source for regenerative medicine and tissue replacement after injury or disease., however, there are currently no approved treatments using ES cells. The first human trial was approved by the US Food and Drug Administration in January 2009. However, the human trial was not initiated until October 13, 2010 in Atlanta for spinal cord injury research . On November 14, 2011
1024-478: A topic of active research. Use of stem cells from amniotic fluid overcomes the ethical objections to using human embryos as a source of cells. Roman Catholic teaching forbids the use of embryonic stem cells in experimentation; accordingly, the Vatican newspaper " Osservatore Romano " called amniotic stem cells "the future of medicine". It is possible to collect amniotic stem cells for donors or for autologous use:
1088-459: Is a rich source of adult stem cells, which have been used in treating several conditions including liver cirrhosis, chronic limb ischemia and endstage heart failure. The quantity of bone marrow stem cells declines with age and is greater in males than females during reproductive years. Much adult stem cell research to date has aimed to characterize their potency and self-renewal capabilities. DNA damage accumulates with age in both stem cells and
1152-535: Is absent. Rather, the Cyclin E/Cdk2 complex is constitutively active throughout the cycle, keeping retinoblastoma protein (pRb) hyperphosphorylated and thus inactive. This allows for direct transition from M phase to the late G1 phase, leading to absence of D-type cyclins and therefore a shortened G1 phase. Cdk2 activity is crucial for both cell cycle regulation and cell-fate decisions in mESCs; downregulation of Cdk2 activity prolongs G1 phase progression, establishes
1216-422: Is also defined by the expression of several transcription factors and cell surface proteins. The transcription factors Oct-4 , Nanog , and Sox2 form the core regulatory network that ensures the suppression of genes that lead to differentiation and the maintenance of pluripotency. The cell surface antigens most commonly used to identify hES cells are the glycolipids stage specific embryonic antigen 3 and 4, and
1280-410: Is demonstrated by their short doubling time, which ranges from 8 to 10 hours, whereas somatic cells have doubling time of approximately 20 hours or longer. As cells differentiate, these properties change: G1 and G2 phases lengthen, leading to longer cell division cycles. This suggests that a specific cell cycle structure may contribute to the establishment of pluripotency. Particularly because G1 phase
1344-516: Is focused on the use of neurotrophic factors , nerve growth factor (NGF) and glial cell line-derived neurotrophic factor GDNF in particular, for neuroprotection and repair. His lab has been involved in the exploration of recombinant adeno-associated virus (rAAV) vectors for neurotrophic factor and enzyme delivery to the brain, as well as the use of rAAV vectors for overexpression of human alpha-synuclein for modeling Parkinson-like neuropathology in rodents and monkeys. In 2013, Björklund received
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#17328554990011408-412: Is not as controversial as the use of embryonic stem cells , because the production of adult stem cells does not require the destruction of an embryo . Additionally, in instances where adult stem cells are obtained from the intended recipient (an autograft ), the risk of rejection is essentially non-existent. Consequently, more US government funding is being provided for adult stem cell research. With
1472-455: Is regulated by complex network of cyclins , cyclin-dependent kinases (Cdk), cyclin-dependent kinase inhibitors (Cdkn), pocket proteins of the retinoblastoma (Rb) family, and other accessory factors. Foundational insight into the distinctive regulation of ESC cell cycle was gained by studies on mouse ESCs (mESCs). mESCs showed a cell cycle with highly abbreviated G1 phase, which enabled cells to rapidly alternate between M phase and S phase. In
1536-424: Is restricted. Nearly all research to date has made use of mouse embryonic stem cells (mES) or human embryonic stem cells (hES) derived from the early inner cell mass. Both have the essential stem cell characteristics, yet they require very different environments in order to maintain an undifferentiated state. Mouse ES cells are grown on a layer of gelatin as an extracellular matrix (for support) and require
1600-615: Is the ability to transplant the cells and save an individual without HSCs. This demonstrates that the cells can produce new blood cells over a long term. It should also be possible to isolate stem cells from the transplanted individual, which can themselves be transplanted into another individual without HSCs, demonstrating that the stem cell was able to self-renew. Properties of stem cells can be illustrated in vitro , using methods such as clonogenic assays , in which single cells are assessed for their ability to differentiate and self-renew. Stem cells can also be isolated by their possession of
1664-408: Is the phase in which cells have increased sensitivity to differentiation, shortened G1 is one of the key characteristics of ESCs and plays an important role in maintaining undifferentiated phenotype . Although the exact molecular mechanism remains only partially understood, several studies have shown insight on how ESCs progress through G1—and potentially other phases—so rapidly. The cell cycle
1728-760: The ECNP Neuropsychopharmacology Award. Stem cell In multicellular organisms , stem cells are undifferentiated or partially differentiated cells that can change into various types of cells and proliferate indefinitely to produce more of the same stem cell. They are the earliest type of cell in a cell lineage . They are found in both embryonic and adult organisms, but they have slightly different properties in each. They are usually distinguished from progenitor cells , which cannot divide indefinitely, and precursor or blast cells, which are usually committed to differentiating into one cell type. In mammals , roughly 50 to 150 cells make up
1792-522: The University of Toronto and the Ontario Cancer Institute in the 1960s. As of 2016 , the only established medical therapy using stem cells is hematopoietic stem cell transplantation , first performed in 1958 by French oncologist Georges Mathé . Since 1998 however, it has been possible to culture and differentiate human embryonic stem cells (in stem-cell lines ). The process of isolating these cells has been controversial , because it typically results in
1856-466: The inner cell mass during the blastocyst stage of embryonic development , around days 5–14. These have stem-cell capability. In vivo , they eventually differentiate into all of the body's cell types (making them pluripotent ). This process starts with the differentiation into the three germ layers – the ectoderm , mesoderm and endoderm – at the gastrulation stage. However, when they are isolated and cultured in vitro , they can be kept in
1920-581: The 1980s, his team at Lund University pioneered the development of stem cell -based therapies for brain repair, and his group has for more than four decades played a leading role in the development and use of dopamine cell replacement in patients with Parkinson's disease Björklund was elected member of the Royal Swedish Academy of Sciences in 1989, and Foreign Member of the National Academy of Sciences , USA, in 2011. Björklund started as
1984-490: The Ink family of inhibitors (p15, p16, p18, and p19), are expressed at low levels or not at all. Thus, similar to mESCs, hESCs show high Cdk activity, with Cdk2 exhibiting the highest kinase activity. Also similar to mESCs, hESCs demonstrate the importance of Cdk2 in G1 phase regulation by showing that G1 to S transition is delayed when Cdk2 activity is inhibited and G1 is arrest when Cdk2 is knocked down. However unlike mESCs, hESCs have
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2048-466: The Optical Society of America Garry Bjorklund (born 1951), American track athlete Hank Bjorklund (born 1950), American football player Steve Bjorklund , American musician [REDACTED] Surname list This page lists people with the surname Björklund . If an internal link intending to refer to a specific person led you to this page, you may wish to change that link by adding
2112-447: The ability to divide indefinitely while keeping their pluripotency , which is made possible through specialized mechanisms of cell cycle control. Compared to proliferating somatic cells , ESCs have unique cell cycle characteristics—such as rapid cell division caused by shortened G1 phase , absent G0 phase , and modifications in cell cycle checkpoints —which leaves the cells mostly in S phase at any given time. ESCs' rapid division
2176-622: The body") stem cells, are stem cells which maintain and repair the tissue in which they are found. There are three known accessible sources of autologous adult stem cells in humans: Stem cells can also be taken from umbilical cord blood just after birth. Of all stem cell types, autologous harvesting involves the least risk. By definition, autologous cells are obtained from one's own body, just as one may bank their own blood for elective surgical procedures. Pluripotent adult stem cells are rare and generally small in number, but they can be found in umbilical cord blood and other tissues. Bone marrow
2240-597: The bone marrow, which requires an aggressive procedure when it comes to isolating the quantity and quality of the isolated cell, and it varies by how old the donor. When comparing the rates of MSC in the bone marrow aspirates and bone marrow stroma, the aspirates tend to have lower rates of MSC than the stroma. MSC are known to be heterogeneous, and they express a high level of pluripotent markers when compared to other types of stem cells, such as embryonic stem cells. MSCs injection leads to wound healing primarily through stimulation of angiogenesis. Embryonic stem cells (ESCs) have
2304-816: The cartilage or bone. The term "meso" means middle, infusion originated from the Greek, signifying that mesenchymal cells are able to range and travel in early embryonic growth among the ectodermal and endodermal layers. This mechanism helps with space-filling thus, key for repairing wounds in adult organisms that have to do with mesenchymal cells in the dermis (skin), bone, or muscle. Mesenchymal stem cells are known to be essential for regenerative medicine. They are broadly studied in clinical trials . Since they are easily isolated and obtain high yield, high plasticity, which makes able to facilitate inflammation and encourage cell growth, cell differentiation, and restoring tissue derived from immunomodulation and immunosuppression. MSC comes from
2368-504: The cells that comprise the stem cell environment. This accumulation is considered to be responsible, at least in part, for increasing stem cell dysfunction with aging (see DNA damage theory of aging ). Most adult stem cells are lineage-restricted ( multipotent ) and are generally referred to by their tissue origin ( mesenchymal stem cell , adipose-derived stem cell, endothelial stem cell , dental pulp stem cell , etc.). Muse cells (multi-lineage differentiating stress enduring cells) are
2432-504: The company conducting the trial ( Geron Corporation ) announced that it will discontinue further development of its stem cell programs. Differentiating ES cells into usable cells while avoiding transplant rejection are just a few of the hurdles that embryonic stem cell researchers still face. Embryonic stem cells, being pluripotent, require specific signals for correct differentiation – if injected directly into another body, ES cells will differentiate into many different types of cells, causing
2496-430: The creation of pluripotent cells, induced pluripotent stem cells (iPSCs), from adult cells. These are not adult stem cells, but somatic cells (e.g. epithelial cells) reprogrammed to give rise to cells with pluripotent capabilities. Using genetic reprogramming with protein transcription factors , pluripotent stem cells with ESC-like capabilities have been derived. The first demonstration of induced pluripotent stem cells
2560-450: The destruction of the embryo. Sources for isolating ESCs have been restricted in some European countries and Canada, but others such as the UK and China have promoted the research. Somatic cell nuclear transfer is a cloning method that can be used to create a cloned embryo for the use of its embryonic stem cells in stem cell therapy. In 2006, a Japanese team led by Shinya Yamanaka discovered
2624-458: The early 1980s, and two PhD students, Patrik Brundin and Ole Isacson, Björklund's group was first to report functional cell replacement in rodent models of Parkinson's and Huntington's disease , and in animal models of hippocampal damage and cognitive decline, using transplants of fetal neural tissue. In 1986, the Lund team obtained permission to use tissue derived from aborted human fetuses in
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2688-494: The expression of only four genes. The feat represents the origin of induced pluripotent stem cells, known as iPS cells. In 2011, a female maned wolf , run over by a truck, underwent stem cell treatment at the Zoo Brasília , this being the first recorded case of the use of stem cells to heal injuries in a wild animal. The classical definition of a stem cell requires that it possesses two properties: Two mechanisms ensure that
2752-485: The first US amniotic stem cells bank was opened in 2009 in Medford, MA, by Biocell Center Corporation and collaborates with various hospitals and universities all over the world. Adult stem cells have limitations with their potency; unlike embryonic stem cells (ESCs), they are not able to differentiate into cells from all three germ layers . As such, they are deemed multipotent . However, reprogramming allows for
2816-608: The formation of murine genetic models, a system in which the genes of mice are deleted or altered in order to study their function in pathology. In 1991, a process that allowed the human stem cell to be isolated was patented by Ann Tsukamoto. By 1998, human embryonic stem cells were first isolated by American biologist James Thomson , which made it possible to have new transplantation methods or various cell types for testing new treatments. In 2006, Shinya Yamanaka 's team in Kyoto, Japan converted fibroblasts into pluripotent stem cells by modifying
2880-416: The gene expression pattern between ESCs and iPSCs, or even iPSCs sourced from different origins. There are thus questions about the "completeness" of reprogramming and the somatic memory of induced pluripotent stem cells. Despite this, inducing somatic cells to be pluripotent appears to be viable. As a result of the success of these experiments, Ian Wilmut , who helped create the first cloned animal Dolly
2944-686: The increased risk of slow growing blood cancers (myeloid malignancies) in the elderly. Several factors appear to influence HSC aging including responses to the production of reactive oxygen species that may cause DNA damage and genetic mutations as well as altered epigenetic profiling. Also called perinatal stem cells, these multipotent stem cells are found in amniotic fluid and umbilical cord blood. These stem cells are very active, expand extensively without feeders and are not tumorigenic. Amniotic stem cells are multipotent and can differentiate in cells of adipogenic, osteogenic, myogenic, endothelial, hepatic and also neuronal lines. Amniotic stem cells are
3008-635: The increasing demand of human adult stem cells for both research and clinical purposes (typically 1–5 million cells per kg of body weight are required per treatment) it becomes of utmost importance to bridge the gap between the need to expand the cells in vitro and the capability of harnessing the factors underlying replicative senescence. Adult stem cells are known to have a limited lifespan in vitro and to enter replicative senescence almost undetectably upon starting in vitro culturing. Hematopoietic stem cells (HSCs) are vulnerable to DNA damage and mutations that increase with age. This vulnerability may explain
3072-619: The keratan sulfate antigens Tra-1-60 and Tra-1-81. The molecular definition of a stem cell includes many more proteins and continues to be a topic of research. By using human embryonic stem cells to produce specialized cells like nerve cells or heart cells in the lab, scientists can gain access to adult human cells without taking tissue from patients. They can then study these specialized adult cells in detail to try to discern complications of diseases, or to study cell reactions to proposed new drugs. Because of their combined abilities of unlimited expansion and pluripotency, embryonic stem cells remain
3136-642: The monoaminergic systems in the brain, the dopaminergic projection systems in particular. In mid-1970s, Björklund´s interests turned to studies on brain regeneration and repair and in close collaboration with his student Ulf Stenevi he pioneered the development of methods for neural transplantation to the mammalian brain, based on the idea that immature neurons and neuroblasts, obtained from the fetal CNS, can be used to replace lost neurons, restore brain circuitry and promote functional recovery in animal models of neurodegenerative diseases. Together with Stephen Dunnett and Rusty Gage , who had joined his lab as postdocs in
3200-439: The muscle, liver, bone marrow and adipose tissue. Mesenchymal stem cells usually function as structural support in various organs as mentioned above, and control the movement of substances. MSC can differentiate into numerous cell categories as an illustration of adipocytes, osteocytes, and chondrocytes, derived by the mesodermal layer. Where the mesoderm layer provides an increase to the body's skeletal elements, such as relating to
3264-491: The neurectoderm to form the neural tube . At the neural tube stage, the anterior portion undergoes encephalization to generate or 'pattern' the basic form of the brain. At this stage of development, the principal cell type of the CNS is considered a neural stem cell . The neural stem cells self-renew and at some point transition into radial glial progenitor cells (RGPs). Early-formed RGPs self-renew by symmetrical division to form
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#17328554990013328-416: The person's given name (s) to the link. Retrieved from " https://en.wikipedia.org/w/index.php?title=Björklund&oldid=1190877580 " Categories : Surnames Swedish-language surnames Norwegian-language surnames Hidden categories: Articles with short description Short description is different from Wikidata All set index articles Anders Bj%C3%B6rklund In
3392-561: The presence of leukemia inhibitory factor (LIF) in serum media. A drug cocktail containing inhibitors to GSK3B and the MAPK/ERK pathway , called 2i, has also been shown to maintain pluripotency in stem cell culture. Human ESCs are grown on a feeder layer of mouse embryonic fibroblasts and require the presence of basic fibroblast growth factor (bFGF or FGF-2). Without optimal culture conditions or genetic manipulation, embryonic stem cells will rapidly differentiate. A human embryonic stem cell
3456-435: The removal of cells with damaged DNA, hence avoiding potential mutations from inaccurate DNA repair. Consistent with this idea, ESCs are hypersensitive to DNA damage to minimize mutations passed onto the next generation. The primitive stem cells located in the organs of fetuses are referred to as fetal stem cells. There are two types of fetal stem cells: Adult stem cells, also called somatic (from Greek σωματικóς, "of
3520-637: The results in some of the grafted patients have been sufficiently impressive to encourage further development of this approach Current efforts, led by Björklund's long-time collaborators Malin Parmar and Agnete Kirkeby and carried out in collaboration with the neurologist Roger Barker at Cambridge University , are focused on the development of transplantable dopamine neurons, derived from human embryonic stam cells, for clinical application with regard to Parkinson's disease A second major research line in Björklund's lab
3584-403: The skin epithelium , and mesenchymal stem cells , which maintain bone, cartilage , muscle and fat cells. Adult stem cells are a small minority of cells; they are vastly outnumbered by the progenitor cells and terminally differentiated cells that they differentiate into. Research into stem cells grew out of findings by Canadian biologists Ernest McCulloch , James Till and Andrew J. Becker at
3648-523: The spleens of the mice that were linearly proportional to the number of bone marrow cells injected. They hypothesized that each lump (colony) was a clone arising from a single marrow cell (stem cell). In subsequent work, McCulloch and Till, joined by graduate student Andrew John Becker and senior scientist Louis Siminovitch , confirmed that each lump did in fact arise from a single cell. Their results were published in Nature in 1963. In that same year, Siminovitch
3712-515: The stem cell. H. Stem cells use telomerase , a protein that restores telomeres , to protect their DNA and extend their cell division limit (the Hayflick limit ). Potency specifies the differentiation potential (the potential to differentiate into different cell types) of the stem cell. In practice, stem cells are identified by whether they can regenerate tissue. For example, the defining test for bone marrow or hematopoietic stem cells (HSCs)
3776-501: The stem-cell stage and are known as embryonic stem cells (ESCs). Adult stem cells are found in a few select locations in the body, known as niches , such as those in the bone marrow or gonads . They exist to replenish rapidly lost cell types and are multipotent or unipotent, meaning they only differentiate into a few cell types or one type of cell. In mammals, they include, among others, hematopoietic stem cells , which replenish blood and immune cells, basal cells , which maintain
3840-478: The thickness of the neural tube wall. It shares some glial characteristics, most notably the expression of glial fibrillary acidic protein (GFAP). The radial glial cell is the primary neural stem cell of the developing vertebrate CNS, and its cell body resides in the ventricular zone , adjacent to the developing ventricular system . Neural stem cells are committed to the neuronal lineages ( neurons , astrocytes , and oligodendrocytes ), and thus their potency
3904-443: The uterus. In human embryonic development the blastocyst stage is reached 4–5 days after fertilization , at which time it consists of 50–150 cells. ESCs are pluripotent and give rise during development to all derivatives of the three germ layers : ectoderm , endoderm and mesoderm . In other words, they can develop into each of the more than 200 cell types of the adult body when given sufficient and necessary stimulation for
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#17328554990013968-795: Was a lead investigator for studies that found colony-forming cells were capable of self-renewal, which is a key defining property of stem cells that Till and McCulloch had theorized. The first therapy using stem cells was a bone marrow transplant performed by French oncologist Georges Mathé in 1956 on five workers at the Vinča Nuclear Institute in Yugoslavia who had been affected by a criticality accident . The workers all survived. In 1981, embryonic stem (ES) cells were first isolated and successfully cultured using mouse blastocysts by British biologists Martin Evans and Matthew Kaufman . This allowed
4032-625: Was conducted by Shinya Yamanaka and his colleagues at Kyoto University . They used the transcription factors Oct3/4 , Sox2 , c-Myc , and Klf4 to reprogram mouse fibroblast cells into pluripotent cells. Subsequent work used these factors to induce pluripotency in human fibroblast cells. Junying Yu , James Thomson , and their colleagues at the University of Wisconsin–Madison used a different set of factors, Oct4, Sox2, Nanog and Lin28, and carried out their experiments using cells from human foreskin . However, they were able to replicate Yamanaka 's finding that inducing pluripotency in human cells
4096-462: Was possible. Induced pluripotent stem cells differ from embryonic stem cells. They share many similar properties, such as pluripotency and differentiation potential, the expression of pluripotency genes, epigenetic patterns, embryoid body and teratoma formation, and viable chimera formation, but there are many differences within these properties. The chromatin of iPSCs appears to be more "closed" or methylated than that of ESCs. Similarly,
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